Psychology is the scientific study of mind and behaviour. The word “psychology” comes from the Greek words “psyche,” meaning life, and “logos,” meaning explanation. Psychology is a popular major for students, a popular topic in the public media, and a part of our everyday lives. Television shows such as Dr. Phil feature psychologists who provide personal advice to those with personal or family difficulties. Psychological television crime dramas such as Cracked, Criminal Minds, Psyche, CSI, and others feature the work of forensic psychologists who use psychological principles to help solve crimes. And many people have direct knowledge of psychology because they have visited psychologists, such as school counsellors, family therapists, and religious, marriage, or bereavement counsellors.

Because we are frequently exposed to the work of psychologists in our everyday lives, we all have an idea about what psychology is and what psychologists do. In many ways I am sure that your conceptions are correct. Psychologists do work in forensic fields, and they do provide counselling and therapy for people in distress. But there are hundreds of thousands of psychologists in the world, and most of them work in other places, doing work that you are probably not aware of.

Most psychologists work in research laboratories, hospitals, and other field settings where they study the behaviour of humans and animals. For instance, my colleagues in the Psychology Department at the University of Maryland study such diverse topics as anxiety in children, the interpretation of dreams, the effects of caffeine on thinking, how birds recognize each other, how praying mantises hear, how people from different cultures react differently in negotiation, and the factors that lead people to engage in terrorism. Other psychologists study topics such as alcohol and drug addiction, memory, emotion, hypnosis, love, what makes people aggressive or helpful, and the psychologies of politics, prejudice, culture, and religion. Psychologists also work in schools and businesses, and they use a variety of methods, including observation, questionnaires, interviews, and laboratory studies, to help them understand behaviour.

This chapter provides an introduction to the broad field of psychology and the many approaches that psychologists take to understanding human behaviour. We will consider how psychologists conduct scientific research, with an overview of some of the most important approaches used and topics studied by psychologists, and also consider the variety of fields in which psychologists work and the careers that are available to people with psychology degrees. I expect that you may find that at least some of your preconceptions about psychology will be challenged and changed, and you will learn that psychology is a field that will provide you with new ways of thinking about your own thoughts, feelings, and actions.

 

Attributions

Figure 1.1:

• “Friendly smoking” by Valentin Ottone (http://www.flickr.com/photos/saneboy/3595175373/) is licensed under CC BY 2.0.
• “At the beach” by Julian Schüngel (http://www.flickr.com/photos/medevac71/4468071278/) is licensed under CC BY-NC-ND 2.0.
• “Bar Trek and friends” by Jim H (http://www.flickr.com/photos/greyloch/10970542456/in/photostream/) is licensed under CC BY-SA 2.0.
• “Physical therapist” by U.S. Navy photo (http://commons.wikimedia.org/wiki/File:US_Navy_081610-A-6522B-002_Physical_therapist_Lt._Cmdr._Mitchel_Ideue,_Officer_in_Charge_of_Inpatient_Services_at_Landstuhl_Regional_Medical_Center,_in_Landstuhl,_Germany,_gives_Army_Sgt._Charlie_McCall_a_physical_therapy_trea.jpg) is in the public domain.
• “couple yelling at each other” by Vic (http://www.flickr.com/photos/59632563@N04/6238711264/in/photostream/) is licensed under CC BY 2.0.

Long Descriptions

Figure 1.1 long description: Five photos:

1. Man in hospital bed with broken leg; a soldier is lifting his leg as is if to give physical therapy.
2. Young girl smoking a cigarette.
3. A man doing a hand stand on a beach with sun setting in background.
4. A man and woman yelling at each other with their heads touching.
5. One man and four women dressed up like Star Trek characters and aliens. [Return to Figure 1.1]

Despite the differences in their interests, areas of study, and approaches, all psychologists have one thing in common: they rely on scientific methods. Research psychologists use scientific methods to create new knowledge about the causes of behaviour, whereas psychologist-practitioners, such as clinical, counselling, industrial-organizational, and school psychologists, use existing research to enhance the everyday life of others. The science of psychology is important for both researchers and practitioners.

In a sense all humans are scientists. We all have an interest in asking and answering questions about our world. We want to know why things happen, when and if they are likely to happen again, and how to reproduce or change them. Such knowledge enables us to predict our own behaviour and that of others. We may even collect data (i.e., any information collected through formal observation or measurement) to aid us in this undertaking. It has been argued that people are “everyday scientists” who conduct research projects to answer questions about behaviour (Nisbett & Ross, 1980). When we perform poorly on an important test, we try to understand what caused our failure to remember or understand the material and what might help us do better the next time. When our good friends Monisha and Charlie break up, despite the fact that they appeared to have a relationship made in heaven, we try to determine what happened. When we contemplate the rise of terrorist acts around the world, we try to investigate the causes of this problem by looking at the terrorists themselves, the situation around them, and others’ responses to them.

The Problem of Intuition

The results of these “everyday” research projects can teach us many principles of human behaviour. We learn through experience that if we give someone bad news, he or she may blame us even though the news was not our fault. We learn that people may become depressed after they fail at an important task. We see that aggressive behaviour occurs frequently in our society, and we develop theories to explain why this is so. These insights are part of everyday social life. In fact, much research in psychology involves the scientific study of everyday behaviour (Heider, 1958; Kelley, 1967).

The problem, however, with the way people collect and interpret data in their everyday lives is that they are not always particularly thorough. Often, when one explanation for an event seems right, we adopt that explanation as the truth even when other explanations are possible and potentially more accurate. For example, eyewitnesses to violent crimes are often extremely confident in their identifications of the perpetrators of these crimes. But research finds that eyewitnesses are no less confident in their identifications when they are incorrect than when they are correct (Cutler & Wells, 2009; Wells & Hasel, 2008). People may also become convinced of the existence of extrasensory perception (ESP), or the predictive value of astrology, when there is no evidence for either (Gilovich, 1993). Furthermore, psychologists have also found that there are a variety of cognitive and motivational biases that frequently influence our perceptions and lead us to draw erroneous conclusions (Fiske & Taylor, 2007; Hsee & Hastie, 2006). In summary, accepting explanations for events without testing them thoroughly may lead us to think that we know the causes of things when we really do not.

Once we learn about the outcome of a given event (e.g., when we read about the results of a research project), we frequently believe that we would have been able to predict the outcome ahead of time. For instance, if half of a class of students is told that research concerning attraction between people has demonstrated that “opposites attract” and the other half is told that research has demonstrated that “birds of a feather flock together,” most of the students will report believing that the outcome that they just read about is true, and that they would have predicted the outcome before they had read about it. Of course, both of these contradictory outcomes cannot be true. (In fact, psychological research finds that “birds of a feather flock together” is generally the case.) The problem is that just reading a description of research findings leads us to think of the many cases we know that support the findings, and thus makes them seem believable. The tendency to think that we could have predicted something that has already occurred that we probably would not have been able to predict is called the hindsight bias.

Why Psychologists Rely on Empirical Methods

All scientists, whether they are physicists, chemists, biologists, sociologists, or psychologists, use empirical methods to study the topics that interest them. Empirical methods include the processes of collecting and organizing data and drawing conclusions about those data. The empirical methods used by scientists have developed over many years and provide a basis for collecting, analyzing, and interpreting data within a common framework in which information can be shared. We can label the scientific method as the set of assumptions, rules, and procedures that scientists use to conduct empirical research.

Although scientific research is an important method of studying human behaviour, not all questions can be answered using scientific approaches. Statements that cannot be objectively measured or objectively determined to be true or false are not within the domain of scientific inquiry. Scientists therefore draw a distinction between values and facts. Values are personal statements such as “Abortion should not be permitted in this country,” “I will go to heaven when I die,” or “It is important to study psychology.” Facts are objective statements determined to be accurate through empirical study. Examples are “There were more than 21,000 homicides in Canada in 2009” or “Research demonstrates that individuals who are exposed to highly stressful situations over long periods of time develop more health problems than those who are not.”

Because values cannot be considered to be either true or false, science cannot prove or disprove them. Nevertheless, as shown in Table 1.1, research can sometimes provide facts that can help people develop their values. For instance, science may be able to objectively measure the impact of unwanted children on a society or the psychological trauma suffered by women who have abortions. The effect of imprisonment on the crime rate in Canada may also be determinable. This factual information can and should be made available to help people formulate their values about abortion and incarceration, as well as to enable governments to articulate appropriate policies. Values also frequently come into play in determining what research is appropriate or important to conduct. For instance, the Canadian government has recently increased funding for university research, designating $37 million annually to the three major research councils dealing with health, social science, and the sciences (Research Canada, 2014).

Table 1.1 Examples of Values and Facts in Scientific Research.Source: Huffington Post, 2014.

[Skip Table]
Personal value	Scientific fact
The environment should be protected.	The Canadian government has reduced environmental funding by $200 million but annually pays more than $1.4 billion in subsidies to the oil and gas industry.
Practical work experience helps to develop skilled workers.	More than $100 million for interest-free loans will be available in 2014 through the Canada Apprentice Loan program, an expansion of the Canada Student Loans Program.
Technology is increasingly necessary.	The federal government in Canada will invest $305 million over five years to extend high-speed broadband to some 280,000 homes in 2014.
It is important to quit smoking.	The Canadian government will raise the cost of cigarettes by more than $4 on a carton in 2014.

Although scientists use research to help establish facts, the distinction between values and facts is not always clear-cut. Sometimes statements that scientists consider to be factual turn out later, on the basis of further research, to be partially or even entirely incorrect. Although scientific procedures do not necessarily guarantee that the answers to questions will be objective and unbiased, science is still the best method for drawing objective conclusions about the world around us. When old facts are discarded, they are replaced with new facts based on newer and more correct data. Although science is not perfect, the requirements of empiricism and objectivity result in a much greater chance of producing an accurate understanding of human behaviour than is available through other approaches.

Levels of Explanation in Psychology

The study of psychology spans many different topics at many different levels of explanation, which are the perspectives that are used to understand behaviour. Lower levels of explanation are more closely tied to biological influences, such as genes, neurons, neurotransmitters, and hormones, whereas the middle levels of explanation refer to the abilities and characteristics of individual people, and the highest levels of explanation relate to social groups, organizations, and cultures (Cacioppo, Berntson, Sheridan, & McClintock, 2000).

The same topic can be studied within psychology at different levels of explanation, as shown in Table 1.2, “Levels of Explanation.” For instance, the psychological disorder known as depression affects millions of people worldwide and is known to be caused by biological, social, and cultural factors. Studying and helping alleviate depression can be accomplished at low levels of explanation by investigating how chemicals in the brain influence the experience of depression. This approach has allowed psychologists to develop and prescribe drugs, such as Prozac, which may decrease depression in many individuals (Williams, Simpson, Simpson, & Nahas, 2009). At the middle levels of explanation, psychological therapy is directed at helping individuals cope with negative life experiences that may cause depression. And at the highest level, psychologists study differences in the prevalence of depression between men and women and across cultures. The occurrence of psychological disorders, including depression, is substantially higher for women than for men, and it is also higher in Western cultures, such as in Canada, the United States, and Europe, than in Eastern cultures, such as in India, China, and Japan (Chen, Wang, Poland, & Lin, 2009; Seedat et al., 2009). These sex and cultural differences provide insight into the factors that cause depression. The study of depression in psychology helps remind us that no one level of explanation can explain everything. All levels of explanation, from biological to personal to cultural, are essential for a better understanding of human behaviour.

Table 1.2 Levels of Explanation

[Skip Table]
Level of Explanation	Underlying Process	Examples
Lower	Biological	Depression is in part genetically influenced. Depression is influenced by the action of neurotransmitters in the brain.
Middle	Interpersonal	People who are depressed may interpret the events that occur to them too negatively. Psychotherapy can be used to help people talk about and combat depression
Higher	Cultural and social	Women experience more depression than do men. The prevalence of depression varies across cultures and historical time periods.

The Challenges of Studying Psychology

Understanding and attempting to alleviate the costs of psychological disorders such as depression is not easy because psychological experiences are extremely complex. The questions psychologists pose are as difficult as those posed by doctors, biologists, chemists, physicists, and other scientists, if not more so (Wilson, 1998).

A major goal of psychology is to predict behaviour by understanding its causes. Making predictions is difficult, in part because people vary and respond differently in different situations. Individual differences are the variations among people on physical or psychological dimensions. For instance, although many people experience at least some symptoms of depression at some times in their lives, the experience varies dramatically among people. Some people experience major negative events, such as severe physical injuries or the loss of significant others, without experiencing much depression, whereas other people experience severe depression for no apparent reason. Other important individual differences that we will discuss in the chapters to come include differences in extraversion, intelligence, self-esteem, anxiety, aggression, and conformity.

Because of the many individual difference variables that influence behaviour, we cannot always predict who will become aggressive or who will perform best in graduate school or on the job. The predictions made by psychologists (and most other scientists) are only probabilistic. We can say, for instance, that people who score higher on an intelligence test will, on average, do better than people who score lower on the same test, but we cannot make very accurate predictions about exactly how any one person will perform.

Another reason that it is difficult to predict behaviour is that almost all behaviour is multiply determined, or produced by many factors. And these factors occur at different levels of explanation. We have seen, for instance, that depression is caused by lower-level genetic factors, by medium-level personal factors, and by higher-level social and cultural factors. You should always be skeptical about people who attempt to explain important human behaviours, such as violence, child abuse, poverty, anxiety, or depression, in terms of a single cause.

Furthermore, these multiple causes are not independent of one another; they are associated such that when one cause is present, other causes tend to be present as well. This overlap makes it difficult to pinpoint which cause or causes are operating. For instance, some people may be depressed because of biological imbalances in neurotransmitters in their brain. The resulting depression may lead them to act more negatively toward other people around them, which then leads those other people to respond more negatively to them, which then increases their depression. As a result, the biological determinants of depression become intertwined with the social responses of other people, making it difficult to disentangle the effects of each cause.

Another difficulty in studying psychology is that much human behaviour is caused by factors that are outside our conscious awareness, making it impossible for us, as individuals, to really understand them. The role of unconscious processes was emphasized in the theorizing of the Austrian neurologist Sigmund Freud (1856-1939), who argued that many psychological disorders were caused by memories that we have repressed and thus remain outside our consciousness. Unconscious processes will be an important part of our study of psychology, and we will see that current research has supported many of Freud’s ideas about the importance of the unconscious in guiding behaviour.

References

Brendl, C. M., Chattopadhyay, A., Pelham, B. W., & Carvallo, M. (2005). Name letter branding: Valence transfers when product specific needs are active. Journal of Consumer Research, 32(3), 405–415.

Cacioppo, J. T., Berntson, G. G., Sheridan, J. F., & McClintock, M. K. (2000). Multilevel integrative analyses of human behavior: Social neuroscience and the complementing nature of social and biological approaches. Psychological Bulletin, 126(6), 829–843.

Chen, P.-Y., Wang, S.-C., Poland, R. E., & Lin, K.-M. (2009). Biological variations in depression and anxiety between East and West. CNS Neuroscience & Therapeutics, 15(3), 283–294.

Cutler, B. L., & Wells, G. L. (2009). Expert testimony regarding eyewitness identification. In J. L. Skeem, S. O. Lilienfeld, & K. S. Douglas (Eds.), Psychological science in the courtroom: Consensus and controversy (pp. 100–123). New York, NY: Guilford Press.

Fiske, S. T., & Taylor, S. E. (2007). Social cognition: From brains to culture. New York, NY: McGraw-Hill.

Gilovich, T. (1993). How we know what isn’t so: The fallibility of human reason in everyday life. New York, NY: Free Press.

Heider, F. (1958). The psychology of interpersonal relations. Hillsdale, NJ: Erlbaum.

Hsee, C. K., & Hastie, R. (2006). Decision and experience: Why don’t we choose what makes us happy? Trends in Cognitive Sciences, 10(1), 31–37.

Hufffington Post. (2014). 2014 Canadian Budget Highlights: What You Need To Know. Retrieved May 2, 2104 from http://www.huffingtonpost.ca/2014/02/11/2014-canadian-budget-highlights_n_4769700.html

Kelley, H. H. (1967). Attribution theory in social psychology. In D. Levine (Ed.), Nebraska symposium on motivation (Vol. 15, pp. 192–240). Lincoln: University of Nebraska Press.

Nisbett, R. E., & Ross, L. (1980). Human inference: Strategies and shortcomings of social judgment. Englewood Cliffs, NJ: Prentice Hall.

Research Canada. (2014). Budget 2014 – What it means for us. Retrieved May 2, 2014 from http://www.rc-rc.ca/blog/budget-2014-research-canadas-analysis

Seedat, S., Scott, K. M., Angermeyer, M. C., Berglund, P., Bromet, E. J., Brugha, T. S., & Kessler, R. C. (2009). Cross-national associations between gender and mental disorders in the World Health Organization World Mental Health Surveys. Archives of General Psychiatry, 66(7), 785–795.

Wells, G. L., & Hasel, L. E. (2008). Eyewitness identification: Issues in common knowledge and generalization. In E. Borgida & S. T. Fiske (Eds.), Beyond common sense: Psychological science in the courtroom (pp. 159–176). Malden, NJ: Blackwell.

Williams, N., Simpson, A. N., Simpson, K., & Nahas, Z. (2009). Relapse rates with long-term antidepressant drug therapy: A meta-analysis. Human Psychopharmacology: Clinical and Experimental, 24(5), 401–408.

Wilson, E. O. (1998). Consilience: The unity of knowledge. New York, NY: Vintage Books.

In this section we will review the history of psychology with a focus on the important questions that psychologists ask and the major approaches (or schools) of psychological inquiry. The schools of psychology that we will review are summarized in Table 1.3, “The Most Important Approaches (Schools) of Psychology,” while Table 1.4, “History of Psychology,” presents a timeline of some of the most important psychologists, beginning with the early Greek philosophers and extending to the present day. Table 1.3 and Table 1.4 both represent a selection of the most important schools and people; to mention all the approaches and all the psychologists who have contributed to the field is not possible in one chapter. The approaches that psychologists have used to assess the issues that interest them have changed dramatically over the history of psychology. Perhaps most importantly, the field has moved steadily from speculation about behaviour toward a more objective and scientific approach as the technology available to study human behaviour has improved (Benjamin & Baker, 2004). There has also been an influx of women into the field. Although most early psychologists were men, now most psychologists, including the presidents of the most important psychological organizations, are women.

Table 1.3 The Most Important Approaches (Schools) of Psychology.

[Skip Table]
School of Psychology	Description	Important Contributors
Structuralism	Uses the method of introspection to identify the basic elements or “structures” of psychological experience	Wilhelm Wundt, Edward B. Titchener
Functionalism	Attempts to understand why animals and humans have developed the particular psychological aspects that they currently possess	William James
Psychodynamic	Focuses on the role of our unconscious thoughts, feelings, and memories and our early childhood experiences in determining behaviour	Sigmund Freud, Carl Jung, Alfred Adler, Erik Erickson
Behaviourism	Based on the premise that it is not possible to objectively study the mind, and therefore that psychologists should limit their attention to the study of behaviour itself	John B. Watson, B. F. Skinner
Cognitive	The study of mental processes, including perception, thinking, memory, and judgments	Hermann Ebbinghaus, Sir Frederic Bartlett, Jean Piaget
Social-cultural	The study of how the social situations and the cultures in which people find themselves influence thinking and behaviour	Fritz Heider, Leon Festinger, Stanley Schachter

Although most of the earliest psychologists were men, women are increasingly contributing to psychology. Here are some examples:

• 1968: Mary Jean Wright became the first woman president of the Canadian Psychological Association.
• 1970: Virginia Douglas became the second woman president of the Canadian Psychological Association.
• 1972: The Underground Symposium was held at the Canadian Psychological Association Convention. After having their individual papers and then a symposium rejected by the Program Committee, a group of six graduate students and non-tenured faculty, including Sandra Pyke and Esther Greenglass, held an independent research symposium that showcased work being done in the field of the psychology of women.
• 1976: The Canadian Research Institute for the Advancement of Women was founded.
• 1987: Janet Stoppard led the Women and Mental Health Committee of the Canadian Mental Health Association.

Although it cannot capture every important psychologist, the following timeline shows some of the most important contributors to the history of psychology. (Adapted by J. Walinga.)

Table 1.4 History of Psychology.

[Skip Table]
Date	Psychologist(s)	Description
428 to 347 BCE	Plato	Greek philosopher who argued for the role of nature in psychological development.
384 to 432 BCE	Aristotle	Greek philosopher who argued for the role of nurture in psychological development.
1588 to 1679 CE	Thomas Hobbes	English philosopher.
1596 to 1650	René Descartes	French philosopher.
1632 to 1704	John Locke	English philosopher.
1712 to 1778	Jean-Jacques Rousseau	French philosopher.
1801 to 1887	Gustav Fechner	German experimental psychologist who developed the idea of the “just noticeable difference” (JND), which is considered to be the first empirical psychological measurement.
1809 to 1882	Charles Darwin	British naturalist whose theory of natural selection influenced the functionalist school and the field of evolutionary psychology.
1832 to 1920	Wilhelm Wundt	German psychologist who opened one of the first psychology laboratories and helped develop the field of structuralism.
1842 to 1910	William James	American psychologist who opened one of the first psychology laboratories and helped develop the field of functionalism.
1849 to 1936	Ivan Pavlov	Russian psychologist whose experiments on learning led to the principles of classical conditioning.
1850 to 1909	Hermann Ebbinghaus	German psychologist who studied the ability of people to remember lists of nonsense syllables under different conditions.
1856 to 1939	Sigmund Freud	Austrian psychologist who founded the field of psychodynamic psychology.
1867 to 1927	Edward Bradford Titchener	American psychologist  who contributed to the field of structuralism.
1878 to 1958	John B. Watson	American psychologist  who contributed to the field of behavioralism.
1886 to 1969	Sir Frederic Bartlett	British psychologist who studied the cognitive and social processes of remembering.
1896 to 1980	Jean Piaget	Swiss psychologist  who developed an important theory of  cognitive development in children.
1904 to  1990	B. F. Skinner	American psychologist who contributed to the school of behaviourism.
1926 to 1993	Donald Broadbent	British cognitive psychologist who was  pioneer in the study of attention.
20th and 21st centuries	Linda Bartoshuk; Daniel Kahneman; Elizabeth Loftus; Geroge Miller.	American psychologists who contributed to the cognitive school of psychology by studying learning, memory, and judgment. An important contribution is the advancement of the field of neuroscience. Daniel Kahneman won the Nobel Prize in Economics for his work on psychological decision making.
1850	Dorothea Dix	Canadian psychologist known for her contributions to mental health and opened one of the first mental hospitals in Halifax, New Brunswick.
1880	William Lyall; James Baldwin	Canadian psychologists who wrote early psychology texts and created first Canadian psychology lab at the University of Toronto.
1950	James Olds; Brenda Milner; Wilder Penfield; Donald Hebb; Endel Telving	Canadian psychologists who contributed to neurological psychology and opened the Montreal Neurological Institute.
1960	Albert Bandura	Canadian psychologist who developed ‘social learning theory’ with his Bobo doll studies illustrating the impact that observation and interaction has on learning.
1970	Hans Selye	Canadian psychologist who contributed significantly in the area of psychology of stress.

Although psychology has changed dramatically over its history, the most important questions that psychologists address have remained constant. Some of these questions follow, and we will discuss them both in this chapter and in the chapters to come:

• Nature versus nurture. Are genes or environment most influential in determining the behaviour of individuals and in accounting for differences among people? Most scientists now agree that both genes and environment play crucial roles in most human behaviours, and yet we still have much to learn about how nature (our biological makeup) and nurture (the experiences that we have during our lives) work together (Harris, 1998; Pinker, 2002). The proportion of the observed differences of characteristics among people (e.g., in terms of their height, intelligence, or optimism) that is due to genetics is known as the heritability of the characteristic, and we will make much use of this term in the chapters to come. We will see, for example, that the heritability of intelligence is very high (about .85 out of 1.0) and that the heritability of extraversion is about .50. But we will also see that nature and nurture interact in complex ways, making the question “Is it nature or is it nurture?” very difficult to answer.
• Free will versus determinism. This question concerns the extent to which people have control over their own actions. Are we the products of our environment, guided by forces out of our control, or are we able to choose the behaviours we engage in? Most of us like to believe in free will, that we are able to do what we want—for instance, that we could get up right now and go fishing. And our legal system is premised on the concept of free will; we punish criminals because we believe that they have choice over their behaviours and freely choose to disobey the law. But as we will discuss later in the research focus in this section, recent research has suggested that we may have less control over our own behaviour than we think we do (Wegner, 2002).
• Accuracy versus inaccuracy. To what extent are humans good information processors? Although it appears that people are good enough to make sense of the world around them and to make decent decisions (Fiske, 2003), they are far from perfect. Human judgment is sometimes compromised by inaccuracies in our thinking styles and by our motivations and emotions. For instance, our judgment may be affected by our desires to gain material wealth and to see ourselves positively and by emotional responses to the events that happen to us. Many studies have explored decision making in crisis situations such as natural disasters, or human error or criminal action, such as in the cases of the Tylenol poisoning, the Maple Leaf meats listeriosis outbreak, the SARS epidemic or the Lac-Mégantic train derailment (Figure 1.2).

• Conscious versus unconscious processing. To what extent are we conscious of our own actions and the causes of them, and to what extent are our behaviours caused by influences that we are not aware of? Many of the major theories of psychology, ranging from the Freudian psychodynamic theories to contemporary work in cognitive psychology, argue that much of our behaviour is determined by variables that we are not aware of.
• Differences versus similarities. To what extent are we all similar, and to what extent are we different? For instance, are there basic psychological and personality differences between men and women, or are men and women by and large similar? And what about people from different ethnicities and cultures? Are people around the world generally the same, or are they influenced by their backgrounds and environments in different ways? Personality, social, and cross-cultural psychologists attempt to answer these classic questions.

Early Psychologists

The earliest psychologists that we know about are the Greek philosophers Plato (428-347 BC) and Aristotle (384-322 BC). These philosophers (see Figure 1.3) asked many of the same questions that today’s psychologists ask; for instance, they questioned the distinction between nature and nurture and the existence of free will. In terms of the former, Plato argued on the nature side, believing that certain kinds of knowledge are innate or inborn, whereas Aristotle was more on the nurture side, believing that each child is born as an “empty slate” (in Latin, a tabula rasa) and that knowledge is primarily acquired through learning and experience.

European philosophers continued to ask these fundamental questions during the Renaissance. For instance, the French philosopher René Descartes (1596-1650) also considered the issue of free will, arguing in its favour and believing that the mind controls the body through the pineal gland in the brain (an idea that made some sense at the time but was later proved incorrect). Descartes also believed in the existence of innate natural abilities. A scientist as well as a philosopher, Descartes dissected animals and was among the first to understand that the nerves controlled the muscles. He also addressed the relationship between mind (the mental aspects of life) and body (the physical aspects of life). Descartes believed in the principle of dualism: that the mind is fundamentally different from the mechanical body. Other European philosophers, including Thomas Hobbes (1588-1679), John Locke (1632-1704), and Jean-Jacques Rousseau (1712-1778), also weighed in on these issues. The fundamental problem that these philosophers faced was that they had few methods for settling their claims. Most philosophers didn’t conduct any research on these questions, in part because they didn’t yet know how to do it, and in part because they weren’t sure it was even possible to objectively study human experience. But dramatic changes came during the 1800s with the help of the first two research psychologists: the German psychologist Wilhelm Wundt (1832-1920), who developed a psychology laboratory in Leipzig, Germany, and the American psychologist William James (1842-1910), who founded a psychology laboratory at Harvard University.

Structuralism: Introspection and the Awareness of Subjective Experience

Wundt’s research in his laboratory in Leipzig focused on the nature of consciousness itself. Wundt and his students believed that it was possible to analyze the basic elements of the mind and to classify our conscious experiences scientifically. Wundt began the field known as structuralism, a school of psychology whose goal was to identify the basic elements or structures of psychological experience. Its goal was to create a periodic table of the elements of sensations, similar to the periodic table of elements that had recently been created in chemistry. Structuralists used the method of introspection to attempt to create a map of the elements of consciousness. Introspection involves asking research participants to describe exactly what they experience as they work on mental tasks, such as viewing colours, reading a page in a book, or performing a math problem. A participant who is reading a book might report, for instance, that he saw some black and coloured straight and curved marks on a white background. In other studies the structuralists used newly invented reaction time instruments to systematically assess not only what the participants were thinking but how long it took them to do so. Wundt discovered that it took people longer to report what sound they had just heard than to simply respond that they had heard the sound. These studies marked the first time researchers realized that there is a difference between the sensation of a stimulus and the perception of that stimulus, and the idea of using reaction times to study mental events has now become a mainstay of cognitive psychology.

Perhaps the best known of the structuralists was Edward Bradford Titchener (1867-1927). Titchener was a student of Wundt’s who came to the United States in the late 1800s and founded a laboratory at Cornell University (Figure 1.4). (Titchener was later rejected by McGill University (1903). Perhaps he was ahead of his time; Brenda Milner did not open the Montreal Neurological Institute until 1950.) In his research using introspection, Titchener and his students claimed to have identified more than 40,000 sensations, including those relating to vision, hearing, and taste. An important aspect of the structuralist approach was that it was rigorous and scientific. The research marked the beginning of psychology as a science, because it demonstrated that mental events could be quantified. But the structuralists also discovered the limitations of introspection. Even highly trained research participants were often unable to report on their subjective experiences. When the participants were asked to do simple math problems, they could easily do them, but they could not easily answer how they did them. Thus the structuralists were the first to realize the importance of unconscious processes—that many important aspects of human psychology occur outside our conscious awareness, and that psychologists cannot expect research participants to be able to accurately report on all of their experiences.

Functionalism and Evolutionary Psychology

In contrast to Wundt, who attempted to understand the nature of consciousness, William James and the other members of the school of functionalism aimed to understand why animals and humans have developed the particular psychological aspects that they currently possess (Hunt, 1993). For James, one’s thinking was relevant only to one’s behaviour. As he put it in his psychology textbook, “My thinking is first and last and always for the sake of my doing” (James, 1890). James and the other members of the functionalist school (Figure 1.5) were influenced by Charles Darwin’s (1809-1882) theory of natural selection, which proposed that the physical characteristics of animals and humans evolved because they were useful, or functional. The functionalists believed that Darwin’s theory applied to psychological characteristics too. Just as some animals have developed strong muscles to allow them to run fast, the human brain, so functionalists thought, must have adapted to serve a particular function in human experience.

Although functionalism no longer exists as a school of psychology, its basic principles have been absorbed into psychology and continue to influence it in many ways. The work of the functionalists has developed into the field of evolutionary psychology, a branch of psychology that applies the Darwinian theory of natural selection to human and animal behaviour (Dennett, 1995; Tooby & Cosmides, 1992). Evolutionary psychology accepts the functionalists’ basic assumption, namely that many human psychological systems, including memory, emotion, and personality, serve key adaptive functions. As we will see in the chapters to come, evolutionary psychologists use evolutionary theory to understand many different behaviours, including romantic attraction, stereotypes and prejudice, and even the causes of many psychological disorders. A key component of the ideas of evolutionary psychology is fitness. Fitness refers to the extent to which having a given characteristic helps the individual organism survive and reproduce at a higher rate than do other members of the species who do not have the characteristic. Fitter organisms pass on their genes more successfully to later generations, making the characteristics that produce fitness more likely to become part of the organism’s nature than characteristics that do not produce fitness. For example, it has been argued that the emotion of jealousy has survived over time in men because men who experience jealousy are more fit than men who do not. According to this idea, the experience of jealousy leads men to be more likely to protect their mates and guard against rivals, which increases their reproductive success (Buss, 2000). Despite its importance in psychological theorizing, evolutionary psychology also has some limitations. One problem is that many of its predictions are extremely difficult to test. Unlike the fossils that are used to learn about the physical evolution of species, we cannot know which psychological characteristics our ancestors possessed or did not possess; we can only make guesses about this. Because it is difficult to directly test evolutionary theories, it is always possible that the explanations we apply are made up after the fact to account for observed data (Gould & Lewontin, 1979). Nevertheless, the evolutionary approach is important to psychology because it provides logical explanations for why we have many psychological characteristics.

Psychodynamic Psychology

Perhaps the school of psychology that is most familiar to the general public is the psychodynamic approach to understanding behaviour, which was championed by Sigmund Freud (1856-1939) and his followers. Psychodynamic psychology is an approach to understanding human behaviour that focuses on the role of unconscious thoughts, feelings, and memories. Freud (Figure 1.6) developed his theories about behaviour through extensive analysis of the patients that he treated in his private clinical practice. Freud believed that many of the problems that his patients experienced, including anxiety, depression, and sexual dysfunction, were the result of the effects of painful childhood experiences that they could no longer remember.

Freud’s ideas were extended by other psychologists whom he influenced, including Carl Jung (1875-1961), Alfred Adler (1870-1937), Karen Horney (1855-1952), and Erik Erikson (1902-1994). These and others who follow the psychodynamic approach believe that it is possible to help the patient if the unconscious drives can be remembered, particularly through a deep and thorough exploration of the person’s early sexual experiences and current sexual desires. These explorations are revealed through talk therapy and dream analysis in a process called psychoanalysis. The founders of the school of psychodynamics were primarily practitioners who worked with individuals to help them understand and confront their psychological symptoms. Although they did not conduct much research on their ideas, and although later, more sophisticated tests of their theories have not always supported their proposals, psychodynamics has nevertheless had substantial impact on the field of psychology, and indeed on thinking about human behaviour more generally (Moore & Fine, 1995). The importance of the unconscious in human behaviour, the idea that early childhood experiences are critical, and the concept of therapy as a way of improving human lives are all ideas that are derived from the psychodynamic approach and that remain central to psychology.

Behaviourism and the Question of Free Will

Although they differed in approach, both structuralism and functionalism were essentially studies of the mind. The psychologists associated with the school of behaviourism, on the other hand, were reacting in part to the difficulties psychologists encountered when they tried to use introspection to understand behaviour. Behaviourism is a school of psychology that is based on the premise that it is not possible to objectively study the mind, and therefore that psychologists should limit their attention to the study of behaviour itself. Behaviourists believe that the human mind is a black box into which stimuli are sent and from which responses are received. They argue that there is no point in trying to determine what happens in the box because we can successfully predict behaviour without knowing what happens inside the mind. Furthermore, behaviourists believe that it is possible to develop laws of learning that can explain all behaviours. The first behaviourist was the American psychologist John B. Watson (1878-1958). Watson was influenced in large part by the work of the Russian physiologist Ivan Pavlov (1849-1936), who had discovered that dogs would salivate at the sound of a tone that had previously been associated with the presentation of food. Watson and the other behaviourists began to use these ideas to explain how events that people and other organisms experienced in their environment (stimuli) could produce specific behaviours (responses). For instance, in Pavlov’s research the stimulus (either the food or, after learning, the tone) would produce the response of salivation in the dogs. In his research Watson found that systematically exposing a child to fearful stimuli in the presence of objects that did not themselves elicit fear could lead the child to respond with a fearful behaviour to the presence of the objects (Watson & Rayner, 1920; Beck, Levinson, & Irons, 2009). In the best known of his studies, an eight-month-old boy named Little Albert was used as the subject. Here is a summary of the findings: The boy was placed in the middle of a room; a white laboratory rat was placed near him and he was allowed to play with it. The child showed no fear of the rat. In later trials, the researchers made a loud sound behind Albert’s back by striking a steel bar with a hammer whenever the baby touched the rat. The child cried when he heard the noise. After several such pairings of the two stimuli, the child was again shown the rat. Now, however, he cried and tried to move away from the rat. In line with the behaviourist approach, the boy had learned to associate the white rat with the loud noise, resulting in crying.

The most famous behaviourist was Burrhus Frederick (B. F.) Skinner (1904 to 1990), who expanded the principles of behaviourism and also brought them to the attention of the public at large. Skinner (Figure 1.7) used the ideas of stimulus and response, along with the application of rewards or reinforcements, to train pigeons and other animals. And he used the general principles of behaviourism to develop theories about how best to teach children and how to create societies that were peaceful and productive. Skinner even developed a method for studying thoughts and feelings using the behaviourist approach (Skinner, 1957, 1972).

The behaviourists made substantial contributions to psychology by identifying the principles of learning. Although the behaviourists were incorrect in their beliefs that it was not possible to measure thoughts and feelings, their ideas provided new ideas that helped further our understanding regarding the nature-nurture debate and the question of free will. The ideas of behaviourism are fundamental to psychology and have been developed to help us better understand the role of prior experiences in a variety of areas of psychology.

The Cognitive Approach and Cognitive Neuroscience

Science is always influenced by the technology that surrounds it, and psychology is no exception. Thus it is no surprise that beginning in the 1960s, growing numbers of psychologists began to think about the brain and about human behaviour in terms of the computer, which was being developed and becoming publicly available at that time. The analogy between the brain and the computer, although by no means perfect, provided part of the impetus for a new school of psychology called cognitive psychology. Cognitive psychology is a field of psychology that studies mental processes, including perception, thinking, memory, and judgment. These actions correspond well to the processes that computers perform. Although cognitive psychology began in earnest in the 1960s, earlier psychologists had also taken a cognitive orientation. Some of the important contributors to cognitive psychology include the German psychologist Hermann Ebbinghaus (1850-1909), who studied the ability of people to remember lists of words under different conditions, and the English psychologist Sir Frederic Bartlett (1886-1969), who studied the cognitive and social processes of remembering. Bartlett created short stories that were in some ways logical but also contained some very unusual and unexpected events. Bartlett discovered that people found it very difficult to recall the stories exactly, even after being allowed to study them repeatedly, and he hypothesized that the stories were difficult to remember because they did not fit the participants’ expectations about how stories should go. The idea that our memory is influenced by what we already know was also a major idea behind the cognitive-developmental stage model of Swiss psychologist Jean Piaget (1896-1980). Other important cognitive psychologists include Donald E. Broadbent (1926-1993), Daniel Kahneman (1934-), George Miller (1920-2012), Eleanor Rosch (1938-), and Amos Tversky (1937-1996).

In its argument that our thinking has a powerful influence on behaviour, the cognitive approach provided a distinct alternative to behaviourism. According to cognitive psychologists, ignoring the mind itself will never be sufficient because people interpret the stimuli that they experience. For instance, when a boy turns to a girl on a date and says, “You are so beautiful,” a behaviourist would probably see that as a reinforcing (positive) stimulus. And yet the girl might not be so easily fooled. She might try to understand why the boy is making this particular statement at this particular time and wonder if he might be attempting to influence her through the comment. Cognitive psychologists maintain that when we take into consideration how stimuli are evaluated and interpreted, we understand behaviour more deeply. Cognitive psychology remains enormously influential today, and it has guided research in such varied fields as language, problem solving, memory, intelligence, education, human development, social psychology, and psychotherapy. The cognitive revolution has been given even more life over the past decade as the result of recent advances in our ability to see the brain in action using neuroimaging techniques. Neuroimaging is the use of various techniques to provide pictures of the structure and function of the living brain (Ilardi & Feldman, 2001). These images are used to diagnose brain disease and injury, but they also allow researchers to view information processing as it occurs in the brain, because the processing causes the involved area of the brain to increase metabolism and show up on the scan. We have already discussed the use of one neuroimaging technique, functional magnetic resonance imaging (fMRI), in the research focus earlier in this section, and we will discuss the use of neuroimaging techniques in many areas of psychology in the chapters to follow.

Social-Cultural Psychology

A final school, which takes a higher level of analysis and which has had substantial impact on psychology, can be broadly referred to as the social-cultural approach. The field of social-cultural psychology is the study of how the social situations and the cultures in which people find themselves influence thinking and behaviour. Social-cultural psychologists are particularly concerned with how people perceive themselves and others, and how people influence each other’s behaviour. For instance, social psychologists have found that we are attracted to others who are similar to us in terms of attitudes and interests (Byrne, 1969), that we develop our own beliefs and attitudes by comparing our opinions to those of others (Festinger, 1954), and that we frequently change our beliefs and behaviours to be similar to those of the people we care about—a process known as conformity. An important aspect of social-cultural psychology are social norms—the ways of thinking, feeling, or behaving that are shared by group members and perceived by them as appropriate (Asch, 1952; Cialdini, 1993). Norms include customs, traditions, standards, and rules, as well as the general values of the group. Many of the most important social norms are determined by the culture in which we live, and these cultures are studied by cross-cultural psychologists. A culture represents the common set of social norms, including religious and family values and other moral beliefs, shared by the people who live in a geographical region (Fiske, Kitayama, Markus, & Nisbett, 1998; Markus, Kitayama, & Heiman, 1996; Matsumoto, 2001). Cultures influence every aspect of our lives, and it is not inappropriate to say that our culture defines our lives just as much as does our evolutionary experience (Mesoudi, 2009). Psychologists have found that there is a fundamental difference in social norms between Western cultures (including those in Canada, the United States, Western Europe, Australia, and New Zealand) and East Asian cultures (including those in China, Japan, Taiwan, Korea, India, and Southeast Asia). Norms in Western cultures are primarily oriented toward individualism, which is about valuing the self and one’s independence from others. Children in Western cultures are taught to develop and to value a sense of their personal self, and to see themselves in large part as separate from the other people around them. Children in Western cultures feel special about themselves; they enjoy getting gold stars on their projects and the best grade in the class. Adults in Western cultures are oriented toward promoting their own individual success, frequently in comparison to (or even at the expense of) others. Norms in the East Asian culture, on the other hand, are oriented toward interdependence or collectivism. In these cultures children are taught to focus on developing harmonious social relationships with others. The predominant norms relate to group togetherness and connectedness, and duty and responsibility to one’s family and other groups. When asked to describe themselves, the members of East Asian cultures are more likely than those from Western cultures to indicate that they are particularly concerned about the interests of others, including their close friends and their colleagues (Figure 1.8, “East vs West”).

Another important cultural difference is the extent to which people in different cultures are bound by social norms and customs, rather than being free to express their own individuality without considering social norms (Chan, Gelfand, Triandis, & Tzeng, 1996). Cultures also differ in terms of personal space, such as how closely individuals stand to each other when talking, as well as the communication styles they employ. It is important to be aware of cultures and cultural differences because people with different cultural backgrounds increasingly come into contact with each other as a result of increased travel and immigration and the development of the Internet and other forms of communication. In Canada, for instance, there are many different ethnic groups, and the proportion of the population that comes from minority (non-White) groups is increasing from year to year. The social-cultural approach to understanding behaviour reminds us again of the difficulty of making broad generalizations about human nature. Different people experience things differently, and they experience them differently in different cultures.

The Many Disciplines of Psychology

Psychology is not one discipline but rather a collection of many subdisciplines that all share at least some common approaches and that work together and exchange knowledge to form a coherent discipline (Yang & Chiu, 2009). Because the field of psychology is so broad, students may wonder which areas are most suitable for their interests and which types of careers might be available to them. Table 1.5, “Some Career Paths in Psychology,” will help you consider the answers to these questions. You can learn more about these different fields of psychology and the careers associated with them at http://www.psyccareers.com/.

Table 1.5 Some Career Paths in Psychology.

[Skip Table]
Psychology field	Description	Career opportunities
Biopsychology and neuroscience	This field examines the physiological bases of behaviour in animals and humans by studying the functioning of different brain areas and the effects of hormones and neurotransmitters on behaviour.	Most biopsychologists work in research settings—for instance, at universities, for the federal government, and in private research labs.
Clinical and counselling psychology	These are the largest fields of psychology. The focus is on the assessment, diagnosis, causes, and treatment of mental disorders.	Clinical and counseling psychologists provide therapy to patients with the goal of improving their life experiences. They work in hospitals, schools, social agencies, and private practice. Because the demand for this career is high, entry to academic programs is highly competitive.
Cognitive psychology	This field uses sophisticated research methods, including reaction time and brain imaging, to study memory, language, and thinking of humans.	Cognitive psychologists work primarily in research settings, although some (such as those who specialize in human-computer interactions) consult for businesses.
Developmental psychology	These psychologists conduct research on the cognitive, emotional, and social changes that occur across the lifespan.	Many work in research settings, although others work in schools and community agencies to help improve and evaluate the effectiveness of intervention programs such as Head Start.
Forensic psychology	Forensic psychologists apply psychological principles to understand the behaviour of judges, lawyers, courtroom juries, and others in the criminal justice system.	Forensic psychologists work in the criminal justice system. They may testify in court and may provide information about the reliability of eyewitness testimony and jury selection.
Health psychology	Health psychologists are concerned with understanding how biology, behaviour, and the social situation influence health and illness.	Health psychologists work with medical professionals in clinical settings to promote better health, conduct research, and teach at universities.
Industrial-organizational and environmental psychology	Industrial-organizational psychology applies psychology to the workplace with the goal of improving the performance and well-being of employees.	There are a wide variety of career opportunities in these fields, generally working in businesses. These psychologists help select employees, evaluate employee performance, and examine the effects of different working conditions on behaviour. They may also work to design equipment and environments that improve employee performance and reduce accidents.
Personality psychology	These psychologists study people and the differences among them. The goal is to develop theories that explain the psychological processes of individuals, and to focus on individual differences.	Most work in academic settings, but the skills of personality psychologists are also in demand in business—for instance, in advertising and marketing. PhD programs in personality psychology are often connected with programs in social psychology.
School and educational psychology	This field studies how people learn in school, the effectiveness of school programs, and the psychology of teaching.	School psychologists work in elementary and secondary schools or school district offices with students, teachers, parents, and administrators. They may assess children’s psychological and learning problems and develop programs to minimize the impact of these problems.
Social and cross-cultural psychology	This field examines people’s interactions with other people. Topics of study include conformity, group behaviour, leadership, attitudes, and personal perception.	Many social psychologists work in marketing, advertising, organizational, systems design, and other applied psychology fields.
Sports psychology	This field studies the psychological aspects of sports behaviour. The goal is to understand the psychological factors that influence performance in sports, including the role of exercise and team interactions.	Sports psychologists work in gyms, schools, professional sports teams, and other areas where sports are practiced.

Psychology in Everyday Life: How to Effectively Learn and Remember

One way that the findings of psychological research may be particularly helpful to you is in terms of improving your learning and study skills. Psychological research has provided a substantial amount of knowledge about the principles of learning and memory. This information can help you do better in this and other courses, and can also help you better learn new concepts and techniques in other areas of your life. The most important thing you can learn in college is how to better study, learn, and remember. These skills will help you throughout your life, as you learn new jobs and take on other responsibilities. There are substantial individual differences in learning and memory, such that some people learn faster than others. But even if it takes you longer to learn than you think it should, the extra time you put into studying is well worth the effort. And you can learn to learn—learning to study effectively and to remember information is just like learning any other skill, such as playing a sport or a video game.

To learn well, you need to be ready to learn. You cannot learn well when you are tired, when you are under stress, or if you are abusing alcohol or drugs. Try to keep a consistent routine of sleeping and eating. Eat moderately and nutritiously, and avoid drugs that can impair memory, particularly alcohol. There is no evidence that stimulants such as caffeine, amphetamines, or any of the many “memory-enhancing drugs” on the market will help you learn (Gold, Cahill, & Wenk, 2002; McDaniel, Maier, & Einstein, 2002). Memory supplements are usually no more effective than drinking a can of sugared soda, which releases glucose and thus improves memory slightly.

Psychologists have studied the ways that best allow people to acquire new information, to retain it over time, and to retrieve information that has been stored in our memories. One important finding is that learning is an active process. To acquire information most effectively, we must actively manipulate it. One active approach is rehearsal—repeating the information that is to be learned over and over again. Although simple repetition does help us learn, psychological research has found that we acquire information most effectively when we actively think about or elaborate on its meaning and relate the material to something else. When you study, try to elaborate by connecting the information to other things that you already know. If you want to remember the different schools of psychology, for instance, try to think about how each of the approaches is different from the others. As you compare the approaches, determine what is most important about each one and then relate it to the features of the other approaches.

In an important study showing the effectiveness of elaborative encoding, Rogers, Kuiper, and Kirker (1977) found that students learned information best when they related it to aspects of themselves (a phenomenon known as the self-reference effect). This research suggests that imagining how the material relates to your own interests and goals will help you learn it. An approach known as the method of loci involves linking each of the pieces of information that you need to remember to places that you are familiar with. You might think about the house that you grew up in and the rooms in it. You could put the behaviourists in the bedroom, the structuralists in the living room, and the functionalists in the kitchen. Then when you need to remember the information, you retrieve the mental image of your house and should be able to “see” each of the people in each of the areas.

One of the most fundamental principles of learning is known as the spacing effect. Both humans and animals more easily remember or learn material when they study the material in several shorter study periods over a longer period of time, rather than studying it just once for a long period of time. Cramming for an exam is a particularly ineffective way to learn. Psychologists have also found that performance is improved when people set difficult yet realistic goals for themselves (Locke & Latham, 2006). You can use this knowledge to help you learn. Set realistic goals for the time you are going to spend studying and what you are going to learn, and try to stick to those goals. Do a small amount every day, and by the end of the week you will have accomplished a lot.

Our ability to adequately assess our own knowledge is known as metacognition. Research suggests that our metacognition may make us overconfident, leading us to believe that we have learned material even when we have not. To counteract this problem, don’t just go over your notes again and again. Instead, make a list of questions and then see if you can answer them. Study the information again and then test yourself again after a few minutes. If you made any mistakes, study again. Then wait for a half hour and test yourself again. Then test again after one day and after two days. Testing yourself by attempting to retrieve information in an active manner is better than simply studying the material because it will help you determine if you really know it. In summary, everyone can learn to learn better. Learning is an important skill, and following the previously mentioned guidelines will likely help you learn better.

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Image Attributions

Figure 1.2:  https://twitter.com/sureteduquebec/status/353519189769732096/photo/1

Figure 1.3: Plato photo (http://commons.wikimedia.org/wiki/File:Platon2.jpg.) courtesy of Bust of Aristotle by Giovanni Dall’Orto, (http://commons.wikimedia.org/wiki/File:Busto_di_Aristotele_conservato_a_Palazzo_Altaemps, _Roma._Foto_di_Giovanni_Dall%27Orto.jpg) used under CC BY license.

Figure 1.4: Wundt research group by Kenosis, (http://commons.wikimedia.org/wiki/File:Wundt-research-group.jpg) is in the public domain; Edward B. Titchener (http://en.wikipedia.org/wiki/File:Edward_B._Titchener.jpg) is in the public domain.

Figure 1.5: William James (http://commons.wikimedia.org/wiki/File:William_James,_philosopher.jpg). Charles Darwin by George Richmond (http://commons.wikimedia.org/wiki/File:Charles_Darwin_by_G._Richmond.jpg) is in public domain.

Figure 1.6: Sigmund Freud by Max Halberstadt (http://commons.wikimedia.org/wiki/File:Sigmund_Freud_LIFE.jpg) is in public domain.

Figure 1.7: B.F. Skinner at Harvard circa 1950 (http://commons.wikimedia.org/wiki/File:B.F._Skinner_at_Harvard_circa _1950.jpg) used under CC BY 3.0 license (http://creativecommons.org/licenses/by/3.0/deed.en).

Figure 1.8: “West Wittering Wonderful As Always” by Gareth Williams (http://www.flickr.com/photos/gareth1953/7976359044/) is licensed under CC BY 2.0. “Family playing a board game” by Bill Branson (http://commons.wikimedia.org/wiki/File:Family_playing_a_board_game_(3).jpg) is in public domain.

 

Psychology is the scientific study of mind and behaviour. Most psychologists work in research laboratories, hospitals, and other field settings where they study the behaviour of humans and animals. Some psychologists are researchers and others are practitioners, but all psychologists use scientific methods to inform their work.

Although it is easy to think that everyday situations have commonsense answers, scientific studies have found that people are not always as good at predicting outcomes as they often think they are. The hindsight bias leads us to think that we could have predicted events that we could not actually have predicted.

Employing the scientific method allows psychologists to objectively and systematically understand human behaviour.

Psychologists study behaviour at different levels of explanation, ranging from lower biological levels to higher social and cultural levels. The same behaviours can be studied and explained within psychology at different levels of explanation.

The first psychologists were philosophers, but the field became more objective as more sophisticated scientific approaches were developed and employed. Some of the most important historical schools of psychology include structuralism, functionalism, behaviourism, and psychodynamic psychology. Cognitive psychology, evolutionary psychology, and social-cultural psychology are some important contemporary approaches.

Some of the basic questions asked by psychologists, both historically and currently, include those about the relative roles of nature versus nurture in behaviour, free will versus determinism, accuracy versus inaccuracy, and conscious versus unconscious processing.

Psychological phenomena are complex, and making predictions about them is difficult because they are multiply determined at different levels of explanation. Research has found that people are frequently unaware of the causes of their own behaviours.

There are a variety of available career choices within psychology that provide employment in many different areas of interest.

Jennifer Walinga

Scientific areas of study are often guided by a paradigm (prevailing model). In astronomy, Ptolemy placed Earth at the centre of the universe and thereby shaped the way people conceived of all things related to that science. Later, the Copernican paradigm placed the Sun at the centre of the universe, which shifted perspectives and understandings. A paradigm presents a generally accepted approach to the whole field during a particular era. A paradigm equips scientists and practitioners with a set of assumptions about what is to be studied as well as a set of research methods for how those phenomena should be examined. In physics, the Aristotelian view of the composition of matter prevailed until Newton’s 17th-century mechanical model emerged and overtook it, which in turn was expanded by Einstein’s 20th-century relativity paradigm (Watson, 1967). With each shift in knowledge and insight, a form of revolution occurs (Kuhn, 1970).

However, psychology lacks a guiding or prevailing paradigm due to its youth and scope. Instead, the field of psychology has travelled the course of several movements, schools of thought, or perspectives, which provide frameworks for organizing data and connecting theories but no overall guidance or stance. In psychology, each new line of thinking emerges in response to another. New ideas or ways of thinking challenge prior thinking and require further research in order to resolve, clarify, or expand tensions between concepts. Often, new methodologiesResearch study design principles. emerge as well, and new questions demand new tools or approaches in order to be answered.

Major psychological perspectives discussed by researchers and practitioners today include biological, psychodynamic, behaviouristic, humanistic, cognitive, and evolutionary perspectives (Figure 2.1, “Major Psychological Perspectives Timeline”). It appears that a new perspective emerges every 20 to 30 years.

This list of perspectives changes, of course, as the field of psychology grows and evolves, and as our conceptualization of psychology expands and develops. The first structuralist psychologists, such as Wilhelm Wundt and Edward B. Titchener of the late 1800s, thought of psychology in biological or physiological terms and focused on the elements of human experience and sensation — the “what” of human experience. But the wave of functionalist, behavioural, and cognitive psychologists to follow began to include the “how” of human experience. Influenced by Charles Darwin’s theories, William James and others later began to consider the “why” of human experience by focusing on interactions between mind and body, including perceptions and emotions, as well as the influence of environment on human experience (Figure 2.2, “The Elements of Psychology”).

Reflecting on psychological developments today (e.g., positive psychology, multiple intelligences, systems thinking), we can foresee psychology moving toward an integrative approach that incorporates much of the prior learning that has come before it. Dr. Evan Thompson, a professor of philosophy at the University of British Columbia, who works in the fields of cognitive science, philosophy of mind, phenomenology, and cross-cultural philosophy, especially Asian philosophy and contemporary Buddhist philosophy in dialogue with Western philosophy and science, speaks and writes about an integrative psychology, which is psychology that combines the nature and actions of mind, body, and spirit (Varela, Rosch, & Thompson, 1992). Perhaps an integrative perspective will be the next developmental stage for the field of psychology and will move the field that much closer to its own established paradigm.

References

Freud, S. (1900). The interpretation of dreams. In J. Strachey (Ed. & Trans.), The standard edition of the complete works of Sigmund Freud (Vol. 4). London: Hogarth Press.

Kuhn, T. S. (1970). The structure of scientific revolutions (2nd ed.). Chicago: University of Chicago Press.

Maslow, A. H. (1954).  Motivation and personality. New York: Harper.

Neisser, U. (1967). Cognitive Psychology. Englewood Cliffs, NJ: Prentice Hall.

Pavlov, I. P. (1927). Conditional reflexes (G. V. Anrep, Trans.). New York: Oxford University Press.

Rogers, C. R. (1942). Counseling and psychotherapy: Newer concepts in practice. Boston: Houghton Mifflin.

Varela, Francisco J., Rosch, Eleanor, & Thompson, Evan. (1992). The Embodied Mind: Cognitive Science and Human Experience. Cambridge, MA: MIT Press.

Watson, R. I. (1967). Psychology: A prescriptive science. American Psychologist, 22, 435–443.

Long Descriptions

Figure 2.1 Long Description – Major Psychological Perspectives Timeline.

Physiological Perspective	Year	Person
Biological – Physiological Psychology	1874	Wundt
	1898	Titchener
Phsychodynamic – Interpretation of Dreams	1990	Freud
Behaviouristic – Stimulus and Response	1927	Pavlov
	1938	Skinner
Humanistic – Self Actualization	1942	Rogers
	1954	Maslow
Cognitive – Information Processing	1967	Neisser
Evolutionary – Adaptation	1999	Buss

[Return to Figure 2.1]

Figure 2.2 long description: There are three elements of psychology: Why? How? and What? “Why” deals with things like evolution, environment, and culture. “How” deals with things like cognition, behaviour, and subconscious. “What” deals with sensations, emotions, thoughts, perceptions, and actions. [Return to Figure 2.2]

Jennifer Walinga

Biological psychologists are interested in measuring biological, physiological, or genetic variables in an attempt to relate them to psychological or behavioural variables. Because all behaviour is controlled by the central nervous system, biological psychologists seek to understand how the brain functions in order to understand behaviour. Key areas of focus include sensation and perception; motivated behaviour (such as hunger, thirst, and sex); control of movement; learning and memory; sleep and biological rhythms; and emotion. As technical sophistication leads to advancements in research methods, more advanced topics such as language, reasoning, decision making, and consciousness are now being studied.

Biological psychology has its roots in early structuralist and functionalist psychological studies, and as with all of the major perspectives, it has relevance today. In section 1.2, we discuss the history and development of functionalism and structuralism. In this chapter, we extend this discussion to include the theoretical and methodological aspects of these two approaches within the biological perspective and provide examples of relevant studies.

The early structural and functional psychologists believed that the study of conscious thoughts would be the key to understanding the mind. Their approaches to the study of the mind were based on systematic and rigorous observation, laying the foundation for modern psychological experimentation. In terms of research focus, Wundt and Titchener explored topics such as attention span, reaction time, vision, emotion, and time perception, all of which are still studied today.

Wundt’s primary method of research was introspection, which involves training people to concentrate and report on their conscious experiences as they react to stimuli. This approach is still used today in modern neuroscience research; however, many scientists criticize the use of introspection for its lack of empirical approach and objectivity. Structuralism was also criticized because its subject of interest – the conscious experience – was not easily studied with controlled experimentation. Structuralism’s reliance on introspection, despite Titchener’s rigid guidelines, was criticized for its lack of reliability. Critics argued that self-analysis is not feasible, and that introspection can yield different results depending on the subject. Critics were also concerned about the possibility of retrospection, or the memory of sensation rather than the sensation itself.

Today, researchers argue for introspective methods as crucial for understanding certain experiences and contexts.Two Minnesota researchers (Jones & Schmid, 2000) used autoethnography, a narrative approach to introspective analysis (Ellis, 1999), to study the phenomenological experience of the prison world and the consequent adaptations and transformations that it evokes. Jones, serving a year-and-a-day sentence in a maximum security prison, relied on his personal documentation of his experience to later study the psychological impacts of his experience.

From Structuralism to Functionalism

As structuralism struggled to survive the scrutiny of the scientific method, new approaches to studying the mind were sought. One important alternative was functionalism, founded by William James in the late 19th century, described and discussed in his two-volume publication The Principles of Psychology (1890) (see Chapter 1.2 for details). Built on structuralism’s concern for the anatomy of the mind, functionalism led to greater concern about the functions of the mind, and later on to behaviourism.

One of James’s students, James Angell, captured the functionalist perspective in relation to a discussion of free will in his 1906 text Psychology: An Introductory Study of the Structure and Function of Human Consciousness:

Inasmuch as consciousness is a systematising, unifying activity, we find that with increasing maturity our impulses are commonly coordinated with one another more and more perfectly. We thus come to acquire definite and reliable habits of action. Our wills become formed. Such fixation of modes of willing constitutes character. The really good man is not obliged to hesitate about stealing. His moral habits all impel him immediately and irrepressibly away from such actions. If he does hesitate, it is in order to be sure that the suggested act is stealing, not because his character is unstable. From one point of view the development of character is never complete, because experience is constantly presenting new aspects of life to us, and in consequence of this fact we are always engaged in slight reconstructions of our modes of conduct and our attitude toward life. But in a practical common-sense way most of our important habits of reaction become fixed at a fairly early and definite time in life.

Functionalism considers mental life and behaviour in terms of active adaptation to the person’s environment. As such, it provides the general basis for developing psychological theories not readily testable by controlled experiments such as applied psychology. William James’s functionalist approach to psychology was less concerned with the composition of the mind than with examining the ways in which the mind adapts to changing situations and environments. In functionalism, the brain is believed to have evolved for the purpose of bettering the survival of its carrier by acting as an information processor.A system for taking information in one form and transforming it into another. In processing information the brain is considered to execute functions similar to those executed by a computer and much like what is shown in Figure 2.3 below of a complex adaptive system.

The functionalists retained an emphasis on conscious experience. John Dewey, George Herbert Mead, Harvey A. Carr, and especially James Angell were the additional proponents of functionalism at the University of Chicago. Another group at Columbia University, including James McKeen Cattell, Edward L. Thorndike, and Robert S. Woodworth, shared a functionalist perspective.

Biological psychology is also considered reductionist. For the reductionist, the simple is the source of the complex. In other words, to explain a complex phenomenon (like human behaviour) a person needs to reduce it to its elements. In contrast, for the holist, the whole is more than the sum of the parts. Explanations of a behaviour at its simplest level can be deemed reductionist. The experimental and laboratory approach in various areas of psychology (e.g., behaviourist, biological, cognitive) reflects a reductionist position. This approach inevitably must reduce a complex behaviour to a simple set of variables that offer the possibility of identifying a cause and an effect (i.e., the biological approach suggests that psychological problems can be treated like a disease and are therefore often treatable with drugs).

The brain and its functions (Figure 2.4) garnered great interest from the biological psychologists and continue to be a focus for psychologists today. Cognitive psychologists rely on the functionalist insights in discussing how affect, or emotion, and environment or events interact and result in specific perceptions. Biological psychologists study the human brain in terms of specialized parts, or systems, and their exquisitely complex relationships. Studies have shown neurogenesisThe generation or growth of new brain cells, specifically when neurons are created from neural stem cells. in the hippocampus (Gage, 2003). In this respect, the human brain is not a static mass of nervous tissue. As well, it has been found that influential environmental factors operate throughout the life span. Among the most negative factors, traumatic injury and drugs can lead to serious destruction. In contrast, a healthy diet, regular programs of exercise, and challenging mental activities can offer long-term, positive impacts on the brain and psychological development (Kolb, Gibb, & Robinson, 2003).

The brain comprises four lobes:

1. Frontal lobe: also known as the motor cortex, this portion of the brain is involved in motor skills, higher level cognition, and expressive language.
2. Occipital lobe: also known as the visual cortex, this portion of the brain is involved in interpreting visual stimuli and information.
3. Parietal lobe: also known as the somatosensory cortex, this portion of the brain is involved in the processing of other tactile sensory information such as pressure, touch, and pain.
4. Temporal lobe: also known as the auditory cortex, this portion of the brain is involved in the interpretation of the sounds and language we hear.

Another important part of the nervous system is the peripheral nervous system, which is divided into two parts:

1. The somatic nervous system, which controls the actions of skeletal muscles.
2. The autonomic nervous system, which regulates automatic processes such as heart rate, breathing, and blood pressure. The autonomic nervous system, in turn has two parts:
   1. The sympathetic nervous system, which controls the fight-or-flight response, a reflex that prepares the body to respond to danger in the environment.
   2. The parasympathetic nervous system, which works to bring the body back to its normal state after a fight-or-flight response.

In further biologically oriented psychological research at the University of Toronto, Schmitz, Cheng, and De Rosa (2010) showed that visual attention — the brain’s ability to selectively filter unattended or unwanted information from reaching awareness — diminishes with age, leaving older adults less capable of filtering out distracting or irrelevant information. This age-related “leaky” attentional filter fundamentally impacts the way visual information is encoded into memory. Older adults with impaired visual attention have better memory for “irrelevant” information. In the study, the research team examined brain images using functional magnetic resonance imaging (fMRI) on a group of young (mean age = 22 years) and older adults (mean age = 77 years) while they looked at pictures of overlapping faces and places (houses and buildings). Participants were asked to pay attention only to the faces and to identify the gender of the person. Even though they could see the place in the image, it was not relevant to the task at hand (Read about the study’s findings at http://www.artsci.utoronto.ca/main/newsitems/brains-ability).

The authors noted:

In young adults, the brain region for processing faces was active while the brain region for processing places was not. However, both the face and place regions were active in older people. This means that even at early stages of perception, older adults were less capable of filtering out the distracting information. Moreover, on a surprise memory test 10 minutes after the scan, older adults were more likely to recognize what face was originally paired with what house.

The findings suggest that under attentionally demanding conditions, such as a person looking for keys on a cluttered table, age-related problems with “tuning in” to the desired object may be linked to the way in which information is selected and processed in the sensory areas of the brain. Both the relevant sensory information — the keys — and the irrelevant information — the clutter — are perceived and encoded more or less equally. In older adults, these changes in visual attention may broadly influence many of the cognitive deficits typically observed in normal aging, particularly memory.

Image Attributions

Figure 2.3: Complex Adaptive System by Acadac (http://commons.wikimedia.org/wiki/File:Complex-adaptive-system.jpg) is in the public domain.

Figure 2.4: Left and Right Brain by Webber (http://commons.wikimedia.org/wiki/File:Left_and_Right_Brain.jpg) is in the public domain.

References

Angell, James Rowland. (1906).”Character and the Will”, Chapter 22 in Psychology: An Introductory Study of the Structure and Function of Human Consciousness, Third edition, revised. New York: Henry Holt and Company, p. 376-381.

Ellis, Carolyn. (1999). Heartful Autoethnography. Qualitative Health Research, 9(53), 669-683.

Gage, F. H. (2003, September). Brain, repair yourself. Scientific American, 46–53.

James, W. (1890). The Principles of Psychology. New York, NY: Henry Holt and Co.

Jones, R.S. & Schmid, T. J. (2000). Doing Time: Prison experience and identity. Stamford, CT: JAI Press.

Kolb, B., Gibb, K., & Robinson, T. E. (2003). Brain plasticity and behavior. Current Directions in Psychological Science, 12, 1–5.

Schmitz, T.W., Cheng, F.H. & De Rosa, E. (2010). Failing to ignore: paradoxical neural effects of perceptual load on early attentional selection in normal aging. Journal of Neuroscience, 30(44), 14750 –14758.

Totsika, V., & Wulf, G. (2003). The influence of external and internal foci of attention on transfer to novel situations and skills. Research Quarterly Exercise and Sport, 74, 220–225.

Wulf, G., Höß, M., & Prinz, W. (1998). Instructions for motor learning: Differential effects of internal versus external focus of attention. Journal of Motor Behavior, 30, 169–179.

Jennifer Walinga

Sigmund Freud

The psychodynamic perspective in psychology proposes that there are psychological forces underlying human behaviour, feelings, and emotions. Psychodynamics originated with Sigmund Freud (Figure 2.5) in the late 19th century, who suggested that psychological processes are flows of psychological energy (libido) in a complex brain. In response to the more reductionist approach of biological, structural, and functional psychology movements, the psychodynamic perspective marks a pendulum swing back toward more holistic, systemic, and abstract concepts and their influence on the more concrete behaviours and actions. Freud’s theory of psychoanalysis assumes that much of mental life is unconscious, and that past experiences, especially in early childhood, shape how a person feels and behaves throughout life.

Consciousness is the awareness of the self in space and time. It can be defined as human awareness of both internal and external stimuli. Researchers study states of human consciousness and differences in perception in order to understand how the body works to produce conscious awareness. Consciousness varies in both arousal and content, and there are two types of conscious experience: phenomenal, or in the moment, and access, which recalls experiences from memory.

First appearing in the historical records of the ancient Mayan and Incan civilizations, various theories of multiple levels of consciousness have pervaded spiritual, psychological, medical, and moral speculations in both Eastern and Western cultures. The ancient Mayans were among the first to propose an organized sense of each level of consciousness, its purpose, and its temporal connection to humankind. Because consciousness incorporates stimuli from the environment as well as internal stimuli, the Mayans believed it to be the most basic form of existence, capable of evolution. The Incas, however, considered consciousness to be a progression, not only of awareness but of concern for others as well.

Sigmund Freud divided human consciousness into three levels of awareness: the conscious, preconscious, and unconscious. Each of these levels corresponds to and overlaps with Freud’s ideas of the id, ego, and superego. The conscious level consists of all those things we are aware of, including things that we know about ourselves and our surroundings. The preconscious consists of those things we could pay conscious attention to if we so desired, and where many memories are stored for easy retrieval. Freud saw the preconscious as those thoughts that are unconscious at the particular moment in question, but that are not repressed and are therefore available for recall and easily capable of becoming conscious (e.g., the “tip of the tongue” effect). The unconscious consists of those things that are outside of conscious awareness, including many memories, thoughts, and urges of which we are not aware. Much of what is stored in the unconscious is thought to be unpleasant or conflicting; for example, sexual impulses that are deemed “unacceptable.” While these elements are stored out of our awareness, they are nevertheless thought to influence our behaviour.

Figure 2.6  illustrates the respective levels of id, ego, and superego. In this diagram, the bright blue line represents the divide between consciousness (above) and unconsciousness (below). Below this line, but above the id, is the preconscious level. The lowest segment is the unconscious.  Like the ego, the superego has conscious and unconscious elements, while the id is completely unconscious. When all three parts of the personality are in dynamic equilibrium, the individual is thought to be mentally healthy. However if the ego is unable to mediate between the id and the superego, an imbalance occurs in the form of psychological distress.

While Freud’s theory remains one of the best known, various schools within the field of psychology have developed their own perspectives. For example:

• Developmental psychologists view consciousness not as a single entity, but as a developmental process with potential higher stages of cognitive, moral, and spiritual quality.
• Social psychologists view consciousness as a product of cultural influence having little to do with the individual.
• Neuropsychologists view consciousness as ingrained in neural systems and organic brain structures.
• Cognitive psychologists base their understanding of consciousness on computer science.

Most psychodynamic approaches use talk therapy, or psychoanalysis, to examine maladaptive functions that developed early in life and are, at least in part, unconscious.  Psychoanalysis is a type of analysis that involves attempting to affect behavioural change through having patients talk about their difficulties. Practising psychoanalysts today collect their data in much the same way as Freud did, through case studies, but often without the couch. The analyst listens and observes, gathering information about the patient. Psychoanalytic scientists today also collect data in formal laboratory experiments, studying groups of people in more restricted, controlled ways (Cramer, 2000; Westen, 1998).

Carl Jung

Carl Jung (1875-1961) expanded on Freud’s theories, introducing the concepts of the archetype, the collective unconscious, and individuation — or the psychological process of integrating the opposites, including the conscious with the unconscious, while still maintaining their relative autonomy (Figure 2.7). Jung focused less on infantile development and conflict between the id and superego, and more on integration between different parts of the person.

The following are Jung’s concepts that are still prevalent today:

Active imagination: This refers to activating our imaginal processes in waking life in order to tap into the unconscious meanings of our symbols.

Archetypes: These primordial images reflect basic patterns or universal themes common to us all and that are present in the unconscious. These symbolic images exist outside space and time. Examples are the shadow, animus, anima, the old wise person, and the innocent child. There are also nature archetypes, like fire, ocean, river, mountain.

1. Anima is the archetype symbolizing the unconscious female component of the male psyche. Tendencies or qualities often thought of as feminine.
2. Animus is the archetype symbolizing the unconscious male component of the female psyche. Tendencies or qualities often thought of as masculine.
3. Self is the archetype symbolizing the totality of the personality. It represents the striving for unity, wholeness, and integration.
4. Persona is the mask or image a person presents to the world. It is designed to make a particular impression on others, while concealing a person’s true nature.
5. Shadow is the side of a personality that a person does not consciously display in public. It may have positive or negative qualities.
6. Dreams are specific expressions of the unconscious that have a definite, purposeful structure indicating an underlying idea or intention. The general function of dreams is to restore a person’s total psychic equilibrium.
7. Complexes are usually unconscious and repressed emotionally toned symbolic material that is incompatible with consciousness. Complexes can cause constant psychological disturbances and symptoms of neurosis. With intervention, they can become conscious and greatly reduced in their impact.

Individuation:  Jung believed that a human being is inwardly whole, but that most people have lost touch with important parts of themselves. Through listening to the messages of our dreams and waking imagination, we can contact and reintegrate our different parts. The goal of life is individuation, which is the process of integrating the conscious with the unconscious, synergizing the many components of the psyche. Jung asserted: “Trust that which gives you meaning and accept it as your guide” (Jung, 1951, p. 3). Each human being has a specific nature and calling uniquely his or her own, and unless these are fulfilled through a union of conscious and unconscious, the person can become sick. Today, the term “individuation” is used in the media industry to describe new printing and online technologies that permit “mass customization” of media (newspaper, online, television) so that its contents match each individual user’s unique interests, shifting from the mass media practice of producing the same contents for all readers, viewers, listeners, or online users (Chen, Wang, & Tseng, 2009). Marshall McLuhan, the communications theorist, alluded to this trend in customization when discussing the future of printed books in an electronically interconnected world (McLuhan & Nevitt, 1972).

Mandala: For Jung, the mandala (which is the Sanskrit word for “circle”) was a symbol of wholeness, completeness, and perfection, and symbolized the self.

Mystery: For Jung, life was a great mystery, and he believed that humans know and understand very little of it. He never hesitated to say, “I don’t know,” and he always admitted when he came to the end of his understanding.

Neurosis: Jung had a hunch that what passed for normality often was the very force that shattered the personality of the patient. He proposed that trying to be “normal” violates a person’s inner nature and is itself a form of pathology. In the psychiatric hospital, he wondered why psychiatrists were not interested in what their patients had to say.

Story: Jung concluded that every person has a story, and when derangement occurs, it is because the personal story has been denied or rejected. Healing and integration come when the person discovers or rediscovers his or her own personal story.

Symbol: A symbol is a name, term, or picture that is familiar in daily life, but for Jung it had other connotations besides its conventional and obvious meaning. To Jung, a symbol implied something vague and partially unknown or hidden, and was never precisely defined. Dream symbols carried messages from the unconscious to the rational mind.

Unconscious: This basic tenet, as expressed by Jung, states that all products of the unconscious are symbolic and can be taken as guiding messages. Within this concept, there are two types:

1. Personal unconscious: This aspect of the psyche does not usually enter an individual’s awareness, but, instead, appears in overt behaviour or in dreams.
2. Collective unconscious: This aspect of the unconscious manifests in universal themes that run through all human life. The idea of the collective unconscious assumes that the history of the human race, back to the most primitive times, lives on in all people.

Word association test: This is a research technique that Jung used to explore the complexes in the personal unconscious. It consisted of reading 100 words to someone, one at a time, and having the person respond quickly with a word of his or her own.

Psychological Types

According to Jung, people differ in certain basic ways, even though the instincts that drive us are the same. Jung distinguished two general attitudes–introversion and extraversion–and four functions–thinking, feeling, sensing, and intuiting:

1. Introvert: Inner-directed; needs privacy and space; chooses solitude to recover energy; often reflective.
2. Extravert: Outer-directed; needs sociability; chooses people as a source of energy; often action-oriented.
3. Thinking function: Logical; sees cause and effect relations; cool, distant, frank, and questioning.
4. Feeling function: Creative, warm, intimate; has a sense of valuing positively or negatively. (Note that this is not the same as emotion.)
5. Sensing function: Sensory; oriented toward the body and senses; detailed, concrete, and present.
6. Intuitive: Sees many possibilities in situations; goes with hunches; impatient with earthy details; impractical; sometimes not present

The Myers-Briggs Type Indicator (MBTI) assessment is a psychometric questionnaire designed to measure psychological preferences in how people perceive the world and make decisions. The original developers of the Myers-Briggs personality inventory were Katharine Cook Briggs and her daughter, Isabel Briggs-Myers (1980, 1995). Having studied the work of Jung, the mother-daughter team turned their interest in human behaviour into a practical application of the theory of psychological types. They began creating the indicator during World War II, believing that a knowledge of personality preferences would help women who were entering the industrial workforce for the first time to identify the sort of wartime jobs that would be “most comfortable and effective.”

The initial questionnaire became the Myers-Briggs Type Indicator (MBTI), first published in 1962 and emphasizing the value of naturally occurring differences (CAPT, 2012). These preferences were extrapolated from the typological theories proposed by Jung and first published in his 1921 book Psychological Types (Adler & Hull, 2014). Jung theorized that there are four principal psychological functions by which we experience the world: sensation, intuition, feeling, and thinking, with one of these four functions being dominant most of the time. The MBTI provides individuals with a measure of their dominant preferences based on the Jungian functions.

Dreaming and Psychodynamic Psychology

Freud showed a great interest in the interpretation of human dreams, and his theory centred on the notion of repressed longing — the idea that dreaming allows us to sort through unresolved, repressed wishes. Freud’s theory described dreams as having both latent and manifest content. Latent content relates to deep unconscious wishes or fantasies, while manifest content is superficial and meaningless. Manifest content often masks or obscures latent content.

Theories emerging from the work of Freud include the following:

Threat-simulation theory suggests that dreaming should be seen as an ancient biological defence mechanism. Dreams are thought to provide an evolutionary advantage because of their capacity to repeatedly simulate potential threatening events. This process enhances the neurocognitive mechanisms required for efficient threat perception and avoidance. During much of human evolution, physical and interpersonal threats were serious enough to reward reproductive advantage to those who survived them. Therefore, dreaming evolved to replicate these threats and continually practice dealing with them. This theory suggests that dreams serve the purpose of allowing for the rehearsal of threatening scenarios in order to better prepare an individual for real-life threats.

Expectation fulfillment theory posits that dreaming serves to discharge emotional arousals (however minor) that haven’t been expressed during the day. This practice frees up space in the brain to deal with the emotional arousals of the next day and allows instinctive urges to stay intact. In effect, the expectation is fulfilled (i.e., the action is completed) in the dream, but only in a metaphorical form so that a false memory is not created. This theory explains why dreams are usually forgotten immediately afterwards.

Other neurobiological theories also exist:

Activation-synthesis theory: One prominent neurobiological theory of dreaming is the activation-synthesis theory, which states that dreams don’t actually mean anything. They are merely electrical brain impulses that pull random thoughts and imagery from our memories. The theory posits that humans construct dream stories after they wake up, in a natural attempt to make sense of the nonsensical. However, given the vast documentation of realistic aspects to human dreaming as well as indirect experimental evidence that other mammals (e.g., cats) also dream, evolutionary psychologists have theorized that dreaming does indeed serve a purpose.

Continual-activation theory: The continual-activation theory of dreaming proposes that dreaming is a result of brain activation and synthesis. Dreaming and REM sleep are simultaneously controlled by different brain mechanisms. The hypothesis states that the function of sleep is to process, encode, and transfer data from short-term memory to long-term memory through a process called “consolidation.” However, there is not much evidence to back up consolidation as a theory. NREM (non-rapid eye movement or non-REM) sleep processes the conscious-related memory (declarative memory), and REM (rapid eye movement) sleep processes the unconscious-related memory (procedural memory).

The underlying assumption of continual-activation theory is that during REM sleep, the unconscious part of a brain is busy processing procedural memory. Meanwhile, the level of activation in the conscious part of the brain descends to a very low level as the inputs from the senses are basically disconnected. This triggers the “continual-activation” mechanism to generate a data stream from the memory stores to flow through to the conscious part of the brain.

Nielsen and colleagues (2003) investigated the dimensional structure of dreams by administering the Typical Dreams Questionnaire (TDQ) to 1,181 first-year university students in three Canadian cities. A profile of themes was found that varied little by age, gender, or region; however, differences that were identified correlated with developmental milestones, personality attributes, or sociocultural factors. Factor analysis found that women’s dreams related mostly to negative factors (failure, loss of control, snakes/insects), while men’s dreams related primarily to positive factors (magic/myth, alien life).

There are several hypotheses that aim to explain the conscious-unconscious effects on problem solving:

1. Spreading activation: When problem solvers disengage from the problem-solving task, they naturally expose themselves to more information that can serve to inform the problem-solving process. Solvers are sensitized to certain information and can benefit from conceptual combination of disparate ideas related to the problem.
2. Selective forgetting: Once disengaged from the problem-solving process, solvers are freer to let go of certain ideas or concepts that may be inhibiting the problem-solving process, allowing a cleaner, fresher view of the problem and revealing clearer pathways to solution.
3. Problem restructuring: When problem solvers let go of the initial problem, they are then freed to restructure or reorganize their representation of the problem and thereby capitalize on relevant information not previously noticed, switch strategies, or rearrange problem information in a manner more conducive to solution pathways.

The study of neural correlates of consciousness (NCC) seeks to link activity within the brain to subjective human experiences in the physical world. Progress in neurophilosophy has come from focusing on the body rather than the mind (Squire, 2008). In this context, the neuronal correlates of consciousness may be viewed as its causes, and consciousness may be thought of as a state-dependent property of some undefined complex, adaptive, and highly interconnected biological system. The NCC constitute the smallest set of neural events and structures sufficient for a given conscious percept or explicit memory (Figure 2.9).

In the investigation into the NCC, our capacity to manipulate visual percepts in time and space has made vision a focus of study. Psychologists have perfected a number of techniques in which the seemingly simple relationship between a physical stimulus in the world and its associated principle in the subject’s mind is disturbed and therefore open for understanding. In this manner the neural mechanisms can be isolated, permitting visual consciousness to be tracked in the brain. In a perceptual illusion, the physical stimulus remains fixed while the perception fluctuates. The best known example is the Necker Cube (Koch, 2004): the 12 lines in the cube can be perceived in one of two different ways in depth (Figure 2.10).

A number of functional magnetic resonance imaging (fMRI) experiments have identified the activity underlying visual consciousness in humans and demonstrated quite conclusively that activity in various areas of the brain follows the mental perception and not the retinal stimulus (Rees & Frith, 2007), making it possible to link brain activity with perception (Figure 2.11).

Image Attributions

Figure 2.5: Freud Jung in front of Clark Hall (http://upload.wikimedia.org/wikipedia/commons/b/b5/Hall_Freud_Jung_in_front_of_Clark.jpg) is in the public domain.

Figure 2.6: Visual representation of Freud’s id, ego and superego and the level of consciousness (http://commons.wikimedia.org/wiki/File:Id_ego_superego.png) used under CC BY SA 3.0 license (http://creativecommons.org/licenses/by-sa/3.0/deed.en).

Figure 2.7: Graphical model of Carl Jung’s theory – English version by Andrzej Brodziak (http://commons.wikimedia.org/wiki/File:Scheme-Jung.jpg) used under CC-BY-SA 2.5 Generic license (http://creativecommons.org/licenses/by-sa/2.5/deed.en).

Figure 2.8: Neuromarketing schema by Benoit Rochon  (http://commons.wikimedia.org/wiki/File:Neuromarketing_fr.svg) used under CC BY 3.0 license (http://creativecommons.org/licenses/by/3.0/deed.en).

Figure 2.9: Neural Correlates Of Consciousness by Christof Koch (http://commons.wikimedia.org/wiki/File:Neural_Correlates_Of_Consciousness.jpg) used under CC BY SA 3.0 license (http://creativecommons.org/licenses/by-sa/3.0/deed.en).

Figure 2.10: Necker’s cube, a type of optical illusion by Stevo-88 (http://commons.wikimedia.org/wiki/File:Necker%27s_cube.svg) is in the public domain.

Figure 2.11: FMRI scan during working memory tasks by John Graner (http://commons.wikimedia.org/wiki/File:FMRI_scan_during_working_memory_tasks.jpg) is in the public domain.

References

Adler, G., & Hull, R. F.C. (2014). Collected Works of C.G. Jung, Volume 6: Psychological Types. Princeton, NJ: Princeton University Press.

Both, L., Needham, D., & Wood, E. (2004). Examining Tasks that Facilitate the Experience of Incubation While Problem-Solving. Alberta Journal of Educational Research, 50(1), 57–67.

Briggs-Myers, Isabel, & Myers, Peter B. (1980, 1995). Gifts differing: Understanding personality type. Mountain View, CA: Davies-Black Publishing.

CAPT (Center for Applications of Psychological Type. (2012). The story of Isabel Briggs Myers. Retrieved from http://www.capt.org/mbti-assessment/isabel-myers.htm

Chen, Songlin, Wang, Yue, & Tseng, Mitchell (2009). Mass Customization as a Collaborative Engineering Effort. International Journal of Collaborative Engineering, 1(2), 152–167.

Cramer, P. (2000). Defense mechanisms in psychology today. American Psychologist, 55, 637–646.

Howard, J., & Sheth, J.N. (1968). Theory of Buyer Behavior. New York, NY: J. Wiley & Sons.

Jung, C. G. (1951). Aion: Researches into the Phenomenology of the Self (Collected Works Vol. 9 Part 2). Princeton, N.J.: Bollingen.

Koch, Christof (2004). The quest for consciousness: a neurobiological approach. Englewood, US-CO: Roberts & Company Publishers.

McLuhan, Marshall, & Nevitt, Barrington. (1972). Take today: The executive as dropout. New York, NY: Harcourt Brace.

Nielsen, Tore A.,  Zadra, Antonio L., Simard, Valérie Saucier, Sébastien Stenstrom, Philippe Smith, Carlyle, & Kuiken, Don (2003). The typical dreams of Canadian university students dreaming. Journal of the Association for the Study of Dreams, 13(4), 211–235.

Rees G., & Frith C. (2007). Methodologies for identifying the neural correlates of consciousness. In: The Blackwell Companion to Consciousness. Velmans, M. & Schneider, S., (Eds.), pp. 553–66. Blackwell: Oxford, UK.

Sandhusen, R. (2000). Marketing. New York, NY: Barron’s Educational Series.

Sio, U.N., & Ormerod, T.C. (2009). Does incubation enhance problem solving? A meta-analytic review. Psychological Bulletin,135(1), 94–120.

Sio U.N., Monaghan P., & Ormerod T. (2013). Sleep on it, but only if it is difficult: Effects of sleep on problem solving. Memory and Cognition, 41(2), 159–66.

Squire, Larry R. (2008). Fundamental neuroscience (3rd ed.). Waltham, Mass: Academic Press. p. 1256.

Westen, D. (1998). The scientific legacy of Sigmund Freud: Toward a psychodynamically informed psychological science. Psychological Bulletin, 124(3), 333–371.

Jennifer Walinga

Emerging in contrast to psychodynamic psychology, behaviourism focuses on observable behaviour as a means to studying the human psyche. The primary tenet of behaviourism is that psychology should concern itself with the observable behaviour of people and animals, not with unobservable events that take place in their minds. The behaviourists criticized the mentalists for their inability to demonstrate empirical evidence to support their claims. The behaviourist school of thought maintains that behaviours can be described scientifically without recourse either to internal physiological events or to hypothetical constructs such as thoughts and beliefs, making behaviour a more productive area of focus for understanding human or animal psychology.

The main influences of behaviourist psychology were Ivan Pavlov (1849-1936), who investigated classical conditioning though often disagreeing with behaviourism or behaviourists; Edward Lee Thorndike (1874-1949), who introduced the concept of reinforcement and was the first to apply psychological principles to learning; John B. Watson (1878-1958), who rejected introspective methods and sought to restrict psychology to experimental methods; and B.F. Skinner (1904-1990), who conducted research on operant conditioning.

The first of these, Ivan Pavlov, is known for his work on one important type of learning, classical conditioning. As we learn, we alter the way we perceive our environment, the way we interpret the incoming stimuli, and therefore the way we interact, or behave. Pavlov, a Russian physiologist, actually discovered classical conditioning accidentally while doing research on the digestive patterns in dogs. During his experiments, he would put meat powder in the mouth of a dog who had tubes inserted into various organs to measure bodily responses. Pavlov discovered that the dog began to salivate before the meat powder was presented to it. Soon the dog began to salivate as soon as the person feeding it entered the room. Pavlov quickly began to gain interest in this phenomenon and abandoned his digestion research in favour of his now famous classical conditioning study.

Basically, Pavlov’s findings support the idea that we develop responses to certain stimuli that are not naturally occurring. When we touch a hot stove, our reflex pulls our hand back. We do this instinctively with no learning involved. The reflex is merely a survival instinct. Pavlov discovered that we make associations that cause us to generalize our response to one stimuli onto a neutral stimuli it is paired with. In other words, hot burner = ouch; stove = burner; therefore, stove = ouch.

In his research with the dogs, Pavlov began pairing a bell sound with the meat powder and found that even when the meat powder was not presented, a dog would eventually begin to salivate after hearing the bell. In this case, since the meat powder naturally results in salivation, these two variables are called the unconditioned stimulus (UCS) and the unconditioned response (UCR), respectively. In the experiment, the bell and salivation are not naturally occurring; the dog is conditioned to respond to the bell. Therefore, the bell is considered the conditioned stimulus (CS), and the salivation to the bell, the conditioned response (CR).

Many of our behaviours today are shaped by the pairing of stimuli. The smell of a cologne, the sound of a certain song, or the occurrence of a specific day of the year can trigger distinct memories, emotions, and associations. When we make these types of associations, we are experiencing classical conditioning.

Operant conditioning is another type of learning that refers to how an organism operates on the environment or how it responds to what is presented to it in the environment (Figure 2.12).

Examples of operant conditioning include the following:

Reinforcement means to strengthen, and is used in psychology to refer to any stimulus which strengthens or increases the probability of a specific response. For example, if you want your dog to sit on command, you may give him a treat every time he sits for you. The dog will eventually come to understand that sitting when told to will result in a treat. This treat is reinforcing the behaviour because the dog likes it and will result in him sitting when instructed to do so. There are four types of reinforcement: positive, negative, punishment, and extinction.

• Positive reinforcement involves adding something in order to increase a response. For example, adding a treat will increase the response of sitting; adding praise will increase the chances of your child cleaning his or her room. The most common types of positive reinforcement are praise and reward, and most of us have experienced this as both the giver and receiver.
• Negative reinforcement involves taking something negative away in order to increase a response. Imagine a teenager who is nagged by his parents to take out the garbage week after week. After complaining to his friends about the nagging, he finally one day performs the task and, to his amazement, the nagging stops. The elimination of this negative stimulus is reinforcing and will likely increase the chances that he will take out the garbage next week.
• Punishment refers to adding something aversive in order to decrease a behaviour. The most common example of this is disciplining (e.g., spanking) a child for misbehaving. The child begins to associate being punished with the negative behaviour. The child does not like the punishment and, therefore, to avoid it, he or she will stop behaving in that manner.
• Extinction involves removing something in order to decrease a behaviour. By having something taken away, a response is decreased.

Research has found positive reinforcement is the most powerful of any of these types of operant conditioning responses. Adding a positive to increase a response not only works better, but allows both parties to focus on the positive aspects of the situation. Punishment, when applied immediately following the negative behaviour, can be effective, but results in extinction when it is not applied consistently. Punishment can also invoke other negative responses such as anger and resentment.

Thorndike’s (1898) work with cats and puzzle boxes illustrates the concept of conditioning. The puzzle boxes were approximately 50 cm long, 38 cm wide, and 30 cm tall (Figure 2.13). Thorndike’s puzzle boxes were built so that the cat, placed inside the box, could escape only if it pressed a bar or pulled a lever, which caused the string attached to the door to lift the weight and open the door. Thorndike measured the time it took the cat to perform the required response (e.g., pulling the lever). Once it had learned the response he gave the cat a reward, usually food.

Thorndike found that once a cat accidentally stepped on the switch, it would then press the switch faster in each succeeding trial inside the puzzle box. By observing and recording how long it took a variety of animals to escape through several trials, Thorndike was able to graph the learning curve (graphed as an S-shape). He observed that most animals had difficulty escaping at first, then began to escape faster and faster with each successive puzzle box trial, and eventually levelled off in their escape times. The learning curve also suggested that different species learned in the same way but at different speeds. His finding was that cats, for instance, consistently showed gradual learning.

From his research with puzzle boxes, Thorndike was able to create his own theory of learning (1932):

1. Learning is incremental.
2. Learning occurs automatically.
3. All animals learn the same way.
4. Law of effect. If an association is followed by satisfaction, it will be strengthened, and if it is followed by annoyance, it will be weakened.
5. Law of use. The more often an association is used, the stronger it becomes.
6. Law of disuse. The longer an association is unused, the weaker it becomes.
7. Law of recency. The most recent response is most likely to reoccur.
8. Multiple response. An animal will try multiple responses (trial and error) if the first response does not lead to a specific state of affairs.
9. Set or attitude. Animals are predisposed to act in a specific way.
10. Prepotency of elements. A subject can filter out irrelevant aspects of a problem and focus on and respond to significant elements of a problem.
11. Response by analogy. Responses from a related or similar context may be used in a new context.
12. Identical elements theory of transfer. The more similar the situations are, the greater the amount of information that will transfer. Similarly, if the situations have nothing in common, information learned in one situation will not be of any value in the other situation.
13. Associative shifting. It is possible to shift any response from occurring with one stimulus to occurring with another stimulus. Associative shift maintains that a response is first made to situation A, then to AB, and then finally to B, thus shifting a response from one condition to another by associating it with that condition.
14. Law of readiness. A quality in responses and connections that results in readiness to act. Behaviour and learning are influenced by the readiness or unreadiness of responses, as well as by their strength.
15. Identifiability. Identification or placement of a situation is a first response of the nervous system, which can recognize it. Then connections may be made to one another or to another response, and these connections depend on the original identification. Therefore, a large amount of learning is made up of changes in the identifiability of situations.
16. Availability. The ease of getting a specific response. For example, it would be easier for a person to learn to touch his or her nose or mouth with closed eyes than it would be to draw a line five inches long with closed eyes.

John B. Watson promoted a change in psychology through his address, Psychology as the Behaviorist Views It (1913), delivered at Columbia University. Through his behaviourist approach, Watson conducted research on animal behaviour, child rearing, and advertising while gaining notoriety for the controversial “Little Albert” experiment. Immortalized in introductory psychology textbooks, this experiment set out to show how the recently discovered principles of classical conditioning could be applied to condition fear of a white rat into Little Albert, an 11-month-old boy. Watson and Rayner (1920) first presented to the boy a white rat and observed that the boy was not afraid. Next they presented him with a white rat and then clanged an iron rod. Little Albert responded by crying. This second presentation was repeated several times. Finally, Watson and Rayner presented the white rat by itself and the boy showed fear. Later, in an attempt to see if the fear transferred to other objects, Watson presented Little Albert with a rabbit, a dog, and a fur coat. He cried at the sight of all of them. This study demonstrated how emotions could become conditioned responses.

Burrhus Frederic Skinner called his particular brand of behaviourism radical behaviourism (1974). Radical behaviourism is the philosophy of the science of behaviour. It seeks to understand behaviour as a function of environmental histories of reinforcing consequences. This applied behaviourism does not accept private events such as thinking, perceptions, and unobservable emotions in a causal account of an organism’s behaviour.

While a researcher at Harvard, Skinner invented the operant conditioning chamber, popularly referred to as the Skinner box (Figure 2.14), used to measure responses of organisms (most often rats and pigeons) and their orderly interactions with the environment. The box had a lever and a food tray, and a hungry rat inside the box could get food delivered to the tray by pressing the lever. Skinner observed that when a rat was first put into the box, it would wander around, sniffing and exploring, and would usually press the bar by accident, at which point a food pellet would drop into the tray. After that happened, the rate of bar pressing would increase dramatically and remain high until the rat was no longer hungry.

Negative reinforcement was also exemplified by Skinner placing rats into an electrified chamber that delivered unpleasant shocks. Levers to cut the power were placed inside these boxes. By running a current through the box, Skinner noticed that the rats, after accidentally pressing the lever in a frantic bid to escape, quickly learned the effects of the lever and consequently used this knowledge to stop the currents both during and prior to electrical shock. These two learned responses are known as escape learning and avoidance learning (Skinner, 1938). The operant chamber for pigeons involved a plastic disk in which the pigeon pecked in order to open a drawer filled with grain. The Skinner box led to the principle of reinforcement, which is the probability of something occurring based on the consequences of a behaviour.

Image Attributions

Figure 2.12: Operant conditioning diagram by studentne (http://commons.wikimedia.org/wiki/File:Operant_conditioning_diagram.png) used under CC BY SA 3.0 license (http://creativecommons.org/licenses/by-sa/3.0/deed.en).

Figure 2.13: Thorndike’s Puzzle Box. by Jacob Sussman (http://commons.wikimedia.org/wiki/File:Puzzle_box.jpg) is in the public domain.

Figure 2.14: Skinner box scheme 01 by Andreas1 (http://commons.wikimedia.org/wiki/File:Skinner_box_scheme_01.png) used under CC BY SA 3.0 license (http://creativecommons.org/licenses/by-sa/3.0/deed.en).

References

Skinner, B.F. (1938). The behavior of organisms: an experimental analysis. Oxford, England: Appleton-Century.

Skinner, B.F. (1974). About behaviorism. New York, NY: Random House.

Thorndike, Edward Lee. (1898). Animal intelligence. Princeton, NJ: MacMillan.

Thorndike, Edward (1932). The fundamentals of learning. New York, NY: AMS Press Inc.

Watson, J. B. (1913). Psychology as the behaviorist views it. Psychological Review, 20, 158-177.

Watson, J. B., & Rayner, R. (1920). Conditioned emotional reactions. Journal of Experimental Psychology, 3, 1-14.

Jennifer Walinga

Humanistic psychology emerged as the third force in psychology after psychodynamic and behaviourist psychology. Humanistic psychology holds a hopeful, constructive view of human beings and of their substantial capacity to be self-determining. This wave of psychology is guided by a conviction that intentionality and ethical values are the key psychological forces determining human behaviour. Humanistic psychologists strive to enhance the human qualities of choice, creativity, the interaction of the body, mind, and spirit, and the capacity to become more aware, free, responsible, life-affirming, and trustworthy.

Emerging in the late 1950s, humanistic psychology began as a reaction against the two schools of thought then dominating American psychology. Behaviourism’s insistence on applying the methods of physical science to human behaviour caused adherents to neglect crucial subjective data, humanists believed. Similarly, psychoanalysis’s emphasis on unconscious drives relegated the conscious mind to relative unimportance.

The early humanistic psychologists sought to restore the importance of consciousness and offer a more holistic view of human life. Humanistic psychology acknowledges that the mind is strongly influenced by determining forces in society and the unconscious, and emphasizes the conscious capacity of individuals to develop personal competence and self-respect. The humanistic orientation has led to the development of therapies to facilitate personal and interpersonal skills and to enhance the quality of life. During the 1950s and 1960s, Carl Rogers, for instance, introduced what he called person or client-centred therapy, which relies on clients’ capacity for self-direction, empathy, and acceptance to promote clients’ development. Abraham Maslow (1908-1970) developed a hierarchy of motivation or hierarchy of needs culminating in self-actualization. Rollo May (1909 – 1994) brought European existential psychotherapy and phenomenology into the field by acknowledging human choice and the tragic aspects of human existence, and Fritz Perls developed gestalt therapy in his workshops and training programs at the Esalan Institute and elsewhere.

During the 1970s and 1980s, the ideas and values of humanistic psychology spread into many areas of society. As a result, humanistic psychology has many branches and extensions, as outlined in Table 2.2.

Table 2.2 Humanistic Therapies and their Theorists.Adapted by J. Walinga.

[Skip Table]
Humanistic Therapies	Theorists
Analytical and Archetypal Psychology	C.G. Jung, James Hillman
Authentic Movement	Mary Whitehouse
Encounter	Carl Rogers, Will Schultz
Existential Analysis	Rollo May, James F.T Bugental
Focusing	Eugene Gendin
Gestalt Art Therapy	Janie Rhyne
Logotherapy	Viktor Frankl
Neuro-Linguistic Programming	Richard Bandler, John Grinder
Psychosynthesis	Roberto Assagioli
Rational-Emotive Therapy	Albert Ellis
Reality Therapy	William Glasser
Self-Disclosure	Sidney Jourard
Sensory Awareness though Movement	Moshe Feldenkreis

Client-centred therapy provides a supportive environment in which clients can re-establish their true identity. Central to this thinking is the idea that the world is judgmental, and many people fear that if they share with the world their true identity, it would judge them relentlessly. People tend to suppress their beliefs, values, or opinions because they are not supported, not socially acceptable, or negatively judged. To re-establish a client’s true identity, the therapist relies on the techniques of unconditional positive regard and empathy. These two techniques are central to client-centred therapy because they build trust between the client and therapist by creating a nonjudgmental and supportive environment for the client.

Existential therapy contrasts the psychoanalysts’ focus on the self and focuses instead on “man in the world.” The counsellor and the client may reflect on how the client has answered life’s questions in the past, but attention ultimately emphasizes the choices to be made in the present and future and enabling a new freedom and responsibility to act. By accepting limitations and mortality, a client can overcome anxieties and instead view life as moments in which he or she is fundamentally free.

Gestalt therapy focuses on the skills and techniques that permit an individual to be more aware of their feelings. According to this approach, it is much more important to understand what patients are feeling and how they are feeling rather than to identify what is causing their feelings. Supporters of gestalt therapy argued that earlier theories spent an unnecessary amount of time making assumptions about what causes behaviour. Instead, gestalt therapy focuses on the here and now.

Humanistic psychology recognizes that human existence consists of multiple layers of reality: the physical, the organic, and the symbolic. It contests the idea — traditionally held by the behavioural sciences — that the only legitimate research method is an experimental test using quantitative data. It argues for the use of additional methods specifically designed to study qualitative factors such as subjective experience, emotion, perception, memory, values, and beliefs. Whereas other approaches take an objective view of people — in essence asking, What is this person like? — humanistic psychologists give priority to understanding people’s subjectivity, asking, What is it like to be this person? (Clay, 2002).

Humanistic psychology has, of course, quietly influenced North American psychology and culture over many decades by informing the civil rights debate and the women’s rights movement, for example. In the academic world, however, humanistic psychology’s rejection of quantitative research in favour of qualitative methods caused its reputation to suffer and its adherents to be marginalized. But in recent years, there’s mounting evidence of renewal in the field itself.

Abraham Maslow’s view of human needs was more complex than Rogers’s. While Rogers believed that people needed unconditional positive regard, Maslow acknowledged that people have a variety of needs that differ in timing and priority (Figure 2.15).

Maslow called the bottom four levels of the pyramid deficiency needs because a person does not feel anything if they are met, but becomes anxious if they are not. Thus, physiological needs such as eating, drinking, and sleeping are deficiency needs, as are safety needs, social needs such as friendship and sexual intimacy, and ego needs such as self-esteem and recognition. In contrast, Maslow called the fifth level of the pyramid a growth needA growth need allows one to reach full potential as a human being. because it enables a person to self-actualize or reach his or her fullest potential as a human being. Once a person has met the deficiency needs, he or she can attend to self-actualization; however, only a small minority of people are able to self-actualize because self-actualization requires uncommon qualities such as honesty, independence, awareness, objectivity, creativity, and originality.

Frederick Taylor’s scientific management principles of the early 1900s, born of the industrial revolution and focused on scientific study of productivity in the workplace, fostered the development of motivation theory, which held that all work consisted largely of simple, uninteresting tasks, and that the only viable method to get people to undertake these tasks was to provide incentives and monitor them carefully. In order to get as much productivity out of workers as possible, it was believed that a person must reward the desired behaviour and punish the rejected behaviour — otherwise known as the “carrot-and-stick” approach.

During this time, scientists believed in two main drives powering human behaviour: the biological drive, including hunger, thirst, and intimacy; and the reward-punishment drive. However, scientists began to encounter situations during their experiments where the reward-punishment drive wasn’t producing the expected performance results. In 1949, Harry F. Harlow, professor of psychology at the University of Wisconsin, began to argue for a third drive: intrinsic motivation — the joy of the task itself.

Harlow’s theory (1950) was based on studies of primate behaviour when solving puzzles. He found that when presented with a puzzle, monkeys seemed to enjoy solving the puzzles without the presence or expectation of rewards. He found these monkeys, driven by intrinsic motivation, solved the puzzles quicker and more accurately than monkeys that received food rewards.

Edward Deci and Richard Ryan (1985) went on to explore and replicate these findings with humans many times over in their studies of families, classrooms, teams, organizations, clinics, and cultures. They concluded that conditions supporting the individual’s experience of autonomy, competence, and relatedness foster the greatest motivation for and engagement in activities while enhancing performance, persistence, and creativity.

Dan Pink (2010) provides ample evidence to support the notion that a traditional carrot-and-stick approach can result in:

• Diminished intrinsic motivation (the third drive)
• Lower performance
• Less creativity
• Crowding out of good behaviour
• Unethical behaviour
• Addictions
• Short-term thinking

Humanistic psychology gave birth to the self-help movement, with concepts grounded in emotion and intuition. The recent positive psychology movement is one form of neo-humanistic psychology that combines emotion and intuition with reason and research. Similarly, modern crisis counselling’s emphasis on empathetic listening finds its roots in Rogers’s humanistic psychology work. In the wider culture, the growing popularity of personal and executive coaching also points to humanistic psychology’s success. Humanistic psychology’s principles may become increasingly relevant as the nation ages, creating a culture preoccupied with facing death and finding meaning in life.

In 1998, a paradigm shift in thinking occurred when University of Pennsylvania psychologist Martin Seligman, in his presidential address to the American Psychological Association (APA), urged psychology to “turn toward understanding and building the human strengths to complement our emphasis on healing damage” (1998b). Though not denying humanity’s flaws, the new approach suggested by positive psychologists recommends focusing on people’s strengths and virtues as a point of departure. Rather than analyze the psychopathology underlying alcoholism, for example, positive psychologists might study the resilience of those who have managed a successful recovery through Alcoholics Anonymous. Instead of viewing religion as a delusion and a crutch, as did Freud, they might identify the mechanisms through which a spiritual practice like meditation enhances mental and physical health. Their lab experiments might seek to define not the conditions that induce depraved behaviour, but those that foster generosity, courage, creativity, and laughter.

Seligman developed the concepts of learned optimism (1998a) and authentic happiness (2002). Learned optimism follows an ABCDE model:

• A=Adversity
• B=Belief
• C=Consequence
• D=Disputation
• E=Energization

In this model, when faced with adversity (A) such as a criticism or failure, a person might form the belief (B) that he or she is underperforming or incapable, and consider the consequence (C) of quitting. However, disputation (D) would challenge the underlying assumptions or beliefs that have formed. The person would then form a new belief in his or her capacity to grow from the critique or learn from the failure. From there, the person would become energized (E) as he or she pursues a new performance path.

In collaboration with Seligman, and within the positive psychology framework, Dr. Mihalyi Csikszentmihályi from Claremont University developed the theory of flow (1988; 1990). Flow is a state of optimal performance. A flow state can be entered while performing any activity, although it is most likely to occur when a person is wholeheartedly performing a task or activity for intrinsic purposes. Csikszentmihályi identified the following six factors as encompassing an experience of flow:

1. Intense and focused concentration on the present moment
2. Merging of action and awareness
3. Loss of reflective self-consciousness
4. Sense of personal control or agency over the situation or activity
5. Distortion of temporal experience (i.e., a person’s subjective experience of time being altered)
6. Experience of the activity being intrinsically rewarding (also referred to as an autotelic experience)

Flow theory suggests that three conditions have to be met to achieve a flow state. First, a person must be involved in an activity with a clear set of goals and progress. This adds direction and structure to the task. Second, the task at hand must have clear and immediate feedback. This helps the person negotiate any changing demands and allows him or her to adjust performance to maintain the flow state. And last, a person must have a good balance between the perceived challenges of the task at hand and his or her own perceived skills. The person must have confidence in his or her ability to complete the task at hand (Figure 2.16).

Cognitive Psychology

Cognitive psychology is the study of mental processes such as attention, memory, perception, language use, problem solving, creativity, and thinking. Much of the work derived from cognitive psychology has been integrated into various other modern disciplines of psychological study including social psychology, personality psychology, abnormal psychology, developmental psychology, educational psychology, and economics.

Ulric Neisser (1928-2012) is credited with formally coining the term cognitive psychology and defining it as “all processes by which the sensory input is transformed, reduced, elaborated, stored, recovered, and used” (1967, page 4). Cognition came to be seen as involved in everything a human being might possibly do: every psychological phenomenon is a cognitive phenomenon. Theories of cognition include developmental, cultural, neural, computational, and moral perspectives.

While behaviourism and cognitive schools of psychological thought may not agree theoretically, they have complemented each other in practical therapeutic applications, such as in cognitive-behavioural therapy (CBT) that has demonstrable utility in treating certain pathologies, such as simple phobias, post-traumatic stress disorder (PTSD), and addiction. CBT replaces maladaptive strategies with more adaptive ones by challenging ways of thinking and reacting. CBT techniques focus on helping individuals challenge their patterns and beliefs and replace erroneous thinking, such as overgeneralizing, magnifying negatives, or catastrophizing, with more realistic and effective thoughts, thus decreasing self-defeating emotions and behaviour and breaking what can otherwise become a negative cycle. These errors in thinking are known as “cognitive distortions.” CBT helps individuals take a more open, mindful, and aware posture toward their distorted thoughts and feelings so as to diminish their impact (Hayes, Villatte, Levin, & Hildebrandt, 2011).

Attention

The psychological definition of attention is a state of focused awareness on a subset of the available perceptual information. The key function of attention is to filter out irrelevant data, enabling the desired data to be distributed to the other mental processes. The human brain may, at times, simultaneously receive inputs in the form of auditory, visual, olfactory, taste, and tactile information. Without the ability to filter out some or most of that simultaneous information and focus on one or typically two inputs at most, the brain would become overloaded as a person attempted to process all the information.

Memory

Modern conceptions of memory typically break it down into three main subclasses:

1. Procedural memory: memory for the performance of particular types of action, is often activated on a subconscious level, or at most requires a minimal amount of conscious effort (e.g., driving to work along the same route).
2. Semantic memory: the encyclopedic knowledge that a person possesses, such as what the Eiffel Tower looks like, or the name of a friend from Grade 6.
3. Episodic memory: memory of autobiographical events that can be explicitly stated, contains all memories that are temporal in nature, such as when you last brushed your teeth, or where you were when you heard about a major news event.

Perception

Perception involves both the physical senses (sight, smell, hearing, taste, touch, and proprioception) as well as the cognitive processes involved in selecting and interpreting those senses. It is how people come to understand the world around them through interpretation of stimuli.

Language use

Cognitive psychologists began exploring the cognitive processes involved with language in the 1870s when Carl Wernicke (1848-1905) proposed a model for the mental processing of language (1875/1995). Significant work has been done recently on understanding the timing of language acquisition and how it can be used to determine if a child has, or is at risk of developing, a learning disability.

Problem solving

Metacognition involves conscious thought about thought processes and might include monitoring a person’s performance on a given task, understanding a person’s capabilities on particular mental tasks, or observing a person’s ability to apply cognitive strategies. Much of the current study regarding metacognition within the field of cognitive psychology deals with its application within the area of education. Educators strive to increase students’ metacognitive abilities in order to enhance their learning, study habits, goal setting, and self-regulation.

Evolutionary Psychology

Evolutionary psychology has emerged as a major perspective in psychology. It seeks to develop and understand ways of expanding the emotional connection between individuals and the natural world, thereby assisting individuals with developing sustainable lifestyles and remedying alienation from nature. The main premise of evolutionary psychology is that while today the human mind is shaped by the modern social world, it is adapted to the natural environment in which it evolved. According to the hypothesis of biologist E.O. Wilson, human beings have an innate instinct to connect emotionally with nature. What distinguishes evolutionary psychologists from many cognitive psychologists is the proposal that the relevant internal mechanisms are adaptations — products of natural selection — that helped our ancestors get around the world, survive, and reproduce. Evolutionary psychology is founded on several core premises:

• The brain is an information-processing device, and it produces behaviour in response to external and internal inputs.
• The brain’s adaptive mechanisms were shaped by natural selection.
• Different neural mechanisms are specialized for solving problems in humanity’s evolutionary past.
• The brain has evolved specialized neural mechanisms that were designed for solving problems that recurred over deep evolutionary time, giving modern humans stone-age minds.
• Most contents and processes of the brain are unconscious; and most mental problems that seem easy to solve are actually extremely difficult problems that are solved unconsciously by complicated neural mechanisms.
• Human psychology consists of many specialized mechanisms, each sensitive to different classes of information or inputs. These mechanisms combine to produce manifest behaviour.

Evolutionary psychologists sometimes present their approach as potentially unifying, or providing a foundation for, all other work that aims to explain human behaviour (Tooby & Cosmides, 1992). This claim has been met with skepticism by many social scientists who see a role for multiple types of explanation of human behaviour, some of which are not reducible to biological explanations of any sort.

Image Attributions

Figure 2.15: Diagram of Maslow’s hierarchy of needs. by J. Finkelstein (http://commons.wikimedia.org/wiki/File:Maslow’s_hierarchy_of_needs.png) used under CC BY SA 3.0 license (http://creativecommons.org/licenses/by-sa/3.0/deed.en).

Figure 2.16: Challenge vs skill Commons by Dr. enh (http://commons.wikimedia.org/wiki/File:Challenge_vs_skill_Commons.jpg) is in the public domain.

References

Clay, Rebecca A. (2002). A renaissance for humanistic psychology. American Psychological Association Monitor, 33 (8), 42.

Csikszentmihályi, M. (1988). The flow experience and its significance for human psychology, in Csikszentmihályi, M., (Ed.) Optimal experience: psychological studies of flow in consciousness, Cambridge, UK: Cambridge University Press, page. 15–35.

Csikszentmihályi, M. (1990). Flow: The psychology of optimal experience. New York: Harper & Row.

Deci, E. L., & Ryan, R. M. (1985). Intrinsic motivation and self-determination in human behavior. New York: Plenum.

Glucksberg, S., & Cowen, C. N., Jr. (1970). Memory for nonattended auditory material. Cognitive Psychology, I, 149-156.

Harlow, H.F. (1950). Early social deprivation and later behavior in the monkey. page. 154-173. In A.Abrams, H.H. Gurner & J.E.P. Tomal, (Eds.), Unfinished tasks in the behavioral sciences (1964). Baltimore: Williams & Wilkins.

Hayes, Steven C., Villatte, Matthieu, Levin, Michael, & Hildebrandt, Mikaela. (2011). Open, aware, and active: Contextual approaches as an emerging trend in the behavioral and cognitive therapies. Annual Review of Clinical Psychology, 7, 141–168.

Mayo, Elton (1945). Social problems of an industrial civilization. Boston: Division of Research, Graduate School of Business Administration, Harvard University, page 64.

Neisser, U. (1967). Cognitive psychology. Englewood Cliffs, NJ: Prentice Hall.

Pink, Daniel H. (2010). Drive – The surprising truth about what motivates us. Edinburgh, UK: Canongate Books.

Rogers, C. R. (1946). Significant aspects of client-centered therapy. American Psychologist, 1, 415-422.

Seligman, M. E. P. (1998a). Building human strength: Psychology’s forgotten mission. APA Monitor, 29(1).

Seligman, M.E.P. (1998b). Learned optimism: How to change your mind and your life. Second edition. New York: Pocket Books (Simon and Schuster).

Seligman, M. E. P. (2002). Authentic happiness: Using the new positive psychology to realize your potential for lasting fulfillment. New York: Free Press.

Tooby, J., & Cosmides, L. (1992). The psychological foundations of culture. In H. Barkow, L. Cosmides & J. Tooby (Eds.), The adapted mind, New York: Oxford University Press, page 19–136.

Wernicke, K. (1875/1995). The aphasia symptom-complex: A psychological study on an anatomical basis. In Paul Eling (Ed.) Reader in the history of aphasia. Amsterdam: John Benjamins Pub Co. page 69–89.

Long Descriptions

Figure 2.12 long description: In Maslow’s hierarchy of needs, there are five levels.

1. Physiological needs: Breathing, food, water, sex, sleep, homeostasis, excretion.
2. Safety needs: Security of body, of employment, of resources, of morality, of the family, of health, of property.
3. Long and belonging needs: Friendship, family, sexual intimacy.
4. Esteem needs: Self-esteem, confidence, chievement, respect of others, respect by others.
5. Self-Actualization: Morality, creativity, spontaneity, problem solving, lack of prejudice, acceptance of facts.

[Return to Figure 2.15]

Figure 2.16 long description: Factors of Flow State.

	Low Skill Level	Medium Skill Level	High Skill Level
Low Challenge	Apathy	Boredom	Relaxation
Medium Challenge	Worry		Control
High Challenge	Anxiety	Arousal	Flow

[Return to Figure 2.16]

Jennifer Walinga

There are many different ways to think about human experience, thought, and behaviour. The multiple perspectives in modern psychology provide researchers and students a variety of ways to approach problems and to understand, explain, predict, and resolve human thought and behaviour.

Perhaps the field of psychology struggles to find a unifying paradigm because human beings are so multifaceted, and human experience so diverse and complex. As with many areas of life, psychology is perhaps best understood through its complexity: psychology seems to move between poles and require a dialectical examination. Human beings are complex systems living within complex adaptive systems (Figure 2.17), possessing multiple ways of knowing and learning and therefore requiring multiple perspectives in order to shed light on the meaning of any one human experience.

The greatest challenge of modern psychology may be holding the whole of human system experience in our minds – biology, cognition, emotion, and belief over time and within an environment and culture – and distilling an understanding from the complex interactions of so many factors.

Image Attributions

Figure 2.17: body by Sue Clark (http://commons.wikimedia.org/wiki/File:Page_214_Nervous_System.jpg) is in the public domain; bullseye from Wikipedia (http://en.wikipedia.org/wiki/Ecological_systems_theory) used under a CC-BY-SA license 3.0 Unported license (http://creativecommons.org/licenses/by-sa/3.0/).

Long Description

Figure 2.17 long description: The individual is surrounded by multiple systems which exercise influence on the individual.

1. An individual’s sex, age, health, etc.
2. Microsystem: Family, peers, church, health services, school.
3. Mesosystem.
4. Exosystem: Social services, neighbours, local politics, mass media, industry.
5. Macrosystem: Attitudes and ideologies of the culture.

[Return to Figure 2.17]

Psychologists study the behaviour of both humans and animals. The main purpose of this research is to help us understand people and to improve the quality of human lives. The results of psychological research are relevant to problems such as learning and memory, homelessness, psychological disorders, family instability, and aggressive behaviour and violence. Psychological research is used in a range of important areas, from public policy to driver safety. It guides court rulings with respect to racism and sexism (Brown v. Board of Education, 1954; Fiske, Bersoff, Borgida, Deaux, & Heilman, 1991), as well as court procedure, in the use of lie detectors during criminal trials, for example (Saxe, Dougherty, & Cross, 1985). Psychological research helps us understand how driver behaviour affects safety (Fajen & Warren, 2003), which methods of educating children are most effective (Alexander & Winne, 2006; Woolfolk-Hoy, 2005), how to best detect deception (DePaulo et al., 2003), and the causes of terrorism (Borum, 2004).

Some psychological research is basic research. Basic research is research that answers fundamental questions about behaviour. For instance, biopsychologists study how nerves conduct impulses from the receptors in the skin to the brain, and cognitive psychologists investigate how different types of studying influence memory for pictures and words. There is no particular reason to examine such things except to acquire a better knowledge of how these processes occur. Applied research is research that investigates issues that have implications for everyday life and provides solutions to everyday problems. Applied research has been conducted to study, among many other things, the most effective methods for reducing depression, the types of advertising campaigns that serve to reduce drug and alcohol abuse, the key predictors of managerial success in business, and the indicators of effective government programs.

Basic research and applied research inform each other, and advances in science occur more rapidly when each type of research is conducted (Lewin, 1999). For instance, although research concerning the role of practice on memory for lists of words is basic in orientation, the results could potentially be applied to help children learn to read. Correspondingly, psychologist-practitioners who wish to reduce the spread of AIDS or to promote volunteering frequently base their programs on the results of basic research. This basic AIDS or volunteering research is then applied to help change people’s attitudes and behaviours.

The results of psychological research are reported primarily in research articles published in scientific journals, and your instructor may require you to read some of these. The research reported in scientific journals has been evaluated, critiqued, and improved by scientists in the field through the process of peer review. In this book there are many citations of original research articles, and I encourage you to read those reports when you find a topic interesting. Most of these papers are readily available online through your college or university library. It is only by reading the original reports that you will really see how the research process works. A list of some of the most important journals in psychology is provided here for your information.

References

Alexander, P. A., & Winne, P. H. (Eds.). (2006). Handbook of educational psychology (2nd ed.). Mahwah, NJ: Lawrence Erlbaum Associates.

Borum, R. (2004). Psychology of terrorism. Tampa: University of South Florida.

Brown v. Board of Education. (1954). 347 U.S, 483.

DePaulo, B. M., Lindsay, J. J., Malone, B. E., Muhlenbruck, L., Charlton, K., & Cooper, H. (2003). Cues to deception. Psychological Bulletin, 129(1), 74–118.

Fajen, B. R., & Warren, W. H. (2003). Behavioral dynamics of steering, obstacle avoidance, and route selection. Journal of Experimental Psychology: Human Perception and Performance, 29(2), 343–362.

Fiske, S. T., Bersoff, D. N., Borgida, E., Deaux, K., & Heilman, M. E. (1991). Social science research on trial: Use of sex stereotyping research in Price Waterhouse v. Hopkins. American Psychologist, 46(10), 1049–1060.

Lewin, K. (1999). The complete social scientist: A Kurt Lewin reader (M. Gold, Ed.). Washington, DC: American Psychological Association.

Saxe, L., Dougherty, D., & Cross, T. (1985). The validity of polygraph testing: Scientific analysis and public controversy. American Psychologist, 40, 355–366.

Woolfolk-Hoy, A. E. (2005). Educational psychology (9th ed.). Boston, MA: Allyn & Bacon.

Psychologists aren’t the only people who seek to understand human behaviour and solve social problems. Philosophers, religious leaders, and politicians, among others, also strive to provide explanations for human behaviour. But psychologists believe that research is the best tool for understanding human beings and their relationships with others. Rather than accepting the claim of a philosopher that people do (or do not) have free will, a psychologist would collect data to empirically test whether or not people are able to actively control their own behaviour. Rather than accepting a politician’s contention that creating (or abandoning) a new centre for mental health will improve the lives of individuals in the inner city, a psychologist would empirically assess the effects of receiving mental health treatment on the quality of life of the recipients. The statements made by psychologists are empirical, which means they are based on systematic collection and analysis of data.

The Scientific Method

All scientists (whether they are physicists, chemists, biologists, sociologists, or psychologists) are engaged in the basic processes of collecting data and drawing conclusions about those data. The methods used by scientists have developed over many years and provide a common framework for developing, organizing, and sharing information. The scientific method is the set of assumptions, rules, and procedures scientists use to conduct research.

In addition to requiring that science be empirical, the scientific method demands that the procedures used be objective, or free from the personal bias or emotions of the scientist. The scientific method proscribes how scientists collect and analyze data, how they draw conclusions from data, and how they share data with others. These rules increase objectivity by placing data under the scrutiny of other scientists and even the public at large. Because data are reported objectively, other scientists know exactly how the scientist collected and analyzed the data. This means that they do not have to rely only on the scientist’s own interpretation of the data; they may draw their own, potentially different, conclusions.

Most new research is designed to replicate — that is, to repeat, add to, or modify — previous research findings. The scientific method therefore results in an accumulation of scientific knowledge through the reporting of research and the addition to and modification of these reported findings by other scientists.

Laws and Theories as Organizing Principles

One goal of research is to organize information into meaningful statements that can be applied in many situations. Principles that are so general as to apply to all situations in a given domain of inquiry are known as laws. There are well-known laws in the physical sciences, such as the law of gravity and the laws of thermodynamics, and there are some universally accepted laws in psychology, such as the law of effect and Weber’s law. But because laws are very general principles and their validity has already been well established, they are themselves rarely directly subjected to scientific test.

The next step down from laws in the hierarchy of organizing principles is theory. A theory is an integrated set of principles that explains and predicts many, but not all, observed relationships within a given domain of inquiry. One example of an important theory in psychology is the stage theory of cognitive development proposed by the Swiss psychologist Jean Piaget. The theory states that children pass through a series of cognitive stages as they grow, each of which must be mastered in succession before movement to the next cognitive stage can occur. This is an extremely useful theory in human development because it can be applied to many different content areas and can be tested in many different ways.

Good theories have four important characteristics. First, good theories are general, meaning they summarize many different outcomes. Second, they are parsimonious, meaning they provide the simplest possible account of those outcomes. The stage theory of cognitive development meets both of these requirements. It can account for developmental changes in behaviour across a wide variety of domains, and yet it does so parsimoniously — by hypothesizing a simple set of cognitive stages. Third, good theories provide ideas for future research. The stage theory of cognitive development has been applied not only to learning about cognitive skills, but also to the study of children’s moral (Kohlberg, 1966) and gender (Ruble & Martin, 1998) development.

Finally, good theories are falsifiable (Popper, 1959), which means the variables of interest can be adequately measured and the relationships between the variables that are predicted by the theory can be shown through research to be incorrect. The stage theory of cognitive development is falsifiable because the stages of cognitive reasoning can be measured and because if research discovers, for instance, that children learn new tasks before they have reached the cognitive stage hypothesized to be required for that task, then the theory will be shown to be incorrect.

No single theory is able to account for all behaviour in all cases. Rather, theories are each limited in that they make accurate predictions in some situations or for some people but not in other situations or for other people. As a result, there is a constant exchange between theory and data: existing theories are modified on the basis of collected data, and the new modified theories then make new predictions that are tested by new data, and so forth. When a better theory is found, it will replace the old one. This is part of the accumulation of scientific knowledge.

The Research Hypothesis

Theories are usually framed too broadly to be tested in a single experiment. Therefore, scientists use a more precise statement of the presumed relationship between specific parts of a theory — a research hypothesis — as the basis for their research. A research hypothesis is a specific and falsifiable prediction about the relationship between or among two or more variables, where a variable is any attribute that can assume different values among different people or across different times or places. The research hypothesis states the existence of a relationship between the variables of interest and the specific direction of that relationship. For instance, the research hypothesis “Using marijuana will reduce learning” predicts that there is a relationship between one variable, “using marijuana,” and another variable called “learning.” Similarly, in the research hypothesis “Participating in psychotherapy will reduce anxiety,” the variables that are expected to be related are “participating in psychotherapy” and “level of anxiety.”

When stated in an abstract manner, the ideas that form the basis of a research hypothesis are known as conceptual variables. Conceptual variables are abstract ideas that form the basis of research hypotheses. Sometimes the conceptual variables are rather simple — for instance, age, gender, or weight. In other cases the conceptual variables represent more complex ideas, such as anxiety, cognitive development, learning, self-esteem, or sexism.

The first step in testing a research hypothesis involves turning the conceptual variables into measured variables, which are variables consisting of numbers that represent the conceptual variables. For instance, the conceptual variable “participating in psychotherapy” could be represented as the measured variable “number of psychotherapy hours the patient has accrued,” and the conceptual variable “using marijuana” could be assessed by having the research participants rate, on a scale from 1 to 10, how often they use marijuana or by administering a blood test that measures the presence of the chemicals in marijuana.

Psychologists use the term operational definition to refer to a precise statement of how a conceptual variable is turned into a measured variable. The relationship between conceptual and measured variables in a research hypothesis is diagrammed in Figure 3.1. The conceptual variables are represented in circles at the top of the figure (Psychotherapy and anxiety), and the measured variables are represented in squares at the bottom (number of hours the patient has spent in psychotherapy and anxiety concerns as reported by the patient). The two vertical arrows, which lead from the conceptual variables to the measured variables, represent the operational definitions of the two variables. The arrows indicate the expectation that changes in the conceptual variables (psychotherapy and anxiety) will cause changes in the corresponding measured variables (number of hours in psychotherapy and reported anxiety concernts). The measured variables are then used to draw inferences about the conceptual variables.

Table 3.1 lists some potential operational definitions of conceptual variables that have been used in psychological research. As you read through this list, note that in contrast to the abstract conceptual variables, the measured variables are very specific. This specificity is important for two reasons. First, more specific definitions mean that there is less danger that the collected data will be misunderstood by others. Second, specific definitions will enable future researchers to replicate the research.

Table 3.1 Examples of the Operational Definitions of Conceptual Variables that Have Been Used in Psychological Research

[Skip Table]
Conceptual variable	Operational definitions
Aggression	Number of presses of a button that administers shock to another student Number of seconds taken to honk the horn at the car ahead after a stoplight turns green
Interpersonal attraction	Number of inches that an individual places his or her chair away from another person Number of millimeters of pupil dilation when one person looks at another
Employee satisfaction	Number of days per month an employee shows up to work on time Rating of job satisfaction from 1 (not at all satisfied) to 9 (extremely satisfied)
Decision-making skills	Number of groups able to correctly solve a group performance task Number of seconds in which a person solves a problem
Depression	Number of negative words used in a creative story Number of appointments made with a psychotherapist

Conducting Ethical Research

One of the questions that all scientists must address concerns the ethics of their research. Physicists are concerned about the potentially harmful outcomes of their experiments with nuclear materials. Biologists worry about the potential outcomes of creating genetically engineered human babies. Medical researchers agonize over the ethics of withholding potentially beneficial drugs from control groups in clinical trials. Likewise, psychologists are continually considering the ethics of their research.

Research in psychology may cause some stress, harm, or inconvenience for the people who participate in that research. For instance, researchers may require introductory psychology students to participate in research projects and then deceive these students, at least temporarily, about the nature of the research. Psychologists may induce stress, anxiety, or negative moods in their participants, expose them to weak electrical shocks, or convince them to behave in ways that violate their moral standards. And researchers may sometimes use animals in their research, potentially harming them in the process.

Decisions about whether research is ethical are made using established ethical codes developed by scientific organizations, such as the Canadian Psychological Association, and federal governments. In Canada, the federal agencies, Health Canada, and the Canadian Institute for Health Research provide the guidelines for ethical standards in research. Some research, such as the research conducted by the Nazis on prisoners during World War II, is perceived as immoral by almost everyone. Other procedures, such as the use of animals in research testing the effectiveness of drugs, are more controversial.

Scientific research has provided information that has improved the lives of many people. Therefore, it is unreasonable to argue that because scientific research has costs, no research should be conducted. This argument fails to consider the fact that there are significant costs to not doing research and that these costs may be greater than the potential costs of conducting the research (Rosenthal, 1994). In each case, before beginning to conduct the research, scientists have attempted to determine the potential risks and benefits of the research and have come to the conclusion that the potential benefits of conducting the research outweigh the potential costs to the research participants.

This list presents some of the most important factors that psychologists take into consideration when designing their research. The most direct ethical concern of the scientist is to prevent harm to the research participants. One example is the well-known research of Stanley Milgram (1974) investigating obedience to authority. In these studies, participants were induced by an experimenter to administer electric shocks to another person so that Milgram could study the extent to which they would obey the demands of an authority figure. Most participants evidenced high levels of stress resulting from the psychological conflict they experienced between engaging in aggressive and dangerous behaviour and following the instructions of the experimenter. Studies such as those by Milgram are no longer conducted because the scientific community is now much more sensitized to the potential of such procedures to create emotional discomfort or harm.

Another goal of ethical research is to guarantee that participants have free choice regarding whether they wish to participate in research. Students in psychology classes may be allowed, or even required, to participate in research, but they are also always given an option to choose a different study to be in, or to perform other activities instead. And once an experiment begins, the research participant is always free to leave the experiment if he or she wishes to. Concerns with free choice also occur in institutional settings, such as in schools, hospitals, corporations, and prisons, when individuals are required by the institutions to take certain tests, or when employees are told or asked to participate in research.

Researchers must also protect the privacy of the research participants. In some cases data can be kept anonymous by not having the respondents put any identifying information on their questionnaires. In other cases the data cannot be anonymous because the researcher needs to keep track of which respondent contributed the data. In this case, one technique is to have each participant use a unique code number to identify his or her data, such as the last four digits of the student ID number. In this way the researcher can keep track of which person completed which questionnaire, but no one will be able to connect the data with the individual who contributed them.

Perhaps the most widespread ethical concern to the participants in behavioural research is the extent to which researchers employ deception. Deception occurs whenever research participants are not completely and fully informed about the nature of the research project before participating in it. Deception may occur in an active way, such as when the researcher tells the participants that he or she is studying learning when in fact the experiment really concerns obedience to authority. In other cases the deception is more passive, such as when participants are not told about the hypothesis being studied or the potential use of the data being collected.

Some researchers have argued that no deception should ever be used in any research (Baumrind, 1985). They argue that participants should always be told the complete truth about the nature of the research they are in, and that when participants are deceived there will be negative consequences, such as the possibility that participants may arrive at other studies already expecting to be deceived. Other psychologists defend the use of deception on the grounds that it is needed to get participants to act naturally and to enable the study of psychological phenomena that might not otherwise get investigated. They argue that it would be impossible to study topics such as altruism, aggression, obedience, and stereotyping without using deception because if participants were informed ahead of time what the study involved, this knowledge would certainly change their behaviour. The codes of ethics of the Canadian Psychological Association and the Tri-Council Policy Statement of Canada’s three federal research agencies (the Canadian Institute of Health Research [CIHR], the Natural Sciences and Engineering Research Council of Canada [NSERC], and the Social Sciences and Humanities Research Council of Canada [SSHRC] or “the Agencies”) allow researchers to use deception, but these codes also require them to explicitly consider how their research might be conducted without the use of deception.

Ensuring that Research Is Ethical

Making decisions about the ethics of research involves weighing the costs and benefits of conducting versus not conducting a given research project. The costs involve potential harm to the research participants and to the field, whereas the benefits include the potential for advancing knowledge about human behaviour and offering various advantages, some educational, to the individual participants. Most generally, the ethics of a given research project are determined through a cost-benefit analysis, in which the costs are compared with the benefits. If the potential costs of the research appear to outweigh any potential benefits that might come from it, then the research should not proceed.

Arriving at a cost-benefit ratio is not simple. For one thing, there is no way to know ahead of time what the effects of a given procedure will be on every person or animal who participates or what benefit to society the research is likely to produce. In addition, what is ethical is defined by the current state of thinking within society, and thus perceived costs and benefits change over time. In Canada, the Tri-Council regulations require that all universities receiving funds from the Agencies set up an Ethical Review Board (ERB) to determine whether proposed research meets department regulations. The ERB is a committee of at least five members whose goal it is to determine the cost-benefit ratio of research conducted within an institution. The ERB must approve the procedures of all the research conducted at the institution before the research can begin. The board may suggest modifications to the procedures, or (in rare cases) it may inform the scientist that the research violates Tri-Council Research Policy Statement and thus cannot be conducted at all.

One important tool for ensuring that research is ethical is the use of informed consent. A sample informed consent form is shown in Figure 3.2, Informed consent, conducted before a participant begins a research session, is designed to explain the research procedures and inform the participant of his or her rights during the investigation. The informed consent explains as much as possible about the true nature of the study, particularly everything that might be expected to influence willingness to participate, but it may in some cases withhold some information that allows the study to work.

The informed consent form explains the research procedures and informs the participant of his or her rights during the investigation. Informed consent should address the following issues:

Because participating in research has the potential for producing long-term changes in the research participants, all participants should be fully debriefed immediately after their participation. The debriefing is a procedure designed to fully explain the purposes and procedures of the research and remove any harmful after-effects of participation.

Research with Animals

Because animals make up an important part of the natural world, and because some research cannot be conducted using humans, animals are also participants in psychological research (Figure 3.3). Most psychological research using animals is now conducted with rats, mice, and birds, and the use of other animals in research is declining (Thomas & Blackman, 1992). As with ethical decisions involving human participants, a set of basic principles has been developed that helps researchers make informed decisions about such research; a summary is shown below.

 

Because the use of animals in research involves a personal value, people naturally disagree about this practice. Although many people accept the value of such research (Plous, 1996), a minority of people, including animal-rights activists, believe that it is ethically wrong to conduct research on animals. This argument is based on the assumption that because animals are living creatures just as humans are, no harm should ever be done to them.

Most scientists, however, reject this view. They argue that such beliefs ignore the potential benefits that have come, and continue to come, from research with animals. For instance, drugs that can reduce the incidence of cancer or AIDS may first be tested on animals, and surgery that can save human lives may first be practised on animals. Research on animals has also led to a better understanding of the physiological causes of depression, phobias, and stress, among other illnesses. In contrast to animal-rights activists, then, scientists believe that because there are many benefits that accrue from animal research, such research can and should continue as long as the humane treatment of the animals used in the research is guaranteed.

Image Attributions

Figure 3.3: “Wistar rat” by Janet Stephens (http://en.wikipedia.org/wiki/File:Wistar_rat.jpg) is in the public domain.

References

Baumrind, D. (1985). Research using intentional deception: Ethical issues revisited. American Psychologist, 40, 165–174.

Canadian Psychological Association. (2000). Canadian code of ethics for psychologists (third edition) [PDF]. Retrieved July 2014 from http://www.cpa.ca/cpasite/userfiles/Documents/Practice_Page/Ethics_Code_Psych.pdf

Kohlberg, L. (1966). A cognitive-developmental analysis of children’s sex-role concepts and attitudes. In E. E. Maccoby (Ed.), The development of sex differences. Stanford, CA: Stanford University Press.

Milgram, S. (1974). Obedience to authority: An experimental view. New York, NY: Harper and Row.

Plous, S. (1996). Attitudes toward the use of animals in psychological research and education. Psychological Science, 7, 352–358.

Popper, K. R. (1959). The logic of scientific discovery. New York, NY: Basic Books.

Rosenthal, R. (1994). Science and ethics in conducting, analyzing, and reporting psychological research. Psychological Science, 5, 127–134.

Ruble, D., & Martin, C. (1998). Gender development. In W. Damon (Ed.), Handbook of child psychology (5th ed., pp. 933–1016). New York, NY: John Wiley & Sons.

Stangor, C. (2011). Research methods for the behavioral sciences (4th ed.). Mountain View, CA: Cengage.

Thomas, G., & Blackman, D. (1992). The future of animal studies in psychology. American Psychologist, 47, 1678.

Long Descriptions

Figure 3.2 long description: Sample research consent form.

My name is [insert your name], and this research project is part of the requirement for a [insert your degree program] at [blank] University. My credentials with [blank] university can be established by telephoning [insert name and number of supervisor].

This document constitutes an agreement to participate in my research project, the objective of which is to [insert research objectives and the sponsoring organization here].

The research will consist of [insert your methodology] and its foreseen to last [insert amount of time]. The foreseen questions will refer to [insert summary of foreseen questions]. In addition to submitting my final report to [blank] University in partial fulfillment for a [insert your degree program], I will also be sharing my search findings with [insert your sponsoring organization]. [Disclose all the purposes to which the research data is going to be put, e.g. journal articles, books, etc.].

Information will be recorded in hand-written format (or taped/videotaped, etc) and where appropriate, summarized, in anonymous format, in the body of the final report. At no time will any specific comments be attributed to any individual unless specific agreement has been obtained beforehand. All documentation will be kept strictly confidential.

A copy of the final report will be published. A copy will be housed at [blank] university, available online through [blank] and will be publicly accessible. Access and distribution will be unrestricted.

[Disclose any and all conflicts of interest and how those will be managed.]

You are not compelled to participate in this research project. If you do choose to participate, you are free to withdraw at any time without prejudice. Similarly, if you choose not to participate in this research project, this information will also be maintained in confidence.

By signing this letter, you give free and informed consent to participate in this project.

Name (Please print), Signed: Date: [Return to Figure 3.2]

Psychologists agree that if their ideas and theories about human behaviour are to be taken seriously, they must be backed up by data. However, the research of different psychologists is designed with different goals in mind, and the different goals require different approaches. These varying approaches, summarized in Table 3.2, are known as research designs. A research design is the specific method a researcher uses to collect, analyze, and interpret data. Psychologists use three major types of research designs in their research, and each provides an essential avenue for scientific investigation. Descriptive research is research designed to provide a snapshot of the current state of affairs. Correlational research is research designed to discover relationships among variables and to allow the prediction of future events from present knowledge. Experimental research is research in which initial equivalence among research participants in more than one group is created, followed by a manipulation of a given experience for these groups and a measurement of the influence of the manipulation. Each of the three research designs varies according to its strengths and limitations, and it is important to understand how each differs.

Table 3.2 Characteristics of the Three Research Designs

[Skip Table]
Research design	Goal	Advantages	Disadvantages
Descriptive	To create a snapshot of the current state of affairs	Provides a relatively complete picture of what is occurring at a given time. Allows the development of questions for further study.	Does not assess relationships among variables. May be unethical if participants do not know they are being observed.
Correlational	To assess the relationships between and among two or more variables	Allows testing of expected relationships between and among variables and the making of predictions. Can assess these relationships in everyday life events.	Cannot be used to draw inferences about the causal relationships between and among the variables.
Experimental	To assess the causal impact of one or more experimental manipulations on a dependent variable	Allows drawing of conclusions about the causal relationships among variables.	Cannot experimentally manipulate many important variables. May be expensive and time consuming.
Source: Stangor, 2011.

Descriptive Research: Assessing the Current State of Affairs

Descriptive research is designed to create a snapshot of the current thoughts, feelings, or behaviour of individuals. This section reviews three types of descriptive research: case studies, surveys, and naturalistic observation (Figure 3.4).

Sometimes the data in a descriptive research project are based on only a small set of individuals, often only one person or a single small group. These research designs are known as case studies — descriptive records of one or more individual’s experiences and behaviour. Sometimes case studies involve ordinary individuals, as when developmental psychologist Jean Piaget used his observation of his own children to develop his stage theory of cognitive development. More frequently, case studies are conducted on individuals who have unusual or abnormal experiences or characteristics or who find themselves in particularly difficult or stressful situations. The assumption is that by carefully studying individuals who are socially marginal, who are experiencing unusual situations, or who are going through a difficult phase in their lives, we can learn something about human nature.

Sigmund Freud was a master of using the psychological difficulties of individuals to draw conclusions about basic psychological processes. Freud wrote case studies of some of his most interesting patients and used these careful examinations to develop his important theories of personality. One classic example is Freud’s description of “Little Hans,” a child whose fear of horses the psychoanalyst interpreted in terms of repressed sexual impulses and the Oedipus complex (Freud, 1909/1964).

Another well-known case study is Phineas Gage, a man whose thoughts and emotions were extensively studied by cognitive psychologists after a railroad spike was blasted through his skull in an accident. Although there are questions about the interpretation of this case study (Kotowicz, 2007), it did provide early evidence that the brain’s frontal lobe is involved in emotion and morality (Damasio et al., 2005). An interesting example of a case study in clinical psychology is described by Rokeach (1964), who investigated in detail the beliefs of and interactions among three patients with schizophrenia, all of whom were convinced they were Jesus Christ.

In other cases the data from descriptive research projects come in the form of a survey — a measure administered through either an interview or a written questionnaire to get a picture of the beliefs or behaviours of a sample of people of interest. The people chosen to participate in the research (known as the sample) are selected to be representative of all the people that the researcher wishes to know about (the population). In election polls, for instance, a sample is taken from the population of all “likely voters” in the upcoming elections.

The results of surveys may sometimes be rather mundane, such as “Nine out of 10 doctors prefer Tymenocin” or “The median income in the city of Hamilton is $46,712.” Yet other times (particularly in discussions of social behaviour), the results can be shocking: “More than 40,000 people are killed by gunfire in the United States every year” or “More than 60% of women between the ages of 50 and 60 suffer from depression.” Descriptive research is frequently used by psychologists to get an estimate of the prevalence (or incidence) of psychological disorders.

A final type of descriptive research — known as naturalistic observation — is research based on the observation of everyday events. For instance, a developmental psychologist who watches children on a playground and describes what they say to each other while they play is conducting descriptive research, as is a biopsychologist who observes animals in their natural habitats. One example of observational research involves a systematic procedure known as the strange situation, used to get a picture of how adults and young children interact. The data that are collected in the strange situation are systematically coded in a coding sheet such as that shown in Table 3.3.

Table 3.3 Sample Coding Form Used to Assess Child’s and Mother’s Behaviour in the Strange Situation

[Skip Table]
Coder name: Olive
This table represents a sample coding sheet from an episode of the “strange situation,” in which an infant (usually about one year old) is observed playing in a room with two adults — the child’s mother and a stranger. Each of the four coding categories is scored by the coder from 1 (the baby makes no effort to engage in the behaviour) to 7 (the baby makes a significant effort to engage in the behaviour). More information about the meaning of the coding can be found in Ainsworth, Blehar, Waters, and Wall (1978).
Coding categories explained
Proximity	The baby moves toward, grasps, or climbs on the adult.
Maintaining contact	The baby resists being put down by the adult by crying or trying to climb back up.
Resistance	The baby pushes, hits, or squirms to be put down from the adult’s arms.
Avoidance	The baby turns away or moves away from the adult.
Episode	Coding categories
	Proximity	Contact	Resistance	Avoidance
Mother and baby play alone	1	1	1	1
Mother puts baby down	4	1	1	1
Stranger enters room	1	2	3	1
Mother leaves room; stranger plays with baby	1	3	1	1
Mother re-enters, greets and may comfort baby, then leaves again	4	2	1	2
Stranger tries to play with baby	1	3	1	1
Mother re-enters and picks up baby	6	6	1	2
Source: Stang0r, 2011.

The results of descriptive research projects are analyzed using descriptive statistics — numbers that summarize the distribution of scores on a measured variable. Most variables have distributions similar to that shown in Figure 3.5 where most of the scores are located near the centre of the distribution, and the distribution is symmetrical and bell-shaped. A data distribution that is shaped like a bell is known as a normal distribution.

 

A distribution can be described in terms of its central tendency — that is, the point in the distribution around which the data are centred — and its dispersion, or spread. The arithmetic average, or arithmetic mean, symbolized by the letter M, is the most commonly used measure of central tendency. It is computed by calculating the sum of all the scores of the variable and dividing this sum by the number of participants in the distribution (denoted by the letter N). In the data presented in Figure 3.5 the mean height of the students is 67.12 inches (170.5 cm). The sample mean is usually indicated by the letter M.

In some cases, however, the data distribution is not symmetrical. This occurs when there are one or more extreme scores (known as outliers) at one end of the distribution. Consider, for instance, the variable of family income (see Figure 3.6), which includes an outlier (a value of $3,800,000). In this case the mean is not a good measure of central tendency. Although it appears from Figure 3.6 that the central tendency of the family income variable should be around $70,000, the mean family income is actually $223,960. The single very extreme income has a disproportionate impact on the mean, resulting in a value that does not well represent the central tendency.

The median is used as an alternative measure of central tendency when distributions are not symmetrical. The median is the score in the center of the distribution, meaning that 50% of the scores are greater than the median and 50% of the scores are less than the median. In our case, the median household income ($73,000) is a much better indication of central tendency than is the mean household income ($223,960).

A final measure of central tendency, known as the mode, represents the value that occurs most frequently in the distribution. You can see from Figure 3.6 that the mode for the family income variable is $93,000 (it occurs four times).

In addition to summarizing the central tendency of a distribution, descriptive statistics convey information about how the scores of the variable are spread around the central tendency. Dispersion refers to the extent to which the scores are all tightly clustered around the central tendency, as seen in Figure 3.7.

 

Or they may be more spread out away from it, as seen in Figure 3.8.

 

One simple measure of dispersion is to find the largest (the maximum) and the smallest (the minimum) observed values of the variable and to compute the range of the variable as the maximum observed score minus the minimum observed score. You can check that the range of the height variable in Figure 3.5 is 72 – 62 = 10. The standard deviation, symbolized as s, is the most commonly used measure of dispersion. Distributions with a larger standard deviation have more spread. The standard deviation of the height variable is s = 2.74, and the standard deviation of the family income variable is s = $745,337.

An advantage of descriptive research is that it attempts to capture the complexity of everyday behaviour. Case studies provide detailed information about a single person or a small group of people, surveys capture the thoughts or reported behaviours of a large population of people, and naturalistic observation objectively records the behaviour of people or animals as it occurs naturally. Thus descriptive research is used to provide a relatively complete understanding of what is currently happening.

Despite these advantages, descriptive research has a distinct disadvantage in that, although it allows us to get an idea of what is currently happening, it is usually limited to static pictures. Although descriptions of particular experiences may be interesting, they are not always transferable to other individuals in other situations, nor do they tell us exactly why specific behaviours or events occurred. For instance, descriptions of individuals who have suffered a stressful event, such as a war or an earthquake, can be used to understand the individuals’ reactions to the event but cannot tell us anything about the long-term effects of the stress. And because there is no comparison group that did not experience the stressful situation, we cannot know what these individuals would be like if they hadn’t had the stressful experience.

Correlational Research: Seeking Relationships among Variables

In contrast to descriptive research, which is designed primarily to provide static pictures, correlational research involves the measurement of two or more relevant variables and an assessment of the relationship between or among those variables. For instance, the variables of height and weight are systematically related (correlated) because taller people generally weigh more than shorter people. In the same way, study time and memory errors are also related, because the more time a person is given to study a list of words, the fewer errors he or she will make. When there are two variables in the research design, one of them is called the predictor variable and the other the outcome variable. The research design can be visualized as shown in Figure 3.9, where the curved arrow represents the expected correlation between these two variables.

One way of organizing the data from a correlational study with two variables is to graph the values of each of the measured variables using a scatter plot. As you can see in Figure 3.10 a scatter plot is a visual image of the relationship between two variables. A point is plotted for each individual at the intersection of his or her scores for the two variables. When the association between the variables on the scatter plot can be easily approximated with a straight line, as in parts (a) and (b) of Figure 3.10 the variables are said to have a linear relationship.

When the straight line indicates that individuals who have above-average values for one variable also tend to have above-average values for the other variable, as in part (a), the relationship is said to be positive linear. Examples of positive linear relationships include those between height and weight, between education and income, and between age and mathematical abilities in children. In each case, people who score higher on one of the variables also tend to score higher on the other variable. Negative linear relationships, in contrast, as shown in part (b), occur when above-average values for one variable tend to be associated with below-average values for the other variable. Examples of negative linear relationships include those between the age of a child and the number of diapers the child uses, and between practice on and errors made on a learning task. In these cases, people who score higher on one of the variables tend to score lower on the other variable.

Relationships between variables that cannot be described with a straight line are known as nonlinear relationships. Part (c) of Figure 3.10 shows a common pattern in which the distribution of the points is essentially random. In this case there is no relationship at all between the two variables, and they are said to be independent. Parts (d) and (e) of Figure 3.10 show patterns of association in which, although there is an association, the points are not well described by a single straight line. For instance, part (d) shows the type of relationship that frequently occurs between anxiety and performance. Increases in anxiety from low to moderate levels are associated with performance increases, whereas increases in anxiety from moderate to high levels are associated with decreases in performance. Relationships that change in direction and thus are not described by a single straight line are called curvilinear relationships.

 

The most common statistical measure of the strength of linear relationships among variables is the Pearson correlation coefficient, which is symbolized by the letter r. The value of the correlation coefficient ranges from r = –1.00 to r = +1.00. The direction of the linear relationship is indicated by the sign of the correlation coefficient. Positive values of r (such as r = .54 or r = .67) indicate that the relationship is positive linear (i.e., the pattern of the dots on the scatter plot runs from the lower left to the upper right), whereas negative values of r (such as r = –.30 or r = –.72) indicate negative linear relationships (i.e., the dots run from the upper left to the lower right). The strength of the linear relationship is indexed by the distance of the correlation coefficient from zero (its absolute value). For instance, r = –.54 is a stronger relationship than r = .30, and r = .72 is a stronger relationship than r = –.57. Because the Pearson correlation coefficient only measures linear relationships, variables that have curvilinear relationships are not well described by r, and the observed correlation will be close to zero.

It is also possible to study relationships among more than two measures at the same time. A research design in which more than one predictor variable is used to predict a single outcome variable is analyzed through multiple regression (Aiken & West, 1991). Multiple regression is a statistical technique, based on correlation coefficients among variables, that allows predicting a single outcome variable from more than one predictor variable. For instance, Figure 3.11 shows a multiple regression analysis in which three predictor variables (Salary, job satisfaction, and years employed) are used to predict a single outcome (job performance). The use of multiple regression analysis shows an important advantage of correlational research designs — they can be used to make predictions about a person’s likely score on an outcome variable (e.g., job performance) based on knowledge of other variables.

An important limitation of correlational research designs is that they cannot be used to draw conclusions about the causal relationships among the measured variables. Consider, for instance, a researcher who has hypothesized that viewing violent behaviour will cause increased aggressive play in children. He has collected, from a sample of Grade 4 children, a measure of how many violent television shows each child views during the week, as well as a measure of how aggressively each child plays on the school playground. From his collected data, the researcher discovers a positive correlation between the two measured variables.

Although this positive correlation appears to support the researcher’s hypothesis, it cannot be taken to indicate that viewing violent television causes aggressive behaviour. Although the researcher is tempted to assume that viewing violent television causes aggressive play, there are other possibilities. One alternative possibility is that the causal direction is exactly opposite from what has been hypothesized. Perhaps children who have behaved aggressively at school develop residual excitement that leads them to want to watch violent television shows at home (Figure 3.13):

Although this possibility may seem less likely, there is no way to rule out the possibility of such reverse causation on the basis of this observed correlation. It is also possible that both causal directions are operating and that the two variables cause each other (Figure 3.14).

Still another possible explanation for the observed correlation is that it has been produced by the presence of a common-causal variable (also known as a third variable). A common-causal variable is a variable that is not part of the research hypothesis but that causes both the predictor and the outcome variable and thus produces the observed correlation between them. In our example, a potential common-causal variable is the discipline style of the children’s parents. Parents who use a harsh and punitive discipline style may produce children who like to watch violent television and who also behave aggressively in comparison to children whose parents use less harsh discipline (Figure 3.15)

In this case, television viewing and aggressive play would be positively correlated (as indicated by the curved arrow between them), even though neither one caused the other but they were both caused by the discipline style of the parents (the straight arrows). When the predictor and outcome variables are both caused by a common-causal variable, the observed relationship between them is said to be spurious. A spurious relationship is a relationship between two variables in which a common-causal variable produces and “explains away” the relationship. If effects of the common-causal variable were taken away, or controlled for, the relationship between the predictor and outcome variables would disappear. In the example, the relationship between aggression and television viewing might be spurious because by controlling for the effect of the parents’ disciplining style, the relationship between television viewing and aggressive behaviour might go away.

Common-causal variables in correlational research designs can be thought of as mystery variables because, as they have not been measured, their presence and identity are usually unknown to the researcher. Since it is not possible to measure every variable that could cause both the predictor and outcome variables, the existence of an unknown common-causal variable is always a possibility. For this reason, we are left with the basic limitation of correlational research: correlation does not demonstrate causation. It is important that when you read about correlational research projects, you keep in mind the possibility of spurious relationships, and be sure to interpret the findings appropriately. Although correlational research is sometimes reported as demonstrating causality without any mention being made of the possibility of reverse causation or common-causal variables, informed consumers of research, like you, are aware of these interpretational problems.

In sum, correlational research designs have both strengths and limitations. One strength is that they can be used when experimental research is not possible because the predictor variables cannot be manipulated. Correlational designs also have the advantage of allowing the researcher to study behaviour as it occurs in everyday life. And we can also use correlational designs to make predictions — for instance, to predict from the scores on their battery of tests the success of job trainees during a training session. But we cannot use such correlational information to determine whether the training caused better job performance. For that, researchers rely on experiments.

Experimental Research: Understanding the Causes of Behaviour

The goal of experimental research design is to provide more definitive conclusions about the causal relationships among the variables in the research hypothesis than is available from correlational designs. In an experimental research design, the variables of interest are called the independent variable (or variables) and the dependent variable. The independent variable in an experiment is the causing variable that is created (manipulated) by the experimenter. The dependent variable in an experiment is a measured variable that is expected to be influenced by the experimental manipulation. The research hypothesis suggests that the manipulated independent variable or variables will cause changes in the measured dependent variables. We can diagram the research hypothesis by using an arrow that points in one direction. This demonstrates the expected direction of causality (Figure 3.16):

Despite the advantage of determining causation, experiments do have limitations. One is that they are often conducted in laboratory situations rather than in the everyday lives of people. Therefore, we do not know whether results that we find in a laboratory setting will necessarily hold up in everyday life. Second, and more important, is that some of the most interesting and key social variables cannot be experimentally manipulated. If we want to study the influence of the size of a mob on the destructiveness of its behaviour, or to compare the personality characteristics of people who join suicide cults with those of people who do not join such cults, these relationships must be assessed using correlational designs, because it is simply not possible to experimentally manipulate these variables.

Image Attributions

Figure 3.4: “Reading newspaper” by Alaskan Dude (http://commons.wikimedia.org/wiki/File:Reading_newspaper.jpg) is licensed under CC BY 2.0

References

Aiken, L., & West, S. (1991). Multiple regression: Testing and interpreting interactions. Newbury Park, CA: Sage.

Ainsworth, M. S., Blehar, M. C., Waters, E., & Wall, S. (1978). Patterns of attachment: A psychological study of the strange situation. Hillsdale, NJ: Lawrence Erlbaum Associates.

Anderson, C. A., & Dill, K. E. (2000). Video games and aggressive thoughts, feelings, and behavior in the laboratory and in life. Journal of Personality and Social Psychology, 78(4), 772–790.

Damasio, H., Grabowski, T., Frank, R., Galaburda, A. M., Damasio, A. R., Cacioppo, J. T., & Berntson, G. G. (2005). The return of Phineas Gage: Clues about the brain from the skull of a famous patient. In Social neuroscience: Key readings. (pp. 21–28). New York, NY: Psychology Press.

Freud, S. (1909/1964). Analysis of phobia in a five-year-old boy. In E. A. Southwell & M. Merbaum (Eds.), Personality: Readings in theory and research (pp. 3–32). Belmont, CA: Wadsworth. (Original work published 1909).

Kotowicz, Z. (2007). The strange case of Phineas Gage. History of the Human Sciences, 20(1), 115–131.

Rokeach, M. (1964). The three Christs of Ypsilanti: A psychological study. New York, NY: Knopf.

Stangor, C. (2011). Research methods for the behavioural sciences (4th ed.). Mountain View, CA: Cengage.

Long Descriptions

Figure 3.6 long description: There are 25 families. 24 families have an income between $44,000 and $111,000 and one family has an income of $3,800,000. The mean income is $223,960 while the median income is $73,000. [Return to Figure 3.6]

Figure 3.10 long description: Types of scatter plots.

1. Positive linear, r=positive .82. The plots on the graph form a rough line that runs from lower left to upper right.
2. Negative linear, r=negative .70. The plots on the graph form a rough line that runs from upper left to lower right.
3. Independent, r=0.00. The plots on the graph are spread out around the centre.
4. Curvilinear, r=0.00. The plots of the graph form a rough line that goes up and then down like a hill.
5. Curvilinear, r=0.00. The plots on the graph for a rough line that goes down and then up like a ditch.

[Return to Figure 3.10]

Good research is valid research. When research is valid, the conclusions drawn by the researcher are legitimate. For instance, if a researcher concludes that participating in psychotherapy reduces anxiety, or that taller people are smarter than shorter people, the research is valid only if the therapy really works or if taller people really are smarter. Unfortunately, there are many threats to the validity of research, and these threats may sometimes lead to unwarranted conclusions. Often, and despite researchers’ best intentions, some of the research reported on websites as well as in newspapers, magazines, and even scientific journals is invalid. Validity is not an all-or-nothing proposition, which means that some research is more valid than other research. Only by understanding the potential threats to validity will you be able to make knowledgeable decisions about the conclusions that can or cannot be drawn from a research project. There are four major types of threats to the validity of research, and informed consumers of research are aware of each type.

One threat to valid research occurs when there is a threat to construct validity. Construct validity refers to the extent to which the variables used in the research adequately assess the conceptual variables they were designed to measure. One requirement for construct validity is that the measure be reliable, where reliability refers to the consistency of a measured variable. A bathroom scale is usually reliable, because if we step on and off it a couple of times, the scale will consistently measure the same weight every time. Other measures, including some psychological tests, may be less reliable, and thus less useful.

Normally, we can assume that the researchers have done their best to assure the construct validity of their measures, but it is not inappropriate for you, as an informed consumer of research, to question this. It is always important to remember that the ability to learn about the relationship between the conceptual variables in a research hypothesis is dependent on the operational definitions of the measured variables. If the measures do not really measure the conceptual variables that they are designed to assess (e.g., if a supposed IQ test does not really measure intelligence), then they cannot be used to draw inferences about the relationship between the conceptual variables (Nunnally, 1978).

The statistical methods that scientists use to test their research hypotheses are based on probability estimates. You will see statements in research reports indicating that the results were statistically significant or not statistically significant. These statements will be accompanied by statistical tests, often including statements such as p < 0.05 or about confidence intervals. These statements describe the statistical significance of the data that have been collected. Statistical significance refers to the confidence with which a scientist can conclude that data are not due to chance or random error. When a researcher concludes that a result is statistically significant, he or she has determined that the observed data was very unlikely to have been caused by chance factors alone. Hence, there is likely a real relationship between or among the variables in the research design. Otherwise, the researcher concludes that the results were not statistically significant.

Statistical conclusion validity refers to the extent to which we can be certain that the researcher has drawn accurate conclusions about the statistical significance of the research. Research will be invalid if the conclusions made about the research hypothesis are incorrect because statistical inferences about the collected data are in error. These errors can occur either because the scientist inappropriately infers that the data do support the research hypothesis when in fact they are due to chance, or when the researcher mistakenly fails to find support for the research hypothesis. Normally, we can assume that the researchers have done their best to ensure the statistical conclusion validity of a research design, but we must always keep in mind that inferences about data are probabilistic and never certain — this is why research never proves a theory.

Internal validity refers to the extent to which we can trust the conclusions that have been drawn about the causal relationship between the independent and dependent variables (Campbell & Stanley, 1963). Internal validity applies primarily to experimental research designs, in which the researcher hopes to conclude that the independent variable has caused the dependent variable. Internal validity is maximized when the research is free from the presence of confounding variables — variables other than the independent variable on which the participants in one experimental condition differ systematically from those in other conditions.

Consider an experiment in which a researcher tested the hypothesis that drinking alcohol makes members of the opposite sex look more attractive. Participants older than 21 years of age were randomly assigned to drink either orange juice mixed with vodka or orange juice alone. To eliminate the need for deception, the participants were told whether or not their drinks contained vodka. After enough time had passed for the alcohol to take effect, the participants were asked to rate the attractiveness of pictures of members of the opposite sex. The results of the experiment showed that, as predicted, the participants who drank the vodka rated the photos as significantly more attractive.

If you think about this experiment for a minute, it may occur to you that although the researcher wanted to draw the conclusion that the alcohol caused the differences in perceived attractiveness, the expectation of having consumed alcohol is confounded with the presence of alcohol. That is, the people who drank alcohol also knew they drank alcohol, and those who did not drink alcohol knew they did not. It is possible that simply knowing that they were drinking alcohol, rather than the effect of the alcohol itself, may have caused the differences (see Figure 3.18, “An Example of Confounding”). One solution to the problem of potential expectancy effects is to tell both groups that they are drinking orange juice and vodka but really give alcohol to only half of the participants (it is possible to do this because vodka has very little smell or taste). If differences in perceived attractiveness are found, the experimenter could then confidently attribute them to the alcohol rather than to the expectancy about having consumed alcohol.

Another threat to internal validity can occur when the experimenter knows the research hypothesis and also knows which experimental condition the participants are in. The outcome is the potential for experimenter bias, a situation in which the experimenter subtly treats the research participants in the various experimental conditions differently, resulting in an invalid confirmation of the research hypothesis. In one study demonstrating experimenter bias, Rosenthal and Fode (1963) sent 12 students to test a research hypothesis concerning maze learning in rats. Although it was not initially revealed to the students, they were actually the participants in an experiment. Six of the students were randomly told that the rats they would be testing had been bred to be highly intelligent, whereas the other six students were led to believe that the rats had been bred to be unintelligent. In reality there were no differences among the rats given to the two groups of students. When the students returned with their data, a startling result emerged. The rats run by students who expected them to be intelligent showed significantly better maze learning than the rats run by students who expected them to be unintelligent. Somehow the students’ expectations influenced their data. They evidently did something different when they tested the rats, perhaps subtly changing how they timed the maze running or how they treated the rats. And this experimenter bias probably occurred entirely out of their awareness.

To avoid experimenter bias, researchers frequently run experiments in which the researchers are blind to condition. This means that although the experimenters know the research hypotheses, they do not know which conditions the participants are assigned to. Experimenter bias cannot occur if the researcher is blind to condition. In a double-blind experiment, both the researcher and the research participants are blind to condition. For instance, in a double-blind trial of a drug, the researcher does not know whether the drug being given is the real drug or the ineffective placebo, and the patients also do not know which they are getting. Double-blind experiments eliminate the potential for experimenter effects and at the same time eliminate participant expectancy effects.

While internal validity refers to conclusions drawn about events that occurred within the experiment, external validity refers to the extent to which the results of a research design can be generalized beyond the specific way the original experiment was conducted. Generalization refers to the extent to which relationships among conceptual variables can be demonstrated in a wide variety of people and a wide variety of manipulated or measured variables.

Psychologists who use university students as participants in their research may be concerned about generalization, wondering if their research will generalize to people who are not college students. And researchers who study the behaviours of employees in one company may wonder whether the same findings would translate to other companies. Whenever there is reason to suspect that a result found for one sample of participants would not hold up for another sample, then research may be conducted with these other populations to test for generalization.

Recently, many psychologists have been interested in testing hypotheses about the extent to which a result will replicate across people from different cultures (Heine, 2010). For instance, a researcher might test whether the effects on aggression of viewing violent video games are the same for Japanese children as they are for Canadian children by showing violent and nonviolent films to a sample of both Japanese and Canadian schoolchildren. If the results are the same in both cultures, then we say that the results have generalized, but if they are different, then we have learned a limiting condition of the effect (see Table 3.4, “A Cross-Cultural Replication”).

Table 3.4 A Cross-Cultural Replication.Adapted by J. Walinga.

Canada	Japan	Gaming behaviour
More aggressive behaviour observed	???	Violent Games
Less aggressive behaviour observed	???	Nonviolent Games

In a cross-cultural replication, external validity is observed if the same effects that have been found in one culture are replicated in another culture. If they are not replicated in the new culture, then a limiting condition of the original results is found.

Unless the researcher has a specific reason to believe that generalization will not hold, it is appropriate to assume that a result found in one population (even if that population is college or university students) will generalize to other populations. Because the investigator can never demonstrate that the research results generalize to all populations, it is not expected that the researcher will attempt to do so. Rather, the burden of proof rests on those who claim that a result will not generalize.

Because any single test of a research hypothesis will always be limited in terms of what it can show, important advances in science are never the result of a single research project. Advances occur through the accumulation of knowledge that comes from many different tests of the same theory or research hypothesis. These tests are conducted by different researchers using different research designs, participants, and operationalizations of the independent and dependent variables. The process of repeating previous research, which forms the basis of all scientific inquiry, is known as replication.

Scientists often use a procedure known as meta-analysis to summarize replications of research findings. A meta-analysis is a statistical technique that uses the results of existing studies to integrate and draw conclusions about those studies. Because meta-analyses provide so much information, they are very popular and useful ways of summarizing research literature.

A meta-analysis provides a relatively objective method of reviewing research findings because it (a) specifies inclusion criteria that indicate exactly which studies will or will not be included in the analysis, (b) systematically searches for all studies that meet the inclusion criteria, and (c) provides an objective measure of the strength of observed relationships. Frequently, the researchers also include — if they can find them — studies that have not been published in journals.

References

Campbell, D. T., & Stanley, J. C. (1963). Experimental and quasi-experimental designs for research. Chicago: Rand McNally.

Heine, S. J. (2010). Cultural psychology. In S. T. Fiske, D. T. Gilbert, & G. Lindzey (Eds.), Handbook of social psychology (5th ed., Vol. 2, pp. 1423–1464). Hoboken, NJ: John Wiley & Sons.

Nunnally, J. C. (1978). Pyschometric theory. New York, NY: McGraw-Hill.

Rosenthal, R., & Fode, K. L. (1963). The effect of experimenter bias on the performance of the albino rat. Behavioral Science, 8, 183–189.

Stangor, C. (2011). Research methods for the behavioral sciences (4th ed.). Mountain View, CA: Cengage.

Psychologists study the behaviour of both humans and animals in order to understand and improve the quality of human lives.

Psychological research may be either basic or applied in orientation. Basic research and applied research inform each other, and advances in science occur more rapidly when both types of research are conducted.

The results of psychological research are reported primarily in research reports in scientific journals. These research reports have been evaluated, critiqued, and improved by other scientists through the process of peer review.

The methods used by scientists have developed over many years and provide a common framework through which information can be collected, organized, and shared.

The scientific method is the set of assumptions, rules, and procedures that scientists use to conduct research. In addition to requiring that science be empirical, the scientific method demands that the procedures used be objective, or free from personal bias.

Scientific findings are organized by theories, which are used to summarize and make new predictions, but theories are usually framed too broadly to be tested in a single experiment. Therefore, scientists normally use the research hypothesis as a basis for their research.

Scientists use operational definitions to turn the ideas of interest — conceptual variables — into measured variables.

Decisions about whether psychological research using human and animals is ethical are made using established ethical codes developed by scientific organizations and on the basis of judgments made by the local Ethical Review Board. These decisions are made through a cost-benefit analysis designed to protect human participants, in which the costs to human participants are compared with the benefits. If the potential costs of the research appear to outweigh any potential benefits that might come from it, then the research should not proceed.

Descriptive research is designed to provide a snapshot of the current state of affairs. Descriptive research allows the development of questions for further study but does not assess relationships among variables. The results of descriptive research projects are analyzed using descriptive statistics.

Correlational research assesses the relationships between and among two or more variables. It allows making predictions but cannot be used to draw inferences about the causal relationships between and among the variables. Linear relationships between variables are normally analyzed using the Pearson correlation coefficient.

The goal of experimental research is to assess the causal impact of one or more experimental manipulations on a dependent variable. Because experimental research creates initial equivalence among the participants in the different experimental conditions, it allows drawing conclusions about the causal relationships among variables. Experimental designs are not always possible because many important variables cannot be experimentally manipulated.

Because all research has the potential for invalidity, research never “proves” a theory or hypothesis.

Threats to construct validity involve potential inaccuracies in the measurement of the conceptual variables.

Threats to statistical conclusion validity involve potential inaccuracies in the statistical testing of the relationships among variables.

Threats to internal validity involve potential inaccuracies in assumptions about the causal role of the independent variable on the dependent variable.

Threats to external validity involve potential inaccuracy regarding the generality of observed findings.

Informed consumers of research are aware of the strengths of research but are also aware of its potential limitations.

Every behaviour begins with biology. Our behaviours, as well as our thoughts and feelings, are produced by the actions of our brains, nerves, muscles, and glands. In this chapter we will begin our journey into the world of psychology by considering the biological makeup of the human being, including the most remarkable of human organs—the brain. We’ll consider the structure of the brain and also the methods that psychologists use to study the brain and to understand how it works.

We will see that the body is controlled by an information highway known as the nervous system, a collection of hundreds of billions of specialized and interconnected cells through which messages are sent between the brain and the rest of the body. The nervous system consists of the central nervous system (CNS), made up of the brain and the spinal cord, and the peripheral nervous system (PNS), the neurons that link the CNS to our skin, muscles, and glands. And we will see that our behaviour is also influenced in large part by the endocrine system, the chemical regulator of the body that consists of glands that secrete hormones.

Although this chapter begins at a very low level of explanation, and although the topic of study may seem at first to be far from the everyday behaviours that we all engage in, a full understanding of the biology underlying psychological processes is an important cornerstone of your new understanding of psychology. We will consider throughout the chapter how our biology influences important human behaviours, including our mental and physical health, our reactions to drugs, as well as our aggressive responses and our perceptions of other people. This chapter is particularly important for contemporary psychology because the ability to measure biological aspects of behaviour, including the structure and function of the human brain, is progressing rapidly, and understanding the biological foundations of behaviour is an increasingly important line of psychological study.

References

Aldhous, P. (2008, April 7). “Boléro”: Beautiful symptom of a terrible disease. New Scientist. Retrieved from http://www.newscientist.com/article/dn13599-bolero-beautiful-symptom-of-a-terrible-disease.html

Amaducci, L., Grassi, E., & Boller, F. (2002). Maurice Ravel and right-hemisphere musical creativity: Influence of disease on his last musical works? European Journal of Neurology, 9(1), 75–82.

Miller, B. L., Boone, K., Cummings, J. L., Read, S. L., & Mishkin, F. (2000). Functional correlates of musical and visual ability in frontotemporal dementia. British Journal of Psychiatry, 176, 458–463.

Seeley, W. W., Matthews, B. R., Crawford, R. K., Gorno-Tempini, M. L., Foti, D., Mackenzie, I. R., & Miller, B. L. (2008). “Unravelling Boléro”: Progressive aphasia, transmodal creativity, and the right posterior neocortex. Brain, 131(1), 39–49.

The nervous system is composed of more than 100 billion cells known as neurons. A neuron is a cell in the nervous system whose function it is to receive and transmit information. As you can see in Figure 4.1, “Components of the Neuron,” neurons are made up of three major parts: a cell body, or soma, which contains the nucleus of the cell and keeps the cell alive; a branching treelike fibre known as the dendrite, which collects information from other cells and sends the information to the soma; and a long, segmented fibre known as the axon, which transmits information away from the cell body toward other neurons or to the muscles and glands. Figure 4.2 shows a photograph of neurons taken using confocal microscopy.

 

Some neurons have hundreds or even thousands of dendrites, and these dendrites may themselves be branched to allow the cell to receive information from thousands of other cells. The axons are also specialized, and some, such as those that send messages from the spinal cord to the muscles in the hands or feet, may be very long — even up to several feet in length. To improve the speed of their communication, and to keep their electrical charges from shorting out with other neurons, axons are often surrounded by a myelin sheath. The myelin sheath is a layer of fatty tissue surrounding the axon of a neuron that both acts as an insulator and allows faster transmission of the electrical signal. Axons branch out toward their ends, and at the tip of each branch is a terminal button.

Neurons Communicate Using Electricity and Chemicals

The nervous system operates using an electrochemical process. An electrical charge moves through the neuron itself, and chemicals are used to transmit information between neurons. Within the neuron, when a signal is received by the dendrites, it is transmitted to the soma in the form of an electrical signal, and, if the signal is strong enough, it may then be passed on to the axon and then to the terminal buttons. If the signal reaches the terminal buttons, they are signalled to emit chemicals known as neurotransmitters, which communicate with other neurons across the spaces between the cells, known as synapses.

The following video clip shows a model of the electrochemical action of the neuron and neurotransmitters:

The Electrochemical Action of the Neuron [YouTube]: http://www.youtube.com/watch?v=TKG0MtH5crc

 

The electrical signal moves through the neuron as a result of changes in the electrical charge of the axon. Normally, the axon remains in the resting potential, a state in which the interior of the neuron contains a greater number of negatively charged ions than does the area outside the cell. When the segment of the axon that is closest to the cell body is stimulated by an electrical signal from the dendrites, and if this electrical signal is strong enough that it passes a certain level or threshold, the cell membrane in this first segment opens its gates, allowing positively charged sodium ions that were previously kept out to enter. This change in electrical charge that occurs in a neuron when a nerve impulse is transmitted is known as the action potential. Once the action potential occurs, the number of positive ions exceeds the number of negative ions in this segment, and the segment temporarily becomes positively charged.

As you can see in Figure 4.3, “The Myelin Sheath and the Nodes of Ranvier,” the axon is segmented by a series of breaks between the sausage-like segments of the myelin sheath. Each of these gaps is a node of Ranvier.The break in the myelin sheath of a nerve fibre. The electrical charge moves down the axon from segment to segment, in a set of small jumps, moving from node to node. When the action potential occurs in the first segment of the axon, it quickly creates a similar change in the next segment, which then stimulates the next segment, and so forth as the positive electrical impulse continues all the way down to the end of the axon. As each new segment becomes positive, the membrane in the prior segment closes up again, and the segment returns to its negative resting potential. In this way the action potential is transmitted along the axon, toward the terminal buttons. The entire response along the length of the axon is very fast — it can happen up to 1,000 times each second.

An important aspect of the action potential is that it operates in an all or nothing manner. What this means is that the neuron either fires completely, such that the action potential moves all the way down the axon, or it does not fire at all. Thus neurons can provide more energy to the neurons down the line by firing faster but not by firing more strongly. Furthermore, the neuron is prevented from repeated firing by the presence of a refractory period — a brief time after the firing of the axon in which the axon cannot fire again because the neuron has not yet returned to its resting potential.

Neurotransmitters: The Body’s Chemical Messengers

Not only do the neural signals travel via electrical charges within the neuron, but they also travel via chemical transmission between the neurons. Neurons are separated by junction areas known as synapses,The small gap between neurons across which nerve impulses are transmitted. areas where the terminal buttons at the end of the axon of one neuron nearly, but don’t quite, touch the dendrites of another. The synapses provide a remarkable function because they allow each axon to communicate with many dendrites in neighbouring cells. Because a neuron may have synaptic connections with thousands of other neurons, the communication links among the neurons in the nervous system allow for a highly sophisticated communication system.

When the electrical impulse from the action potential reaches the end of the axon, it signals the terminal buttons to release neurotransmitters into the synapse. A neurotransmitter is a chemical that relays signals across the synapses between neurons. Neurotransmitters travel across the synaptic space between the terminal button of one neuron and the dendrites of other neurons, where they bind to the dendrites in the neighbouring neurons. Furthermore, different terminal buttons release different neurotransmitters, and different dendrites are particularly sensitive to different neurotransmitters. The dendrites will admit the neurotransmitters only if they are the right shape to fit in the receptor sites on the receiving neuron. For this reason, the receptor sites and neurotransmitters are often compared to a lock and key (Figure 4.4, “The Synapse”).

When neurotransmitters are accepted by the receptors on the receiving neurons, their effect may be either excitatory (i.e., they make the cell more likely to fire) or inhibitory (i.e., they make the cell less likely to fire). Furthermore, if the receiving neuron is able to accept more than one neurotransmitter, it will be influenced by the excitatory and inhibitory processes of each. If the excitatory effects of the neurotransmitters are greater than the inhibitory influences of the neurotransmitters, the neuron moves closer to its firing threshold; if it reaches the threshold, the action potential and the process of transferring information through the neuron begins.

Neurotransmitters that are not accepted by the receptor sites must be removed from the synapse in order for the next potential stimulation of the neuron to happen. This process occurs in part through the breaking down of the neurotransmitters by enzymes, and in part through reuptake, a process in which neurotransmitters that are in the synapse are reabsorbed into the transmitting terminal buttons, ready to again be released after the neuron fires.

More than 100 chemical substances produced in the body have been identified as neurotransmitters, and these substances have a wide and profound effect on emotion, cognition, and behaviour. Neurotransmitters regulate our appetite, our memory, our emotions, as well as our muscle action and movement. And as you can see in Table 4.1, “The Major Neurotransmitters and Their Functions,” some neurotransmitters are also associated with psychological and physical diseases.

Drugs that we might ingest — either for medical reasons or recreationally — can act like neurotransmitters to influence our thoughts, feelings, and behaviour. An agonist is a drug that has chemical properties similar to a particular neurotransmitter and thus mimics the effects of the neurotransmitter. When an agonist is ingested, it binds to the receptor sites in the dendrites to excite the neuron, acting as if more of the neurotransmitter had been present. As an example, cocaine is an agonist for the neurotransmitter dopamine. Because dopamine produces feelings of pleasure when it is released by neurons, cocaine creates similar feelings when it is ingested. An antagonist is a drug that reduces or stops the normal effects of a neurotransmitter. When an antagonist is ingested, it binds to the receptor sites in the dendrite, thereby blocking the neurotransmitter. As an example, the poison curare is an antagonist for the neurotransmitter acetylcholine. When the poison enters the brain, it binds to the dendrites, stops communication among the neurons, and usually causes death. Still other drugs work by blocking the reuptake of the neurotransmitter itself — when reuptake is reduced by the drug, more neurotransmitter remains in the synapse, increasing its action.

Table 4.1 The Major Neurotransmitters and Their Functions

[Skip Table]
Neurotransmitter	Description and function	Notes
Acetylcholine (ACh)	A common neurotransmitter used in the spinal cord and motor neurons to stimulate muscle contractions. It’s also used in the brain to regulate memory, sleeping, and dreaming.	Alzheimer’s disease is associated with an undersupply of acetylcholine. Nicotine is an agonist that acts like acetylcholine.
Dopamine	Involved in movement, motivation, and emotion, Dopamine produces feelings of pleasure when released by the brain’s reward system, and it’s also involved in learning.	Schizophrenia is linked to increases in dopamine, whereas Parkinson’s disease is linked to reductions in dopamine (and dopamine agonists may be used to treat it).
Endorphins	Released in response to behaviours such as vigorous exercise, orgasm, and eating spicy foods.	Endorphins are natural pain relievers. They are related to the compounds found in drugs such as opium, morphine, and heroin. The release of endorphins creates the runner’s high that is experienced after intense physical exertion.
GABA (gamma-aminobutyric acid)	The major inhibitory neurotransmitter in the brain.	A lack of GABA can lead to involuntary motor actions, including tremors and seizures. Alcohol stimulates the release of GABA, which inhibits the nervous system and makes us feel drunk. Low levels of GABA can produce anxiety, and GABA agonists (tranquilizers) are used to reduce anxiety.
Glutamate	The most common neurotransmitter, it’s released in more than 90% of the brain’s synapses. Glutamate is found in the food additive MSG (monosodium glutamate).	Excess glutamate can cause overstimulation, migraines, and seizures.
Serotonin	Involved in many functions, including mood, appetite, sleep, and aggression.	Low levels of serotonin are associated with depression, and some drugs designed to treat depression (known as selective serotonin reuptake inhibitors, or SSRIs) serve to prevent their reuptake.

Image Attributions

Figure 4.2: “Confocal microscopy of mouse brain, cortex” by ZEISS Microscopy (http://www.flickr.com/photos/zeissmicro/10799674936/in/photostream/) used under CC BY-NC-ND 2.0  (http://creativecommons.org/licenses/by-nc-nd/2.0/deed.en_CA) license.

If you were someone who understood brain anatomy and were to look at the brain of an animal that you had never seen before, you would nevertheless be able to deduce the likely capacities of the animal. This is because the brains of all animals are very similar in overall form. In each animal the brain is layered, and the basic structures of the brain are similar (see Figure 4.5, “The Major Structures in the Human Brain”). The innermost structures of the brain — the parts nearest the spinal cord — are the oldest part of the brain, and these areas carry out the same functions they did for our distant ancestors. The “old brain” regulates basic survival functions, such as breathing, moving, resting, and feeding, and creates our experiences of emotion. Mammals, including humans, have developed further brain layers that provide more advanced functions — for instance, better memory, more sophisticated social interactions, and the ability to experience emotions. Humans have a very large and highly developed outer layer known as the cerebral cortex (see Figure 4.6, “Cerebral Cortex”), which makes us particularly adept at these processes.

 

 

The Old Brain: Wired for Survival

The brain stem is the oldest and innermost region of the brain. It’s designed to control the most basic functions of life, including breathing, attention, and motor responses (Figure 4.7, “The Brain Stem and the Thalamus”). The brain stem begins where the spinal cord enters the skull and forms the medulla, the area of the brain stem that controls heart rate and breathing. In many cases the medulla alone is sufficient to maintain life — animals that have the remainder of their brains above the medulla severed are still able to eat, breathe, and even move. The spherical shape above the medulla is the pons, a structure in the brain stem that helps control the movements of the body, playing a particularly important role in balance and walking.

Running through the medulla and the pons is a long, narrow network of neurons known as the reticular formation. The job of the reticular formation is to filter out some of the stimuli that are coming into the brain from the spinal cord and to relay the remainder of the signals to other areas of the brain. The reticular formation also plays important roles in walking, eating, sexual activity, and sleeping. When electrical stimulation is applied to the reticular formation of an animal, it immediately becomes fully awake, and when the reticular formation is severed from the higher brain regions, the animal falls into a deep coma.

 

Above the brain stem are other parts of the old brain that also are involved in the processing of behaviour and emotions (see Figure 4.8, “The Limbic System”). The thalamus is the egg-shaped structure above the brain stem that applies still more filtering to the sensory information that is coming up from the spinal cord and through the reticular formation, and it relays some of these remaining signals to the higher brain levels (Sherman & Guillery, 2006). The thalamus also receives some of the higher brain’s replies, forwarding them to the medulla and the cerebellum. The thalamus is also important in sleep because it shuts off incoming signals from the senses, allowing us to rest.

The cerebellum (literally, “little brain”) consists of two wrinkled ovals behind the brain stem. It functions to coordinate voluntary movement. People who have damage to the cerebellum have difficulty walking, keeping their balance, and holding their hands steady. Consuming alcohol influences the cerebellum, which is why people who are drunk have more difficulty walking in a straight line. Also, the cerebellum contributes to emotional responses, helps us discriminate between different sounds and textures, and is important in learning (Bower & Parsons, 2003).

Whereas the primary function of the brain stem is to regulate the most basic aspects of life, including motor functions, the limbic system is largely responsible for memory and emotions, including our responses to reward and punishment. The limbic system is a brain area, located between the brain stem and the two cerebral hemispheres, that governs emotion and memory. It includes the amygdala, the hypothalamus, and the hippocampus.

The amygdala consists of two “almond-shaped” clusters (amygdala comes from the Latin word for “almond”) and is primarily responsible for regulating our perceptions of, and reactions to, aggression and fear. The amygdala has connections to other bodily systems related to fear, including the sympathetic nervous system (which we will see later is important in fear responses), facial responses (which perceive and express emotions), the processing of smells, and the release of neurotransmitters related to stress and aggression (Best, 2009). In one early study, Klüver and Bucy (1939) damaged the amygdala of an aggressive rhesus monkey. They found that the once angry animal immediately became passive and no longer responded to fearful situations with aggressive behaviour. Electrical stimulation of the amygdala in other animals also influences aggression. In addition to helping us experience fear, the amygdala also helps us learn from situations that create fear. When we experience events that are dangerous, the amygdala stimulates the brain to remember the details of the situation so that we learn to avoid it in the future (Sigurdsson, Doyère, Cain, & LeDoux, 2007).

Located just under the thalamus (hence its name), the hypothalamus is a brain structure that contains a number of small areas that perform a variety of functions, including the regulation of hunger and sexual behaviour, as well as linking the nervous system to the endocrine system via the pituitary gland. Through its many interactions with other parts of the brain, the hypothalamus helps regulate body temperature, hunger, thirst, and sex, and responds to the satisfaction of these needs by creating feelings of pleasure. Olds and Milner (1954) discovered these reward centres accidentally after they had momentarily stimulated the hypothalamus of a rat. The researchers noticed that after being stimulated, the rat continued to move to the exact spot in its cage where the stimulation had occurred, as if it were trying to re-create the circumstances surrounding its original experience. Upon further research into these reward centres, Olds (1958) discovered that animals would do almost anything to re-create enjoyable stimulation, including crossing a painful electrified grid to receive it. In one experiment a rat was given the opportunity to electrically stimulate its own hypothalamus by pressing a pedal. The rat enjoyed the experience so much that it pressed the pedal more than 7,000 times per hour until it collapsed from sheer exhaustion.

The hippocampus consists of two “horns” that curve back from the amygdala. The hippocampus is important in storing information in long-term memory. If the hippocampus is damaged, a person cannot build new memories, living instead in a strange world where everything he or she experiences just fades away, even while older memories from the time before the damage are untouched.

The Cerebral Cortex Creates Consciousness and Thinking

All animals have adapted to their environments by developing abilities that help them survive. Some animals have hard shells, others run extremely fast, and some have acute hearing. Human beings do not have any of these particular characteristics, but we do have one big advantage over other animals — we are very, very smart.

You might think that we should be able to determine the intelligence of an animal by looking at the ratio of the animal’s brain weight to the weight of its entire body. But this does not really work. The elephant’s brain is one-thousandth of its weight, but the whale’s brain is only one ten-thousandth of its body weight. On the other hand, although the human brain is one-sixtieth of its body weight, the mouse’s brain represents one-fortieth of its body weight. Despite these comparisons, elephants do not seem 10 times smarter than whales, and humans definitely seem smarter than mice.

The key to the advanced intelligence of humans is not found in the size of our brains. What sets humans apart from other animals is our larger cerebral cortex — the outer bark-like layer of our brain that allows us to so successfully use language, acquire complex skills, create tools, and live in social groups (Gibson, 2002). In humans, the cerebral cortex is wrinkled and folded, rather than smooth as it is in most other animals. This creates a much greater surface area and size, and allows increased capacities for learning, remembering, and thinking. The folding of the cerebral cortex is referred to as corticalization.

Although the cortex is only about one-tenth of an inch thick, it makes up more than 80% of the brain’s weight. The cortex contains about 20 billion nerve cells and 300 trillion synaptic connections (de Courten-Myers, 1999). Supporting all these neurons are billions more glial cells (glia), cells that surround and link to the neurons, protecting them, providing them with nutrients, and absorbing unused neurotransmitters. The glia come in different forms and have different functions. For instance, the myelin sheath surrounding the axon of many neurons is a type of glial cell. The glia are essential partners of neurons, without which the neurons could not survive or function (Miller, 2005).

The cerebral cortex is divided into two hemispheres, and each hemisphere is divided into four lobes, each separated by folds known as fissures. If we look at the cortex starting at the front of the brain and moving over the top (see Figure 4.9, “The Two Hemispheres”), we see first the frontal lobe (behind the forehead), which is responsible primarily for thinking, planning, memory, and judgment. Following the frontal lobe is the parietal lobe, which extends from the middle to the back of the skull and which is responsible primarily for processing information about touch. Then comes the occipital lobe at the very back of the skull, which processes visual information. Finally, in front of the occipital lobe (pretty much between the ears) is the temporal lobe, responsible primarily for hearing and language.

Functions of the Cortex

When the German physicists Gustav Fritsch and Eduard Hitzig (1870/2009) applied mild electric stimulation to different parts of a dog’s cortex, they discovered that they could make different parts of the dog’s body move. Furthermore, they discovered an important and unexpected principle of brain activity. They found that stimulating the right side of the brain produced movement in the left side of the dog’s body, and vice versa. This finding follows from a general principle about how the brain is structured, called contralateral control, meaning the brain is wired such that in most cases the left hemisphere receives sensations from and controls the right side of the body, and vice versa.

Fritsch and Hitzig also found that the movement that followed the brain stimulation only occurred when they stimulated a specific arch-shaped region that runs across the top of the brain from ear to ear, just at the front of the parietal lobe (see Figure 4.10, “The Sensory Cortex and the Motor Cortex”). Fritsch and Hitzig had discovered the motor cortex, the part of the cortex that controls and executes movements of the body by sending signals to the cerebellum and the spinal cord. More recent research has mapped the motor cortex even more fully, by providing mild electronic stimulation to different areas of the motor cortex in fully conscious patients while observing their bodily responses (because the brain has no sensory receptors, these patients feel no pain). As you can see in Figure 4.10, “The Sensory Cortex and the Motor Cortex,” this research has revealed that the motor cortex is specialized for providing control over the body, in the sense that the parts of the body that require more precise and finer movements, such as the face and the hands, also are allotted the greatest amount of cortical space.

Just as the motor cortex sends out messages to the specific parts of the body, the somatosensory cortex, an area just behind and parallel to the motor cortex at the back of the frontal lobe, receives information from the skin’s sensory receptors and the movements of different body parts. Again, the more sensitive the body region, the more area is dedicated to it in the sensory cortex. Our sensitive lips, for example, occupy a large area in the sensory cortex, as do our fingers and genitals.

Other areas of the cortex process other types of sensory information. The visual cortex is the area located in the occipital lobe (at the very back of the brain) that processes visual information. If you were stimulated in the visual cortex, you would see flashes of light or colour, and perhaps you remember having had the experience of “seeing stars” when you were hit in, or fell on, the back of your head. The temporal lobe, located on the lower side of each hemisphere, contains the auditory cortex, which is responsible for hearing and language. The temporal lobe also processes some visual information, providing us with the ability to name the objects around us (Martin, 2007).

The motor and sensory areas of the cortex account for a relatively small part of the total cortex. The remainder of the cortex is made up of association areas in which sensory and motor information is combined and associated with our stored knowledge. These association areas are the places in the brain that are responsible for most of the things that make human beings seem human. The association areas are involved in higher mental functions, such as learning, thinking, planning, judging, moral reflecting, figuring, and spatial reasoning.

The Brain Is Flexible: Neuroplasticity

The control of some specific bodily functions, such as movement, vision, and hearing, is performed in specified areas of the cortex, and if these areas are damaged, the individual will likely lose the ability to perform the corresponding function. For instance, if an infant suffers damage to facial recognition areas in the temporal lobe, it is likely that he or she will never be able to recognize faces (Farah, Rabinowitz, Quinn, & Liu, 2000). On the other hand, the brain is not divided up in an entirely rigid way. The brain’s neurons have a remarkable capacity to reorganize and extend themselves to carry out particular functions in response to the needs of the organism and to repair damage. As a result, the brain constantly creates new neural communication routes and rewires existing ones. Neuroplasticity refers to the brain’s ability to change its structure and function in response to experience or damage. Neuroplasticity enables us to learn and remember new things and adjust to new experiences.

Our brains are the most “plastic” when we are young children, as it is during this time that we learn the most about our environment. On the other hand, neuroplasticity continues to be observed even in adults (Kolb & Fantie, 1989). The principles of neuroplasticity help us understand how our brains develop to reflect our experiences. For instance, accomplished musicians have a larger auditory cortex compared with the general population (Bengtsson et al., 2005) and also require less neural activity to move their fingers over the keys than do novices (Münte, Altenmüller, & Jäncke, 2002). These observations reflect the changes in the brain that follow our experiences.

Plasticity is also observed when there is damage to the brain or to parts of the body that are represented in the motor and sensory cortexes. When a tumour in the left hemisphere of the brain impairs language, the right hemisphere will begin to compensate to help the person recover the ability to speak (Thiel et al., 2006). And if a person loses a finger, the area of the sensory cortex that previously received information from the missing finger will begin to receive input from adjacent fingers, causing the remaining digits to become more sensitive to touch (Fox, 1984).

Although neurons cannot repair or regenerate themselves as skin or blood vessels can, new evidence suggests that the brain can engage in neurogenesis, the forming of new neurons (Van Praag, Zhao, Gage, & Gazzaniga, 2004). These new neurons originate deep in the brain and may then migrate to other brain areas, where they form new connections with other neurons (Gould, 2007). This leaves open the possibility that someday scientists might be able to “rebuild” damaged brains by creating drugs that help grow neurons.

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Jones, G. V., & Martin, M. (2000). A note on Corballis (1997) and the genetics and evolution of handedness: Developing a unified distributional model from the sex-chromosomes gene hypothesis. Psychological Review, 107(1), 213–218.

Klüver, H., & Bucy, P. C. (1939). Preliminary analysis of functions of the temporal lobes in monkeys. Archives of Neurology & Psychiatry (Chicago), 42, 979–1000.

Kolb, B., & Fantie, B. (1989). Development of the child’s brain and behavior. In C. R. Reynolds & E. Fletcher-Janzen (Eds.), Handbook of clinical child neuropsychology (pp. 17–39). New York, NY: Plenum Press.

Martin, A. (2007). The representation of object concepts in the brain. Annual Review of Psychology, 58, 25–45.

McKeever, W. F., Cerone, L. J., Suter, P. J., & Wu, S. M. (2000). Family size, miscarriage-proneness, and handedness: Tests of hypotheses of the developmental instability theory of handedness. Laterality: Asymmetries of Body, Brain, and Cognition, 5(2), 111–120.

McManus, I. C. (2002). Right hand, left hand: The origins of asymmetry in brains, bodies, atoms, and cultures. Cambridge, MA: Harvard University Press.

Miller, G. (2005). Neuroscience: The dark side of glia. Science, 308(5723), 778–781.

Münte, T. F., Altenmüller, E., & Jäncke, L. (2002). The musician’s brain as a model of neuroplasticity. Nature Reviews Neuroscience, 3(6), 473–478.

Olds, J. (1958). Self-stimulation of the brain: Its use to study local effects of hunger, sex, and drugs. Science, 127, 315–324.

Olds, J., & Milner, P. (1954). Positive reinforcement produced by electrical stimulation of septal area and other regions of rat brain. Journal of Comparative and Physiological Psychology, 47, 419–427.

Peters, M., Reimers, S., & Manning, J. T. (2006). Hand preference for writing and associations with selected demographic and behavioral variables in 255,100 subjects: The BBC Internet study. Brain and Cognition, 62(2), 177–189.

Sherman, S. M., & Guillery, R. W. (2006). Exploring the thalamus and its role in cortical function (2nd ed.). Cambridge, MA: MIT Press.

Sigurdsson, T., Doyère, V., Cain, C. K., & LeDoux, J. E. (2007). Long-term potentiation in the amygdala: A cellular mechanism of fear learning and memory. Neuropharmacology, 52(1), 215–227.

Soroker, N., Kasher, A., Giora, R., Batori, G., Corn, C., Gil, M., & Zaidel, E. (2005). Processing of basic speech acts following localized brain damage: A new light on the neuroanatomy of language. Brain and Cognition, 57(2), 214–217.

Springer, S. P., & Deutsch, G. (1998). Left brain, right brain: Perspectives from cognitive neuroscience (5th ed.). A series of books in psychology. New York, NY: W. H. Freeman/Times Books/Henry Holt & Co.

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Image Attributions

Figure 4.5: Anatomy of the Brain by artlessstacey (http://commons.wikimedia.org/wiki/File:Brain_headBorder.jpg) is in the public domain.

Figure 4.6: Adapted from Wikia Education. (n.d.). Cerebral cortex. Retrieved from http://psychology.wikia.com/wiki/Cerebral_cortex

One problem in understanding the brain is that it is difficult to get a good picture of what is going on inside it. But there are a variety of empirical methods that allow scientists to look at brains in action, and the number of possibilities has increased dramatically in recent years with the introduction of new neuroimaging techniques. In this section we will consider the various techniques that psychologists use to learn about the brain. Each of the different techniques has some advantages, and when we put them together, we begin to get a relatively good picture of how the brain functions and which brain structures control which activities. Perhaps the most immediate approach to visualizing and understanding the structure of the brain is to directly analyze the brains of human cadavers. When Albert Einstein died in 1955, his brain was removed and stored for later analysis. Researcher Marian Diamond (1999) later analyzed a section of Einstein’s cortex to investigate its characteristics. Diamond was interested in the role of glia, and she hypothesized that the ratio of glial cells to neurons was an important determinant of intelligence. To test this hypothesis, she compared the ratio of glia to neurons in Einstein’s brain with the ratio in the preserved brains of 11 other more “ordinary” men. However, Diamond was able to find support for only part of her research hypothesis. Although she found that Einstein’s brain had relatively more glia in all the areas that she studied than did the control group, the difference was only statistically significant in one of the areas she tested. Diamond admits a limitation in her study is that she had only one Einstein to compare with 11 ordinary men.

Lesions Provide a Picture of What Is Missing

An advantage of the cadaver approach is that the brains can be fully studied, but an obvious disadvantage is that the brains are no longer active. In other cases, however, we can study living brains. The brains of living human beings may be damaged — as a result of strokes, falls, automobile accidents, gunshots, or tumours, for instance. These damages are called lesions. In rare occasions, brain lesions may be created intentionally through surgery, such as that designed to remove brain tumours or (as in split-brain patients) reduce the effects of epilepsy. Psychologists also sometimes intentionally create lesions in animals to study the effects on their behaviour. In so doing, they hope to be able to draw inferences about the likely functions of human brains from the effects of the lesions in animals. Lesions allow the scientist to observe any loss of brain function that may occur. For instance, when an individual suffers a stroke, a blood clot deprives part of the brain of oxygen, killing the neurons in the area and rendering that area unable to process information. In some cases, the result of the stroke is a specific lack of ability. For instance, if the stroke influences the occipital lobe, then vision may suffer, and if the stroke influences the areas associated with language or speech, these functions will suffer. In fact, our earliest understanding of the specific areas involved in speech and language were gained by studying patients who had experienced strokes.

It is now known that a good part of our moral reasoning abilities is located in the frontal lobe, and at least some of this understanding comes from lesion studies. For instance, consider the well-known case of Phineas Gage (Figure 4.12) , a 25-year-old railroad worker who, as a result of an explosion, had an iron rod driven into his cheek and out through the top of his skull, causing major damage to his frontal lobe (Macmillan, 2000). Although, remarkably, Gage was able to return to work after the wounds healed, he no longer seemed to be the same person to those who knew him. The amiable, soft-spoken Gage had become irritable, rude, irresponsible, and dishonest. Although there are questions about the interpretation of this case study (Kotowicz, 2007), it did provide early evidence that the frontal lobe is involved in emotion and morality (Damasio et al., 2005). More recent and more controlled research has also used patients with lesions to investigate the source of moral reasoning. Michael Koenigs and his colleagues (Koenigs et al., 2007) asked groups of normal persons, individuals with lesions in the frontal lobes, and individuals with lesions in other places in the brain to respond to scenarios that involved doing harm to a person, even though the harm ultimately saved the lives of other people (Miller, 2008). In one of the scenarios the participants were asked if they would be willing to kill one person in order to prevent five other people from being killed. As you can see in Figure 4.13, “The Frontal Lobe and Moral Judgment,” they found that the individuals with lesions in the frontal lobe were significantly more likely to agree to do the harm than were individuals from the two other groups.

Recording Electrical Activity in the Brain

In addition to lesion approaches, it is also possible to learn about the brain by studying the electrical activity created by the firing of its neurons. One approach, primarily used with animals, is to place detectors in the brain to study the responses of specific neurons. Research using these techniques has found, for instance, that there are specific neurons, known as feature detectors, in the visual cortex that detect movement, lines and edges, and even faces (Kanwisher, 2000).

A less invasive approach, and one that can be used on living humans, is electroencephalography (EEG), as shown in Figure 4.14. The EEG is a technique that records the electrical activity produced by the brain’s neurons through the use of electrodes that are placed around the research participant’s head. An EEG can show if a person is asleep, awake, or anesthetized because the brainwave patterns are known to differ during each state. EEGs can also track the waves that are produced when a person is reading, writing, and speaking, and are useful for understanding brain abnormalities, such as epilepsy. A particular advantage of EEG is that the participant can move around while the recordings are being taken, which is useful when measuring brain activity in children, who often have difficulty keeping still. Furthermore, by following electrical impulses across the surface of the brain, researchers can observe changes over very fast time periods.

Peeking inside the Brain: Neuroimaging

Although the EEG can provide information about the general patterns of electrical activity within the brain, and although the EEG allows the researcher to see these changes quickly as they occur in real time, the electrodes must be placed on the surface of the skull, and each electrode measures brainwaves from large areas of the brain. As a result, EEGs do not provide a very clear picture of the structure of the brain. But techniques exist to provide more specific brain images. Functional magnetic resonance imaging (fMRI) is a type of brain scan that uses a magnetic field to create images of brain activity in each brain area. The patient lies on a bed within a large cylindrical structure containing a very strong magnet. Neurons that are firing use more oxygen, and the need for oxygen increases blood flow to the area. The fMRI detects the amount of blood flow in each brain region, and thus is an indicator of neural activity. Very clear and detailed pictures of brain structures can be produced via fMRI (see Figure 4.15, “fMRI Image”). Often, the images take the form of cross-sectional “slices” that are obtained as the magnetic field is passed across the brain. The images of these slices are taken repeatedly and are superimposed on images of the brain structure itself to show how activity changes in different brain structures over time. When the research participant is asked to engage in tasks while in the scanner (e.g., by playing a game with another person), the images can show which parts of the brain are associated with which types of tasks. Another advantage of the fMRI is that it is noninvasive. The research participant simply enters the machine and the scans begin. Although the scanners themselves are expensive, the advantages of fMRIs are substantial, and they are now available in many university and hospital settings. The fMRI is now the most commonly used method of learning about brain structure.

There is still one more approach that is being more frequently implemented to understand brain function, and although it is new, it may turn out to be the most useful of all. Transcranial magnetic stimulation (TMS) is a procedure in which magnetic pulses are applied to the brain of a living person with the goal of temporarily and safely deactivating a small brain region. In TMS studies the research participant is first scanned in an fMRI machine to determine the exact location of the brain area to be tested. Then the electrical stimulation is provided to the brain before or while the participant is working on a cognitive task, and the effects of the stimulation on performance are assessed. If the participant’s ability to perform the task is influenced by the presence of the stimulation, the researchers can conclude that this particular area of the brain is important to carrying out the task. The primary advantage of TMS is that it allows the researcher to draw causal conclusions about the influence of brain structures on thoughts, feelings, and behaviours. When the TMS pulses are applied, the brain region becomes less active, and this deactivation is expected to influence the research participant’s responses. Current research has used TMS to study the brain areas responsible for emotion and cognition and their roles in how people perceive intention and approach moral reasoning (Kalbe et al., 2010; Van den Eynde et al., 2010; Young, Camprodon, Hauser, Pascual-Leone, & Saxe, 2010). TMS is also used as a treatment for a variety of psychological conditions, including migraine, Parkinson’s disease, and major depressive disorder.

References

Chen, Z., Williams, K. D., Fitness, J., & Newton, N. C. (2008). When hurt will not heal: Exploring the capacity to relive social and physical pain. Psychological Science, 19(8), 789–795.

Damasio, H., Grabowski, T., Frank, R., Galaburda, A. M., Damasio, A. R., Cacioppo, J. T., & Berntson, G. G. (2005). The return of Phineas Gage: Clues about the brain from the skull of a famous patient. In Social neuroscience: Key readings (pp. 21–28). New York, NY: Psychology Press.

Diamond, M. C. (1999). Why Einstein’s brain? New Horizons for Learning. Retrieved from http://www.newhorizons.org/neuro/diamond_einstein.htm

Eisenberger, N. I., Lieberman, M. D., & Williams, K. D. (2003). Does rejection hurt? An fMRI study of social exclusion. Science, 302(5643), 290–292.

Kalbe, E., Schlegel, M., Sack, A. T., Nowak, D. A., Dafotakis, M., Bangard, C., & Kessler, J. (2010). Dissociating cognitive from affective theory of mind: A TMS study. Cortex: A Journal Devoted to the Study of the Nervous System and Behavior, 46(6), 769–780.

Kanwisher, N. (2000). Domain specificity in face perception. Nature Neuroscience, 3(8), 759–763.

Koenigs, M., Young, L., Adolphs, R., Tranel, D., Cushman, F., Hauser, M., & Damasio, A. (2007). Damage to the prefontal cortex increases utilitarian moral judgments. Nature, 446(7138), 908–911.

Kotowicz, Z. (2007). The strange case of Phineas Gage. History of the Human Sciences, 20(1), 115–131.

Macmillan, M. (2000). An odd kind of fame: Stories of Phineas Gage. Cambridge, MA: MIT Press.

Miller, G. (2008). The roots of morality. Science, 320, 734–737.

Van den Eynde, F., Claudino, A. M., Mogg, A., Horrell, L., Stahl, D., & Schmidt, U. (2010). Repetitive transcranial magnetic stimulation reduces cue-induced food craving in bulimic disorders. Biological Psychiatry, 67(8), 793–795.

Wesselmann, E. D., Bagg, D., & Williams, K. D. (2009). “I feel your pain”: The effects of observing ostracism on the ostracism detection system. Journal of Experimental Social Psychology, 45(6), 1308–1311.

Young, L., Camprodon, J. A., Hauser, M., Pascual-Leone, A., & Saxe, R. (2010). Disruption of the right temporoparietal junction with transcranial magnetic stimulation reduces the role of beliefs in moral judgments. PNAS Proceedings of the National Academy of Sciences of the United States of America, 107(15), 6753–6758.

Image Attributions

Figure 4.12: “Phineas gage – 1868 skull diagram” by John M. Harlow, M.D. (http://it.wikipedia.org/wiki/File:Phineas_gage_-_1868_skull_diagram.jpg) is in the public domain.

Figure 4.14: “EEG cap” by Thuglas (http://commons.wikimedia.org/wiki/File:EEG_cap.jpg) is in the public domain.

Figure 4.15: Face recognition by National Institutes of Health (http://commons.wikimedia.org/wiki/File:Face_recognition.jpg) is in public domain.

Long Descriptions

Figure 4.13 long description: The Frontal Lobe and Moral Judgement

	Control Participants	Participants with lesions in areas other than the frontal lobes	Participants with lesions in the frontal lobes
Proportion of participants who engaged in harm	0.23	0.20	0.46

[Return to Figure 4.13]

Now that we have considered how individual neurons operate and the roles of the different brain areas, it is time to ask how the body manages to put it all together. How do the complex activities in the various parts of the brain, the simple all-or-nothing firings of billions of interconnected neurons, and the various chemical systems within the body work together to allow the body to respond to the social environment and engage in everyday behaviours? In this section we will see that the complexities of human behaviour are accomplished through the joint actions of electrical and chemical processes in the nervous system and the endocrine system.

Electrical Control of Behaviour: The Nervous System

The nervous system (see Figure 4.16, “The Functional Divisions of the Nervous System”), the electrical information highway of the body, is made up of nerves — bundles of interconnected neurons that fire in synchrony to carry messages. The central nervous system (CNS), made up of the brain and spinal cord, is the major controller of the body’s functions, charged with interpreting sensory information and responding to it with its own directives. The CNS interprets information coming in from the senses, formulates an appropriate reaction, and sends responses to the appropriate system to respond accordingly. Everything that we see, hear, smell, touch, and taste is conveyed to us from our sensory organs as neural impulses, and each of the commands that the brain sends to the body, both consciously and unconsciously, travels through this system as well.

Nerves are differentiated according to their function. A sensory (or afferent) neuron carries information from the sensory receptors, whereas a motor (or efferent) neuron transmits information to the muscles and glands. An interneuron, which is by far the most common type of neuron, is located primarily within the CNS and is responsible for communicating among the neurons. Interneurons allow the brain to combine the multiple sources of available information to create a coherent picture of the sensory information being conveyed.

The spinal cord is the long, thin, tubular bundle of nerves and supporting cells that extends down from the brain. It is the central throughway of information for the body. Within the spinal cord, ascending tracts of sensory neurons relay sensory information from the sense organs to the brain while descending tracts of motor neurons relay motor commands back to the body. When a quicker-than-usual response is required, the spinal cord can do its own processing, bypassing the brain altogether. A reflex is an involuntary and nearly instantaneous movement in response to a stimulus. Reflexes are triggered when sensory information is powerful enough to reach a given threshold and the interneurons in the spinal cord act to send a message back through the motor neurons without relaying the information to the brain (see Figure 4.17, “The Reflex”). When you touch a hot stove and immediately pull your hand back, or when you fumble your cell phone and instinctively reach to catch it before it falls, reflexes in your spinal cord order the appropriate responses before your brain even knows what is happening.

If the central nervous system is the command centre of the body, the peripheral nervous system (PNS) represents the front line. The PNS links the CNS to the body’s sense receptors, muscles, and glands. As you can see in Figure 4.18, “The Autonomic Nervous System,” the peripheral nervous system is itself divided into two subsystems, one controlling internal responses and one controlling external responses.

The autonomic nervous system (ANS) is the division of the PNS that governs the internal activities of the human body, including heart rate, breathing, digestion, salivation, perspiration, urination, and sexual arousal. Many of the actions of the ANS, such as heart rate and digestion, are automatic and out of our conscious control, but others, such as breathing and sexual activity, can be controlled and influenced by conscious processes.

The somatic nervous system (SNS) is the division of the PNS that controls the external aspects of the body, including the skeletal muscles, skin, and sense organs. The somatic nervous system consists primarily of motor nerves responsible for sending brain signals for muscle contraction.

The autonomic nervous system itself can be further subdivided into the sympathetic and parasympathetic systems. The sympathetic division of the ANS is involved in preparing the body for behaviour, particularly in response to stress, by activating the organs and the glands in the endocrine system. The parasympathetic division of the ANS tends to calm the body by slowing the heart and breathing and by allowing the body to recover from the activities that the sympathetic system causes. The sympathetic and the parasympathetic divisions normally function in opposition to each other, with the sympathetic division acting a bit like the accelerator pedal on a car and the parasympathetic division acting like the brake.

Our everyday activities are controlled by the interaction between the sympathetic and parasympathetic nervous systems. For example, when we get out of bed in the morning, we would experience a sharp drop in blood pressure if it were not for the action of the sympathetic system, which automatically increases blood flow through the body. Similarly, after we eat a big meal, the parasympathetic system automatically sends more blood to the stomach and intestines, allowing us to efficiently digest the food. And perhaps you have had the experience of not being at all hungry before a stressful event, such as a sports game or an exam (when the sympathetic division was primarily in action), but suddenly finding yourself feeling starved afterward, as the parasympathetic takes over. The two systems work together to maintain vital bodily functions, resulting in homeostasis, the natural balance in the body’s systems.

The Body’s Chemicals Help Control Behaviour: The Endocrine System

The nervous system is designed to protect us from danger through its interpretation of and reactions to stimuli. But a primary function of the sympathetic and parasympathetic nervous systems is to interact with the endocrine system to elicit chemicals that provide another system for influencing our feelings and behaviours.

A gland in the endocrine system is made up of groups of cells that function to secrete hormones. A hormone is a chemical that moves throughout the body to help regulate emotions and behaviours. When the hormones released by one gland arrive at receptor tissues or other glands, these receiving receptors may trigger the release of other hormones, resulting in a series of complex chemical chain reactions. The endocrine system works together with the nervous system to influence many aspects of human behaviour, including growth, reproduction, and metabolism. And the endocrine system plays a vital role in emotions. Because the glands in men and women differ, hormones also help explain some of the observed behavioural differences between men and women. The major glands in the endocrine system are shown in Figure 4.19, “The Major Glands of the Endocrine System.”

The pituitary gland, a small pea-sized gland located near the centre of the brain, is responsible for controlling the body’s growth, but it also has many other influences that make it of primary importance to regulating behaviour. The pituitary secretes hormones that influence our responses to pain as well as hormones that signal the ovaries and testes to make sex hormones. The pituitary gland also controls ovulation and the menstrual cycle in women. Because the pituitary has such an important influence on other glands, it is sometimes known as the “master gland.”

Other glands in the endocrine system include the pancreas, which secretes hormones designed to keep the body supplied with fuel to produce and maintain stores of energy; the pineal gland, located in the middle of the brain, which secretes melatonin, a hormone that helps regulate the wake-sleep cycle; and the thyroid and parathyroid glands, which are responsible for determining how quickly the body uses energy and hormones, and controlling the amount of calcium in the blood and bones.

The body has two triangular adrenal glands, one atop each kidney. The adrenal glands produce hormones that regulate salt and water balance in the body, and they are involved in metabolism, the immune system, and sexual development and function. The most important function of the adrenal glands is to secrete the hormones epinephrine (also known as adrenaline) and norepinephrine (also known as noradrenaline) when we are excited, threatened, or stressed. Epinephrine and norepinephrine stimulate the sympathetic division of the ANS, causing increased heart and lung activity, dilation of the pupils, and increases in blood sugar, which give the body a surge of energy to respond to a threat. The activity and role of the adrenal glands in response to stress provide an excellent example of the close relationship and interdependency of the nervous and endocrine systems. A quick-acting nervous system is essential for immediate activation of the adrenal glands, while the endocrine system mobilizes the body for action.

The male sex glands, known as the testes, secrete a number of hormones, the most important of which is testosterone, the male sex hormone. Testosterone regulates body changes associated with sexual development, including enlargement of the penis, deepening of the voice, growth of facial and pubic hair, and the increase in muscle growth and strength. The ovaries, the female sex glands, are located in the pelvis. They produce eggs and secrete the female hormones estrogen and progesterone. Estrogen is involved in the development of female sexual features, including breast growth, the accumulation of body fat around the hips and thighs, and the growth spurt that occurs during puberty. Both estrogen and progesterone are also involved in pregnancy and the regulation of the menstrual cycle.

Recent research has pinpointed some of the important roles of the sex hormones in social behaviour. Dabbs, Hargrove, and Heusel (1996) measured the testosterone levels of 240 men who were members of 12 fraternities at two universities. They also obtained descriptions of the fraternities from university officials, fraternity officers, yearbook and chapter house photographs, and researcher field notes. The researchers correlated the testosterone levels and the descriptions of each fraternity. They found that the fraternities with the highest average testosterone levels were also more wild and unruly, and one of these fraternities was known across campus for the crudeness of its behaviour. On the other hand, the fraternities with the lowest average testosterone levels were more well behaved, friendly and pleasant, academically successful, and socially responsible. Banks and Dabbs (1996) found that juvenile delinquents and prisoners who had high levels of testosterone also acted more violently, and Tremblay and colleagues (1998) found that testosterone was related to toughness and leadership behaviours in adolescent boys. Although testosterone levels are higher in men than in women, the relationship between testosterone and aggression is not limited to males. Studies have also shown a positive relationship between testosterone and aggression and related behaviours (such as competitiveness) in women (Cashdan, 2003).

Keep in mind that the observed relationships between testosterone levels and aggressive behaviour that have been found in these studies do not prove that testosterone causes aggression — the relationships are only correlational. In fact, there is evidence that the relationship between violence and testosterone also goes in the other direction: playing an aggressive game, such as tennis or even chess, increases the testosterone levels of the winners and decreases the testosterone levels of losers (Gladue, Boechler, & McCaul, 1989; Mazur, Booth, & Dabbs, 1992), and perhaps this is why excited soccer fans sometimes riot when their team wins.

Recent research has also begun to document the role that female sex hormones may play in reactions to others. A study about hormonal influences on social-cognitive functioning (Macrae, Alnwick, Milne, & Schloerscheidt, 2002) found that women were more easily able to perceive and categorize male faces during the more fertile phases of their menstrual cycles. Although researchers did not directly measure the presence of hormones, it is likely that phase-specific hormonal differences influenced the women’s perceptions.

At this point you can begin to see the important role the hormones play in behaviour. But the hormones we have reviewed in this section represent only a subset of the many influences that hormones have on our behaviours. In the chapters to come we will consider the important roles that hormones play in many other behaviours, including sleeping, sexual activity, and helping and harming others.

References

Banks, T., & Dabbs, J. M., Jr. (1996). Salivary testosterone and cortisol in delinquent and violent urban subculture. Journal of Social Psychology, 136(1), 49–56.

Cashdan, E. (2003). Hormones and competitive aggression in women. Aggressive Behavior, 29(2), 107–115.

Dabbs, J. M., Jr., Hargrove, M. F., & Heusel, C. (1996). Testosterone differences among college fraternities: Well-behaved vs. rambunctious. Personality and Individual Differences, 20(2), 157–161.

Gladue, B. A., Boechler, M., & McCaul, K. D. (1989). Hormonal response to competition in human males. Aggressive Behavior, 15(6), 409–422.

Macrae, C. N., Alnwick, K. A., Milne, A. B., & Schloerscheidt, A. M. (2002). Person perception across the menstrual cycle: Hormonal influences on social-cognitive functioning. Psychological Science, 13(6), 532–536.

Mazur, A., Booth, A., & Dabbs, J. M. (1992). Testosterone and chess competition. Social Psychology Quarterly, 55(1), 70–77.

Tremblay, R. E., Schaal, B., Boulerice, B., Arseneault, L., Soussignan, R. G., Paquette, D., & Laurent, D. (1998). Testosterone, physical aggression, dominance, and physical development in early adolescence. International Journal of Behavioral Development, 22(4), 753–777.

Long Descriptions

Figure 4.16 long description: The nervous system is made up of two parts: The central nervous system consisting of the brain and spinal cord and the peripheral nervous system. The peripheral nervous system is both autonomic (controlling internal activities of organs and glands) and somatic (controlling external actions of skin and muscles). [Return to Figure 4.16]

Figure 4.18 long description: The Sympathetic and Parasympathetic Nervous System

Sympathetic Nervous System	Parasympathetic Nervous System
Dilates pupil	Contracts pupil
Accelerates heartbeat	Slows heartbeat
Inhibits digestive activity	Stimulates digestive activity
Stimulates glucose release
Stimulates secretion of epinephrine and norepinephrine

[Return to Figure 4.18]

All human behaviour, thoughts, and feelings are produced by the actions of our brains, nerves, muscles, and glands.

The body is controlled by the nervous system, consisting of the central nervous system (CNS) and the peripheral nervous system (PNS) and the endocrine system, which is made up of glands that create and control hormones.

Neurons are the cells in the nervous system. Neurons are composed of a soma that contains the nucleus of the cell; a dendrite that collects information from other cells and sends the information to the soma; and a long segmented fiber, known as the axon, which transmits information away from the cell body toward other neurons and to the muscles and glands.

The nervous system operates using an electrochemical process. An electrical charge moves through the neuron itself, and chemicals are used to transmit information between neurons. Within the neuron, the electrical charge occurs in the form of an action potential. The action potential operates in an all-or-nothing manner.

Neurons are separated by junction areas known as synapses. Neurotransmitters travel across the synaptic space between the terminal button of one neuron and the dendrites of other neurons, where they bind to the dendrites in the neighboring neurons. More than 100 chemical substances produced in the body have been identified as neurotransmitters, and these substances have a wide and profound effect on emotion, cognition, and behaviour.

Drugs that we ingest may either mimic (agonists) or block (antagonists) the operations of neurotransmitters.

The brains of all animals are layered and generally quite similar in overall form.

The brain stem is the oldest and innermost region of the brain. It controls the most basic functions of life, including breathing, attention, and motor responses. The brain stem includes the medulla, the pons, and the reticular formation.

Above the brain stem are other parts of the old brain involved in the processing of behaviour and emotions, including the thalamus, the cerebellum, and the limbic system. The limbic system includes the amygdala, the hypothalamus, and the hippocampus.

The cerebral cortex contains about 20 billion nerve cells and 300 trillion synaptic connections, and it’s supported by billions more glial cells that surround and link to the neurons. The cerebral cortex is divided into two hemispheres, and each hemisphere is divided into four lobes, each separated by folds known as fissures.

The frontal lobe is primarily responsible for thinking, planning, memory, and judgment. The parietal lobe is responsible for processing information about touch. The occipital lobe processes visual information, and the temporal lobe is responsible for hearing and language. The cortex also includes the motor cortex, the somatosensory cortex, the visual cortex, the auditory cortex, and the association areas.

The brain can develop new neurons, a process known as neurogenesis, as well as new routes for neural communications (neuroplasticity).

Psychologists study the brain using cadaver and lesion approaches, as well as through neuroimaging techniques that include electroencephalography (EEG), functional magnetic resonance imaging (fMRI), and transcranial magnetic stimulation (TMS).

Sensory (afferent) neurons carry information from the sensory receptors, whereas motor (efferent) neurons transmit information to the muscles and glands. Interneurons, by far the most common of neurons, are located primarily within the CNS and responsible for communicating among the neurons.

The peripheral nervous system is itself divided into two subsystems, one controlling internal responses (the autonomic nervous system, ANS) and one controlling external responses (the somatic nervous system). The sympathetic division of the ANS is involved in preparing the body for behaviour by activating the organs and the glands in the endocrine system. The parasympathetic division of the ANS tends to calm the body by slowing the heart and breathing and by allowing the body to recover from the activities that the sympathetic system causes.

Glands in the endocrine system include the pituitary gland, the pancreas, the adrenal glands, and the male and female sex glands. The male sex hormone testosterone and the female sex hormones estrogen and progesterone play important roles in behaviour and contribute to gender differences.

The ability to detect and interpret the events that are occurring around us allows us to respond to these stimuli appropriately (Gibson & Pick, 2000). In most cases the system is successful, but as you can see from the above example, it is not perfect. In this chapter we will discuss the strengths and limitations of these capacities, focusing on both sensation — awareness resulting from the stimulation of a sense organ — and perception — the organization and interpretation of sensations. Sensation and perception work seamlessly together to allow us to experience the world through our eyes, ears, nose, tongue, and skin, but also to combine what we are currently learning from the environment with what we already know about it to make judgments and to choose appropriate behaviours.

The study of sensation and perception is exceedingly important for our everyday lives because the knowledge generated by psychologists is used in so many ways to help so many people. Psychologists work closely with mechanical and electrical engineers, with experts in defence and military contractors, and with clinical, health, and sports psychologists to help them apply this knowledge to their everyday practices. The research is used to help us understand and better prepare people to cope with such diverse events as driving cars, flying planes, creating robots, and managing pain (Fajen & Warren, 2003).

We will begin the chapter with a focus on the six senses of seeing, hearing, smelling, touching, tasting, and monitoring the body’s positions (proprioception). We will see that sensation is sometimes relatively direct, in the sense that the wide variety of stimuli around us inform and guide our behaviours quickly and accurately, but nevertheless is always the result of at least some interpretation. We do not directly experience stimuli, but rather we experience those stimuli as they are created by our senses. Each sense accomplishes the basic process of transduction — the conversion of stimuli detected by receptor cells to electrical impulses that are then transported to the brain — in different, but related, ways.

After we have reviewed the basic processes of sensation, we will turn to the topic of perception, focusing on how the brain’s processing of sensory experience can not only help us make quick and accurate judgments, but also mislead us into making perceptual and judgmental errors, such as those that allowed the Chaser group to breach security at the APEC meeting.

References

Fajen, B. R., & Warren, W. H. (2003). Behavioral dynamics of steering, obstacle avoidance, and route selection. Journal of Experimental Psychology: Human Perception and Performance, 29(2), 343–362.

Gibson, E. J., & Pick, A. D. (2000). An ecological approach to perceptual learning and development. New York, NY: Oxford University Press.

Image Attributions

Figure 5.1: Caroline ouellette by Genevieve2 (http://en.wikipedia.org/wiki/File:Caroline_Ouellette_8_janvier_2011.jpg) used under CC BY SA 3.0 license (http://creativecommons.org/licenses/by-sa/3.0/deed.en); Arcade by Belinda Hankins Miller (http://it.wikipedia.org/wiki/File:Arcade-20071020-a.jpg) used under CC BY 2.0 license (http://creativecommons.org/licenses/by/2.0/deed.it); Niagara Bridge, Canada by Tony Hisgett (http://commons.wikimedia.org/wiki/File:Niagara_Bridge,_Canada.jpg) used under CC BY 2.0 license (http://creativecommons.org/licenses/by/2.0/deed.en).

Sensory Thresholds: What Can We Experience?

Humans possess powerful sensory capacities that allow us to sense the kaleidoscope of sights, sounds, smells, and tastes that surround us. Our eyes detect light energy and our ears pick up sound waves. Our skin senses touch, pressure, hot, and cold. Our tongues react to the molecules of the foods we eat, and our noses detect scents in the air. The human perceptual system is wired for accuracy, and people are exceedingly good at making use of the wide variety of information available to them (Stoffregen & Bardy, 2001).

In many ways our senses are quite remarkable. The human eye can detect the equivalent of a single candle flame burning 30 miles away and can distinguish among more than 300,000 different colours. The human ear can detect sounds as low as 20 hertz (vibrations per second) and as high as 20,000 hertz, and it can hear the tick of a clock about 20 feet away in a quiet room. We can taste a teaspoon of sugar dissolved in two gallons of water, and we are able to smell one drop of perfume diffused in a three-room apartment. We can feel the wing of a bee on our cheek dropped from one centimeter above (Galanter, 1962).

 

Although there is much that we do sense, there is even more that we do not. Dogs (Figure 5.2), bats, whales, and some rodents all have much better hearing than we do, and many animals have a far richer sense of smell. Birds are able to see the ultraviolet light that we cannot (see Figure 5.3, “Ultraviolet Light and Bird Vision”) and can also sense the pull of the earth’s magnetic field. Cats have an extremely sensitive and sophisticated sense of touch, and they are able to navigate in complete darkness using their whiskers. The fact that different organisms have different sensations is part of their evolutionary adaptation. Each species is adapted to sensing the things that are most important to them, while being blissfully unaware of the things that don’t matter.

Measuring Sensation

Psychophysics is the branch of psychology that studies the effects of physical stimuli on sensory perceptions and mental states. The field of psychophysics was founded by the German psychologist Gustav Fechner (1801-1887), who was the first to study the relationship between the strength of a stimulus and a person’s ability to detect the stimulus.

The measurement techniques developed by Fechner and his colleagues are designed in part to help determine the limits of human sensation. One important criterion is the ability to detect very faint stimuli. The absolute threshold of a sensation is defined as the intensity of a stimulus that allows an organism to just barely detect it.

In a typical psychophysics experiment, an individual is presented with a series of trials in which a signal is sometimes presented and sometimes not, or in which two stimuli are presented that are either the same or different. Imagine, for instance, that you were asked to take a hearing test. On each of the trials your task is to indicate either “yes” if you heard a sound or “no” if you did not. The signals are purposefully made to be very faint, making accurate judgments difficult.

The problem for you is that the very faint signals create uncertainty. Because our ears are constantly sending background information to the brain, you will sometimes think that you heard a sound when none was there, and you will sometimes fail to detect a sound that is there. Your task is to determine whether the neural activity that you are experiencing is due to the background noise alone or is the result of a signal within the noise.

The responses that you give on the hearing test can be analyzed using signal detection analysis. Signal detection analysis is a technique used to determine the ability of the perceiver to separate true signals from background noise (Macmillan & Creelman, 2005; Wickens, 2002). As you can see in Figure 5.4, “Outcomes of a Signal Detection Analysis,” each judgment trial creates four possible outcomes: A hit occurs when you, as the listener, correctly say “yes” when there was a sound. A false alarm occurs when you respond “yes” to no signal. In the other two cases you respond “no” — either a miss (saying “no” when there was a signal) or a correct rejection (saying “no” when there was in fact no signal).

The analysis of the data from a psychophysics experiment creates two measures. One measure, known as sensitivity, refers to the true ability of the individual to detect the presence or absence of signals. People who have better hearing will have higher sensitivity than will those with poorer hearing. The other measure, response bias, refers to a behavioural tendency to respond “yes” to the trials, which is independent of sensitivity.

Imagine, for instance, that rather than taking a hearing test, you are a soldier on guard duty, and your job is to detect the very faint sound of the breaking of a branch that indicates that an enemy is nearby. You can see that in this case making a false alarm by alerting the other soldiers to the sound might not be as costly as a miss (a failure to report the sound), which could be deadly. Therefore, you might well adopt a very lenient response bias in which whenever you are at all unsure, you send a warning signal. In this case your responses may not be very accurate (your sensitivity may be low because you are making a lot of false alarms) and yet the extreme response bias can save lives.

Another application of signal detection occurs when medical technicians study body images for the presence of cancerous tumours. Again, a miss (in which the technician incorrectly determines that there is no tumour) can be very costly, but false alarms (referring patients who do not have tumours to further testing) also have costs. The ultimate decisions that the technicians make are based on the quality of the signal (clarity of the image), their experience and training (the ability to recognize certain shapes and textures of tumours), and their best guesses about the relative costs of misses versus false alarms.

Although we have focused to this point on the absolute threshold, a second important criterion concerns the ability to assess differences between stimuli. The difference threshold (or just noticeable difference [JND]), refers to the change in a stimulus that can just barely be detected by the organism. The German physiologist Ernst Weber (1795-1878) made an important discovery about the JND — namely, that the ability to detect differences depends not so much on the size of the difference but on the size of the difference in relation to the absolute size of the stimulus. Weber’s law maintains that the just noticeable difference of a stimulus is a constant proportion of the original intensity of the stimulus. As an example, if you have a cup of coffee that has only a very little bit of sugar in it (say one teaspoon), adding another teaspoon of sugar will make a big difference in taste. But if you added that same teaspoon to a cup of coffee that already had five teaspoons of sugar in it, then you probably wouldn’t taste the difference as much (in fact, according to Weber’s law, you would have to add five more teaspoons to make the same difference in taste).

One interesting application of Weber’s law is in our everyday shopping behaviour. Our tendency to perceive cost differences between products is dependent not only on the amount of money we will spend or save, but also on the amount of money saved relative to the price of the purchase. For example, if you were about to buy a soda or candy bar in a convenience store, and the price of the items ranged from $1 to $3, you would likely think that the $3 item cost “a lot more” than the $1 item. But now imagine that you were comparing between two music systems, one that cost $397 and one that cost $399. Probably you would think that the cost of the two systems was “about the same,” even though buying the cheaper one would still save you $2.

Another example of processing that occurs outside our awareness is seen when certain areas of the visual cortex are damaged, causing blindsight, a condition in which people are unable to consciously report on visual stimuli but nevertheless are able to accurately answer questions about what they are seeing. When people with blindsight are asked directly what stimuli look like, or to determine whether these stimuli are present at all, they cannot do so at better than chance levels. They report that they cannot see anything. However, when they are asked more indirect questions, they are able to give correct answers. For example, people with blindsight are able to correctly determine an object’s location and direction of movement, as well as identify simple geometrical forms and patterns (Weiskrantz, 1997). It seems that although conscious reports of the visual experiences are not possible, there is still a parallel and implicit process at work, enabling people to perceive certain aspects of the stimuli.

References

Dijksterhuis, A. (2010). Automaticity and the unconscious. In S. T. Fiske, D. T. Gilbert, & G. Lindzey (Eds.), Handbook of social psychology (5th ed., Vol. 1, pp. 228–267). Hoboken, NJ: John Wiley & Sons.

Galanter, E. (1962). Contemporary Psychophysics. In R. Brown, E. Galanter, E. H. Hess, & G. Mandler (Eds.), New directions in psychology. New York, NY: Holt, Rinehart and Winston.

Harris, J. L., Bargh, J. A., & Brownell, K. D. (2009). Priming effects of television food advertising on eating behavior. Health Psychology, 28(4), 404–413.

Karremans, J. C., Stroebe, W., & Claus, J. (2006). Beyond Vicary’s fantasies: The impact of subliminal priming and brand choice. Journal of Experimental Social Psychology, 42(6), 792–798.

Macmillan, N. A., & Creelman, C. D. (2005). Detection theory: A user’s guide (2nd ed). Mahwah, NJ: Lawrence Erlbaum Associates.

Saegert, J. (1987). Why marketing should quit giving subliminal advertising the benefit of the doubt. Psychology and Marketing, 4(2), 107–120.

Stoffregen, T. A., & Bardy, B. G. (2001). On specification and the senses. Behavioral and Brain Sciences, 24(2), 195–261.

Trappey, C. (1996). A meta-analysis of consumer choice and subliminal advertising. Psychology and Marketing, 13, 517–530.

Weiskrantz, L. (1997). Consciousness lost and found: A neuropsychological exploration. New York, NY: Oxford University Press.

Wickens, T. D. (2002). Elementary signal detection theory. New York, NY: Oxford University Press.

Image Attributions

Figure 5.2: Police officer with sniffer dog by Harald Dettenborn, http://commons.wikimedia.org/wiki/File:Msc2010_dett_0036.jpg used under CC BY 3.0 license(http://creativecommons.org/licenses/by/3.0/de/deed.en).

Figure 5.3: Adapted from Fatal Light Awareness Program. (2008), http://www.flap.org/research.htm.

Whereas other animals rely primarily on hearing, smell, or touch to understand the world around them, human beings rely in large part on vision. A large part of our cerebral cortex is devoted to seeing, and we have substantial visual skills. Seeing begins when light falls on the eyes, initiating the process of transduction. Once this visual information reaches the visual cortex, it is processed by a variety of neurons that detect colours, shapes, and motion, and that create meaningful perceptions out of the incoming stimuli.

The air around us is filled with a sea of electromagnetic energy: pulses of energy waves that can carry information from place to place. As you can see in Figure 5.6, “The Electromagnetic Spectrum,” electromagnetic waves vary in their wavelength — the distance between one wave peak and the next wave peak — with the shortest gamma waves being only a fraction of a millimeter in length and the longest radio waves being hundreds of kilometers long. Humans are blind to almost all of this energy — our eyes detect only the range from about 400 to 700 billionths of a meter, the part of the electromagnetic spectrum known as the visible spectrum.

The Sensing Eye and the Perceiving Visual Cortex

As you can see in Figure 5.7, “Anatomy of the Human Eye,” light enters the eye through the cornea, a clear covering that protects the eye and begins to focus the incoming light. The light then passes through the pupil, a small opening in the centre of the eye. The pupil is surrounded by the iris, the coloured part of the eye that controls the size of the pupil by constricting or dilating in response to light intensity. When we enter a dark movie theatre on a sunny day, for instance, muscles in the iris open the pupil and allow more light to enter. Complete adaptation to the dark may take up to 20 minutes.

Behind the pupil is the lens, a structure that focuses the incoming light on the retina, the layer of tissue at the back of the eye that contains photoreceptor cells. As our eyes move from near objects to distant objects, a process known as visual accommodation occurs. Visual accommodation is the process of changing the curvature of the lens to keep the light entering the eye focused on the retina. Rays from the top of the image strike the bottom of the retina and vice versa, and rays from the left side of the image strike the right part of the retina and vice versa, causing the image on the retina to be upside down and backward. Furthermore, the image projected on the retina is flat, and yet our final perception of the image will be three dimensional.

Accommodation is not always perfect (Figure 5.8) if the focus is in front of the retina, we say that the person is nearsighted, and when the focus is behind the retina, we say that the person is farsighted. Eyeglasses and contact lenses correct this problem by adding another lens in front of the eye, and laser eye surgery corrects the problem by reshaping the eye’s own lens.

The retina contains layers of neurons specialized to respond to light (see Figure 5.9, “The Retina with Its Specialized Cells”). As light falls on the retina, it first activates receptor cells known as rods and cones. The activation of these cells then spreads to the bipolar cells and then to the ganglion cells, which gather together and converge, like the strands of a rope, forming the optic nerve. The optic nerve is a collection of millions of ganglion neurons that sends vast amounts of visual information, via the thalamus, to the brain. Because the retina and the optic nerve are active processors and analyzers of visual information, it is appropriate to think of these structures as an extension of the brain itself.

Rods are visual neurons that specialize in detecting black, white, and gray colours. There are about 120 million rods in each eye. The rods do not provide a lot of detail about the images we see, but because they are highly sensitive to shorter-waved (darker) and weak light, they help us see in dim light — for instance, at night. Because the rods are located primarily around the edges of the retina, they are particularly active in peripheral vision (when you need to see something at night, try looking away from what you want to see). Cones are visual neurons that are specialized in detecting fine detail and colours. The five million or so cones in each eye enable us to see in colour, but they operate best in bright light. The cones are located primarily in and around the fovea, which is the central point of the retina.

To demonstrate the difference between rods and cones in attention to detail, choose a word in this text and focus on it. Do you notice that the words a few inches to the side seem more blurred? This is because the word you are focusing on strikes the detail-oriented cones, while the words surrounding it strike the less-detail-oriented rods, which are located on the periphery.

Margaret Livingstone (2000) (Figure 5.10) found an interesting effect that demonstrates the different processing capacities of the eye’s rods and cones — namely, that the Mona Lisa’s smile, which is widely referred to as “elusive,” is perceived differently depending on how one looks at the painting. Because Leonardo da Vinci painted the smile in low-detail brush strokes, these details are better perceived by our peripheral vision (the rods) than by the cones. Livingstone found that people rated the Mona Lisa as more cheerful when they were instructed to focus on her eyes than they did when they were asked to look directly at her mouth. As Livingstone put it, “She smiles until you look at her mouth, and then it fades, like a dim star that disappears when you look directly at it.”

As you can see in Figure 5.11, “Pathway of Visual Images through the Thalamus and into the Visual Cortex,” the sensory information received by the retina is relayed through the thalamus to corresponding areas in the visual cortex, which is located in the occipital lobe at the back of the brain. Although the principle of contralateral control might lead you to expect that the left eye would send information to the right brain hemisphere and vice versa, nature is smarter than that. In fact, the left and right eyes each send information to both the left and the right hemisphere, and the visual cortex processes each of the cues separately and in parallel. This is an adaptational advantage to an organism that loses sight in one eye, because even if only one eye is functional, both hemispheres will still receive input from it.

The visual cortex is made up of specialized neurons that turn the sensations they receive from the optic nerve into meaningful images. Because there are no photoreceptor cells at the place where the optic nerve leaves the retina, a hole or blind spot in our vision is created (see Figure 5.12, “Blind Spot Demonstration”). When both of our eyes are open, we don’t experience a problem because our eyes are constantly moving, and one eye makes up for what the other eye misses. But the visual system is also designed to deal with this problem if only one eye is open — the visual cortex simply fills in the small hole in our vision with similar patterns from the surrounding areas, and we never notice the difference. The ability of the visual system to cope with the blind spot is another example of how sensation and perception work together to create meaningful experience.

Perception is created in part through the simultaneous action of thousands of feature detector neurons — specialized neurons, located in the visual cortex, that respond to the strength, angles, shapes, edges, and movements of a visual stimulus (Kelsey, 1997; Livingstone & Hubel, 1988). The feature detectors work in parallel, each performing a specialized function. When faced with a red square, for instance, the parallel line feature detectors, the horizontal line feature detectors, and the red colour feature detectors all become activated. This activation is then passed on to other parts of the visual cortex, where other neurons compare the information supplied by the feature detectors with images stored in memory. Suddenly, in a flash of recognition, the many neurons fire together, creating the single image of the red square that we experience (Rodriguez et al., 1999). See Figure 5.13 for an explanation about the Necker cube.

Some feature detectors are tuned to selectively respond to particularly important objects, such as faces, smiles, and other parts of the body (Downing, Jiang, Shuman, & Kanwisher, 2001; Haxby et al., 2001). When researchers disrupted face recognition areas of the cortex using the magnetic pulses of transcranial magnetic stimulation (TMS), people were temporarily unable to recognize faces, and yet they were still able to recognize houses (McKone, Kanwisher, & Duchaine, 2007; Pitcher, Walsh, Yovel, & Duchaine, 2007).

Perceiving Colour

It has been estimated that the human visual system can detect and discriminate among seven million colour variations (Geldard, 1972), but these variations are all created by the combinations of the three primary colours: red, green, and blue. The shade of a colour, known as hue, is conveyed by the wavelength of the light that enters the eye (we see shorter wavelengths as more blue and longer wavelengths as more red), and we detect brightness from the intensity or height of the wave (bigger or more intense waves are perceived as brighter), as shown in Figure 5.14.

 

In his important research on colour vision, Hermann von Helmholtz (1821-1894) theorized that colour is perceived because the cones in the retina come in three types. One type of cone reacts primarily to blue light (short wavelengths), another reacts primarily to green light (medium wavelengths), and a third reacts primarily to red light (long wavelengths). The visual cortex then detects and compares the strength of the signals from each of the three types of cones, creating the experience of colour. According to this Young-Helmholtz trichromatic colour theory what colour we see depends on the mix of the signals from the three types of cones. If the brain is receiving primarily red and blue signals, for instance, it will perceive purple; if it is receiving primarily red and green signals it will perceive yellow; and if it is receiving messages from all three types of cones it will perceive white.

The different functions of the three types of cones are apparent in people who experience colour blindness — the inability to detect green and/or red colours. About one in 50 people, mostly men, lack functioning in the red- or green-sensitive cones, leaving them only able to experience either one or two colours (Figure 5.15).

The trichromatic colour theory cannot explain all of human vision, however. For one, although the colour purple does appear to us as a mix of red and blue, yellow does not appear to be a mix of red and green. And people with colour blindness, who cannot see either green or red, nevertheless can still see yellow. An alternative approach to the Young-Helmholtz theory, known as the opponent-process colour theory, proposes that we analyze sensory information not in terms of three colours but rather in three sets of “opponent colours”: red-green, yellow-blue, and white-black. Evidence for the opponent-process theory comes from the fact that some neurons in the retina and in the visual cortex are excited by one colour (e.g., red) but inhibited by another colour (e.g., green).

One example of opponent processing occurs in the experience of an afterimage. If you stare at the shape on the top left side of Figure 5.16, “Afterimages,” for about 30 seconds (the longer you look, the better the effect), and then move your eyes to the blank area to the right of it, you will see the afterimage. Now try this by staring at the image of the Italian flag below and then shifting your eyes to the blank area beside it. When we stare at the green stripe, our green receptors habituate and begin to process less strongly, whereas the red receptors remain at full strength. When we switch our gaze, we see primarily the red part of the opponent process. Similar processes create blue after yellow and white after black.

The tricolour and the opponent-process mechanisms work together to produce colour vision. When light rays enter the eye, the red, blue, and green cones on the retina respond in different degrees and send different strength signals of red, blue, and green through the optic nerve. The colour signals are then processed both by the ganglion cells and by the neurons in the visual cortex (Gegenfurtner & Kiper, 2003).

Perceiving Form

One of the important processes required in vision is the perception of form. German psychologists in the 1930s and 1940s, including Max Wertheimer (1880-1943), Kurt Koffka (1886-1941), and Wolfgang Köhler (1887-1967), argued that we create forms out of their component sensations based on the idea of the gestalt, a meaningfully organized whole. The idea of the gestalt is that the “whole is more than the sum of its parts.” Some examples of how gestalt principles lead us to see more than what is actually there are summarized in Table 5.1, “Summary of Gestalt Principles of Form Perception.”

Table 5.1 Summary of Gestalt Principles of Form Perception.

[Skip Table]
Principle	Description	Example	Image
Figure and ground	We structure input so that we always see a figure (image) against a ground (background).	At right, you may see a vase or you may see two faces, but in either case, you will organize the image as a figure against a ground.
Similarity	Stimuli that are similar to each other tend to be grouped together.	You are more likely to see three similar columns among the XYX characters at right than you are to see four rows.
Proximity	We tend to group nearby figures together.	Do you see four or eight images at right? Principles of proximity suggest that you might see only four.
Continuity	We tend to perceive stimuli in smooth, continuous ways rather than in more discontinuous ways.	At right, most people see a line of dots that moves from the lower left to the upper right, rather than a line that moves from the left and then suddenly turns down. The principle of continuity leads us to see most lines as following the smoothest possible path.
Closure	We tend to fill in gaps in an incomplete image to create a complete, whole object.	Closure leads us to see a single spherical object at right rather than a set of unrelated cones.

Perceiving Depth

Depth perception is the ability to perceive three-dimensional space and to accurately judge distance. Without depth perception, we would be unable to drive a car, thread a needle, or simply navigate our way around the supermarket (Howard & Rogers, 2001). Research has found that depth perception is in part based on innate capacities and in part learned through experience (Witherington, 2005).

Psychologists Eleanor Gibson and Richard Walk (1960) tested the ability to perceive depth in six- to 14-month-old infants by placing them on a visual cliff, a mechanism that gives the perception of a dangerous drop-off, in which infants can be safely tested for their perception of depth (Figure 5.17 “Visual Cliff”). The infants were placed on one side of the “cliff,” while their mothers called to them from the other side. Gibson and Walk found that most infants either crawled away from the cliff or remained on the board and cried because they wanted to go to their mothers, but the infants perceived a chasm that they instinctively could not cross. Further research has found that even very young children who cannot yet crawl are fearful of heights (Campos, Langer, & Krowitz, 1970). On the other hand, studies have also found that infants improve their hand-eye coordination as they learn to better grasp objects and as they gain more experience in crawling, indicating that depth perception is also learned (Adolph, 2000).

Depth perception is the result of our use of depth cues, messages from our bodies and the external environment that supply us with information about space and distance. Binocular depth cues are depth cues that are created by retinal image disparity — that is, the space between our eyes — and which thus require the coordination of both eyes. One outcome of retinal disparity is that the images projected on each eye are slightly different from each other. The visual cortex automatically merges the two images into one, enabling us to perceive depth. Three-dimensional movies make use of retinal disparity by using 3-D glasses that the viewer wears to create a different image on each eye. The perceptual system quickly, easily, and unconsciously turns the disparity into 3-D.

An important binocular depth cue is convergence, the inward turning of our eyes that is required to focus on objects that are less than about 50 feet away from us. The visual cortex uses the size of the convergence angle between the eyes to judge the object’s distance. You will be able to feel your eyes converging if you slowly bring a finger closer to your nose while continuing to focus on it. When you close one eye, you no longer feel the tension — convergence is a binocular depth cue that requires both eyes to work.

The visual system also uses accommodation to help determine depth. As the lens changes its curvature to focus on distant or close objects, information relayed from the muscles attached to the lens helps us determine an object’s distance. Accommodation is only effective at short viewing distances, however, so while it comes in handy when threading a needle or tying shoelaces, it is far less effective when driving or playing sports.

Although the best cues to depth occur when both eyes work together, we are able to see depth even with one eye closed. Monocular depth cues are depth cues that help us perceive depth using only one eye (Sekuler & Blake, 2006). Some of the most important are summarized in Table 5.2, “Monocular Depth Cues That Help Us Judge Depth at a Distance.”

Table 5.2 Monocular Depth Cues That Help Us Judge Depth at a Distance.

[Skip Table]
Name	Description	Example	Image
Position	We tend to see objects higher up in our field of vision as farther away.	The fence posts at right appear farther away not only because they become smaller but also because they appear higher up in the picture.
Relative size	Assuming that the objects in a scene are the same size, smaller objects are perceived as farther away.	At right, the cars in the distance appear smaller than those nearer to us.
Linear perspective	Parallel lines appear to converge at a distance.	We know that the tracks at right are parallel. When they appear closer together, we determine they are farther away.
Light and shadow	The eye receives more reflected light from objects that are closer to us. Normally, light comes from above, so darker images are in shadow.	We see the images at right as extending and indented according to their shadowing. If we invert the picture, the images will reverse.
Interposition	When one object overlaps another object, we view it as closer.	At right, because the blue star covers the pink bar, it is seen as closer than the yellow moon.
Aerial perspective	Objects that appear hazy, or that are covered with smog or dust, appear farther away.	The artist who painted the picture on the right used aerial perspective to make the clouds more hazy and thus appear farther away.

Perceiving Motion

Many animals, including human beings, have very sophisticated perceptual skills that allow them to coordinate their own motion with the motion of moving objects in order to create a collision with that object. Bats and birds use this mechanism to catch up with prey, dogs use it to catch a Frisbee, and humans use it to catch a moving football. The brain detects motion partly from the changing size of an image on the retina (objects that look bigger are usually closer to us) and in part from the relative brightness of objects.

We also experience motion when objects near each other change their appearance. The beta effect refers to the perception of motion that occurs when different images are presented next to each other in succession (see “Beta Effect and Phi Phenomenon”). The visual cortex fills in the missing part of the motion and we see the object moving. The beta effect is used in movies to create the experience of motion. A related effect is the phi phenomenon, in which we perceive a sensation of motion caused by the appearance and disappearance of objects that are near each other. The phi phenomenon looks like a moving zone or cloud of background colour surrounding the flashing objects. The beta effect and the phi phenomenon are other examples of the importance of the gestalt — our tendency to “see more than the sum of the parts.”

References

Adolph, K. E. (2000). Specificity of learning: Why infants fall over a veritable cliff. Psychological Science, 11(4), 290–295.

Campos, J. J., Langer, A., & Krowitz, A. (1970). Cardiac responses on the visual cliff in prelocomotor human infants. Science, 170(3954), 196–197.

Downing, P. E., Jiang, Y., Shuman, M., & Kanwisher, N. (2001). A cortical area selective for visual processing of the human body. Science, 293(5539), 2470–2473.

Gegenfurtner, K. R., & Kiper, D. C. (2003). Color vision. Annual Review of Neuroscience, 26, 181–206.

Geldard, F. A. (1972). The human senses (2nd ed.). New York, NY: John Wiley & Sons.

Gibson, E. J., & Walk, R. D. (1960). The “visual cliff.” Scientific American, 202(4), 64–71.

Haxby, J. V., Gobbini, M. I., Furey, M. L., Ishai, A., Schouten, J. L., & Pietrini, P. (2001). Distributed and overlapping representations of faces and objects in ventral temporal cortex. Science, 293(5539), 2425–2430.

Howard, I. P., & Rogers, B. J. (2001). Seeing in depth: Basic mechanisms (Vol. 1). Toronto, ON: Porteous.

Kelsey, C.A. (1997). Detection of visual information. In W. R. Hendee & P. N. T. Wells (Eds.), The perception of visual information (2nd ed.). New York, NY: Springer Verlag.

Livingstone, M., & Hubel, D. (1998). Segregation of form, color, movement, and depth: Anatomy, physiology, and perception. Science, 240, 740–749.

Livingstone M. S. (2000). Is it warm? Is it real? Or just low spatial frequency? Science, 290, 1299.

McKone, E., Kanwisher, N., & Duchaine, B. C. (2007). Can generic expertise explain special processing for faces? Trends in Cognitive Sciences, 11, 8–15.

Pitcher, D., Walsh, V., Yovel, G., & Duchaine, B. (2007). TMS evidence for the involvement of the right occipital face area in early face processing. Current Biology, 17, 1568–1573.

Rodriguez, E., George, N., Lachaux, J.-P., Martinerie, J., Renault, B., & Varela, F. J. (1999). Perception’s shadow: Long-distance synchronization of human brain activity. Nature, 397(6718), 430–433.

Sekuler, R., & Blake, R. (2006). Perception (5th ed.). New York, NY: McGraw-Hill.

Witherington, D. C. (2005). The development of prospective grasping control between 5 and 7 months: A longitudinal study. Infancy, 7(2), 143–161.

Image Attributions

Figure 5.10: Mona Lisa detail face (http://commons.wikimedia.org/wiki/File:Mona_Lisa_detail_face.jpg) is in the public domain.

Figure 5.15: Ishihara Plate No.11 (http://commons.wikimedia.org/wiki/File:Ishihara_11.PNG) and Ishihara Plate No.23 (http://commons.wikimedia.org/wiki/File:Ishihara_23.PNG) is in the public domain.

Figure 5.16: Nachbild by Freddy2001 (http://commons.wikimedia.org/wiki/File:Nachbild-1.svg) and Italian Flag Inverted by Pcessna (http://commons.wikimedia.org/wiki/File:ItalianFlagInverted.gif) is in the public domain.

Figure 5.17: Perception-Conception (http://perception-connection.wikispaces.com/3)+Key+Findings) used with CC-BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0/).

Like vision and all the other senses, hearing begins with transduction. Sound waves that are collected by our ears are converted into neural impulses, which are sent to the brain where they are integrated with past experience and interpreted as the sounds we experience. The human ear is sensitive to a wide range of sounds, from the faint tick of a clock in a nearby room to the roar of a rock band at a nightclub, and we have the ability to detect very small variations in sound. But the ear is particularly sensitive to sounds in the same frequency as the human voice. A mother can pick out her child’s voice from a host of others, and when we pick up the phone we quickly recognize a familiar voice. In a fraction of a second, our auditory system receives the sound waves, transmits them to the auditory cortex, compares them to stored knowledge of other voices, and identifies the caller.

The Ear

Just as the eye detects light waves, the ear detects sound waves. Vibrating objects (such as the human vocal cords or guitar strings) cause air molecules to bump into each other and produce sound waves, which travel from their source as peaks and valleys, much like the ripples that expand outward when a stone is tossed into a pond. Unlike light waves, which can travel in a vacuum, sound waves are carried within media such as air, water, or metal, and it is the changes in pressure associated with these media that the ear detects.

As with light waves, we detect both the wavelength and the amplitude of sound waves. The wavelength of the sound wave (known as frequency) is measured in terms of the number of waves that arrive per second and determines our perception of pitch, the perceived frequency of a sound. Longer sound waves have lower frequency and produce a lower pitch, whereas shorter waves have higher frequency and a higher pitch.

The amplitude, or height of the sound wave, determines how much energy it contains and is perceived as loudness (the degree of sound volume). Larger waves are perceived as louder. Loudness is measured using the unit of relative loudness known as the decibel. Zero decibels represent the absolute threshold for human hearing, below which we cannot hear a sound. Each increase in 10 decibels represents a tenfold increase in the loudness of the sound (see Figure 5.18, “Sounds in Everyday Life”). The sound of a typical conversation (about 60 decibels) is 1,000 times louder than the sound of a faint whisper (30 decibels), whereas the sound of a jackhammer (130 decibels) is 10 billion times louder than the whisper.

Audition begins in the pinna, the external and visible part of the ear, which is shaped like a funnel to draw in sound waves and guide them into the auditory canal. At the end of the canal, the sound waves strike the tightly stretched, highly sensitive membrane known as the tympanic membrane (or eardrum), which vibrates with the waves. The resulting vibrations are relayed into the middle ear through three tiny bones, known as the ossicles — the hammer (or malleus), anvil (or incus), and stirrup (or stapes) — to the cochlea, a snail-shaped liquid-filled tube in the inner ear that contains the cilia. The vibrations cause the oval window, the membrane covering the opening of the cochlea, to vibrate, disturbing the fluid inside the cochlea (Figure 5.19).

The movements of the fluid in the cochlea bend the hair cells of the inner ear, in much the same way that a gust of wind bends over wheat stalks in a field. The movements of the hair cells trigger nerve impulses in the attached neurons, which are sent to the auditory nerve and then to the auditory cortex in the brain. The cochlea contains about 16,000 hair cells, each of which holds a bundle of fibres known as cilia on its tip. The cilia are so sensitive that they can detect a movement that pushes them the width of a single atom. To put things in perspective, cilia swaying the width of an atom is equivalent to the tip of the Eiffel Tower swaying half an inch (Corey et al., 2004).

Although loudness is directly determined by the number of hair cells that are vibrating, two different mechanisms are used to detect pitch. The frequency theory of hearing proposes that whatever the pitch of a sound wave, nerve impulses of a corresponding frequency will be sent to the auditory nerve. For example, a tone measuring 600 hertz will be transduced into 600 nerve impulses a second. This theory has a problem with high-pitched sounds, however, because the neurons cannot fire fast enough. To reach the necessary speed, the neurons work together in a sort of volley system in which different neurons fire in sequence, allowing us to detect sounds up to about 4,000 hertz.

Not only is frequency important, but location is critical as well. The cochlea relays information about the specific area, or place, in the cochlea that is most activated by the incoming sound. The place theory of hearing proposes that different areas of the cochlea respond to different frequencies. Higher tones excite areas closest to the opening of the cochlea (near the oval window). Lower tones excite areas near the narrow tip of the cochlea, at the opposite end. Pitch is therefore determined in part by the area of the cochlea firing the most frequently.

Just as having two eyes in slightly different positions allows us to perceive depth, so the fact that the ears are placed on either side of the head enables us to benefit from stereophonic, or three-dimensional, hearing. If a sound occurs on your left side, the left ear will receive the sound slightly sooner than the right ear, and the sound it receives will be more intense, allowing you to quickly determine the location of the sound. Although the distance between our two ears is only about six inches, and sound waves travel at 750 miles an hour, the time and intensity differences are easily detected (Middlebrooks & Green, 1991). When a sound is equidistant from both ears, such as when it is directly in front, behind, beneath, or overhead, we have more difficulty pinpointing its location. It is for this reason that dogs (and people, too) tend to cock their heads when trying to pinpoint a sound, so that the ears receive slightly different signals.

Hearing Loss

In 2006, 1,266,120 (5.0%) Canadians aged 15 and older reported having a hearing limitation. Over eight in 10 (83.2%) hearing limitations were mild in nature, while the remaining 16.8% were classified as severe (Statistics Canada, 2006). Conductive hearing loss is caused by physical damage to the ear (such as to the eardrums or ossicles) that reduces the ability of the ear to transfer vibrations from the outer ear to the inner ear. Sensorineural hearing loss, which is caused by damage to the cilia or to the auditory nerve, is less common overall but frequently occurs with age (Tennesen, 2007). The cilia are extremely fragile, and by the time we are 65 years old, we will have lost 40% of them, particularly those that respond to high-pitched sounds (Chisolm, Willott, & Lister, 2003).

Prolonged exposure to loud sounds will eventually create sensorineural hearing loss as the cilia are damaged by the noise. People who constantly operate noisy machinery without using appropriate ear protection are at high risk of hearing loss, as are people who listen to loud music on their headphones or who engage in noisy hobbies, such as hunting or motorcycling. Sounds that are 85 decibels or more can cause damage to your hearing, particularly if you are exposed to them repeatedly. Sounds of more than 130 decibels are dangerous even if you are exposed to them infrequently. People who experience tinnitus (a ringing or a buzzing sensation) after being exposed to loud sounds have very likely experienced some damage to their cilia. Taking precautions when being exposed to loud sounds is important, as cilia do not grow back.

While conductive hearing loss can often be improved through hearing aids that amplify the sound, they are of little help to sensorineural hearing loss. But if the auditory nerve is still intact, a cochlear implant may be used. A cochlear implant is a device made up of a series of electrodes that are placed inside the cochlea. The device serves to bypass the hair cells by stimulating the auditory nerve cells directly. The latest implants utilize place theory, enabling different spots on the implant to respond to different levels of pitch. The cochlear implant can help children who would normally be deaf hear. If the device is implanted early enough, these children can frequently learn to speak, often as well as children born without hearing loss do (Dettman, Pinder, Briggs, Dowell, & Leigh, 2007; Dorman & Wilson, 2004).

References

Chisolm, T. H., Willott, J. F., & Lister, J. J. (2003). The aging auditory system: Anatomic and physiologic changes and implications for rehabilitation. International Journal of Audiology, 42(Suppl. 2), 2S3–2S10.

Corey, D. P., García-Añoveros, J., Holt, J. R., Kwan, K. Y., Lin, S.-Y., Vollrath, M. A., Amalfitano, A.,…Zhang, D.-S. (2004). TRPA1 is a candidate for the mechano-sensitive transduction channel of vertebrate hair cells. Nature, 432, 723–730. Retrieved from http://www.nature.com/nature/journal/v432/n7018/full/nature03066.html

Dettman, S. J., Pinder, D., Briggs, R. J. S., Dowell, R. C., & Leigh, J. R. (2007). Communication development in children who receive the cochlear implant younger than 12 months: Risk versus benefits. Ear and Hearing, 28(2, Suppl.), 11S–18S.

Dorman, M. F., & Wilson, B. S. (2004). The design and function of cochlear implants. American Scientist, 92, 436–445.

Middlebrooks, J. C., & Green, D. M. (1991). Sound localization by human listeners. Annual Review of Psychology, 42, 135–159.

Statistics Canada. (2006). Participation and activity limitation survey, 2006. Retrieved June 2014 from http://www.statcan.gc.ca/pub/89-628-x/2009012/fs-fi/fs-fi-eng.htm

Tennesen, M. (2007, March 10). Gone today, hear tomorrow. New Scientist, 2594, 42–45.

Long Description

Figure 5.18 long description: Levels of Noise

Decibels (dB)	Description	Examples
140	Painful and dangerous, use hearing protection or avoid.	Fireworks, gunshots, custom car stereos (at full volume)
130	Painful and dangerous, use hearing protection or avoid.	Jackhammers, ambulances
120	Uncomfortable, dangerous over 30 seconds	Jet planes (during takeoff)
110	Very loud, dangerous over 30 seconds	Concerts, car horns, sporting events
100	Very loud, dangerous over 30 seconds	Snowmobiles, MP3 players (at full volume)
90	Very loud, dangerous over 30 seconds	Lawnmowers, power tools, blenders, hair dryers
85	Over 85 dB for extended periods can cause permanent hearing loss.
80	Loud	Alarm clocks
70	Loud	Traffic, vacuum cleaners
60	Moderate	Normal conversation, dishwashers
50	Moderate	Moderate raindall
40	Soft	Quiet library
20	Faint	Leaves rustling

[Return to Figure 5.18]

Although vision and hearing are by far the most important senses, human sensation is rounded out by four others, each of which provides an essential avenue to a better understanding of and response to the world around us. These other senses are touch, taste, and smell, and our sense of body position and movement (proprioception).

Tasting

Taste is important not only because it allows us to enjoy the food we eat, but, even more crucial, because it leads us toward foods that provide energy (sugar, for instance) and away from foods that could be harmful. Many children are picky eaters for a reason — they are biologically predisposed to be very careful about what they eat. Together with the sense of smell, taste helps us maintain appetite, assess potential dangers (such as the odour of a gas leak or a burning house), and avoid eating poisonous or spoiled food.

Our ability to taste begins at the taste receptors on the tongue. The tongue detects six different taste sensations, known respectively as sweet, salty, sour, bitter, piquancy (spicy), and umami (savory). Umami is a meaty taste associated with meats, cheeses, soy, seaweed, and mushrooms, and is particularly found in monosodium glutamate (MSG), a popular flavour enhancer (Ikeda, 1909/2002; Sugimoto & Ninomiya, 2005).

Our tongues are covered with taste buds, which are designed to sense chemicals in the mouth. Most taste buds are located in the top outer edges of the tongue, but there are also receptors at the back of the tongue as well as on the walls of the mouth and at the back of the throat. As we chew food, it dissolves and enters the taste buds, triggering nerve impulses that are transmitted to the brain (Northcutt, 2004). Human tongues are covered with 2,000 to 10,000 taste buds, and each bud contains between 50 and 100 taste receptor cells. Taste buds are activated very quickly; a salty or sweet taste that touches a taste bud for even one-tenth of a second will trigger a neural impulse (Kelling & Halpern, 1983). On average, taste buds live for about five days, after which new taste buds are created to replace them. As we get older, however, the rate of creation decreases, making us less sensitive to taste. This change helps explain why some foods that seem so unpleasant in childhood are more enjoyable in adulthood.

The area of the sensory cortex that responds to taste is in a very similar location to the area that responds to smell, a fact that helps explain why the sense of smell also contributes to our experience of the things we eat. You may remember having had difficulty tasting food when you had a bad cold, and if you block your nose and taste slices of raw potato, apple, and parsnip, you will not be able to taste the differences between them. Our experience of texture in a food (the way we feel it on our tongues) also influences how we taste it.

Smelling

As we breathe in air through our nostrils, we inhale airborne chemical molecules, which are detected by the 10 million to 20 million receptor cells embedded in the olfactory membrane of the upper nasal passage. The olfactory receptor cells are topped with tentacle-like protrusions that contain receptor proteins. When an odour receptor is stimulated, the membrane sends neural messages up the olfactory nerve to the brain (see Figure 5.20. “Smell Receptors”).

We have approximately 1,000 types of odour receptor cells (Bensafi et al., 2004), and it is estimated that we can detect 10,000 different odours (Malnic, Hirono, Sato, & Buck, 1999). The receptors come in many different shapes and respond selectively to different smells. Like a lock and key, different chemical molecules fit into different receptor cells, and odours are detected according to their influence on a combination of receptor cells. Just as the 10 digits from 0 to 9 can combine in many different ways to produce an endless array of phone numbers, odour molecules bind to different combinations of receptors, and these combinations are decoded in the olfactory cortex. As you can see in Figure 5.21, “Age Differences in Smell,” the sense of smell peaks in early adulthood and then begins a slow decline. By ages 60 to 70, the sense of smell has become sharply diminished. In addition, women tend to have a more acute sense of smell than men.

Touching

The sense of touch is essential to human development. Infants thrive when they are cuddled and attended to, but not if they are deprived of human contact (Baysinger, Plubell, & Harlow, 1973; Feldman, 2007; Haradon, Bascom, Dragomir, & Scripcaru, 1994). Touch communicates warmth, caring, and support, and is an essential part of the enjoyment we gain from our social interactions with close others (Field et al., 1997; Keltner, 2009).

The skin, the largest organ in the body, is the sensory organ for touch. The skin contains a variety of nerve endings, combinations of which respond to particular types of pressures and temperatures. When you touch different parts of the body, you will find that some areas are more ticklish, whereas other areas respond more to pain, cold, or heat.

The thousands of nerve endings in the skin respond to four basic sensations — pressure, hot, cold, and pain — but only the sensation of pressure has its own specialized receptors. Other sensations are created by a combination of the other four. For instance:

• The experience of a tickle is caused by the stimulation of neighbouring pressure receptors.
• The experience of heat is caused by the stimulation of hot and cold receptors.
• The experience of itching is caused by repeated stimulation of pain receptors.
• The experience of wetness is caused by repeated stimulation of cold and pressure receptors.

The skin is important not only in providing information about touch and temperature, but also in proprioception — the ability to sense the position and movement of our body parts. Proprioception is accomplished by specialized neurons located in the skin, joints, bones, ears, and tendons, which send messages about the compression and the contraction of muscles throughout the body. Without this feedback from our bones and muscles, we would be unable to play sports, walk, or even stand upright.

The ability to keep track of where the body is moving is also provided by the vestibular system, a set of liquid-filled areas in the inner ear that monitors the head’s position and movement, maintaining the body’s balance. As you can see in Figure 5.22, “The Vestibular System,” the vestibular system includes the semicircular canals and the vestibular sacs. These sacs connect the canals with the cochlea. The semicircular canals sense the rotational movements of the body, and the vestibular sacs sense linear accelerations. The vestibular system sends signals to the neural structures that control eye movement and to the muscles that keep the body upright.

Experiencing Pain

We do not enjoy it, but the experience of pain is how the body informs us that we are in danger. The burn when we touch a hot radiator and the sharp stab when we step on a nail lead us to change our behaviour, preventing further damage to our bodies. People who cannot experience pain are in serious danger of damage from wounds that others with pain would quickly notice and attend to.

The gate control theory of pain proposes that pain is determined by the operation of two types of nerve fibres in the spinal cord. One set of smaller nerve fibres carries pain from the body to the brain, whereas a second set of larger fibres is designed to stop or start (as a gate would) the flow of pain (Melzack & Wall, 1996). It is for this reason that massaging an area where you feel pain may help alleviate it — the massage activates the large nerve fibres that block the pain signals of the small nerve fibres (Wall, 2000).

Experiencing pain is a lot more complicated than simply responding to neural messages, however. It is also a matter of perception. We feel pain less when we are busy focusing on a challenging activity (Bantick et al., 2002), which can help explain why sports players may feel their injuries only after the game. We also feel less pain when we are distracted by humour (Zweyer, Velker, & Ruch, 2004). And pain is soothed by the brain’s release of endorphins, natural hormonal pain killers. The release of endorphins can explain the euphoria experienced in the running of a marathon (Sternberg, Bailin, Grant, & Gracely, 1998).

References

Bantick, S. J., Wise, R. G., Ploghaus, A., Clare, S., Smith, S. M., & Tracey, I. (2002). Imaging how attention modulates pain in humans using functional MRI. Brain: A Journal of Neurology, 125(2), 310–319.

Baysinger, C. M., Plubell, P. E., & Harlow, H. F. (1973). A variable-temperature surrogate mother for studying attachment in infant monkeys. Behavior Research Methods & Instrumentation, 5(3), 269–272.

Bensafi, M., Zelano, C., Johnson, B., Mainland, J., Kahn, R., & Sobel, N. (2004). Olfaction: From sniff to percept. In M. S. Gazzaniga (Ed.), The cognitive neurosciences (3rd ed.). Cambridge, MA: MIT Press.

Feldman, R. (2007). Maternal-infant contact and child development: Insights from the kangaroo intervention. In L. L’Abate (Ed.), Low-cost approaches to promote physical and mental health: Theory, research, and practice (pp. 323–351). New York, NY: Springer Science + Business Media.

Field, T., Lasko, D., Mundy, P., Henteleff, T., Kabat, S., Talpins, S., & Dowling, M. (1997). Brief report: Autistic children’s attentiveness and responsivity improve after touch therapy. Journal of Autism and Developmental Disorders, 27(3), 333–338.

Haradon, G., Bascom, B., Dragomir, C., & Scripcaru, V. (1994). Sensory functions of institutionalized Romanian infants: A pilot study. Occupational Therapy International, 1(4), 250–260.

Ikeda, K. (1909/2002). [New seasonings]. Chemical Senses, 27(9), 847–849. Translated and shortened to 75% by Y. Ogiwara & Y. Ninomiya from the Journal of the Chemical Society of Tokyo, 30, 820–836. (Original work published 1909).

Kelling, S. T., & Halpern, B. P. (1983). Taste flashes: Reaction times, intensity, and quality. Science, 219, 412–414.

Keltner, D. (2009). Born to be good: The science of a meaningful life. New York, NY: Norton.

Malnic, B., Hirono, J., Sato, T., & Buck, L. B. (1999). Combinatorial receptor codes for odors. Cell, 96, 713–723.

Melzack, R., & Wall, P. (1996). The challenge of pain. London, England: Penguin.

Murphy, C. (1986). Taste and smell in the elderly. In H. L. Meiselman & R. S. Rivlin (Eds.), Clinical measurement of taste and smell (Vol. 1, pp. 343–371). New York, NY: Macmillan.

Northcutt, R. G. (2004). Taste buds: Development and evolution. Brain, Behavior and Evolution, 64(3), 198–206.

Sternberg, W. F., Bailin, D., Grant, M., & Gracely, R. H. (1998). Competition alters the perception of noxious stimuli in male and female athletes. Pain, 76(1–2), 231–238.

Sugimoto, K., & Ninomiya, Y. (2005). Introductory remarks on umami research: Candidate receptors and signal transduction mechanisms on umami. Chemical Senses, 30(Suppl. 1), Pi21–i22.

Wall, P. (2000). Pain: The science of suffering. New York, NY: Columbia University Press.

Zweyer, K., Velker, B., & Ruch, W. (2004). Do cheerfulness, exhilaration, and humor production moderate pain tolerance? A FACS study. Humor: International Journal of Humor Research, 17(1-2), 85–119.

Image Attributions

Figure 5.21: Adapted from Murphy (1986).

The eyes, ears, nose, tongue, and skin sense the world around us, and in some cases perform preliminary information processing on the incoming data. But by and large, we do not experience sensation — we experience the outcome of perception, the total package that the brain puts together from the pieces it receives through our senses and that the brain creates for us to experience. When we look out the window at a view of the countryside, or when we look at the face of a good friend, we don’t just see a jumble of colours and shapes — we see, instead, an image of a countryside or an image of a friend (Goodale & Milner, 2006).

How the Perceptual System Interprets the Environment

This meaning making involves the automatic operation of a variety of essential perceptual processes. One of these is sensory interaction — the working together of different senses to create experience. Sensory interaction is involved when taste, smell, and texture combine to create the flavour we experience in food. It is also involved when we enjoy a movie because of the way the images and the music work together.

Although you might think that we understand speech only through our sense of hearing, it turns out that the visual aspect of speech is also important. One example of sensory interaction is shown in the McGurk effect — an error in perception that occurs when we misperceive sounds because the audio and visual parts of the speech are mismatched. You can witness the effect yourself by viewing “The McGurk Effect.”

Watch The McGurk Effect [YouTube]: http://www.youtube.com/watch?v=jtsfidRq2tw

The McGurk effect is an error in sound perception that occurs when there is a mismatch between the senses of hearing and seeing. You can experience it here.

Other examples of sensory interaction include the experience of nausea that can occur when the sensory information being received from the eyes and the body does not match information from the vestibular system (Flanagan, May, & Dobie, 2004) and synesthesia — an experience in which one sensation (e.g., hearing a sound) creates experiences in another (e.g., vision). Most people do not experience synesthesia, but those who do link their perceptions in unusual ways, for instance, by experiencing colour when they taste a particular food or by hearing sounds when they see certain objects (Ramachandran, Hubbard, Robertson, & Sagiv, 2005).

Another important perceptual process is selective attention — the ability to focus on some sensory inputs while tuning out others. View “Video Clip: Selective Attention,” and count the number of times the people in white playing with the ball pass it to each other. You may find that, like many other people who view it for the first time, you miss something important because you selectively attend to only one aspect of the video (Simons & Chabris, 1999). Perhaps knowledge of the process of selective attention can help you see why the security guards completely missed the fact that the Chaser group’s motorcade was a fake — they focused on some aspects of the situation, such as the colour of the cars and the fact that they were there at all, and completely ignored others (the details of the security information).

Watch Selective Attention [YouTube]: http://www.youtube.com/watch?v=vJG698U2Mvo

Watch this video and carefully count how many times the people in white pass the ball to each other.

Selective attention also allows us to focus on a single talker at a party while ignoring other conversations that are occurring around us (Broadbent, 1958; Cherry, 1953). Without this automatic selective attention, we’d be unable to focus on the single conversation we want to hear. But selective attention is not complete; we also, at the same time, monitor what’s happening in the channels we are not focusing on. Perhaps you have had the experience of being at a party and talking to someone in one part of the room, when suddenly you hear your name being mentioned by someone in another part of the room. This cocktail party phenomenon shows us that although selective attention is limiting what we process, we are nevertheless simultaneously doing a lot of unconscious monitoring of the world around us — you didn’t know you were attending to the background sounds of the party, but evidently you were.

A second fundamental process of perception is sensory adaptation — a decreased sensitivity to a stimulus after prolonged and constant exposure. When you step into a swimming pool, the water initially feels cold, but after a while you stop noticing it. After prolonged exposure to the same stimulus, our sensitivity toward it diminishes and we no longer perceive it. The ability to adapt to the things that don’t change around us is essential to our survival, as it leaves our sensory receptors free to detect the important and informative changes in our environment and to respond accordingly. We ignore the sounds that our car makes every day, which leaves us free to pay attention to the sounds that are different from normal, and thus likely to need our attention. Our sensory receptors are alert to novelty and are fatigued after constant exposure to the same stimulus.

If sensory adaptation occurs with all senses, why doesn’t an image fade away after we stare at it for a period of time? The answer is that, although we are not aware of it, our eyes are constantly flitting from one angle to the next, making thousands of tiny movements (called saccades) every minute. This constant eye movement guarantees that the image we are viewing always falls on fresh receptor cells. What would happen if we could stop the movement of our eyes? Psychologists have devised a way of testing the sensory adaptation of the eye by attaching an instrument that ensures a constant image is maintained on the eye’s inner surface. Participants are fitted with a contact lens that has a miniature slide projector attached to it. Because the projector follows the exact movements of the eye, the same image is always projected, stimulating the same spot, on the retina. Within a few seconds, interesting things begin to happen. The image will begin to vanish, then reappear, only to disappear again, either in pieces or as a whole. Even the eye experiences sensory adaptation (Yarbus, 1967).

One of the major problems in perception is to ensure that we always perceive the same object in the same way, even when the sensations it creates on our receptors change dramatically. The ability to perceive a stimulus as constant despite changes in sensation is known as perceptual constancy. Consider our image of a door as it swings. When it is closed, we see it as rectangular, but when it is open, we see only its edge and it appears as a line. But we never perceive the door as changing shape as it swings — perceptual mechanisms take care of the problem for us by allowing us to see a constant shape.

The visual system also corrects for colour constancy. Imagine that you are wearing blue jeans and a bright white T-shirt. When you are outdoors, both colours will be at their brightest, but you will still perceive the white T-shirt as bright and the blue jeans as darker. When you go indoors, the light shining on the clothes will be significantly dimmer, but you will still perceive the T-shirt as bright. This is because we put colours in context and see that, compared with its surroundings, the white T-shirt reflects the most light (McCann, 1992). In the same way, a green leaf on a cloudy day may reflect the same wavelength of light as a brown tree branch does on a sunny day. Nevertheless, we still perceive the leaf as green and the branch as brown.

Illusions

Although our perception is very accurate, it is not perfect. Illusions occur when the perceptual processes that normally help us correctly perceive the world around us are fooled by a particular situation so that we see something that does not exist or that is incorrect. Figure 5.23, “Optical Illusions as a Result of Brightness Constancy (Left) and Colour Constancy (Right),” presents two situations in which our normally accurate perceptions of visual constancy have been fooled.

Another well-known illusion is the Mueller-Lyer illusion (see Figure 5.24, “The Mueller-Lyer Illusion”). The line segment in the bottom arrow looks longer to us than the one on the top, even though they are both actually the same length. It is likely that the illusion is, in part, the result of the failure of monocular depth cues — the bottom line looks like an edge that is normally farther away from us, whereas the top one looks like an edge that is normally closer.

The moon illusion refers to the fact that the moon is perceived to be about 50% larger when it is near the horizon than when it is seen overhead, despite the fact that in both cases the moon is the same size and casts the same size retinal image. The monocular depth cues of position and aerial perspective (see Figure 5.25, “The Moon Illusion”) create the illusion that things that are lower and more hazy are farther away. The skyline of the horizon (trees, clouds, outlines of buildings) also gives a cue that the moon is far away, compared to when it is at its zenith. If we look at a horizon moon through a tube of rolled-up paper, taking away the surrounding horizon cues, the moon will immediately appear smaller.

 

The Ponzo illusion operates on the same principle. As you can see in Figure 5.26, “The Ponzo Illusion,” the top yellow bar seems longer than the bottom one, but if you measure them you’ll see that they are exactly the same length. The monocular depth cue of linear perspective leads us to believe that, given two similar objects, the distant one can only cast the same size retinal image as the closer object if it is larger. The topmost bar therefore appears longer.

Illusions demonstrate that our perception of the world around us may be influenced by our prior knowledge. But the fact that some illusions exist in some cases does not mean that the perceptual system is generally inaccurate — in fact, humans normally become so closely in touch with their environment that the physical body and the particular environment that we sense and perceive becomes embodied — that is, built into and linked with our cognition, such that the world around us becomes part of our brain (Calvo & Gomila, 2008). The close relationship between people and their environments means that, although illusions can be created in the lab and under some unique situations, they may be less common with active observers in the real world (Runeson, 1988).

The Important Role of Expectations in Perception

Our emotions, mindset, expectations, and the contexts in which our sensations occur all have a profound influence on perception. People who are warned that they are about to taste something bad rate what they do taste more negatively than people who are told that the taste won’t be so bad (Nitschke et al., 2006), and people perceive a child and adult pair as looking more alike when they are told that they are parent and child (Bressan & Dal Martello, 2002). Similarly, participants who see images of the same baby rate it as stronger and bigger when they are told it is a boy as opposed to when they are told it is a girl (Stern & Karraker, 1989), and research participants who learn that a child is from a lower-class background perceive the child’s scores on an intelligence test as lower than people who see the same test taken by a child they are told is from an upper-class background (Darley & Gross, 1983). Plassmann, O’Doherty, Shiv, and Rangel (2008) found that wines were rated more positively and caused greater brain activity in brain areas associated with pleasure when they were said to cost more than when they were said to cost less. And even experts can be fooled: professional referees tended to assign more penalty cards to soccer teams for videotaped fouls when they were told that the team had a history of aggressive behaviour than when they had no such expectation (Jones, Paull, & Erskine, 2002).

Our perceptions are also influenced by our desires and motivations. When we are hungry, food-related words tend to grab our attention more than non-food-related words (Mogg, Bradley, Hyare, & Lee, 1998), we perceive objects that we can reach as bigger than those that we cannot reach (Witt & Proffitt, 2005), and people who favour a political candidate’s policies view the candidate’s skin colour more positively than do those who oppose the candidate’s policies (Caruso, Mead, & Balcetis, 2009). Even our culture influences perception. Chua, Boland, and Nisbett (2005) showed American and Asian graduate students different images, such as an airplane, an animal, or a train, against complex backgrounds. They found that (consistent with their overall individualistic orientation) the American students tended to focus more on the foreground image, while Asian students (consistent with their interdependent orientation) paid more attention to the image’s context. Furthermore, Asian-American students focused more or less on the context depending on whether their Asian or their American identity had been activated.

References

Bressan, P., & Dal Martello, M. F. (2002). Talis pater, talis filius: Perceived resemblance and the belief in genetic relatedness. Psychological Science, 13, 213–218.

Broadbent, D. E. (1958). Perception and communication. New York, NY: Pergamon.

Calvo, P., & Gomila, T. (Eds.). (2008). Handbook of cognitive science: An embodied approach. San Diego, CA: Elsevier.

Caruso, E. M., Mead, N. L., & Balcetis, E. (2009). Political partisanship influences perception of biracial candidates’ skin tone. PNAS Proceedings of the National Academy of Sciences of the United States of America, 106(48), 20168–20173.

Cherry, E. C. (1953). Some experiments on the recognition of speech, with one and with two ears. Journal of the Acoustical Society of America, 25, 975–979.

Chua, H. F., Boland, J. E., & Nisbett, R. E. (2005). Cultural variation in eye movements during scene perception. Proceedings of the National Academy of Sciences, 102, 12629–12633.

Darley, J. M., & Gross, P. H. (1983). A hypothesis-confirming bias in labeling effects. Journal of Personality and Social Psychology, 44, 20–33.

Flanagan, M. B., May, J. G., & Dobie, T. G. (2004). The role of vection, eye movements, and postural instability in the etiology of motion sickness. Journal of Vestibular Research: Equilibrium and Orientation, 14(4), 335–346.

Goodale, M., & Milner, D. (2006). One brain — Two visual systems. Psychologist, 19(11), 660–663.

Jones, M. V., Paull, G. C., & Erskine, J. (2002). The impact of a team’s aggressive reputation on the decisions of association football referees. Journal of Sports Sciences, 20, 991–1000.

Kraft, C. (1978). A psychophysical approach to air safety: Simulator studies of visual illusions in night approaches. In H. L. Pick, H. W. Leibowitz, J. E. Singer, A. Steinschneider, & H. W. Steenson (Eds.), Psychology: From research to practice. New York, NY: Plenum Press.

Lee, J., & Strayer, D. (2004). Preface to the special section on driver distraction. Human Factors, 46(4), 583.

McCann, J. J. (1992). Rules for color constancy. Ophthalmic and Physiologic Optics, 12(2), 175–177.

Mogg, K., Bradley, B. P., Hyare, H., & Lee, S. (1998). Selective attention to food related stimuli in hunger. Behavior Research & Therapy, 36(2), 227–237.

Nickerson, R. S. (1998). Applied experimental psychology. Applied Psychology: An International Review, 47, 155–173.

Nitschke, J. B., Dixon, G. E., Sarinopoulos, I., Short, S. J., Cohen, J. D., Smith, E. E.,…Davidson, R. J. (2006). Altering expectancy dampens neural response to aversive taste in primary taste cortex. Nature Neuroscience 9, 435–442.

Plassmann, H., O’Doherty, J., Shiv, B., & Rangel, A. (2008). Marketing actions can moderate neural representations of experienced pleasantness. Proceedings of the National Academy of Sciences, 105(3), 1050–1054.

Proctor, R. W., & Van Zandt, T. (2008). Human factors in simple and complex systems (2nd ed.). Boca Raton, FL: CRC Press.

Ramachandran, V. S., Hubbard, E. M., Robertson, L. C., & Sagiv, N. (2005). The emergence of the human mind: Some clues from synesthesia. In Synesthesia: Perspectives From Cognitive Neuroscience (pp. 147–190). New York, NY: Oxford University Press.

Runeson, S. (1988). The distorted room illusion, equivalent configurations, and the specificity of static optic arrays. Journal of Experimental Psychology: Human Perception and Performance, 14(2), 295–304.

Silverstein, L. D., Krantz, J. H., Gomer, F. E., Yeh, Y., & Monty, R. W. (1990). The effects of spatial sampling and luminance quantization on the image quality of color matrix displays. Journal of the Optical Society of America, Part A, 7, 1955–1968.

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Stern, M., & Karraker, K. H. (1989). Sex stereotyping of infants: A review of gender labeling studies. Sex Roles, 20(9–10), 501–522.

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Image Attributions

Figure 5.23: Grey Square Optical Illusion by Edward H. Adelson, http://commons.wikimedia.org/wiki/File:Grey_square_optical_illusion.PNG is in the public domain.

Figure 5.25: “Full Moon Through The Clouds” by Jake Khuon (http://www.flickr.com/photos/wintrhawk/443408898/) is licensed under CC BY-NC 2.0 license(http://creativecommons.org/licenses/by-nc/2.0/deed.en_CA). “Last Sail Under a Full Moon” by Kipp Baker (http://www.flickr.com/photos/mrpixure/3356957620/in/photostream) is licensed under CC BY-NC-ND 2.0 license (http://creativecommons.org/licenses/by-nc-nd/2.0/deed.en_CA).

Figure 5.27: “DC-9 Cockpit” by Dmitry Denisenkov (http://en.wikipedia.org/wiki/File:DC-9_Cockpit.jpg) is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported.(http://creativecommons.org/licenses/by-sa/3.0/deed.en) “Airbus A380 cockpit” by Naddsy (http://en.wikipedia.org/wiki/File:Airbus_A380_cockpit.jpg) used under the Creative Commons Attribution 2.0 Generic (http://creativecommons.org/licenses/by/2.0/deed.en).

Sensation and perception work seamlessly together to allow us to detect both the presence of, and changes in, the stimuli around us.

The study of sensation and perception is exceedingly important for our everyday lives because the knowledge generated by psychologists is used in so many ways to help so many people.

Each sense accomplishes the basic process of transduction — the conversion of stimuli detected by receptor cells into electrical impulses that are then transported to the brain — in different, but related, ways.

Psychophysics is the branch of psychology that studies the effects of physical stimuli on sensory perceptions. Psychophysicists study the absolute threshold of sensation as well as the difference threshold, or just noticeable difference (JND). Weber’s law maintains that the JND of a stimulus is a constant proportion of the original intensity of the stimulus.

Most of our cerebral cortex is devoted to seeing, and we have substantial visual skills. The eye is a specialized system that includes the cornea, pupil, iris, lens, and retina. Neurons, including rods and cones, react to light landing on the retina and send it to the visual cortex via the optic nerve.

Images are perceived, in part, through the action of feature detector neurons.

The shade of a colour, known as hue, is conveyed by the wavelength of the light that enters the eye. The Young-Helmholtz trichromatic colour theory and the opponent-process colour theory are theories of how the brain perceives colour.

Depth is perceived using both binocular and monocular depth cues. Monocular depth cues are based on gestalt principles. The beta effect and the phi phenomenon are important in detecting motion.

The ear detects both the amplitude (loudness) and frequency (pitch) of sound waves.

Important structures of the ear include the pinna, eardrum, ossicles, cochlea, and oval window.

The frequency theory of hearing proposes that as the pitch of a sound wave increases, nerve impulses of a corresponding frequency are sent to the auditory nerve. The place theory of hearing proposes that different areas of the cochlea respond to different frequencies.

Sounds that are 85 decibels or more can cause damage to your hearing, particularly if you are exposed to them repeatedly. Sounds that exceed 130 decibels are dangerous, even if you are exposed to them infrequently.

The tongue detects six different taste sensations, known respectively as sweet, salty, sour, bitter, piquancy (spicy), and umami (savory).

We have approximately 1,000 types of odour receptor cells and it is estimated that we can detect 10,000 different odours.

Thousands of nerve endings in the skin respond to four basic sensations — pressure, hot, cold, and pain — but only the sensation of pressure has its own specialized receptors. The ability to keep track of where the body is moving is provided by the vestibular system.

Perception involves the processes of sensory interaction, selective attention, sensory adaptation, and perceptual constancy.

Although our perception is very accurate, it is not perfect. Our expectations and emotions colour our perceptions and may result in illusions.

Consciousness is defined as our subjective awareness of ourselves and our environment (Koch, 2004). The experience of consciousness is fundamental to human nature. We all know what it means to be conscious, and we assume (although we can never be sure) that other human beings experience their consciousness similarly to how we experience ours.

The study of consciousness has long been important to psychologists and plays a role in many important psychological theories. For instance, Sigmund Freud’s personality theories differentiated between the unconscious and the conscious aspects of behaviour, and present-day psychologists distinguish between automatic (unconscious) and controlled (conscious) behaviours and between implicit (unconscious) and explicit (conscious) memory (Petty, Wegener, Chaiken, & Trope, 1999; Shanks, 2005).

Some philosophers and religious practices argue that the mind (or soul) and the body are separate entities. For instance, the French philosopher René Descartes (1596-1650), shown in Figure 6.1, was a proponent of dualism, the idea that the mind, a nonmaterial entity, is separate from (although connected to) the physical body. In contrast to the dualists, psychologists believe that consciousness (and thus the mind) exists in the brain, not separate from it. In fact, psychologists believe that consciousness is the result of the activity of the many neural connections in the brain, and that we experience different states of consciousness depending on what our brain is currently doing (Dennett, 1991; Koch & Greenfield, 2007).

The study of consciousness is also important to the fundamental psychological question regarding the presence of free will. Although we may understand and believe that some of our behaviours are caused by forces that are outside our awareness (i.e., unconscious), we nevertheless believe that we have control over, and are aware that we are engaging in, most of our behaviours. To discover that we have, or someone else has, engaged in a complex behaviour, such as driving in a car and causing severe harm to others, without being at all conscious of these actions, is so unusual as to be shocking. And yet psychologists are increasingly certain that a great deal of our behaviour is caused by processes of which we are unaware and over which we have little or no control (Libet, 1999; Wegner, 2003).

Our experience of consciousness is functional because we use it to guide and control our behaviour, and to think logically about problems (DeWall, Baumeister, & Masicampo, 2008). Consciousness allows us to plan activities and to monitor our progress toward the goals we set for ourselves. And consciousness is fundamental to our sense of morality — we believe that we have the free will to perform moral actions while avoiding immoral behaviours.

But in some cases consciousness may become aversive — for instance, when we become aware that we are not living up to our own goals or expectations, or when we believe that other people perceive us negatively. In these cases we may engage in behaviours that help us escape from consciousness; for example, through the use of alcohol or other psychoactive drugs (Baumeister, 1998).

Because the brain varies in its current level and type of activity, consciousness is transitory. If we drink too much coffee or beer, the caffeine or alcohol influences the activity in our brain, and our consciousness may change. When we are anesthetized before an operation or experience a concussion after a knock on the head, we may lose consciousness entirely as a result of changes in brain activity. We also lose consciousness when we sleep, and it is with this altered state of consciousness that we begin our chapter.

References

Baumeister, R. (1998). The self. In The handbook of social psychology (4th ed., Vol. 2, pp. 680–740). New York, NY: McGraw-Hill.

Broughton, R. J., Billings, R., Cartwright, R., & Doucette, D. (1994). Homicidal somnambulism: A case report. Sleep: Journal of Sleep Research & Sleep Medicine, 17(3), 253–264.

Dennett, D. C. (1991). Consciousness explained. Boston, MA: Little, Brown and Company.

DeWall, C., Baumeister, R., & Masicampo, E. (2008). Evidence that logical reasoning depends on conscious processing. Consciousness and Cognition, 17(3), 628.

Koch, C. (2004). The quest for consciousness: A neurobiological approach. Englewood, CO: Roberts & Co.

Koch, C., & Greenfield, S. (2007). How does consciousness happen? Scientific American, 76–83.

Libet, B. (1999). Do we have free will? Journal of Consciousness Studies, 6, 8(9), 47–57.

Martin, L. (2009). Can sleepwalking be a murder defense? Sleep Disorders: For Patients and Their Families. Retrieved from http://www.lakesidepress.com/pulmonary/Sleep/sleep-murder.htm

Petty, R., Wegener, D., Chaiken, S., & Trope, Y. (1999). Dual-process theories in social psychology. New York, NY: Guilford Press.

Shanks, D. (2005). Implicit learning. In K. Lamberts (Ed.), Handbook of cognition (pp. 202–220). London, England: Sage.

Wegner, D. M. (2003). The mind’s best trick: How we experience conscious will. Trends in Cognitive Sciences, 7(2), 65–69.

Wilson, C. (1998). The mammoth book of true crime. New York, NY: Robinson Publishing.

Image Attributions

Figure 6.1: Portrait of René Descartes by André Hatala, (http://commons.wikimedia.org/wiki/File:Frans_Hals_-_Portret_van_René_Descartes.jpg) is in the public domain.

The lives of all organisms, including humans, are influenced by regularly occurring cycles of behaviours known as biological rhythms. One important biological rhythm is the annual cycle that guides the migration of birds and the hibernation of bears. Women also experience a 28-day cycle that guides their fertility and menstruation. But perhaps the strongest and most important biorhythm is the daily circadian rhythm (from the Latin circa, meaning “about” or “approximately,” and dian, meaning “daily”) that guides the daily waking and sleeping cycle in many animals.Many biological rhythms are coordinated by changes in the level and duration of ambient light — for instance, as winter turns into summer and as night turns into day. In some animals, such as birds, the pineal gland in the brain is directly sensitive to light, and its activation influences behaviour, such as mating and annual migrations. Light also has a profound effect on humans. We are more likely to experience depression during the dark winter months than during the lighter summer months, an experience known as seasonal affective disorder (SAD), and exposure to bright lights can help reduce this depression (McGinnis, 2007).

Sleep is also influenced by ambient light. The ganglion cells in the retina send signals to a brain area above the thalamus called the suprachiasmatic nucleus, which is the body’s primary circadian pacemaker. The suprachiasmatic nucleus analyzes the strength and duration of the light stimulus and sends signals to the pineal gland when the ambient light level is low or its duration is short. In response, the pineal gland secretes melatonin, a powerful hormone that facilitates the onset of sleep.

Sleep Stages: Moving through the Night

Although we lose consciousness as we sleep, the brain nevertheless remains active. The patterns of sleep have been tracked in thousands of research participants who have spent nights sleeping in research labs (Figure 6.3) while their brainwaves were recorded by monitors, such as an electroencephalogram, or EEG.

Sleep researchers have found that sleeping people undergo a fairly consistent pattern of sleep stages, each lasting about 90 minutes. As you can see in Figure 6.4, “Stages of Sleep,” these stages are of two major types: rapid eye movement and non-rapid eye movement. Rapid eye movement (REM) sleep is a sleep stage characterized by the presence of quick eye movements and dreaming. REM sleep accounts for about 25% of our total sleep time. During REM sleep, our awareness of external events is dramatically reduced, and consciousness is dominated primarily by internally generated images and a lack of overt thinking (Hobson, 2004). During this sleep stage our muscles shut down, and this is probably a good thing as it protects us from hurting ourselves or trying to act out the scenes that are playing in our dreams. The second major sleep type, non-rapid eye movement (non-REM) sleep is a deep sleep, characterized by very slow brainwaves, that is further subdivided into three stages: N1, N2, and N3. Each of the sleep stages has its own distinct pattern of brain activity (Dement & Kleitman, 1957).

As you can see in Figure 6.5, “EEG Recordings of Brain Patterns During Sleep,” the brainwaves that are recorded by an EEG as we sleep show that the brain’s activity changes during each stage of sleeping. When we are awake, our brain activity is characterized by the presence of very fast beta waves. When we first begin to fall asleep, the waves get longer (alpha waves), and as we move into stage N1 sleep, which is characterized by the experience of drowsiness, the brain begins to produce even slower theta waves. During stage N1 sleep, some muscle tone is lost, as well as most awareness of the environment. Some people may experience sudden jerks or twitches and even vivid hallucinations during this initial stage of sleep.

Normally, if we are allowed to keep sleeping, we will move from stage N1 to stage N2 sleep. During stage N2, muscular activity is further decreased and conscious awareness of the environment is lost. This stage typically represents about half of the total sleep time in normal adults. Stage N2 sleep is characterized by theta waves interspersed with bursts of rapid brain activity known as sleep spindles.

Stage N3, also known as slow wave sleep, is the deepest level of sleep, characterized by an increased proportion of very slow delta waves. This is the stage in which most sleep abnormalities, such as sleepwalking, sleeptalking, nightmares, and bedwetting occur. The sleepwalking murders committed by Mr. Parks would have occurred in this stage. Some skeletal muscle tone remains, making it possible for affected individuals to rise from their beds and engage in sometimes very complex behaviours, but consciousness is distant. Even in the deepest sleep, however, we are still aware of the external world. If smoke enters the room or if we hear the cry of a baby we are likely to react, even though we are sound asleep. These occurrences again demonstrate the extent to which we process information outside consciousness.

After falling initially into a very deep sleep, the brain begins to become more active again, and we normally move into the first period of REM sleep about 90 minutes after falling asleep. REM sleep is accompanied by an increase in heart rate, facial twitches, and the repeated rapid eye movements that give this stage its name. People who are awakened during REM sleep almost always report that they were dreaming, while those awakened in other stages of sleep report dreams much less often. REM sleep is also emotional sleep. Activity in the limbic system, including the amygdala, is increased during REM sleep, and the genitals become aroused, even if the content of the dreams we are having is not sexual. A typical 25-year-old man may have an erection nearly half the night, and the common “morning erection” is left over from the last REM period before waking.

Normally we will go through several cycles of REM and non-REM sleep each night (Figure 6.5, “EEG Recordings of Brain Patterns During Sleep”). The length of the REM portion of the cycle tends to increase through the night, from about five to 10 minutes early in the night to 15 to 20 minutes shortly before awakening in the morning. Dreams also tend to become more elaborate and vivid as the night goes on. Eventually, as the sleep cycle finishes, the brain resumes its faster alpha and beta waves and we awake, normally refreshed.

Sleep Disorders: Problems in Sleeping

According to a recent poll (Statistics Canada, 2011), six in 10 Canadian adults say they feel tired most of the time. These people are suffering from a sleep disorder known as insomnia, defined as persistent difficulty falling or staying asleep. Most cases of insomnia are temporary, lasting from a few days to several weeks, but in some cases insomnia can last for years.

Insomnia can result from physical disorders such as pain due to injury or illness, or from psychological problems such as stress, financial worries, or relationship difficulties. Changes in sleep patterns, such as jet lag, changes in work shift, or even the movement to or from daylight saving time can produce insomnia. Sometimes the sleep that the insomniac does get is disturbed and nonrestorative, and the lack of quality sleep produces impairment of functioning during the day. Ironically, the problem may be compounded by people’s anxiety over insomnia itself: their fear of being unable to sleep may wind up keeping them awake. Some people may also develop a conditioned anxiety to the bedroom or the bed.

People who have difficulty sleeping may turn to drugs to help them sleep. Barbiturates, benzodiazepines, and other sedatives (Figure 6.6) are frequently marketed and prescribed as sleep aids, but they may interrupt the natural stages of the sleep cycle, and in the end are likely to do more harm than good. In some cases they may also promote dependence. Most practitioners of sleep medicine today recommend making environmental and scheduling changes first, followed by therapy for underlying problems, with pharmacological remedies used only as a last resort.

According to the Canadian Sleep Society, some steps that can be used to combat insomnia include the following:

• Use the bed and bedroom for sleep and sex only. Do not spend time in bed during the day.
• Establish a regular bedtime routine and a regular sleep-wake schedule.
• Do not eat or drink too much close to bedtime.
• Create a sleep-promoting environment that is dark, cool, and comfortable.
• Avoid disturbing noises — consider a bedside fan or white-noise machine to block out disturbing sounds.
• Consume less or no caffeine, particularly late in the day.
• Avoid alcohol and nicotine, especially close to bedtime.
• Exercise, but not within three hours before bedtime.
• Avoid naps, particularly in the late afternoon or evening.

Another common sleep problem is sleep apnea, a sleep disorder characterized by pauses in breathing that last at least 10 seconds during sleep (Morgenthaler, Kagramanov, Hanak, & Decker, 2006). In addition to preventing restorative sleep, sleep apnea can also cause high blood pressure and may increase the risk of stroke and heart attack (Yaggi et al., 2005).

Most sleep apnea is caused by an obstruction of the walls of the throat that occurs when we fall asleep. It is most common in obese or older individuals who have lost muscle tone and is particularly common in men. Sleep apnea caused by obstructions is usually treated with an air machine that uses a mask to create a continuous pressure that prevents the airway from collapsing, or with mouthpieces that keep the airway open. If all other treatments have failed, sleep apnea may be treated with surgery to open the airway.

Narcolepsy is a disorder characterized by extreme daytime sleepiness with frequent episodes of nodding off. The syndrome may also be accompanied by attacks of cataplexy, in which the individual loses muscle tone, resulting in a partial or complete collapse. It is estimated that one in 2,000 people suffer from narcolepsy.

Narcolepsy is in part the result of genetics — people who suffer from the disease lack neurotransmitters that are important in keeping us alert (Taheri, Zeitzer, & Mignot, 2002) — and is also the result of a lack of deep sleep. While most people descend through the sequence of sleep stages, then move back up to REM sleep soon after falling asleep, narcolepsy sufferers move directly into REM and undergo numerous awakenings during the night, often preventing them from getting good sleep.

Narcolepsy can be treated with stimulants, such as amphetamines, to counteract the daytime sleepiness, or with antidepressants to treat a presumed underlying depression. However, since these drugs further disrupt already abnormal sleep cycles, these approaches may, in the long run, make the problem worse. Many sufferers find relief by taking a number of planned short naps during the day, and some individuals may find it easier to work in jobs that allow them to sleep during the day and work at night.

Other sleep disorders occur when cognitive or motor processes that should be turned off or reduced in magnitude during sleep operate at higher than normal levels (Mahowald & Schenck, 2000). One example is somnambulism (sleepwalking), in which the person leaves the bed and moves around while still asleep. Sleepwalking is more common in childhood, with the most frequent occurrences around the age of 12 years. About 4% of adults experience somnambulism (Mahowald & Schenck, 2000).

Sleep terrors is a disruptive sleep disorder, most frequently experienced in childhood, that may involve loud screams and intense panic. The sufferer cannot wake from sleep even though he or she is trying to. In extreme cases, sleep terrors may result in bodily harm or property damage as the sufferer moves about abruptly. Up to 3% of adults suffer from sleep terrors, which typically occur in sleep stage N3 (Mahowald & Schenck, 2000).

Other sleep disorders include bruxism, in which the sufferer grinds his teeth during sleep; restless legs syndrome, in which the sufferer reports an itching, burning, or otherwise uncomfortable feeling in his legs, usually exacerbated when resting or asleep; and periodic limb movement disorder, which involves sudden involuntary movement of limbs. The last of these, periodic limb movement disorder, can cause sleep disruption and injury for both the sufferer and bed partner.

Although many sleep disorders occur during non-REM sleep, some occur during REM sleep. REM sleep behaviour disorder (Mahowald & Schenck, 2005) is a condition in which people (usually middle-aged or older men) engage in vigorous and bizarre physical activities during REM sleep in response to intense, violent dreams. As their actions may injure themselves or their sleeping partners, this disorder, thought to be neurological in nature, is normally treated with hypnosis and medications.

The Heavy Costs of Not Sleeping

Our preferred sleep times and our sleep requirements vary throughout our life cycle. Newborns tend to sleep between 16 and 18 hours per day, preschoolers tend to sleep between 10 and 12 hours per day, school-aged children and teenagers usually prefer at least nine hours of sleep per night, and most adults say that they require seven to eight hours per night (Mercer, Merritt, & Cowell, 1998; Statistics Canada, 2011). There are also individual differences in need for sleep. Some adults do quite well with fewer than six hours of sleep per night, whereas others need nine hours or more. The most recent study by Mental Health Canada (2014) suggests that adults should get between seven and nine hours of sleep per night (Figure 6.7, “Average Hours of Required Sleep per Night”), and yet 15% of Canadians average fewer than 6.5 hours and 47% of Canadians stated that they cut down on sleep in an attempt to squeeze more time out of the day.

Getting needed rest is difficult in part because school and work schedules still follow the early-to-rise timetable that was set years ago. We tend to stay up late to enjoy activities in the evening but then are forced to get up early to go to work or school. The situation is particularly bad for university students, who are likely to combine a heavy academic schedule with an active social life and who may, in some cases, also work. Getting enough sleep is a luxury that many of us seem to be unable or unwilling to afford, and yet sleeping is one of the most important things we can do for ourselves. Continued over time, a nightly deficit of even only one or two hours can have a substantial impact on mood and performance (Figure 6.8).

Sleep has a vital restorative function, and a prolonged lack of sleep results in increased anxiety, diminished performance, and, if severe and extended, even death. Many road accidents involve sleep deprivation, and people who are sleep deprived show decrements in driving performance similar to those who have ingested alcohol (Hack, Choi, Vijayapalan, Davies, & Stradling, 2001; Williamson & Feyer, 2000). Poor treatment by doctors (Smith-Coggins, Rosekind, Hurd, & Buccino, 1994) and a variety of industrial accidents have also been traced in part to the effects of sleep deprivation.

Good sleep is also important to our health and longevity. It is no surprise that we sleep more when we are sick, because sleep works to fight infection. Sleep deprivation suppresses immune responses that fight off infection, and can lead to obesity, hypertension, and memory impairment (Ferrie et al., 2007; Kushida, 2005). Sleeping well can even save our lives. Dew and colleagues (2003) found that older adults who had better sleep patterns also lived longer.

Dreams and Dreaming

Dreams are the succession of images, thoughts, sounds, and emotions that passes through our minds while sleeping. When people are awakened from REM sleep, they normally report that they have been dreaming, suggesting that people normally dream several times a night but that most dreams are forgotten on awakening (Dement, 1997). The content of our dreams generally relates to our everyday experiences and concerns, and frequently our fears and failures (Cartwright, Agargun, Kirkby, & Friedman, 2006; Domhoff, Meyer-Gomes, & Schredl, 2005).

Many cultures regard dreams as having great significance for the dreamer, either by revealing something important about the dreamer’s present circumstances or predicting his or her future. The Austrian psychologist Sigmund Freud (1913/1988) analyzed the dreams of his patients to help him understand their unconscious needs and desires, and psychotherapists still make use of this technique today. Freud believed that the primary function of dreams was wish fulfilment, or the idea that dreaming allows us to act out the desires that we must repress during the day. He differentiated between the manifest content of the dream (i.e., its literal actions) and its latent content (i.e., the hidden psychological meaning of the dream). Freud believed that the real meaning of dreams is often suppressed by the unconscious mind in order to protect the individual from thoughts and feelings that are hard to cope with. By uncovering the real meaning of dreams through psychoanalysis, Freud believed that people could better understand their problems and resolve the issues that create difficulties in their lives.

Although Freud and others have focused on the meaning of dreams, other theories about the causes of dreams are less concerned with their content. One possibility is that we dream primarily to help with consolidation, or the moving of information into long-term memory (Alvarenga et al., 2008; Zhang (2004). Rauchs, Desgranges, Foret, and Eustache (2005) found that rats that had been deprived of REM sleep after learning a new task were less able to perform the task again later than were rats that had been allowed to dream, and these differences were greater on tasks that involved learning unusual information or developing new behaviours. Payne and Nadel (2004)  argued that the content of dreams is the result of consolidation — we dream about the things that are being moved into long-term memory. Thus dreaming may be an important part of the learning that we do while sleeping (Hobson, Pace-Schott, and Stickgold, 2000).

The activation-synthesis theory of dreaming (Hobson & McCarley, 1977; Hobson, 2004) proposes still another explanation for dreaming — namely, that dreams are our brain’s interpretation of the random firing of neurons in the brain stem. According to this approach, the signals from the brain stem are sent to the cortex, just as they are when we are awake, but because the pathways from the cortex to skeletal muscles are disconnected during REM sleep, the cortex does not know how to interpret the signals. As a result, the cortex strings the messages together into the coherent stories we experience as dreams.

Although researchers are still trying to determine the exact causes of dreaming, one thing remains clear — we need to dream. If we are deprived of REM sleep, we quickly become less able to engage in the important tasks of everyday life, until we are finally able to dream again.

References

Alvarenga, T. A., Patti, C. L., Andersen, M. L., Silva, R. H., Calzavara, M. B., Lopez, G.B.,…Tufik, S. (2008). Paradoxical sleep deprivation impairs acquisition, consolidation and retrieval of a discriminative avoidance task in rats. Neurobiology of Learning and Memory, 90, 624–632.

Bodenhausen, G. V. (1990). Stereotypes as judgmental heuristics: Evidence of circadian variations in discrimination. Psychological Science, 1, 319–322.

Cartwright, R., Agargun, M., Kirkby, J., & Friedman, J. (2006). Relation of dreams to waking concerns. Psychiatry Research, 141(3), 261–270.

Dement, W. (1997). What all undergraduates should know about how their sleeping lives affect their waking lives. Sleepless at Stanford. Retrieved from http://www.Stanford.edu/~dement/sleepless.html

Dement, W., & Kleitman, N. (1957). Cyclic variations in EEG during sleep. Electroencephalography & Clinical Neurophysiology, 9, 673–690.

Dew, M. A., Hoch, C. C., Buysse, D. J., Monk, T. H., Begley, A. E., Houck, P. R.,…Reynolds, C. F., III. (2003). Healthy older adults’ sleep predicts all-cause mortality at 4 to 19 years of follow-up. Psychosomatic Medicine, 65(1), 63–73.

Domhoff, G. W., Meyer-Gomes, K., & Schredl, M. (2005). Dreams as the expression of conceptions and concerns: A comparison of German and American college students. Imagination, Cognition and Personality, 25(3), 269–282.

Ferrie, J. E., Shipley, M. J., Cappuccio, F. P., Brunner, E., Miller, M. A., Kumari, M., & Marmot, M. G. (2007). A prospective study of change in sleep duration: Associations with mortality in the Whitehall II cohort. Sleep, 30(12), 1659.

Freud, S., & Classics of Medicine Library. (1913/1988). The interpretation of dreams (Special ed.). Birmingham, AL: The Classics of Medicine Library. (Original work published 1913).

Hack, M. A., Choi, S. J., Vijayapalan, P., Davies, R. J. O., & Stradling, J. R. S. (2001). Comparison of the effects of sleep deprivation, alcohol and obstructive sleep apnoea (OSA) on simulated steering performance. Respiratory medicine, 95(7), 594–601.

Hobson, A. (2004). A model for madness? Dream consciousness: Our understanding of the neurobiology of sleep offers insight into abnormalities in the waking brain. Nature, 430, 69–95.

Hobson, J. A., & McCarley, R. (1977). The brain as a dream state generator: An activation-synthesis hypothesis of the dream process. American Journal of Psychiatry, 134, 1335–1348.

Hobson, J. A., Pace-Schott, E. F., & Stickgold, R. (2000). Dreaming and the brain: Toward a cognitive neuroscience of conscious states. Behavioral and Brain Sciences, 23(6), 793–842, 904–1018, 1083–1121.

Kushida, C. (2005). Sleep deprivation: basic science, physiology, and behavior. London, England: Informa Healthcare.

Mahowald, M., & Schenck, C. (2000). REM sleep parasomnias. Principles and Practice of Sleep Medicine, 724–741.

Mahowald, M., & Schenck, C. (2005). REM sleep behavior disorder. Handbook of Clinical Neurophysiology, 6, 245–253.

McGinniss, P. (2007). Seasonal affective disorder (SAD) — Treatment and drugs. Mayo Clinic. Retrieved from http://www.mayoclinic.com/health/seasonal-affective-disorder/DS00195/DSECTION=treatments%2Dand%2Ddrugs

Mental Health Canada. (2014). Understanding sleep. Retrieved June 2014 from http://www.mentalhealthcanada.com/article_detail.asp?lang=e&id=28

Mercer, P., Merritt, S., & Cowell, J. (1998). Differences in reported sleep need among adolescents. Journal of Adolescent Health, 23(5), 259–263.

Morgenthaler, T. I., Kagramanov, V., Hanak, V., & Decker, P. A. (2006). Complex sleep apnea syndrome: Is it a unique clinical syndrome? Sleep, 29(9), 1203–1209. Retrieved from http://www.journalsleep.org/ViewAbstract.aspx?pid=26630

Payne, J., & Nadel, L. (2004). Sleep, dreams, and memory consolidation: The role of the stress hormone cortisol. Learning & Memory, 11(6), 671.

Rauchs, G., Desgranges, B., Foret, J., & Eustache, F. (2005). The relationships between memory systems and sleep stages. Journal of Sleep Research, 14, 123–140.

Ross, J. J. (1965). Neurological findings after prolonged sleep deprivation. Archives of Neurology, 12, 399–403.

Smith-Coggins, R., Rosekind, M. R., Hurd, S., & Buccino, K. R. (1994). Relationship of day versus night sleep to physician performance and mood. Annals of Emergency Medicine, 24(5), 928–934.

Statistics Canada. (2011). General social survey, 2010: Overview of the time use of Canadians. Statistics Canada Reference No. 89-647-X. Ottawa. bit.ly/rickWR

Taheri, S., Zeitzer, J. M., & Mignot, E. (2002). The role of hypocretins (Orexins) in sleep regulation and narcolepsy. Annual Review of Neuroscience, 25, 283–313.

Williamson, A., & Feyer, A. (2000). Moderate sleep deprivation produces impairments in cognitive and motor performance equivalent to legally prescribed levels of alcohol intoxication. Occupational and Environmental Medicine, 57(10), 649.

Yaggi, H. K., Concato, J., Kernan, W. N., Lichtman, J. H., Brass, L. M., & Mohsenin, V. (2005). Obstructive sleep apnea as a risk factor for stroke and death. The New England Journal of Medicine, 353(19), 2034–2041.

Zhang, J. (2004). Memory process and the function of sleep. Journal of Theoretics, 6(6), 1–7.

Image Attributions

Figure 6.2: Adapted from Bodenhausen (1990).

Figure 6.3: 140307_jwl_sleep-1 by JBLM PAO (https://www.flickr.com/photos/jblmpao/13069628253/in/photolist-bLybHR-xSqVE) used under CC-BY-NC-SA 2.0 (https://creativecommons.org/licenses/by-nc-sa/2.0/).

Figure 6.6: “The little blue painkillers” by Stephen Cummings (http://www.flickr.com/photos/spcummings/) is licensed under CC BY 2.0 (http://creativecommons.org/licenses/by/2.0/deed.en_CA).

Figure 6.7: Adapted by J. Walinga (Mental Health Canada, 2014).

Figure 6.8: Adapted from Ross (1965).

Long Descriptions

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Figure 6.2 long description: Guilty judgements based on stereotypes for morning and evening types depending on the time of day.

	Morning Types		Evening Types
	9 am	8 pm	9 am	8 pm
Judgements of guilt	5.9	6.5	6.8	5.6

[Return to Figure 6.2]

Figure 6.7 long description: How much sleep do you really need?

Age	Sleep needs
Newborns (0 to 2 months)	12 to 18 hours
Infants (3 to 11 months)	14 to 15 hours
Toddlers (1 to 3 years)	12 to 14 hours
Preschoolers (3 to 5 years)	11 to 13 hours
School-age children (5 to 10 years)	10 to 11 hours
Teens (10 to 17 years)	8.5 to 9.25 hours
Adults	7 to 9 hours

[Return to Figure 6.7]
Figure 6.8 long description: Effects of Sleep deprivation. Day 1: Difficulty focusing eyes. Day 2: Moodiness, difficulty focusing eyes. Day 3: Irritability, memory lapses, first hallucination. Day 4: Hallucinations, with recognition that they were not real. Day 5 and onward: paranoia. [Return to Figure 6.8]

A psychoactive drug is a chemical that changes our states of consciousness, and particularly our perceptions and moods. These drugs are commonly found in everyday foods and beverages, including chocolate, coffee, and soft drinks, as well as in alcohol and in over-the-counter drugs, such as aspirin, Tylenol, and cold and cough medication. Psychoactive drugs are also frequently prescribed as sleeping pills, tranquilizers, and antianxiety medications, and they may be taken illegally for recreational purposes. As you can see in Table 6.1, “Psychoactive Drugs by Class,” the four primary classes of psychoactive drugs are stimulants, depressants, opioids, and hallucinogens.

Psychoactive drugs affect consciousness by influencing how neurotransmitters operate at the synapses of the central nervous system (CNS). Some psychoactive drugs are agonists, which mimic the operation of a neurotransmitter; some are antagonists, which block the action of a neurotransmitter; and some work by blocking the reuptake of neurotransmitters at the synapse.

Table 6.1 Psychoactive Drugs by Class.

[Skip Table]
Mechanism	Symptoms	Drug	Dangers and Side Effects	Psychological Dependence	Physical Dependence	Addiction Potential
Stimulants: Stimulants block the reuptake of dopamine, norepinephrine, and serotonin in the synapses of the CNS.	Enhanced mood and increased energy	Caffeine	May create dependence	Low	Low	Low
		Nicotine	Has major negative health effects if smoked or chewed	High	High	High
		Cocaine	Decreased appetite, headache	Low	Low	Moderate
		Amphetamines	Possible dependence, accompanied by severe “crash” with depression as drug effects wear off, particularly if smoked or injected	Moderate	Low	Moderate to High
Depressants: Depressants change consciousness by increasing the production of the neurotransmitter GABA and decreasing the production of the neurotransmitter acetylcholine, usually at the level of the thalamus and the reticular formation.	Calming effects, sleep, pain relief, slowed heart rate and respiration	Alcohol	Impaired judgment, loss of coordination, dizziness, nausea, and eventually a loss of consciousness	Moderate	Moderate	Moderate
		Barbiturates and benzodiazepines	Sluggishness, slowed speech, drowsiness, in severe cases, coma or death	Moderate	Moderate	Moderate
		Toxic inhalants	Brain damage and death	High	High	High
Opioids: The chemical makeup of opioids is similar to the endorphins, the neurotransmitters that serve as the body’s “natural pain reducers.”	Slowing of many body functions, constipation, respiratory and cardiac depression, and the rapid development of tolerance	Opium	Side effects include nausea, vomiting, tolerance, and addiction.	Moderate	Moderate	Moderate
		Morphine	Restlessness, irritability, headache and body aches, tremors, nausea, vomiting, and severe abdominal pain	High	Moderate	Moderate
		Heroin	All side effects of morphine but about twice as addictive as morphine	High	Moderate	High
Hallucinogens: The chemical compositions of the hallucinogens are similar to the neurotransmitters serotonin and epinephrine, and they act primarily by mimicking them.	Altered consciousness; hallucinations	Marijuana	Mild intoxication; enhanced perception	Low	Low	Low
		LSD, mescaline, PCP, and peyote	Hallucinations; enhanced perception	Low	Low	Low

In some cases the effects of psychoactive drugs mimic other naturally occurring states of consciousness. For instance, sleeping pills are prescribed to create drowsiness, and benzodiazepines are prescribed to create a state of relaxation. In other cases psychoactive drugs are taken for recreational purposes with the goal of creating states of consciousness that are pleasurable or that help us escape our normal consciousness.

The use of psychoactive drugs, especially those that are used illegally, has the potential to create very negative side effects. This does not mean that all drugs are dangerous, but rather that all drugs can be dangerous, particularly if they are used regularly over long periods of time. Psychoactive drugs create negative effects not so much through their initial use but through the continued use, accompanied by increasing doses, that ultimately may lead to drug abuse.

The problem is that many drugs create tolerance: an increase in the dose required to produce the same effect, which makes it necessary for the user to increase the dosage or the number of times per day that the drug is taken. As the use of the drug increases, the user may develop a dependence, defined as a need to use a drug or other substance regularly. Dependence can be psychological, in which case the drug is desired and has become part of the everyday life of the user, but no serious physical effects result if the drug is not obtained; or physical, in which case serious physical and mental effects appear when the drug is withdrawn. Cigarette smokers who try to quit, for example, experience physical withdrawal symptoms, such as becoming tired and irritable, as well as extreme psychological cravings to enjoy a cigarette in particular situations, such as after a meal or when they are with friends.

Users may wish to stop using the drug, but when they reduce their dosage they experience withdrawal — negative experiences that accompany reducing or stopping drug use, including physical pain and other symptoms. When the user powerfully craves the drug and is driven to seek it out, over and over again, no matter what the physical, social, financial, and legal cost, we say that he or she has developed an addiction to the drug.

It is a common belief that addiction is an overwhelming, irresistibly powerful force, and that withdrawal from drugs is always an unbearably painful experience. But the reality is more complicated and in many cases less extreme. For one, even drugs that we do not generally think of as being addictive, such as caffeine, nicotine, and alcohol, can be very difficult to quit using, at least for some people. On the other hand, drugs that are normally associated with addiction, including amphetamines, cocaine, and heroin, do not immediately create addiction in their users. Even for a highly addictive drug like cocaine, only about 15% of users become addicted (Robinson & Berridge, 2003; Wagner & Anthony, 2002). Furthermore, the rate of addiction is lower for those who are taking drugs for medical reasons than for those who are using drugs recreationally. Patients who have become physically dependent on morphine administered during the course of medical treatment for a painful injury or disease are able to be rapidly weaned off the drug afterward, without becoming addicts. Robins, Davis, and Goodwin (1974) found that the majority of soldiers who had become addicted to morphine while overseas were quickly able to stop using after returning home.

This does not mean that using recreational drugs is not dangerous. For people who do become addicted to drugs, the success rate of recovery is low. These drugs are generally illegal and carry with them potential criminal consequences if one is caught in possession of them and arrested. Drugs that are smoked may produce throat and lung cancers and other problems. Snorting (“sniffing”) drugs can lead to a loss of the sense of smell, nosebleeds, difficulty in swallowing, hoarseness, and chronic runny nose. Injecting drugs intravenously carries with it the risk of contracting infections such as hepatitis and HIV. Furthermore, the quality and contents of illegal drugs are generally unknown, and the doses can vary substantially from purchase to purchase. The drugs may also contain toxic chemicals.

Another problem is the unintended consequences of combining drugs, which can produce serious side effects. Combining drugs is dangerous because their combined effects on the CNS can increase dramatically and can lead to accidental or even deliberate overdoses. For instance, ingesting alcohol or benzodiazepines along with the usual dose of heroin is a frequent cause of overdose deaths in opiate addicts, and combining alcohol and cocaine can have a dangerous impact on the cardiovascular system (McCance-Katz, Kosten, & Jatlow, 1998).

Although all recreational drugs are dangerous, some can be more deadly than others. One way to determine how dangerous recreational drugs are is to calculate a safety ratio, based on the dose that is likely to be fatal divided by the normal dose needed to feel the effects of the drug. Drugs with lower ratios are more dangerous because the difference between the normal and the lethal dose is small. For instance, heroin has a safety ratio of 6 because the average fatal dose is only six times greater than the average effective dose. On the other hand, marijuana has a safety ratio of 1,000. This is not to say that smoking marijuana cannot be deadly, but it is much less likely to be deadly than is heroin. The safety ratios of common recreational drugs are shown in Table 6.2, “Popular Recreational Drugs and Their Safety Ratios.”

Table 6.2 Popular Recreational Drugs and Their Safety Ratios. Adapted from Gable (2004).

[Skip Table]
Drug	Description	Street or brand names	Safety ratio
Heroin	Strong depressant	Smack, junk, H	6
GHB (Gamma hydroxy butyrate)	“Rave” drug (not Ecstacy), also used as a “date rape” drug	Georgia home boy, liquid ecstasy, liquid X, liquid G, fantasy	8
Isobutyl nitrite	Depressant and toxic inhalant	Poppers, rush, locker room	8
Alcohol	Active compound is ethanol		10
DXM (Dextromethorphan)	Active ingredient in over-the-counter cold and cough medicines		10
Methamphetamine	May be injected or smoked	Meth, crank	10
Cocaine	May be inhaled or smoked	Crack, coke, rock, blue	15
MDMA (methylene­dioxymetham­phetamine)	Very powerful stimulant	Ecstasy	16
Codeine	Depressant		20
Methadone	Opioid		20
Mescaline	Hallucinogen		24
Benzodiazepine	Prescription tranquilizer	Centrax, Dalmane, Doral, Halcion, Librium, ProSom, Restoril, Xanax, Valium	30
Ketamine	Prescription anesthetic	Ketanest, Ketaset, Ketalar	40
DMT (Dimethyl­tryptamine)	Hallucinogen		50
Phenobarbital	Usually prescribed as a sleeping pill	Luminal (Phenobarbital), Mebaraland, Nembutal, Seconal, Sombulex	50
Prozac	Antidepressant		100
Nitrous oxide	Often inhaled from whipped-cream dispensers	Laughing gas	150
Lysergic acid diethylamide (LSD)		Acid	1,000
Marijuana (Cannabis)	Active ingredient is THC	Pot, spliff, weed	1,000
Drugs with lower safety ratios have a greater risk of brain damage and death.

Speeding Up the Brain With Stimulants: Caffeine, Nicotine, Cocaine, and Amphetamines

A stimulant is a psychoactive drug that operates by blocking the reuptake of dopamine, norepinephrine, and serotonin in the synapses of the CNS. Because more of these neurotransmitters remain active in the brain, the result is an increase in the activity of the sympathetic division of the autonomic nervous system (ANS). Effects of stimulants include increased heart and breathing rates, pupil dilation, and increases in blood sugar accompanied by decreases in appetite. For these reasons, stimulants are frequently used to help people stay awake and to control weight.

Used in moderation, some stimulants may increase alertness, but used in an irresponsible fashion they can quickly create dependency. A major problem is the “crash” that results when the drug loses its effectiveness and the activity of the neurotransmitters returns to normal. The withdrawal from stimulants can create profound depression and lead to an intense desire to repeat the high.

Caffeine is a bitter psychoactive drug found in the beans, leaves, and fruits of plants, where it acts as a natural pesticide. It is found in a wide variety of products, including coffee, tea, soft drinks, candy, and desserts. In North America, more than 80% of adults consume caffeine daily (Lovett, 2005). Caffeine acts as a mood enhancer and provides energy. Although Health Canada lists caffeine as a safe food substance, it has at least some characteristics of dependence. People who reduce their caffeine intake often report being irritable, restless, and drowsy, as well as experiencing strong headaches, and these withdrawal symptoms may last up to a week. Most experts feel that using small amounts of caffeine during pregnancy is safe, but larger amounts of caffeine can be harmful to the fetus (Health Canada, 2014).

Nicotine is a psychoactive drug found in tobacco and other members of the nightshade family of plants, where it acts as a natural pesticide. Nicotine is the main cause for the dependence-forming properties of tobacco use, and tobacco use is a major health threat. Nicotine creates both psychological and physical addiction, and it is one of the hardest addictions to break. Nicotine content in cigarettes has slowly increased over the years, making quitting smoking more and more difficult. Nicotine is also found in smokeless (chewing) tobacco.

People who want to quit smoking sometimes use other drugs to help them. For instance, the prescription drug Chantix acts as an antagonist, binding to nicotine receptors in the synapse, which prevents users from receiving the normal stimulant effect when they smoke. At the same time, the drug also releases dopamine, the reward neurotransmitter. In this way Chantix dampens nicotine withdrawal symptoms and cravings. In many cases, people are able to get past the physical dependence, allowing them to quit smoking at least temporarily. In the long run, however, the psychological enjoyment of smoking may lead to relapse.

Cocaine is an addictive drug obtained from the leaves of the coca plant (Figure 6.9). In the late 19th and early 20th centuries, it was a primary constituent in many popular tonics and elixirs and, although it was removed in 1905, was one of the original ingredients in Coca-Cola. Today cocaine is taken illegally as a recreational drug.

Cocaine has a variety of adverse effects on the body. It constricts blood vessels, dilates pupils, and increases body temperature, heart rate, and blood pressure. It can cause headaches, abdominal pain, and nausea. Since cocaine also tends to decrease appetite, chronic users may become malnourished. The intensity and duration of cocaine’s effects, which include increased energy and reduced fatigue, depend on how the drug is taken. The faster the drug is absorbed into the bloodstream and delivered to the brain, the more intense the high. Injecting or smoking cocaine produces a faster, stronger high than snorting it. However, the faster the drug is absorbed, the faster the effects subside. The high from snorting cocaine may last 30 minutes, whereas the high from smoking “crack” cocaine may last only 10 minutes. In order to sustain the high, the user must administer the drug again, which may lead to frequent use, often in higher doses, over a short period of time (National Institute on Drug Abuse, 2009a). Cocaine has a safety ratio of 15, making it a very dangerous recreational drug.

An amphetamine is a stimulant that produces increased wakefulness and focus, along with decreased fatigue and appetite. Amphetamines are used in prescription medications to treat attention deficit disorder (ADD) and narcolepsy, and to control appetite. Some brand names of amphetamines are Adderall, Benzedrine, Dexedrine, and Vyvanse. But amphetamine (“speed”) is also used illegally as a recreational drug. The methylated version of amphetamine, methamphetamine (“meth” or “crank”), is currently favoured by users, partly because it is available in ampoules ready for use by injection (Csaky & Barnes, 1984). Meth is a highly dangerous drug with a safety ratio of only 10.

Amphetamines may produce a very high level of tolerance, leading users to increase their intake, often in “jolts” taken every half hour or so. Although the level of physical dependency is small, amphetamines may produce very strong psychological dependence, effectively amounting to addiction. Continued use of stimulants may result in severe psychological depression. The effects of the stimulant methylenedioxymethamphetamine (MDMA), also known as “Ecstasy,” provide a good example. MDMA is a very strong stimulant that very successfully prevents the reuptake of serotonin, dopamine, and norepinephrine. It is so effective that when used repeatedly it can seriously deplete the amount of neurotransmitters available in the brain, producing a catastrophic mental and physical “crash” resulting in serious, long-lasting depression. MDMA also affects the temperature-regulating mechanisms of the brain, so in high doses, and especially when combined with vigorous physical activity like dancing, it can cause the body to become so drastically overheated that users can literally “burn up” and die from hyperthermia and dehydration.

Slowing Down the Brain with Depressants: Alcohol, Barbiturates and Benzodiazepines, and Toxic Inhalants

In contrast to stimulants, which work to increase neural activity, a depressant acts to slow down consciousness. A depressant is a psychoactive drug that reduces the activity of the CNS. Depressants are widely used as prescription medicines to relieve pain, to lower heart rate and respiration, and as anticonvulsants. Depressants change consciousness by increasing the production of the neurotransmitter GABA and decreasing the production of the neurotransmitter acetylcholine, usually at the level of the thalamus and the reticular formation. The outcome of depressant use (similar to the effects of sleep) is a reduction in the transmission of impulses from the lower brain to the cortex (Csaky & Barnes, 1984).

The most commonly used of the depressants is alcohol, a colorless liquid, produced by the fermentation of sugar or starch, that is the intoxicating agent in fermented drinks (Figure 6.10). Alcohol is the oldest and most widely used drug of abuse in the world. In low to moderate doses, alcohol first acts to remove social inhibitions by slowing activity in the sympathetic nervous system. In higher doses, alcohol acts on the cerebellum to interfere with coordination and balance, producing the staggering gait of drunkenness. At high blood levels, further CNS depression leads to dizziness, nausea, and eventually a loss of consciousness. High enough blood levels, such as those produced by “guzzling” large amounts of hard liquor at parties, can be fatal. Alcohol is not a “safe” drug by any means — its safety ratio is only 10.

Alcohol use is highly costly to societies because so many people abuse alcohol and because judgment after drinking can be substantially impaired. It is estimated that almost half of automobile fatalities are caused by alcohol use, and excessive alcohol consumption is involved in a majority of violent crimes, including rape and murder (Abbey, Ross, McDuffie, & McAuslan, 1996). Alcohol increases the likelihood that people will respond aggressively to provocations (Bushman, 1993, 1997; Graham, Osgood, Wells, & Stockwell, 2006). Even people who are not normally aggressive may react with aggression when they are intoxicated. Alcohol use also leads to rioting, unprotected sex, and other negative outcomes.

Alcohol increases aggression in part because it reduces the ability of the person who has consumed it to inhibit his or her aggression (Steele & Southwick, 1985). When people are intoxicated, they become more self-focused and less aware of the social situation. As a result, they become less likely to notice the social constraints that normally prevent them from engaging aggressively, and are less likely to use those social constraints to guide them. For instance, we might normally notice the presence of a police officer or other people around us, which would remind us that being aggressive is not appropriate. But when we are drunk, we are less likely to be so aware. The narrowing of attention that occurs when we are intoxicated also prevents us from being cognizant of the negative outcomes of our aggression. When we are sober, we realize that being aggressive may produce retaliation, as well as cause a host of other problems, but we are less likely to realize these potential consequences when we have been drinking (Bushman & Cooper, 1990). Alcohol also influences aggression through expectations. If we expect that alcohol will make us more aggressive, then we tend to become more aggressive when we drink.

Barbiturates are depressants that are commonly prescribed as sleeping pills and painkillers. Brand names include Luminal (Phenobarbital), Mebaraland, Nembutal, Seconal, and Sombulex. In small to moderate doses, barbiturates produce relaxation and sleepiness, but in higher doses symptoms may include sluggishness, difficulty in thinking, slowness of speech, drowsiness, faulty judgment, and eventually coma or even death (Medline Plus, 2008).

Related to barbiturates, benzodiazepines are a family of depressants used to treat anxiety, insomnia, seizures, and muscle spasms. In low doses, they produce mild sedation and relieve anxiety; in high doses, they induce sleep. In the United States, benzodiazepines are among the most widely prescribed medications that affect the CNS. Brand names include Centrax, Dalmane, Doral, Halcion, Librium, ProSom, Restoril, Xanax, and Valium.

Toxic inhalants are also frequently abused as depressants. These drugs are easily accessible as the vapours of glue, gasoline, propane, hairspray, and spray paint, and are inhaled to create a change in consciousness. Related drugs are the nitrites (amyl and butyl nitrite; “poppers,” “rush,” “locker room”) and anesthetics such as nitrous oxide (laughing gas) and ether. Inhalants are some of the most dangerous recreational drugs, with a safety index below 10, and their continued use may lead to permanent brain damage.

Opioids: Opium, Morphine, Heroin, and Codeine

Opioids are chemicals that increase activity in opioid receptor neurons in the brain and in the digestive system, producing euphoria, analgesia, slower breathing, and constipation. Their chemical makeup is similar to the endorphins, the neurotransmitters that serve as the body’s “natural pain reducers.” Natural opioids are derived from the opium poppy, which is widespread in Eurasia, but they can also be created synthetically.

Opium is the dried juice of the unripe seed capsule of the opium poppy. It may be the oldest drug on record, known to the Sumerians before 4000 BC. Morphine and heroin (Figure 6.11) are stronger, more addictive drugs derived from opium, while codeine is a weaker analgesic and less addictive member of the opiate family. When morphine was first refined from opium in the early 19th century, it was touted as a cure for opium addiction, but it didn’t take long to discover that it was actually more addicting than raw opium. When heroin was produced a few decades later, it was also initially thought to be a more potent, less addictive painkiller but was soon found to be much more addictive than morphine. Heroin is about twice as addictive as morphine, and creates severe tolerance, moderate physical dependence, and severe psychological dependence. The danger of heroin is demonstrated in the fact that it has the lowest safety ratio (6) of all the drugs listed in Table 6.1, “Psychoactive Drugs by Class.”

The opioids activate the sympathetic division of the ANS, causing blood pressure and heart rate to increase, often to dangerous levels that can lead to heart attack or stroke. At the same time the drugs also influence the parasympathetic division, leading to constipation and other negative side effects. Symptoms of opioid withdrawal include diarrhea, insomnia, restlessness, irritability, and vomiting, all accompanied by a strong craving for the drug. The powerful psychological dependence of the opioids and the severe effects of withdrawal make it very difficult for morphine and heroin abusers to quit using. In addition, because many users take these drugs intravenously and share contaminated needles, they run a very high risk of being infected with diseases. Opioid addicts suffer a high rate of infections such as HIV, pericarditis (an infection of the membrane around the heart), and hepatitis B, any of which can be fatal.

Hallucinogens: Cannabis, Mescaline, and LSD

The drugs that produce the most extreme alteration of consciousness are the hallucinogens, psychoactive drugs that alter sensation and perception and that may create hallucinations. The hallucinogens are frequently known as “psychedelics.” Drugs in this class include lysergic acid diethylamide (LSD, or “acid”), mescaline, and phencyclidine (PCP), as well as a number of natural plants including cannabis (marijuana), peyote, and psilocybin. The chemical compositions of the hallucinogens are similar to the neurotransmitters serotonin and epinephrine, and they act primarily as agonists by mimicking the action of serotonin at the synapses. The hallucinogens may produce striking changes in perception through one or more of the senses. The precise effects a user experiences are a function not only of the drug itself, but also of the user’s pre-existing mental state and expectations of the drug experience. In large part, the user tends to get out of the experience what he or she brings to it. The hallucinations that may be experienced when taking these drugs are strikingly different from everyday experience and frequently are more similar to dreams than to everyday consciousness.

Cannabis (marijuana) is the most widely used hallucinogen. Marijuana also acts as a stimulant, producing giggling, laughing, and mild intoxication. It acts to enhance perception of sights, sounds, and smells, and may produce a sensation of time slowing down. It is much less likely to lead to antisocial acts than that other popular intoxicant, alcohol, and it is also the one psychedelic drug whose use has not declined in recent years (National Institute on Drug Abuse, 2009b).

In recent years, cannabis has again been frequently prescribed for the treatment of pain and nausea, particularly in cancer sufferers, as well as for a wide variety of other physical and psychological disorders (Ben Amar, 2006). While medical marijuana is now legal in several Canadian provinces, it is still banned under federal law, putting those provinces in conflict with the federal government. The provinces of Ontario, Quebec, Newfoundland and Labrador, and British Columbia are known to have more relaxed enforcement of cannabis laws and do not normally pursue criminal charges for possession of relatively small amounts of cannabis. These four provinces also refuse to implement and enforce the federal government’s new “tough on crime” Bill C-10. British Columbia is taking an extraordinary step in considering the passage of legislation to effectively decriminalize cannabis by proposing a provincial law (to be called the Sensible Policing Act) that redirects police resources from the pursuit of criminal charges for simple possession of cannabis in favour of other means such as tickets and civil citations as well as diversion programs for youth. The cultivation of the hemp plant of the genus Cannabis (family Cannabaceae) is currently legal in Canada for seed, grain, and fibre production only under licenses issued by Health Canada (Health Canada, 2012).

Although the hallucinogens are powerful drugs that produce striking “mind-altering” effects, they do not produce physiological or psychological tolerance or dependence. While they are not addictive and pose little physical threat to the body, their use is not advisable in any situation in which the user needs to be alert and attentive, exercise focused awareness or good judgment, or demonstrate normal mental functioning, such as driving a car, studying, or operating machinery.

Why We Use Psychoactive Drugs

People have used, and often abused, psychoactive drugs for thousands of years. Perhaps this should not be suprising, because many people find using drugs to be fun and enjoyable. Even when we know the potential costs of using drugs, we may engage in them anyway because the pleasures of using the drugs are occurring right now, whereas the potential costs are abstract and occur in the future.

Individual ambitions, expectations, and values also influence drug use. Vaughan, Corbin, and Fromme (2009) found that university students who expressed positive academic values and strong ambitions had less alcohol consumption and fewer alcohol-related problems, and cigarette smoking has declined more among youth from wealthier and more educated homes than among those from lower socioeconomic backgrounds (Johnston, O’Malley, Bachman, & Schulenberg, 2004).

Drug use is in part the result of socialization. Children try drugs when their friends convince them to do it, and these decisions are based on social norms about the risks and benefits of various drugs (Figure 6.12). In the period 1991 to 1997, the percentage of Grade 12 students who responded that they perceived “great harm in regular marijuana use” declined from 79% to 58%, while annual use of marijuana in this group rose from 24% to 39% (Johnston et al., 2004). And students binge drink in part when they see that many other people around them are also binging (Clapp, Reed, Holmes, Lange, & Voas, 2006).

 

Despite the fact that young people have experimented with cigarettes, alcohol, and other dangerous drugs for many generations, it would be better if they did not. All recreational drug use is associated with at least some risks, and those who begin using drugs earlier are also more likely to use more dangerous drugs later (Lynskey et al., 2003). Furthermore, as we will see in the next section, there are many other enjoyable ways to alter consciousness that are safer.

References

Abbey, A., Ross, L. T., McDuffie, D., & McAuslan, P. (1996). Alcohol and dating risk factors for sexual assault among college women. Psychology of Women Quarterly, 20(1), 147–169.

Ben Amar, M. (2006). Cannabinoids in medicine: A review of their therapeutic potential. Journal of Ethnopharmacology, 105, 1–25.

Bushman, B. J. (1993). Human aggression while under the influence of alcohol and other drugs: An integrative research review. Current Directions in Psychological Science, 2(5), 148–152.

Bushman, B. J. (Ed.). (1997). Effects of alcohol on human aggression: Validity of proposed explanations. New York, NY: Plenum Press.

Bushman, B. J., & Cooper, H. M. (1990). Effects of alcohol on human aggression: An integrative research review. Psychological Bulletin, 107(3), 341–354.

Clapp, J., Reed, M., Holmes, M., Lange, J., & Voas, R. (2006). Drunk in public, drunk in private: The relationship between college students, drinking environments and alcohol consumption. The American Journal of Drug and Alcohol Abuse, 32(2), 275–285.

Csaky, T. Z., & Barnes, B. A. (1984). Cutting’s handbook of pharmacology (7th ed.). East Norwalk, CT: Appleton-Century-Crofts.

Gable, R. (2004). Comparison of acute lethal toxicity of commonly abused psychoactive substances. Addiction, 99(6), 686–696.

Graham, K., Osgood, D. W., Wells, S., & Stockwell, T. (2006). To what extent is intoxication associated with aggression in bars? A multilevel analysis. Journal of Studies on Alcohol, 67(3), 382–390.

Health Canada. (2012). Industrial Hemp Regulation Program FAQ. Health Canada. November 2012. Retrieved June 2014 from http://www.hc-sc.gc.ca/hc-ps/substancontrol/hemp-chanvre/about-apropos/faq/index-eng.php

Health Canada. (2014). Food and nutrition: Caffeine in food. Retrieved June 2014 from http://www.hc-sc.gc.ca/fn-an/securit/addit/caf/food-caf-aliments-eng.php

Johnston, L. D., O’Malley, P. M., Bachman, J. G., & Schulenberg, J. E. (2004). Monitoring the future: National results on adolescent drug use. Ann Arbor, MI: Institute for Social Research, University of Michigan (conducted for the National Institute on Drug Abuse, National Institute of Health).

Lejuez, C. W., Aklin, W. M., Bornovalova, M. A., & Moolchan, E. T. (2005). Differences in risk-taking propensity across inner-city adolescent ever- and never-smokers. Nicotine & Tobacco Research, 7(1), 71–79.

Lejuez, C. W., Read, J. P., Kahler, C. W., Richards, J. B., Ramsey, S. E., Stuart, G. L.,…Brown, R. A. (2002). Evaluation of a behavioral measure of risk taking: The Balloon Analogue Risk Task (BART). Journal of Experimental Psychology: Applied, 8(2), 75–85.

Lovett, R. (2005, September 24). Coffee: The demon drink? New Scientist, 2518. Retrieved from http://www.newscientist.com/article.ns?id=mg18725181.700

Lynskey, M. T., Heath, A. C., Bucholz, K. K., Slutske, W. S., Madden, P. A. F., Nelson, E. C.,…Martin, N. G. (2003). Escalation of drug use in early-onset cannabis users vs co-twin controls. Journal of the American Medical Association, 289(4), 427–433.

McCance-Katz, E., Kosten, T., & Jatlow, P. (1998). Concurrent use of cocaine and alcohol is more potent and potentially more toxic than use of either alone — A multiple-dose study 1. Biological Psychiatry, 44(4), 250–259.

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National Institute on Drug Abuse. (2009a). Cocaine abuse and addiction. Retrieved from http://www.nida.nih.gov/researchreports/cocaine/cocaine.html

National Institute on Drug Abuse. (2009b). NIDA InfoFacts: High School and Youth Trends. Retrieved from http://www.drugabuse.gov/infofacts/HSYouthTrends.html

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Image Attributions

Figure 6.9: “Cocaine” by perturbao (http://www.flickr.com/photos/33373325@N04/3144560302) is licensed under CC BY-SA 2.0 (http://creativecommons.org/licenses/by-sa/2.0/deed.en_CA).

Figure 6.10: “Liquor bottles” by scottfeldstein (href=”http://en.wikipedia.org/wiki/File:Liquor_bottles.jpg) is licensed under CC BY 2.0 (http://creativecommons.org/licenses/by/2.0/deed.en).

Figure 6.11: “Injecting heroin” (http://commons.wikimedia.org/wiki/File:Injecting_heroin.jpg) is licensed under CC BY 2.0

Long Descriptions

Figure 6.12 long description: Use of drugs by grade 12 students in 2005

	Cocaine	Opioids	Hallucinogens	Amphetamines	Marijuana/hashish	Any illicit drug	Alcohol
Percentage who reported having used the drug	6%	10%	6%	10%	35%	39%	71%

[Return to Figure 6.12]

Although the use of psychoactive drugs can easily and profoundly change our experience of consciousness, we can also — and often more safely — alter our consciousness without drugs. These altered states of consciousness are sometimes the result of simple and safe activities, such as sleeping, watching television, exercising, or working on a task that intrigues us. In this section we consider the changes in consciousness that occur through hypnosis, sensory deprivation, and meditation, as well as through other non-drug-induced mechanisms.

Changing Behaviour through Suggestion: The Power of Hypnosis

Franz Anton Mesmer (1734-1815) was an Austrian doctor who believed that all living bodies were filled with magnetic energy (Figure 6.13). In his practice, Mesmer passed magnets over the bodies of his patients while telling them their physical and psychological problems would disappear. The patients frequently lapsed into a trancelike state (they were said to be “mesmerized”) and reported feeling better when they awoke (Hammond, 2008).

Although subsequent research testing the effectiveness of Mesmer’s techniques did not find any long-lasting improvements in his patients, the idea that people’s experiences and behaviours could be changed through the power of suggestion has remained important in psychology. James Braid, a Scottish physician, coined the term hypnosis in 1843, basing it on the Greek word for sleep (Callahan, 1997).

Hypnosis is a trancelike state of consciousness, usually induced by a procedure known as hypnotic induction, which consists of heightened suggestibility, deep relaxation, and intense focus (Nash & Barnier, 2008). Hypnosis became famous in part through its use by Sigmund Freud in an attempt to make unconscious desires and emotions conscious and thus able to be considered and confronted (Baker & Nash, 2008).

Because hypnosis is based on the power of suggestion, and because some people are more suggestible than others, these people are more easily hypnotized. Hilgard (1965) found that about 20% of the participants he tested were entirely unsusceptible to hypnosis, whereas about 15% were highly responsive to it. The best participants for hypnosis are people who are willing or eager to be hypnotized, who are able to focus their attention and block out peripheral awareness, who are open to new experiences, and who are capable of fantasy (Spiegel, Greenleaf, & Spiegel, 2005).

People who want to become hypnotized are motivated to be good subjects, to be open to suggestions by the hypnotist, and to fulfill the role of a hypnotized person as they perceive it (Spanos, 1991). The hypnotized state results from a combination of conformity, relaxation, obedience, and suggestion (Fassler, Lynn, & Knox, 2008). This does not necessarily indicate that hypnotized people are “faking” or lying about being hypnotized. Kinnunen, Zamansky, and Block (1994) used measures of skin conductance (which indicates emotional response by measuring perspiration, and therefore renders it a reliable indicator of deception) to test whether hypnotized people were lying about having been hypnotized. Their results suggested that almost 90% of their supposedly hypnotized subjects truly believed that they had been hypnotized.

One common misconception about hypnosis is that the hypnotist is able to “take control” of hypnotized patients and thus can command them to engage in behaviours against their will. Although hypnotized people are suggestible (Jamieson & Hasegawa, 2007), they nevertheless retain awareness and control of their behaviour and are able to refuse to comply with the hypnotist’s suggestions if they so choose (Kirsch & Braffman, 2001). In fact, people who have not been hypnotized are often just as suggestible as those who have been (Orne & Evans, 1965).

Another common belief is that hypnotists can lead people to forget the things that happened to them while they were hypnotized. Hilgard and Cooper (1965) investigated this question and found that they could lead people who were very highly susceptible to hypnosis to show at least some signs of post-hypnotic amnesia (i.e., forgetting where they had learned information that had been told to them while they were under hypnosis), but that this effect was not strong or common.

Some hypnotists have tried to use hypnosis to help people remember events, such as childhood experiences or details of crime scenes, that they have forgotten or repressed. The idea is that some memories have been stored but can no longer be retrieved, and that hypnosis can aid in the retrieval process. But research finds that this is not successful: people who are hypnotized and then asked to relive their childhood act like children, but they do not accurately recall the things that occurred to them in their own childhood (Silverman & Retzlaff, 1986). Furthermore, the suggestibility produced through hypnosis may lead people to erroneously recall experiences that they did not have (Newman & Baumeister, 1996). Many states and jurisdictions have therefore banned the use of hypnosis in criminal trials because the “evidence” recovered through hypnosis is likely to be fabricated and inaccurate.

Hypnosis is also frequently used to attempt to change unwanted behaviours, such as to reduce smoking, overeating, and alcohol abuse. The effectiveness of hypnosis in these areas is controversial, although at least some successes have been reported. Kirsch, Montgomery, and Sapirstein (1995) found that adding hypnosis to other forms of therapy increased the effectiveness of the treatment, and Elkins and Perfect (2008) reported that hypnosis was useful in helping people stop smoking. Hypnosis is also effective in improving the experiences of patients who are experiencing anxiety disorders, such as post-traumatic stress disorder (PTSD) (Cardena, 2000; Montgomery, David, Winkel, Silverstein, & Bovbjerg, 2002), and for reducing pain (Montgomery, DuHamel, & Redd, 2000; Patterson & Jensen, 2003).

Reducing Sensation to Alter Consciousness: Sensory Deprivation

Sensory deprivation is the intentional reduction of stimuli affecting one or more of the five senses, with the possibility of resulting changes in consciousness. Sensory deprivation is used for relaxation or meditation purposes, and in physical and mental health-care programs to produce enjoyable changes in consciousness. But when deprivation is prolonged, it is unpleasant and can be used as a means of torture.

Although the simplest forms of sensory deprivation require nothing more than a blindfold to block the person’s sense of sight or earmuffs to block the sense of sound, more complex devices have also been devised to temporarily cut off the senses of smell, taste, touch, heat, and gravity. In 1954, John Lilly, a neurophysiologist at the National Institute of Mental Health, developed the sensory deprivation tank. The tank is filled with water that is the same temperature as the human body, and salts are added to the water so that the body floats, thus reducing the sense of gravity. The tank is dark and soundproof, and the person’s sense of smell is blocked by the use of chemicals in the water, such as chlorine.

The sensory deprivation tank has been used for therapy and relaxation (Figure 6.14). In a typical session for alternative healing and meditative purposes, a person may rest in an isolation tank for up to an hour. Treatment in isolation tanks has been shown to help with a variety of medical issues, including insomnia and muscle pain (Suedfeld, 1990b; Bood, Sundequist, Kjellgren, Nordström, & Norlander, 2007; Kjellgren, Sundequist, Norlander, & Archer, 2001), headaches (Wallbaum, Rzewnicki, Steele, & Suedfeld, 1991), and addictive behaviours such as smoking, alcoholism, and obesity (Suedfeld, 1990a).

Although relatively short sessions of sensory deprivation can be relaxing and both mentally and physically beneficial, prolonged sensory deprivation can lead to disorders of perception, including confusion and hallucinations (Yuksel, Kisa, Aydemir, & Goka, 2004). It is for this reason that sensory deprivation is sometimes used as an instrument of torture (Benjamin, 2006).

Meditation

Meditation refers to techniques in which the individual focuses on something specific, such as an object, a word, or one’s breathing, with the goal of ignoring external distractions, focusing on one’s internal state, and achieving a state of relaxation and well-being. Followers of various Eastern religions (Hinduism, Buddhism, and Taoism) use meditation to achieve a higher spiritual state, and popular forms of meditation in the West, such as yoga, Zen, and Transcendental Meditation, have originated from these practices. Many meditative techniques are very simple. You simply need to sit in a comfortable position with your eyes closed and practise deep breathing. You might want to try it out for yourself (see Video Clip: “Try Meditation”).

Here is a simple meditation exercise you can do in your own home: Watch: Try Meditation [YouTube]

 

Brain imaging studies have indicated that meditation is not only relaxing but can also induce an altered state of consciousness (Figure 6.15). Cahn and Polich (2006) found that experienced meditators in a meditative state had more prominent alpha and theta waves, and other studies have shown declines in heart rate, skin conductance, oxygen consumption, and carbon dioxide elimination during meditation (Dillbeck, Cavanaugh, Glenn, & Orme-Johnson, 1987; Fenwick, 1987). These studies suggest that the action of the sympathetic division of the autonomic nervous system (ANS) is suppressed during meditation, creating a more relaxed physiological state as the meditator moves into deeper states of relaxation and consciousness.

Research has found that regular meditation can mediate the effects of stress and depression, and promote well-being (Grossman, Niemann, Schmidt, & Walach, 2004; Reibel, Greeson, Brainard, & Rosenzweig, 2001; Salmon et al., 2004). Meditation has also been shown to assist in controlling blood pressure (Barnes, Treiber, & Davis, 2001; Walton et al., 2004). A study by Lyubimov (1992) showed that during meditation, a larger area of the brain was responsive to sensory stimuli, suggesting that there is greater coordination between the two brain hemispheres as a result of meditation. Lutz, Greischar, Rawlings, Ricard,and Davidson (2004) demonstrated that those who meditate regularly (as opposed to those who do not) tend to utilize a greater part of their brain and that their gamma waves are faster and more powerful. And a study of Tibetan Buddhist monks who meditate daily found that several areas of the brain can be permanently altered by the long-term practice of meditation (Lutz et al. 2004).

It is possible that the positive effects of meditation could also be found by using other methods of relaxation. Although advocates of meditation claim that meditation enables people to attain a higher and purer consciousness, perhaps any kind of activity that calms and relaxes the mind, such as working on crossword puzzles, watching television or movies, or engaging in other enjoyed behaviours, might be equally effective in creating positive outcomes. Regardless of the debate, the fact remains that meditation is, at the very least, a worthwhile relaxation strategy.

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Cardena, E. (2000). Hypnosis in the treatment of trauma: A promising, but not fully supported, efficacious intervention. International Journal of Clinical Experimental Hypnosis, 48, 225–238.

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Jamieson, G. A., & Hasegawa, H. (2007). New paradigms of hypnosis research. Hypnosis and conscious states: The cognitive neuroscience perspective. In G.A. Jamieson (Ed.), Hypnosis and conscious states: The cognitive neuroscience perspective (pp. 133–144). New York, NY: Oxford University Press.

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Lutz, A., Greischar, L., Rawlings, N., Ricard, M., & Davidson, R. (2004). Long-term meditators self-induce high-amplitude gamma synchrony during mental practice. Proceedings of the National Academy of Sciences, 101, 16369–16373.

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Suedfeld, P. (1990a). Restricted environmental stimulation and smoking cessation: A 15-year progress report. International Journal of the Addictions. 25(8), 861–888.

Suedfeld, P. (1990b). Restricted environmental stimulation techniques in health enhancement and disease prevention. In K. D. Craig & S. M. Weiss (Eds.), Health enhancement, disease prevention, and early intervention: Biobehavioral perspectives (pp. 206–230). New York, NY: Springer Publishing.

Wallbaum, A. B., Rzewnicki, R., Steele, H., & Suedfeld, P. (1991). Progressive muscle relaxation and restricted environmental stimulation therapy for chronic tension headache: A pilot study. International Journal of Psychosomatics. 38(1–4), 33–39.

Walton, K. G., Fields, J. Z., Levitsky, D. K., Harris, D. A., Pugh, N. D., & Schneider, R. H. (2004). Lowering cortisol and CVD risk in postmenopausal women: A pilot study using the Transcendental Meditation program. In R. Yehuda & B. McEwen (Eds.), Biobehavioral stress response: Protective and damaging effects (Annals of the New York Academy of Sciences) (Vol. 1032, pp. 211–215). New York, NY: New York Academy of Sciences.

Yuksel, F. V., Kisa, C., Aydemir, C., & Goka, E. (2004). Sensory deprivation and disorders of perception. The Canadian Journal of Psychiatry, 49(12), 867–868.

Image Attributions

Figure 6.13: Franz Anton Mesmer (http://commons.wikimedia.org/wiki/File:Franz_Anton_Mesmer.jpg) is in the public domain.

Figure 6.14: Flotation Tank SMC by SeanMack (http://commons.wikimedia.org/wiki/File:Flotation_tank_SMC.jpg) used under CC BY SA 3.0 license (http://creativecommons.org/licenses/by-sa/3.0/deed.en).

Figure 6.15: “Meditate” by RelaxingMusic (http://www.flickr.com/photos/83905817@N08/7676623576/in/photostream/) is licensed under CC BY-NC-SA 2.0 (http://creativecommons.org/licenses/by-nc-sa/2.0/deed.en_CA).

Consciousness is our subjective awareness of ourselves and our environment.

Consciousness is functional because we use it to reason logically, to plan activities, and to monitor our progress toward the goals we set for ourselves.

Consciousness has been central to many theories of psychology. Freud’s personality theories differentiated between the unconscious and the conscious aspects of behaviour, and present-day psychologists distinguish between automatic (unconscious) and controlled (conscious) behaviours and between implicit (unconscious) and explicit (conscious) cognitive processes.

The French philosopher René Descartes (1596-1650) was a proponent of dualism, the idea that the mind, a nonmaterial entity, is separate from (although connected to) the physical body. In contrast to the dualists, psychologists believe the consciousness (and thus the mind) exists in the brain, not separate from it.

The behaviour of organisms is influenced by biological rhythms, including the daily circadian rhythms that guide the waking and sleeping cycle in many animals.

Sleep researchers have found that sleeping people undergo a fairly consistent pattern of sleep stages, each lasting about 90 minutes. Each of the sleep stages has its own distinct pattern of brain activity. Rapid eye movement (REM) accounts for about 25% of our total sleep time, during which we dream. Non-rapid eye movement (non-REM) sleep is a deep sleep characterized by very slow brain waves, and is further subdivided into three stages: N1, N2, and N3.

Sleep has a vital restorative function, and a prolonged lack of sleep results in increased anxiety, diminished performance, and, if severe and extended, even death. Sleep deprivation suppresses immune responses that fight off infection, and it can lead to obesity, hypertension, and memory impairment.

Some people suffer from sleep disorders, including insomnia, sleep apnea, narcolepsy, sleepwalking, and REM sleep behaviour disorder.

Freud believed that the primary function of dreams was wish fulfilment, and he differentiated between the manifest and latent content of dreams. Other theories of dreaming propose that we dream primarily to help with consolidation — the moving of information into long-term memory. The activation-synthesis theory of dreaming proposes that dreams are simply our brain’s interpretation of the random firing of neurons in the brain stem.

Psychoactive drugs are chemicals that change our states of consciousness, and particularly our perceptions and moods. The use (especially in combination) of psychoactive drugs has the potential to create very negative side effects, including tolerance, dependence, withdrawal symptoms, and addiction.

Stimulants, including caffeine, nicotine, cocaine, and amphetamine, are psychoactive drugs that operate by blocking the reuptake of dopamine, norepinephrine, and serotonin in the synapses of the central nervous system (CNS). Some amphetamines, such as Ecstasy, have very low safety ratios and thus are highly dangerous.

Depressants, including alcohol, barbiturates, benzodiazepines, and toxic inhalants, reduce the activity of the CNS. They are widely used as prescription medicines to relieve pain, to lower heart rate and respiration, and as anticonvulsants. Toxic inhalants are some of the most dangerous recreational drugs, with a safety index below 10, and their continued use may lead to permanent brain damage.

Opioids, including opium, morphine, heroin, and codeine, are chemicals that increase activity in opioid receptor neurons in the brain and in the digestive system, producing euphoria, analgesia, slower breathing, and constipation.

Hallucinogens, including cannabis, mescaline, and LSD, are psychoactive drugs that alter sensation and perception and which may create hallucinations.

Even when we know the potential costs of using drugs, we may engage in using them anyway because the rewards from using the drugs are occurring right now, whereas the potential costs are abstract and only in the future. And drugs are not the only things we enjoy or can abuse. It is normal to refer to the abuse of other behaviours, such as gambling, sex, overeating, and even overworking, as “addictions” to describe the overuse of pleasant stimuli.

Hypnosis is a trancelike state of consciousness, usually induced by a procedure known as hypnotic induction, which consists of heightened suggestibility, deep relaxation, and intense focus. Hypnosis also is frequently used to attempt to change unwanted behaviours, such as to reduce smoking, eating, and alcohol abuse.

Sensory deprivation is the intentional reduction of stimuli affecting one or more of the five senses, with the possibility of resulting changes in consciousness. Although sensory deprivation is used for relaxation or meditation purposes and to produce enjoyable changes in consciousness, when deprivation is prolonged, it is unpleasant and can be used as a means of torture.

Meditation refers to techniques in which the individual focuses on something specific, such as an object, a word, or one’s breathing, with the goal of ignoring external distractions. Meditation has a variety of positive health effects.

The goal of this chapter is to investigate the fundamental, complex, and essential process of human development. Development refers to the physiological, behavioural, cognitive, and social changes that occur throughout human life, which are guided by both genetic predispositions (nature) and by environmental influences (nurture). We will begin our study of development at the moment of conception, when the father’s sperm unites with the mother’s egg, and then consider prenatal development in the womb. Next we will focus on infancy, the developmental stage that begins at birth and continues to one year of age, and childhood, the period between infancy and the onset of puberty. Finally, we will consider the developmental changes that occur during adolescence — the years between the onset of puberty and the beginning of adulthood; the stages of adulthood itself, including emerging, early, middle, and older adulthood; and the preparations for and eventual facing of death.

Each of the stages of development has its unique physical, cognitive, and emotional changes that define the stage and that make each one unique from the others. The psychologist and psychoanalyst Erik Erikson (1963, p. 202) proposed a model of life-span development that provides a useful guideline for thinking about the changes we experience throughout life. As you can see in Table 7.1, “Challenges of Development as Proposed by Erik Erikson,” Erikson believed that each life stage has a unique challenge that the person who reaches it must face. And according to Erikson, successful development involves dealing with and resolving the goals and demands of each of the life stages in a positive way.

Table 7.1 Challenges of Development as Proposed by Erik Erikson. Adapted from Erikson (1963).

[Skip Table]
Stage	Age range	Key challenge	Positive resolution of challenge
Oral-sensory	Birth to 12 to 18 months	Trust versus mistrust	The child develops a feeling of trust in his or her caregivers.
Muscular-anal	18 months to 3 years	Autonomy versus shame/doubt	The child learns what he or she can and cannot control and develops a sense of free will.
Locomotor	3 to 6 years	Initiative versus guilt	The child learns to become independent by exploring, manipulating, and taking action.
Latency	6 to 12 years	Industry versus inferiority	The child learns to do things well or correctly according to standards set by others, particularly in school.
Adolescence	12 to 18 years	Identity versus role confusion	The adolescent develops a well-defined and positive sense of self in relationship to others.
Young adulthood	19 to 40 years	Intimacy versus isolation	The person develops the ability to give and receive love and to make long-term commitments.
Middle adulthood	40 to 65 years	Generativity versus stagnation	The person develops an interest in guiding the development of the next generation, often by becoming a parent.
Late adulthood	65 to death	Ego integrity versus despair	The person develops acceptance of his or her life as it was lived.

As we progress through this chapter, we will see that Robert Klark Graham was in part right — nature does play a substantial role in development (it has been found, for instance, that identical twins, who share all of their genetic code, usually begin sitting up and walking on the exact same days). But nurture is also important — we begin to be influenced by our environments even while still in the womb, and these influences remain with us throughout our development. Furthermore, we will see that we play an active role in shaping our own lives. Our own behaviour influences how and what we learn, how people respond to us, and how we develop as individuals. As you read the chapter, you will no doubt get a broader view of how we each pass through our own lives. You will see how we learn and adapt to life’s changes, and this new knowledge may help you better understand and better guide your own personal life journey.

References

Erikson, E. H. (1963). Childhood and society. New York, NY: Norton.

Olding, P. (2006, June 15). The genius sperm bank. BBC News. Retrieved from http://www.bbc.co.uk/sn/tvradio/programmes/horizon/broadband/tx/spermbank/doron/index_textonly.shtml

Plotz, D. (2001, February 8). The “genius babies,” and how they grew. Slate. Retrieved from http://www.slate.com/id/100331

Conception occurs when an egg from the mother is fertilized by a sperm from the father. In humans, the conception process begins with ovulation, when an ovum, or egg (the largest cell in the human body), which has been stored in one of the mother’s two ovaries, matures and is released into the fallopian tube. Ovulation occurs about halfway through the woman’s menstrual cycle and is aided by the release of a complex combination of hormones. In addition to helping the egg mature, the hormones also cause the lining of the uterus to grow thicker and more suitable for implantation of a fertilized egg.

If the woman has had sexual intercourse within one or two days of the egg’s maturation, one of the up to 500 million sperm deposited by the man’s ejaculation, which are travelling up the fallopian tube, may fertilize the egg. Although few of the sperm are able to make the long journey, some of the strongest swimmers succeed in meeting the egg. As the sperm reach the egg in the fallopian tube, they release enzymes that attack the outer jellylike protective coating of the egg, each trying to be the first to enter. As soon as one of the millions of sperm enters the egg’s coating, the egg immediately responds by both blocking out all other challengers and at the same time pulling in the single successful sperm.

The Zygote

Within several hours of conception, half of the 23 chromosomes from the egg and half of the 23 chromosomes from the sperm fuse together, creating a zygote — a fertilized ovum. The zygote continues to travel down the fallopian tube to the uterus. Although the uterus is only about four inches away in the woman’s body, the zygote’s journey is nevertheless substantial for a microscopic organism, and fewer than half of zygotes survive beyond this earliest stage of life. If the zygote is still viable when it completes the journey, it will attach itself to the wall of the uterus, but if it is not, it will be flushed out in the woman’s menstrual flow. During this time, the cells in the zygote continue to divide: the original two cells become four, those four become eight, and so on, until there are thousands (and eventually trillions) of cells. Soon the cells begin to differentiate, each taking on a separate function. The earliest differentiation is between the cells on the inside of the zygote, which will begin to form the developing human being, and the cells on the outside, which will form the protective environment that will provide support for the new life throughout the pregnancy.

The Embryo

Once the zygote attaches to the wall of the uterus, it is known as the embryo. During the embryonic phase, which will last for the next six weeks, the major internal and external organs are formed, each beginning at the microscopic level, with only a few cells. The changes in the embryo’s appearance will continue rapidly from this point until birth.

While the inner layer of embryonic cells is busy forming the embryo itself, the outer layer is forming the surrounding protective environment that will help the embryo survive the pregnancy. This environment consists of three major structures: The amniotic sac is the fluid-filled reservoir in which the embryo (soon to be known as a fetus) will live until birth, and which acts as both a cushion against outside pressure and as a temperature regulator. The placenta is an organ that allows the exchange of nutrients between the embryo and the mother, while at the same time filtering out harmful material. The filtering occurs through a thin membrane that separates the mother’s blood from the blood of the fetus, allowing them to share only the material that is able to pass through the filter. Finally, the umbilical cord links the embryo directly to the placenta and transfers all material to the fetus. Thus the placenta and the umbilical cord protect the fetus from many foreign agents in the mother’s system that might otherwise pose a threat.

The Fetus

Beginning in the ninth week after conception, the embryo becomes a fetus. The defining characteristic of the fetal stage is growth. All the major aspects of the growing organism have been formed in the embryonic phase, and now the fetus has approximately six months to go from weighing less than an ounce to weighing an average of six to eight pounds. That’s quite a growth spurt.

The fetus begins to take on many of the characteristics of a human being, including moving (by the third month the fetus is able to curl and open its fingers, form fists, and wiggle its toes), sleeping, as well as early forms of swallowing and breathing. The fetus begins to develop its senses, becoming able to distinguish tastes and respond to sounds. Research has found that the fetus even develops some initial preferences. A newborn prefers the mother’s voice to that of a stranger, the languages heard in the womb over other languages (DeCasper & Fifer, 1980; Moon, Cooper, & Fifer, 1993), and even the kinds of foods that the mother ate during the pregnancy (Mennella, Jagnow, & Beauchamp, 2001). By the end of the third month of pregnancy, the sexual organs are visible.

How the Environment Can Affect the Vulnerable Fetus

Prenatal development is a complicated process and may not always go as planned. About 45% of pregnancies result in a miscarriage, often without the mother ever being aware it has occurred (Moore & Persaud, 1993). Although the amniotic sac and the placenta are designed to protect the embryo, substances that can harm the fetus, known as teratogens, may nevertheless cause problems. Teratogens include general environmental factors, such as air pollution and radiation, but also the cigarettes, alcohol, and drugs that the mother may use. Teratogens do not always harm the fetus, but they are more likely to do so when they occur in larger amounts, for longer time periods, and during the more sensitive phases, as when the fetus is growing most rapidly. The most vulnerable period for many of the fetal organs is very early in the pregnancy — before the mother even knows she is pregnant.

Harmful substances that the mother ingests may harm the child. Cigarette smoking, for example, reduces the blood oxygen for both the mother and child and can cause a fetus to be born severely underweight. Another serious threat is fetal alcohol syndrome (FAS), a condition caused by maternal alcohol drinking that can lead to numerous detrimental developmental effects, including limb and facial abnormalities, genital anomalies, and mental retardation. Each year in Canada, it is estimated that nine babies in every 1,000 are born with fetal alcohol spectrum disorder (FASD), and it is considered one of the leading causes of retardation in the world today (Health Canada, 2006; Niccols, 1994). Because there is no known safe level of alcohol consumption for a pregnant woman, the Public Health Agency of Canada (2011) states that there is no safe amount or safe time to drink alcohol during pregnancy. Therefore, the best approach for expectant mothers is to avoid alcohol completely. Maternal drug abuse is also of major concern and is considered one of the greatest risk factors facing unborn children.

The environment in which the mother is living also has a major impact on infant development (Duncan & Brooks-Gunn, 2000; Haber & Toro, 2004). Children born into homelessness or poverty are more likely to have mothers who are malnourished, who suffer from domestic violence, stress, and other psychological problems, and who smoke or abuse drugs. And children born into poverty are also more likely to be exposed to teratogens. Poverty’s impact may also amplify other issues, creating substantial problems for healthy child development (Evans & English, 2002; Gunnar & Quevedo, 2007).

Mothers normally receive genetic and blood tests during the first months of pregnancy to determine the health of the embryo or fetus. They may undergo sonogram, ultrasound, amniocentesis, or other testing (Figure 7.1). The screenings detect potential birth defects, including neural tube defects, chromosomal abnormalities (such as Down syndrome), genetic diseases, and other potentially dangerous conditions. Early diagnosis of prenatal problems can allow medical treatment to improve the health of the fetus.

References

DeCasper, A. J., & Fifer, W. P. (1980). Of human bonding: Newborns prefer their mothers’ voices. Science, 208, 1174–1176.

Duncan, G., & Brooks-Gunn, J. (2000). Family poverty, welfare reform, and child development. Child Development, 71(1), 188–196.

Evans, G. W., & English, K. (2002). The environment of poverty: Multiple stressor exposure, psychophysiological stress, and socio-emotional adjustment. Child Development, 73(4), 1238–1248.

Gunnar, M., & Quevedo, K. (2007). The neurobiology of stress and development. Annual Review of Psychology, 58, 145–173.

Haber, M., & Toro, P. (2004). Homelessness among families, children, and adolescents: An ecological-developmental perspective. Clinical Child and Family Psychology Review, 7(3), 123–164.

Health Canada. (2006). It’s your health: Fetal alcohol spectrum disorder [PDF]. Retrieved June 2014 from http://www.hc-sc.gc.ca/hl-vs/alt_formats/pacrb-dgapcr/pdf/iyh-vsv/diseases-maladies/fasd-etcaf-eng.pdf

Mennella, J. A., Jagnow, C. P., & Beauchamp, G. K. (2001). Prenatal and postnatal flavor learning by human infants. Pediatrics, 107(6), e88.

Moon, C., Cooper, R. P., & Fifer, W. P. (1993). Two-day-olds prefer their native language. Infant Behavior & Development, 16, 495–500.

Moore, K., & Persaud, T. (1993). The developing human: Clinically oriented embryology (5th ed.). Philadelphia, PA: Saunders.

Niccols, G. A. (1994). Fetal alcohol syndrome: Implications for psychologists. Clinical Psychology Review, 14, 91–111.

Public Health Agency of Canada. (2011). The healthy pregnancy guide. Retrieved May 10, 2014 from http://www.phac-aspc.gc.ca/hp-gs/guide/index-eng.php

Image Attributions

Figure 7.1: “Leipzig, Universitätsklinik, Untersuchung” by Grubitzsch (http://en.wikipedia.org/wiki/File:Bundesarchiv_Bild_183-1990-0417-001,_Leipzig,_Universit%C3%A4tsklinik,_Untersuchung.jpg) is licensed under CC BY-SA 3.0 DE (http://creativecommons.org/licenses/by-sa/3.0/de/deed.en).

If all has gone well, a baby is born sometime around the 38th week of pregnancy. The fetus is responsible, at least in part, for its own birth because chemicals released by the developing fetal brain trigger the muscles in the mother’s uterus to start the rhythmic contractions of childbirth. The contractions are initially spaced at about 15-minute intervals but come more rapidly with time. When the contractions reach an interval of two to three minutes, the mother is requested to assist in the labour and help push the baby out.

The Newborn Arrives With Many Behaviours Intact

Newborns are already prepared to face the new world they are about to experience. As you can see in Table 7.2, “Survival Reflexes in Newborns,” babies are equipped with a variety of reflexes, each providing an ability that will help them survive their first few months of life as they continue to learn new routines to help them survive in and manipulate their environments.

Table 7.2 Survival Reflexes in Newborns.

[Skip Table]
Name	Stimulus	Response	Significance	Video Example
Rooting reflex	The baby’s cheek is stroked.	The baby turns its head toward the stroking, opens its mouth, and tries to suck.	Ensures the infant’s feeding will be a reflexive habit	Watch “The Rooting Reflex” [YouTube]
Blink reflex	A light is flashed in the baby’s eyes.	The baby closes both eyes.	Protects eyes from strong and potentially dangerous stimuli	Watch “Baby Blinking” [YouTube]
Withdrawal reflex	A soft pinprick is applied to the sole of the baby’s foot.	The baby flexes the leg.	Keeps the exploring infant away from painful stimuli	Watch “Baby Withdraw Reflex” [YouTube]
Tonic neck reflex	The baby is laid down on its back.	The baby turns its head to one side and extends the arm on the same side.	Helps develop hand-eye coordination	Watch “Tonic Neck Reflex” [YouTube]
Grasp reflex	An object is pressed into the palm of the baby.	The baby grasps the object pressed and can even hold its own weight for a brief period.	Helps in exploratory learning	Watch “Grasp reflex” [YouTube]
Moro reflex	Loud noises or a sudden drop in height while holding the baby.	The baby extends arms and legs and quickly brings them in as if trying to grasp something.	Protects from falling; could have assisted infants in holding on to their mothers during rough travelling	Watch “Moro Reflex” [YouTube]
Stepping reflex	The baby is suspended with bare feet just above a surface and is moved forward.	Baby makes stepping motions as if trying to walk.	Helps encourage motor development	Watch “Stepping Reflex” [YouTube]

In addition to reflexes, newborns have preferences — they like sweet-tasting foods at first, while becoming more open to salty items by four months of age (Beauchamp, Cowart, Menellia, & Marsh, 1994; Blass & Smith, 1992). Newborns also prefer the smell of their mothers. An infant only six days old is significantly more likely to turn toward its own mother’s breast pad than to the breast pad of another baby’s mother (Porter, Makin, Davis, & Christensen, 1992), and a newborn also shows a preference for the face of its own mother (Bushnell, Sai, & Mullin, 1989).

Although infants are born ready to engage in some activities, they also contribute to their own development through their own behaviours. The child’s knowledge and abilities increase as it babbles, talks, crawls, tastes, grasps, plays, and interacts with the objects in the environment (Gibson, Rosenzweig, & Porter, 1988; Gibson & Pick, 2000; Smith & Thelen, 2003). Parents may help in this process by providing a variety of activities and experiences for the child. Research has found that animals raised in environments with more novel objects and that engage in a variety of stimulating activities have more brain synapses and larger cerebral cortexes, and they perform better on a variety of learning tasks compared with animals raised in more impoverished environments (Juraska, Henderson, & Müller, 1984). Similar effects are likely occurring in children who have opportunities to play, explore, and interact with their environments (Soska, Adolph, & Johnson, 2010).

Cognitive Development During Childhood

Childhood is a time in which changes occur quickly. The child is growing physically, and cognitive abilities are also developing. During this time the child learns to actively manipulate and control the environment, and is first exposed to the requirements of society, particularly the need to control the bladder and bowels. According to Erik Erikson, the challenges that the child must attain in childhood relate to the development of initiative, competence, and independence. Children need to learn to explore the world, to become self-reliant, and to make their own way in the environment.

These skills do not come overnight. Neurological changes during childhood provide children the ability to do some things at certain ages, and yet make it impossible for them to do other things. This fact was made apparent through the groundbreaking work of the Swiss psychologist Jean Piaget (Figure 7.3). During the 1920s, Piaget was administering intelligence tests to children in an attempt to determine the kinds of logical thinking that children were capable of. In the process of testing them, Piaget became intrigued, not so much by the answers that the children got right, but more by the answers they got wrong. Piaget believed that the incorrect answers the children gave were not mere shots in the dark but rather represented specific ways of thinking unique to the children’s developmental stage. Just as almost all babies learn to roll over before they learn to sit up by themselves, and learn to crawl before they learn to walk, Piaget believed that children gain their cognitive ability in a developmental order. These insights — that children at different ages think in fundamentally different ways — led to Piaget’s stage model of cognitive development.

Piaget argued that children do not just passively learn but also actively try to make sense of their worlds. He argued that, as they learn and mature, children develop schemas — patterns of knowledge in long-term memory — that help them remember, organize, and respond to information. Furthermore, Piaget thought that when children experience new things, they attempt to reconcile the new knowledge with existing schemas. Piaget believed that children use two distinct methods in doing so, methods that he called assimilation and accommodation (see Figure 7.4, “Assimilation and Accommodation”).

When children employ assimilation, they use already developed schemas to understand new information. If children have learned a schema for horses, then they may call the striped animal they see at the zoo a horse rather than a zebra. In this case, children fit the existing schema to the new information and label the new information with the existing knowledge. Accommodation, on the other hand, involves learning new information and thus changing the schema. When a mother says, “No, honey, that’s a zebra, not a horse,” the child may adapt the schema to fit the new stimulus, learning that there are different types of four-legged animals, only one of which is a horse.

Piaget’s most important contribution to understanding cognitive development, and the fundamental aspect of his theory, was the idea that development occurs in unique and distinct stages, with each stage occurring at a specific time, in a sequential manner, and in a way that allows the child to think about the world using new capacities. Piaget’s stages of cognitive development are summarized in Table 7.3, “Piaget’s Stages of Cognitive Development.”

Table 7.3 Piaget’s Stages of Cognitive Development.

[Skip Table]
Stage	Approximate age range	Characteristics	Stage attainments
Sensorimotor	Birth to about 2 years	The child experiences the world through the fundamental senses of seeing, hearing, touching, and tasting.	Object permanence
Preoperational	2 to 7 years	Children acquire the ability to internally represent the world through language and mental imagery. They also start to see the world from other people’s perspectives.	Theory of mind; rapid increase in language ability
Concrete operational	7 to 11 years	Children become able to think logically. They can increasingly perform operations on objects that are only imagined.	Conservation
Formal operational	11 years to adulthood	Adolescents can think systematically, can reason about abstract concepts, and can understand ethics and scientific reasoning.	Abstract logic

The first developmental stage for Piaget was the sensorimotor stage, the cognitive stage that begins at birth and lasts until around the age of two. It is defined by the direct physical interactions that babies have with the objects around them. During this stage, babies form their first schemas by using their primary senses — they stare at, listen to, reach for, hold, shake, and taste the things in their environments.

During the sensorimotor stage, babies’ use of their senses to perceive the world is so central to their understanding that whenever babies do not directly perceive objects, as far as they are concerned, the objects do not exist. Piaget found, for instance, that if he first interested babies in a toy and then covered the toy with a blanket, children who were younger than six months of age would act as if the toy had disappeared completely — they never tried to find it under the blanket but would nevertheless smile and reach for it when the blanket was removed. Piaget found that it was not until about eight months that the children realized that the object was merely covered and not gone. Piaget used the term object permanence to refer to the child’s ability to know that an object exists even when the object cannot be perceived.

Children younger than about eight months of age do not understand object permanence.

Watch: Object Permanence [YouTube]: http://www.youtube.com/v/nwXd7WyWNHY

 

At about two years of age, and until about seven years of age, children move into the preoperational stage. During this stage, children begin to use language and to think more abstractly about objects, with capacity to form mental images; however, their understanding is more intuitive and they lack much ability to deduce or reason. The thinking is preoperational, meaning that the child lacks the ability to operate on or transform objects mentally. In one study that showed the extent of this inability, Judy DeLoache (1987) showed children a room within a small dollhouse. Inside the room, a small toy was visible behind a small couch. The researchers took the children to another lab room, which was an exact replica of the dollhouse room, but full-sized. When children who were 2.5 years old were asked to find the toy, they did not know where to look — they were simply unable to make the transition across the changes in room size. Three-year-old children, on the other hand, immediately looked for the toy behind the couch, demonstrating that they were improving their operational skills.

The inability of young children to view transitions also leads them to be egocentric — unable to readily see and understand other people’s viewpoints. Developmental psychologists define the theory of mind as the ability to take another person’s viewpoint, and the ability to do so increases rapidly during the preoperational stage. In one demonstration of the development of theory of mind, a researcher shows a child a video of another child (let’s call her Anna) putting a ball in a red box. Then Anna leaves the room, and the video shows that while she is gone, a researcher moves the ball from the red box into a blue box. As the video continues, Anna comes back into the room. The child is then asked to point to the box where Anna will probably look to find her ball. Children who are younger than four years of age typically are unable to understand that Anna does not know that the ball has been moved, and they predict that she will look for it in the blue box. After four years of age, however, children have developed a theory of mind — they realize that different people can have different viewpoints and that (although she will be wrong) Anna will nevertheless think that the ball is still in the red box.

After about seven years of age until 11, the child moves into the concrete operational stage, which is marked by more frequent and more accurate use of transitions, operations, and abstract concepts, including those of time, space, and numbers. An important milestone during the concrete operational stage is the development of conservation — the understanding that changes in the form of an object do not necessarily mean changes in the quantity of the object. Children younger than seven years generally think that a glass of milk that is tall holds more milk than a glass of milk that is shorter and wider, and they continue to believe this even when they see the same milk poured back and forth between the glasses. It appears that these children focus only on one dimension (in this case, the height of the glass) and ignore the other dimension (width). However, when children reach the concrete operational stage, their abilities to understand such transformations make them aware that, although the milk looks different in the different glasses, the amount must be the same.

Children younger than about seven years of age do not understand the principles of conservation.

Watch: “Conservation” [YouTube]: http://www.youtube.com/watch?v=YtLEWVu815o&feature=youtu.be

At about 11 years of age, children enter the formal operational stage, which is marked by the ability to think in abstract terms and to use scientific and philosophical lines of thought. Children in the formal operational stage are better able to systematically test alternative ideas to determine their influences on outcomes. For instance, rather than haphazardly changing different aspects of a situation that allows no clear conclusions to be drawn, they systematically make changes in one thing at a time and observe what difference that particular change makes. They learn to use deductive reasoning, such as “if this, then that,” and they become capable of imagining situations that “might be,” rather than just those that actually exist.

Piaget’s theories have made a substantial and lasting contribution to developmental psychology. His contributions include the idea that children are not merely passive receptacles of information but rather actively engage in acquiring new knowledge and making sense of the world around them. This general idea has generated many other theories of cognitive development, each designed to help us better understand the development of the child’s information-processing skills (Klahr & MacWhinney, 1998; Shrager & Siegler, 1998). Furthermore, the extensive research that Piaget’s theory has stimulated has generally supported his beliefs about the order in which cognition develops. Piaget’s work has also been applied in many domains — for instance, many teachers make use of Piaget’s stages to develop educational approaches aimed at the level children are developmentally prepared for (Driscoll, 1994; Levin, Siegler, & Druyan, 1990).

Over the years, Piagetian ideas have been refined. For instance, it is now believed that object permanence develops gradually, rather than more immediately, as a true stage model would predict, and that it can sometimes develop much earlier than Piaget expected. Renée Baillargeon and her colleagues (Baillargeon, 2004; Wang, Baillargeon, & Brueckner, 2004) placed babies in a habituation setup, having them watch as an object was placed behind a screen, entirely hidden from view. The researchers then arranged for the object to reappear from behind another screen in a different place. Babies who saw this pattern of events looked longer at the display than did babies who witnessed the same object physically being moved between the screens. These data suggest that the babies were aware that the object still existed even though it was hidden behind the screen, and thus that they were displaying object permanence as early as three months of age, rather than the eight months that Piaget predicted.

Another factor that might have surprised Piaget is the extent to which a child’s social surroundings influence learning. In some cases, children progress to new ways of thinking and retreat to old ones depending on the type of task they are performing, the circumstances they find themselves in, and the nature of the language used to instruct them (Courage & Howe, 2002). And children in different cultures show somewhat different patterns of cognitive development. Dasen (1972) found that children in non-Western cultures moved to the next developmental stage about a year later than did children from Western cultures, and that level of schooling also influenced cognitive development. In short, Piaget’s theory probably understated the contribution of environmental factors to social development.

More recent theories (Cole, 1996; Rogoff, 1990; Tomasello, 1999), based in large part on the sociocultural theory of the Russian scholar Lev Vygotsky (1962, 1978), argue that cognitive development is not isolated entirely within the child but occurs at least in part through social interactions. These scholars argue that children’s thinking develops through constant interactions with more competent others, including parents, peers, and teachers.

An extension of Vygotsky’s sociocultural theory is the idea of community learning, in which children serve as both teachers and learners. This approach is frequently used in classrooms to improve learning as well as to increase responsibility and respect for others. When children work cooperatively in groups to learn material, they can help and support each other’s learning as well as learn about each other as individuals, thereby reducing prejudice (Aronson, Blaney, Stephan, Sikes, & Snapp, 1978; Brown, 1997).

Social Development During Childhood

It is through the remarkable increases in cognitive ability that children learn to interact with and understand their environments. But these cognitive skills are only part of the changes that are occurring during childhood. Equally crucial is the development of the child’s social skills — the ability to understand, predict, and create bonds with the other people in their environments.

Knowing the Self: The Development of the Self-Concept

One of the important milestones in a child’s social development is learning about his or her own self-existence (Figure 7.5). This self-awareness is known as consciousness, and the content of consciousness is known as the self-concept. The self-concept is a knowledge representation or schema that contains knowledge about us, including our beliefs about our personality traits, physical characteristics, abilities, values, goals, and roles, as well as the knowledge that we exist as individuals (Kagan, 1991).

Some animals, including chimpanzees, orangutans, and perhaps dolphins, have at least a primitive sense of self (Boysen & Himes, 1999). In one study (Gallup, 1970), researchers painted a red dot on the foreheads of anesthetized chimpanzees and then placed each animal in a cage with a mirror. When the chimps woke up and looked in the mirror, they touched the dot on their faces, not the dot on the faces in the mirror. These actions suggest that the chimps understood that they were looking at themselves and not at other animals, and thus we can assume that they are able to realize that they exist as individuals. On the other hand, most other animals, including, for instance, dogs, cats, and monkeys, never realize that it is themselves in the mirror.

Infants who have a similar red dot painted on their foreheads recognize themselves in a mirror in the same way that the chimps do, and they do this by about 18 months of age (Povinelli, Landau, & Perilloux, 1996). The child’s knowledge about the self continues to develop as the child grows. By age two, the infant becomes aware of his or her sex, as a boy or a girl. By age four, self-descriptions are likely to be based on physical features, such as hair colour and possessions, and by about age six, the child is able to understand basic emotions and the concepts of traits, being able to make statements such as “I am a nice person” (Harter, 1998).

Soon after children enter school (at about age five or six), they begin to make comparisons with other children, a process known as social comparison. For example, a child might describe himself as being faster than one boy but slower than another (Moretti & Higgins, 1990). According to Erikson, the important component of this process is the development of competence and autonomy — the recognition of one’s own abilities relative to other children. And children increasingly show awareness of social situations — they understand that other people are looking at and judging them the same way that they are looking at and judging others (Doherty, 2009).

Successfully Relating to Others: Attachment

One of the most important behaviours a child must learn is how to be accepted by others — the development of close and meaningful social relationships. The emotional bonds that we develop with those with whom we feel closest, and particularly the bonds that an infant develops with the mother or primary caregiver, are referred to as attachment (Cassidy & Shaver, 1999). See examples in Figure 7.6.

As late as the 1930s, psychologists believed that children who were raised in institutions such as orphanages, and who received good physical care and proper nourishment, would develop normally, even if they had little interaction with their caretakers. But studies by the developmental psychologist John Bowlby (1953) and others showed that these children did not develop normally — they were usually sickly, emotionally slow, and generally unmotivated. These observations helped make it clear that normal infant development requires successful attachment with a caretaker.

In one classic study showing the importance of attachment, Wisconsin University psychologists Harry and Margaret Harlow investigated the responses of young monkeys, separated from their biological mothers, to two surrogate mothers introduced to their cages. One — the wire mother — consisted of a round wooden head, a mesh of cold metal wires, and a bottle of milk from which the baby monkey could drink. The second mother was a foam-rubber form wrapped in a heated terry-cloth blanket. The Harlows found that although the infant monkeys went to the wire mother for food, they overwhelmingly preferred and spent significantly more time with the warm terry-cloth mother that provided no food but did provide comfort (Harlow, 1958).

The studies by the Harlows showed that young monkeys preferred the warm mother that provided a secure base to the cold mother that provided food.

Watch: “The Harlows’s Monkeys” [YouTube]: http://www.youtube.com/watch?v=MmbbfisRiwA

The Harlows’s studies confirmed that babies have social as well as physical needs. Both monkeys and human babies need a secure base that allows them to feel safe. From this base, they can gain the confidence they need to venture out and explore their worlds. Erikson (Table 7.1, “Challenges of Development as Proposed by Erik Erikson”) was in agreement on the importance of a secure base, arguing that the most important goal of infancy was the development of a basic sense of trust in one’s caregivers.

Developmental psychologist Mary Ainsworth, a student of John Bowlby, was interested in studying the development of attachment in infants. Ainsworth created a laboratory test that measured an infant’s attachment to his or her parent. The test is called the strange situation — a measure of attachment in young children in which the child’s behaviours are assessed in a situation in which the caregiver and a stranger move in and out of the environment — because it is conducted in a context that is unfamiliar to the child and therefore likely to heighten the child’s need for his or her parent (Ainsworth, Blehar, Waters, & Wall, 1978). During the procedure, which lasts about 20 minutes, the parent and the infant are first left alone, while the infant explores the room full of toys. Then a strange adult enters the room and talks for a minute to the parent, after which the parent leaves the room. The stranger stays with the infant for a few minutes, and then the parent again enters and the stranger leaves the room. During the entire session, a video camera records the child’s behaviours, which are later coded by trained coders.

In the strange situation, children are observed responding to the comings and goings of parents and unfamiliar adults in their environments.

Watch: “The Strange Situation” [YouTube]: http://www.youtube.com/watch?v=QTsewNrHUHU

On the basis of their behaviours, the children are categorized into one of four groups, where each group reflects a different kind of attachment relationship with the caregiver. A child with a secure attachment style usually explores freely while the mother is present and engages with the stranger. The child may be upset when the mother departs but is also happy to see the mother return. A child with an ambivalent (sometimes called insecure-resistant) attachment style is wary about the situation in general, particularly the stranger, and stays close or even clings to the mother rather than exploring the toys. When the mother leaves, the child is extremely distressed and is ambivalent when she returns. The child may rush to the mother but then fail to cling to her when she picks up the child. A child with an avoidant (sometimes called insecure-avoidant) attachment style will avoid or ignore the mother, showing little emotion when the mother departs or returns. The child may run away from the mother when she approaches. The child will not explore very much, regardless of who is there, and the stranger will not be treated much differently from the mother.

Finally, a child with a disorganized attachment style seems to have no consistent way of coping with the stress of the strange situation — the child may cry during the separation but avoid the mother when she returns, or the child may approach the mother but then freeze or fall to the floor. Although some cultural differences in attachment styles have been found (Rothbaum, Weisz, Pott, Miyake, & Morelli, 2000), research has also found that the proportion of children who fall into each of the attachment categories is relatively constant across cultures (see Figure 7.7, “Proportion of Children With Different Attachment Styles”).

You might wonder whether differences in attachment style are determined more by the child (nature) or more by the parents (nurture). Most developmental psychologists believe that socialization is primary, arguing that a child becomes securely attached when the mother is available and able to meet the needs of the child in a responsive and appropriate manner, but that the insecure styles occur when the mother is insensitive and responds inconsistently to the child’s needs. In a direct test of this idea, Dutch researcher Dymphna van den Boom (1994) randomly assigned some babies’ mothers to a training session in which they learned to better respond to their children’s needs. The research found that these mothers’ babies were more likely to show a secure attachment style compared with the babies of the mothers in a control group that did not receive training.

But the attachment behaviour of the child is also likely influenced, at least in part, by temperament, the innate personality characteristics of the infant. Some children are warm, friendly, and responsive, whereas others tend to be more irritable, less manageable, and difficult to console. These differences may also play a role in attachment (Gillath, Shaver, Baek, & Chun, 2008; Seifer, Schiller, Sameroff, Resnick, & Riordan, 1996). Taken together, it seems safe to say that attachment, like most other developmental processes, is affected by an interplay of genetic and socialization influences.

References

Ainsworth, M. S., Blehar, M. C., Waters, E., & Wall, S. (1978). Patterns of attachment: A psychological study of the strange situation. Hillsdale, NJ: Lawrence Erlbaum Associates.

Aronson, E., Blaney, N., Stephan, C., Sikes, J., & Snapp, M. (1978). The jigsaw classroom. Beverly Hills, CA: Sage.

Baillargeon, R. (2004). Infants’ physical world. Current Directions in Psychological Science, 13(3), 89–94.

Beauchamp, D. K., Cowart, B. J., Menellia, J. A., & Marsh, R. R. (1994). Infant salt taste: Developmental, methodological, and contextual factors. Developmental Psychology, 27, 353–365.

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Bowlby, J. (1953). Some pathological processes set in train by early mother-child separation. Journal of Mental Science, 99, 265–272.

Boysen, S. T., & Himes, G. T. (1999). Current issues and emerging theories in animal cognition. Annual Review of Psychology, 50, 683–705.

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Cassidy, J. E., & Shaver, P. R. E. (1999). Handbook of attachment: Theory, research, and clinical applications. New York, NY: Guilford Press.

Cole, M. (1996). Culture in mind. Cambridge, MA: Harvard University Press.

Courage, M. L., & Howe, M. L. (2002). From infant to child: The dynamics of cognitive change in the second year of life. Psychological Bulletin, 128(2), 250–276.

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DeLoache, J. S. (1987). Rapid change in the symbolic functioning of very young children. Science, 238(4833), 1556–1556.

Doherty, M. J. (2009). Theory of mind: How children understand others’ thoughts and feelings. New York, NY: Psychology Press.

Driscoll, M. P. (1994). Psychology of learning for instruction. Boston, MA: Allyn & Bacon.

Gallup, G. G., Jr. (1970). Chimpanzees: Self-recognition. Science, 167(3914), 86–87.

Gibson, E. J., & Pick, A. D. (2000). An ecological approach to perceptual learning and development. New York, NY: Oxford University Press.

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Gillath, O., Shaver, P. R., Baek, J.-M., & Chun, D. S. (2008). Genetic correlates of adult attachment style. Personality and Social Psychology Bulletin, 34(10), 1396–1405.

Harlow, H. (1958). The nature of love. American Psychologist, 13, 573–685.

Harter, S. (1998). The development of self-representations. In W. Damon & N. Eisenberg (Eds.), Handbook of child psychology: Social, emotional, & personality development (5th ed., Vol. 3, pp. 553–618). New York, NY: John Wiley & Sons.

James, W. (1890). The principles of psychology. New York, NY: Dover.

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Klahr, D., & MacWhinney, B. (1998). Information Processing. In D. Kuhn & R. S. Siegler (Eds.), Handbook of child psychology: Cognition, perception, & language (5th ed., Vol. 2, pp. 631–678). New York, NY: John Wiley & Sons.

Levin, I., Siegler, S. R., & Druyan, S. (1990). Misconceptions on motion: Development and training effects. Child Development, 61, 1544–1556.

Lucas-Thompson, R., & Clarke-Stewart, K. A. (2007). Forecasting friendship: How marital quality, maternal mood, and attachment security are linked to children’s peer relationships. Journal of Applied Developmental Psychology, 28(5–6), 499–514.

Moretti, M. M., & Higgins, E. T. (1990). The development of self-esteem vulnerabilities: Social and cognitive factors in developmental psychopathology. In R. J. Sternberg & J. Kolligian, Jr. (Eds.), Competence considered (pp. 286–314). New Haven, CT: Yale University Press.

Porter, R. H., Makin, J. W., Davis, L. B., & Christensen, K. M. (1992). Breast-fed infants respond to olfactory cues from their own mother and unfamiliar lactating females. Infant Behavior & Development, 15(1), 85–93.

Povinelli, D. J., Landau, K. R., & Perilloux, H. K. (1996). Self-recognition in young children using delayed versus live feedback: Evidence of a developmental asynchrony. Child Development, 67(4), 1540–1554.

Rogoff, B. (1990). Apprenticeship in thinking: Cognitive development in social context. New York, NY: Oxford University Press.

Rothbaum, F., Weisz, J., Pott, M., Miyake, K., & Morelli, G. (2000). Attachment and culture: Security in the United States and Japan. American Psychologist, 55(10), 1093–1104.

Seifer, R., Schiller, M., Sameroff, A. J., Resnick, S., & Riordan, K. (1996). Attachment, maternal sensitivity, and infant temperament during the first year of life. Developmental Psychology, 32(1), 12–25.

Shrager, J., & Siegler, R. S. (1998). SCADS: A model of children’s strategy choices and strategy discoveries. Psychological Science, 9, 405–422.

Smith, L. B., & Thelen, E. (2003). Development as a dynamic system. Trends in Cognitive Sciences, 7(8), 343–348.

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Tomasello, M. (1999). The cultural origins of human cognition. Cambridge, MA: Harvard University Press.

Trehub, S., & Rabinovitch, M. (1972). Auditory-linguistic sensitivity in early infancy. Developmental Psychology, 6(1), 74–77.

van den Boom, D. C. (1994). The influence of temperament and mothering on attachment and exploration: An experimental manipulation of sensitive responsiveness among lower-class mothers with irritable infants. Child Development, 65(5), 1457–1476.

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Image Attributions

Figure 7.2: Adapted from Wynn (1995).

Figure 7.3: Jean Piaget by Anton Johansson, http://www.flickr.com/photos/mirjoran/455878802 used under CC BY 2.0 license (https://creativecommons.org/licenses/by/2.0/).

Figure 7.5: “Toddler in mirror” by Samantha Steele (http://www.flickr.com/photos/samanthasteele/3983047059/) is licensed under CC BY-NC-ND 2.0 license (http://creativecommons.org/licenses/by-nc-nd/2.0/deed.en_CA). There’s a monkey in my mirror” by Mor (http://www.flickr.com/photos/mmoorr/1921632741/) is licensed under CC BY-NC 2.0 license (http://creativecommons.org/licenses/by-nc/2.0/deed.en_CA). “mirror mirror who is the most beautiful dog?” by rromer (http://www.flickr.com/photos/rromer/6309501395/) is licensed under CC BY-NC-SA 2.0 license (http://creativecommons.org/licenses/by-nc-sa/2.0/deed.en_CA).

Figure 7.6: Source: “Maternal Bond” by Koivth (http://en.wikipedia.org/wiki/File:MaternalBond.jpg) is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported (http://creativecommons.org/licenses/by-sa/3.0/deed.en_CA). “An admirable dad” by Julien Harneis (http://www.flickr.com/photos/julien_harneis/6342076964/in/photostream/) is licensed under CC BY-SA 2.0 (http://creativecommons.org/licenses/by-sa/2.0/deed.en_CA). “Szymon i Krystian” by Joymaster (http://en.wikipedia.org/wiki/File:Szymon_i_Krystian_003.JPG) is licensed under the Creative Commons Attribution-Share Alike 3.0 (http://creativecommons.org/licenses/by-sa/3.0/deed.en_CA).

Long Descriptions:

Figure 7.7 long description: Childrens’ Attachment Styles. 60% are secure. 15% are disorganized. 15% are avoidant. 10% are ambivalent. [Return to Figure 7.7]

Adolescence is defined as the years between the onset of puberty and the beginning of adulthood. In the past, when people were likely to marry in their early 20s or younger, this period might have lasted only 10 years or less — starting roughly between ages 12 and 13 and ending by age 20, at which time the child got a job or went to work on the family farm, married, and started his or her own family. Today, children mature more slowly, move away from home at later ages, and maintain ties with their parents longer. For instance, children may go away to university but still receive financial support from parents, and they may come home on weekends or even to live for extended time periods. Thus the period between puberty and adulthood may well last into the late 20s, merging into adulthood itself. In fact, it is appropriate now to consider the period of adolescence and that of emerging adulthood (the ages between 18 and the middle or late 20s) together.

During adolescence, the child continues to grow physically, cognitively, and emotionally, changing from a child into an adult. The body grows rapidly in size, and the sexual and reproductive organs become fully functional. At the same time, as adolescents develop more advanced patterns of reasoning and a stronger sense of self, they seek to forge their own identities, developing important attachments with people other than their parents. Particularly in Western societies, where the need to forge a new independence is critical (Baumeister & Tice, 1986; Twenge, 2006), this period can be stressful for many children, as it involves new emotions, the need to develop new social relationships, and an increasing sense of responsibility and independence.

Although adolescence can be a time of stress for many teenagers, most of them weather the trials and tribulations successfully. For example, the majority of adolescents experiment with alcohol sometime before high school graduation. Although many will have been drunk at least once, relatively few teenagers will develop long-lasting drinking problems or permit alcohol to adversely affect their school or personal relationships. Similarly, a great many teenagers break the law during adolescence, but very few young people develop criminal careers (Farrington, 1995). These facts do not, however, mean that using drugs or alcohol is a good idea. The use of recreational drugs can have substantial negative consequences, and the likelihood of these problems (including dependence, addiction, and even brain damage) is significantly greater for young adults who begin using drugs at an early age.

Physical Changes in Adolescence

Adolescence begins with the onset of puberty, a developmental period in which hormonal changes cause rapid physical alterations in the body, culminating in sexual maturity. Although the timing varies to some degree across cultures, the average age range for reaching puberty is between nine and 14 years for girls and between 10 and 17 years for boys (Marshall & Tanner, 1986).

Puberty begins when the pituitary gland begins to stimulate the production of the male sex hormone testosterone in boys and the female sex hormones estrogen and progesterone in girls. The release of these sex hormones triggers the development of the primary sex characteristics, the sex organs concerned with reproduction (Figure 7.8, “Sex Characteristics”). These changes include the enlargement of the testicles and the penis in boys and the development of the ovaries, uterus, and vagina in girls. In addition, secondary sex characteristics (features that distinguish the two sexes from each other but are not involved in reproduction) are also developing, such as an enlarged Adam’s apple, a deeper voice, and pubic and underarm hair in boys, and enlargement of the breasts and hips and the appearance of pubic and underarm hair in girls (Figure 7.8, “Sex Characteristics”). The enlargement of breasts is usually the first sign of puberty in girls and, on average, occurs between ages 10 and 12 (Marshall & Tanner, 1986). Boys typically begin to grow facial hair between ages 14 and 16, and both boys and girls experience a rapid growth spurt during this stage. The growth spurt for girls usually occurs earlier than that for boys, with some boys continuing to grow into their 20s.

A major milestone in puberty for girls is menarche, the first menstrual period, typically experienced at around 12 or 13 years of age (Anderson, Dannal, & Must, 2003). The age of menarche varies substantially and is determined by genetics, as well as by diet and lifestyle, since a certain amount of body fat is needed to attain menarche. Girls who are very slim, who engage in strenuous athletic activities, or who are malnourished may begin to menstruate later. Even after menstruation begins, girls whose level of body fat drops below the critical level may stop having their periods. The sequence of events for puberty is more predictable than the age at which they occur. Some girls may begin to grow pubic hair at age 10 but not attain menarche until age 15. In boys, facial hair may not appear until 10 years after the initial onset of puberty.

The timing of puberty in both boys and girls can have significant psychological consequences. Boys who mature earlier attain some social advantages because they are taller and stronger and, therefore, often more popular (Lynne, Graber, Nichols, Brooks-Gunn, & Botvin, 2007). At the same time, however, early-maturing boys are at greater risk for delinquency and are more likely than their peers to engage in antisocial behaviours, including drug and alcohol use, truancy, and precocious sexual activity. Girls who mature early may find their maturity stressful, particularly if they experience teasing or sexual harassment (Mendle, Turkheimer, & Emery, 2007; Pescovitz & Walvoord, 2007). Early-maturing girls are also more likely to have emotional problems, a lower self-image, and higher rates of depression, anxiety, and disordered eating than their peers (Ge, Conger, & Elder, 1996).

Cognitive Development in Adolescence

Although the most rapid cognitive changes occur during childhood, the brain continues to develop throughout adolescence, and even into the 20s (Weinberger, Elvevåg, & Giedd, 2005). During adolescence, the brain continues to form new neural connections, but also casts off unused neurons and connections (Blakemore, 2008). As teenagers mature, the prefrontal cortex, the area of the brain responsible for reasoning, planning, and problem solving, also continues to develop (Goldberg, 2001). And myelin, the fatty tissue that forms around axons and neurons and helps speed transmissions between different regions of the brain, also continues to grow (Rapoport et al., 1999).

Adolescents often seem to act impulsively, rather than thoughtfully, and this may be in part because the development of the prefrontal cortex is, in general, slower than the development of the emotional parts of the brain, including the limbic system (Blakemore, 2008). Furthermore, the hormonal surge that is associated with puberty, which primarily influences emotional responses, may create strong emotions and lead to impulsive behaviour. It has been hypothesized that adolescents may engage in risky behaviour, such as smoking, drug use, dangerous driving, and unprotected sex, in part because they have not yet fully acquired the mental ability to curb impulsive behaviour or to make entirely rational judgments (Steinberg, 2007).

The new cognitive abilities that are attained during adolescence may also give rise to new feelings of egocentrism, in which adolescents believe that they can do anything and that they know better than anyone else, including their parents (Elkind, 1978). Teenagers are likely to be highly self-conscious, often creating an imaginary audience in which they feel that everyone is constantly watching them (Goossens, Beyers, Emmen, & van Aken, 2002). Because teens think so much about themselves, they mistakenly believe that others must be thinking about them, too (Rycek, Stuhr, McDermott, Benker, & Swartz, 1998). It is no wonder that everything a teen’s parents do suddenly feels embarrassing to them when they are in public.

Social Development in Adolescence

Some of the most important changes that occur during adolescence involve the further development of the self-concept and the development of new attachments. Whereas young children are most strongly attached to their parents, the important attachments of adolescents move increasingly away from parents and increasingly toward peers (Harris, 1998). As a result, parents’ influence diminishes at this stage.

According to Erikson (Table 7.1, “Challenges of Development as Proposed by Erik Erikson”), the main social task of the adolescent is the search for a unique identity — the ability to answer the question “Who am I?” In the search for identity, the adolescent may experience role confusion in which he or she is balancing or choosing among identities, taking on negative or undesirable identities, or temporarily giving up looking for an identity altogether if things are not going well.

One approach to assessing identity development was proposed by James Marcia (1980). In his approach, adolescents are asked questions regarding their exploration of and commitment to issues related to occupation, politics, religion, and sexual behaviour. The responses to the questions allow the researchers to classify the adolescent into one of four identity categories (see Table 7.4, “James Marcia’s Stages of Identity Development”).

Table 7.4 James Marcia’s Stages of Identity Development. Adapted from Marcia (1980).</caption

[Skip Table]
Identity-diffusion status	The individual does not have firm commitments regarding the issues in question and is not making progress toward them.
Foreclosure status	The individual has not engaged in any identity experimentation and has established an identity based on the choices or values of others.
Moratorium status	The individual is exploring various choices but has not yet made a clear commitment to any of them.
Identity-achievement status	The individual has attained a coherent and committed identity based on personal decisions.

Studies assessing how teens pass through Marcia’s stages show that, although most teens eventually succeed in developing a stable identity, the path to it is not always easy and there are many routes that can be taken. Some teens may simply adopt the beliefs of their parents or the first role that is offered to them, perhaps at the expense of searching for other, more promising possibilities (foreclosure status). Other teens may spend years trying on different possible identities (moratorium status) before finally choosing one.

To help them work through the process of developing an identity, teenagers may well try out different identities in different social situations. They may maintain one identity at home and a different type of persona when they are with their peers. Eventually, most teenagers do integrate the different possibilities into a single self-concept and a comfortable sense of identity (identity-achievement status).

For teenagers, the peer group provides valuable information about the self-concept. For instance, in response to the question “What were you like as a teenager? (e.g., cool, nerdy, awkward?),” posed on the website Answerbag, one teenager replied in this way:

I’m still a teenager now, but from 8th-9th grade I didn’t really know what I wanted at all. I was smart, so I hung out with the nerdy kids. I still do; my friends mean the world to me. But in the middle of 8th I started hanging out with whom you may call the “cool” kids…and I also hung out with some stoners, just for variety. I pierced various parts of my body and kept my grades up. Now, I’m just trying to find who I am. I’m even doing my sophomore year in China so I can get a better view of what I want. (Answerbag, 2007)

Responses like this one demonstrate the extent to which adolescents are developing their self-concepts and self-identities and how they rely on peers to help them do that. The writer here is trying out several (perhaps conflicting) identities, and the identities any teen experiments with are defined by the group the person chooses to be a part of. The friendship groups (cliques, crowds, or gangs) that are such an important part of the adolescent experience allow the young adult to try out different identities, and these groups provide a sense of belonging and acceptance (Rubin, Bukowski, & Parker, 2006). A big part of what the adolescent is learning is social identity, the part of the self-concept that is derived from one’s group memberships. Adolescents define their social identities according to how they are similar to and differ from others, finding meaning in the sports, religious, school, gender, and ethnic categories they belong to.

Developing Moral Reasoning: Kohlberg’s Theory

The independence that comes with adolescence requires independent thinking as well as the development of morality — standards of behaviour that are generally agreed on within a culture to be right or proper. Just as Piaget believed that children’s cognitive development follows specific patterns, Lawrence Kohlberg (1984) argued that children learn their moral values through active thinking and reasoning, and that moral development follows a series of stages. To study moral development, Kohlberg posed moral dilemmas to children, teenagers, and adults, such as the following:

In Europe, a woman was near death from a special kind of cancer. There was one drug that the doctors thought might save her. It was a form of radium that a druggist in the same town had recently discovered. The drug was expensive to make, but the druggist was charging 10 times what the drug cost him to make. He paid $400 for the radium and charged $4,000 for a small dose of the drug. The sick woman’s husband, Heinz, went to everyone he knew to borrow the money and tried every legal means, but he could only get together about $2,000, which is half of what it cost. He told the druggist that his wife was dying and asked him to sell it cheaper or let him pay later. But the druggist said, “No, I discovered the drug and I’m going to make money from it.” So, having tried every legal means, Heinz gets desperate and considers breaking into the man’s store to steal the drug for his wife.

1. Should Heinz steal the drug? Why or why not?
2. Is it actually right or wrong for him to steal the drug? Why is it right or wrong?
3. Does Heinz have a duty or obligation to steal the drug? Why or why not? (Kohlberg, 1984)

Watch: People Being Interviewed About Kohlberg’s Stages [YouTube]: http://www.youtube.com/v/zY4etXWYS84

As you can see in Table 7.5, “Lawrence Kohlberg’s Stages of Moral Reasoning,” Kohlberg concluded, on the basis of their responses to the moral questions, that, as children develop intellectually, they pass through three stages of moral thinking: the preconventional level, the conventional level, and the postconventional level.

Table 7.5 Lawrence Kohlberg’s Stages of Moral Reasoning.

[Skip Table]
Age	Moral Stage	Description
Young children	Preconventional morality	Until about the age of nine, children focus on self-interest. At this stage, punishment is avoided and rewards are sought. A person at this level will argue, “The man shouldn’t steal the drug, as he may get caught and go to jail.”
Older children, adolescents, most adults	Conventional morality	By early adolescence, the child begins to care about how situational outcomes impact others and wants to please and be accepted. At this developmental phase, people are able to value the good that can be derived from holding to social norms in the form of laws or less formalized rules. For example, a person at this level may say, “He should not steal the drug, as everyone will see him as a thief, and his wife, who needs the drug, wouldn’t want to be cured because of thievery,” or, “No matter what, he should obey the law because stealing is a crime.”
Many adults	Postconventional morality	At this stage, individuals employ abstract reasoning to justify behaviours. Moral behaviour is based on self-chosen ethical principles that are generally comprehensive and universal, such as justice, dignity, and equality. Someone with self-chosen principles may say, “The man should steal the drug to cure his wife and then tell the authorities that he has done so. He may have to pay a penalty, but at least he has saved a human life.”

Although research has supported Kohlberg’s idea that moral reasoning changes from an early emphasis on punishment and social rules and regulations to an emphasis on more general ethical principles, as with Piaget’s approach, Kohlberg’s stage model is probably too simple. For one, children may use higher levels of reasoning for some types of problems, but revert to lower levels in situations where doing so is more consistent with their goals or beliefs (Rest, 1979). Second, it has been argued that the stage model is particularly appropriate for Western, rather than non-Western, samples in which allegiance to social norms (such as respect for authority) may be particularly important (Haidt, 2001). And there is frequently little correlation between how children score on the moral stages and how they behave in real life.

Perhaps the most important critique of Kohlberg’s theory is that it may describe the moral development of boys better than it describes that of girls. Carol Gilligan (1982) has argued that, because of differences in their socialization, males tend to value principles of justice and rights, whereas females value caring for and helping others. Although there is little evidence that boys and girls score differently on Kohlberg’s stages of moral development (Turiel, 1998), it is true that girls and women tend to focus more on issues of caring, helping, and connecting with others than do boys and men (Jaffee & Hyde, 2000). If you don’t believe this, ask yourself when you last got a thank-you note from a man.

References

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Baumeister, R. F., & Tice, D. M. (1986). How adolescence became the struggle for self: A historical transformation of psychological development. In J. Suls & A. G. Greenwald (Eds.), Psychological perspectives on the self (Vol. 3, pp. 183–201). Hillsdale, NJ: Lawrence Erlbaum Associates.

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Ge, X., Conger, R. D., & Elder, G. H., Jr. (1996). Coming of age too early: Pubertal influences on girls’ vulnerability to psychological distress. Child Development, 67(6), 3386–3400.

Gilligan, C. (1982). In a different voice: Psychological theory and women’s development. Cambridge, MA: Harvard University Press.

Goldberg, E. (2001). The executive brain: Frontal lobes and the civilized mind. New York, NY: Oxford University Press.

Goossens, L., Beyers, W., Emmen, M., & van Aken, M. (2002). The imaginary audience and personal fable: Factor analyses and concurrent validity of the “new look” measures. Journal of Research on Adolescence, 12(2), 193–215.

Haidt, J. (2001). The emotional dog and its rational tail: A social intuitionist approach to moral judgment. Psychological Review, 108(4), 814–834.

Harris, J. (1998). The nurture assumption — Why children turn out the way they do. New York, NY: Free Press.

Jaffee, S., & Hyde, J. S. (2000). Gender differences in moral orientation: A meta-analysis. Psychological Bulletin, 126(5), 703–726.

Kohlberg, L. (1984). The psychology of moral development: Essays on moral development (Vol. 2, p. 200). San Francisco, CA: Harper & Row.

Lynne, S. D., Graber, J. A., Nichols, T. R., Brooks-Gunn, J., & Botvin, G. J. (2007). Links between pubertal timing, peer influences, and externalizing behaviors among urban students followed through middle school. Journal of Adolescent Health, 40, 181.e7–181.e13 (p. 198).

Marcia, J. (1980). Identity in adolescence. Handbook of Adolescent Psychology, 5, 145–160.

Marshall, W. A., & Tanner, J. M. (1986). Puberty. In F. Falkner & J. M. Tanner (Eds.), Human growth: A comprehensive treatise (2nd ed., pp. 171–209). New York, NY: Plenum Press.

Mendle, J., Turkheimer, E., & Emery, R. E. (2007). Detrimental psychological outcomes associated with early pubertal timing in adolescent girls. Developmental Review, 27, 151–171.

Pescovitz, O. H., & Walvoord, E. C. (2007). When puberty is precocious: Scientific and clinical aspects. Totowa, NJ: Humana Press.

Rapoport, J. L., Giedd, J. N., Blumenthal, J., Hamburger, S., Jeffries, N., Fernandez, T.,…Evans, A. (1999). Progressive cortical change during adolescence in childhood-onset schizophrenia: A longitudinal magnetic resonance imaging study. Archives of General Psychiatry, 56(7), 649–654.

Rest, J. (1979). Development in judging moral issues. Minneapolis: University of Minnesota Press.

Rubin, K. H., Bukowski, W. M., & Parker, J. G. (2006). Peer interactions, relationships, and groups. In N. Eisenberg, W. Damon, & R. M. Lerner (Eds.), Handbook of child psychology: Social, emotional, and personality development (6th ed., Vol. 3, pp. 571–645). Hoboken, NJ: John Wiley & Sons.

Rycek, R. F., Stuhr, S. L., McDermott, J., Benker, J., & Swartz, M. D. (1998). Adolescent egocentrism and cognitive functioning during late adolescence. Adolescence, 33, 746–750.

Steinberg, L. (2007). Risk taking in adolescence: New perspectives from brain and behavioral science. Current Directions in Psychological Science, 16, 55–59.

Turiel, E. (1998). The development of morality. In W. Damon (Ed.), Handbook of child psychology: Socialization (5th ed., Vol. 3, pp. 863–932). New York, NY: John Wiley & Sons.

Twenge, J. M. (2006). Generation me: Why today’s young Americans are more confident, assertive, entitled — and more miserable than ever before. New York, NY: Free Press.

Weinberger, D. R., Elvevåg, B., & Giedd, J. N. (2005). The adolescent brain: A work in progress [PDF] National Campaign to Prevent Teen Pregnancy. Retrieved from http://www.thenationalcampaign.org/resources/pdf/BRAIN.pdf

Until the 1970s, psychologists tended to treat adulthood as a single developmental stage, with few or no distinctions made between the various periods that we pass through between adolescence and death. Present-day psychologists realize, however, that physical, cognitive, and emotional responses continue to develop throughout life, with corresponding changes in our social needs and desires. Thus the three stages of early adulthood, middle adulthood, and late adulthood each have their own physical, cognitive, and social challenges.

In this section, we will consider the development of our cognitive and physical aspects that occur during early adulthood and middle adulthood — roughly the ages between 25 and 45 and between 45 and 65, respectively. These stages represent a long period of time — longer, in fact, than any of the other developmental stages — and the bulk of our lives is spent in them. These are also the periods in which most of us make our most substantial contributions to society, by meeting two of Erik Erikson’s life challenges: we learn to give and receive love in a close, long-term relationship, and we develop an interest in guiding the development of the next generation, often by becoming parents.

Physical and Cognitive Changes in Early and Middle Adulthood

Compared with the other stages, the physical and cognitive changes that occur in the stages of early and middle adulthood are less dramatic. As individuals pass into their 30s and 40s, their recovery from muscular strain becomes more prolonged, and their sensory abilities may become somewhat diminished, at least when compared with their prime years, during the teens and early 20s (Panno, 2004). Visual acuity diminishes somewhat, and many people in their late 30s and early 40s begin to notice that their eyes are changing and they need eyeglasses. Adults in their 30s and 40s may also begin to suffer some hearing loss because of damage to the hair cells (cilia) in the inner ear (Lacher-Fougëre & Demany, 2005). And it is during middle adulthood that many people first begin to suffer from ailments such as high cholesterol and high blood pressure as well as low bone density (Shelton, 2006). Corresponding to changes in our physical abilities, our cognitive and sensory abilities also seem to show some, but not dramatic, decline during this stage.

Menopause

The stages of both early and middle adulthood bring about a gradual decline in fertility, particularly for women. Eventually, women experience menopause, the cessation of the menstrual cycle, which usually occurs at around age 50. Menopause occurs because of the gradual decrease in the production of the female sex hormones estrogen and progesterone, which slows the production and release of eggs into the uterus. Women whose menstrual cycles have stopped for 12 consecutive months are considered to have entered menopause (Minkin & Wright, 2004).

Researchers have found that women’s responses to menopause are social as well as physical, and that they vary substantially between both individuals and cultures. Within individuals, some women may react more negatively to menopause, worrying that they have lost their femininity and that their final chance to bear children is over, whereas other women may regard menopause more positively, focusing on the new freedom from menstrual discomfort and unwanted pregnancy. In Western cultures such as in Canada, women are likely to see menopause as a challenging and potentially negative event, whereas in India, where older women enjoy more social privileges than do younger ones, menopause is more positively regarded (Avis & Crawford, 2008).

Menopause may have evolutionary benefits. Infants have better chances of survival when their mothers are younger and have more energy to care for them, and the presence of older women who do not have children of their own to care for (but who can help out with raising grandchildren) can be beneficial to the family group. Also consistent with the idea of an evolutionary benefit of menopause is that the decline in fertility occurs primarily for women, who do most of the child care and who need the energy of youth to accomplish it. If older women were able to have children, they might not be as able to effectively care for them. Most men never completely lose their fertility, but they do experience a gradual decrease in testosterone levels, sperm count, and speed of erection and ejaculation.

Social Changes in Early and Middle Adulthood

Perhaps the major marker of adulthood is the ability to create an effective and independent life. Whereas children and adolescents are generally supported by parents, adults must make their own living and must start their own families. Furthermore, the needs of adults are different from those of younger persons.

Even though the timing of the major life events that occur in early and middle adulthood varies substantially among individuals, the events nevertheless tend to follow a general sequence, known as a social clock. The social clock refers to the culturally preferred “right time” for major life events, such as moving out of the childhood house, getting married, and having children. People who do not appear to be following the social clock (e.g., young adults who still live with their parents, individuals who never marry, and couples who choose not to have children) may be seen as unusual or deviant, and they may be stigmatized by others (DePaulo, 2006; Rook, Catalano, & Dooley, 1989).

Although they are doing it later, on average, than they did even 20 or 30 years ago, most people do eventually marry. Marriage is beneficial to the partners, both in terms of mental health and physical health. People who are married report greater life satisfaction than those who are not married and also suffer fewer health problems (Gallagher & Waite, 2001; Liu & Umberson, 2008).

Divorce is more common now than it was 50 years ago. Fluctuating between 35% and 42%, the proportion of marriages projected to end in divorce has remained relatively stable during the last 20 years in Canada. In 2008, 40.7% of marriages were projected to end in divorce before the 30th wedding anniversary (Statistics Canada, 2011), although about three-quarters of people who divorce will remarry. Most divorces occur for couples in their 20s, because younger people are frequently not mature enough to make good marriage choices or to make marriages last. Marriages are more successful for older adults and for those with more education (Goodwin, Mosher, & Chandra, 2010).

Parenthood also involves a major and long-lasting commitment, and one that can cause substantial stress on the parents. The time and finances invested in children create stress, which frequently results in decreased marital satisfaction (Twenge, Campbell, & Foster, 2003). This decline is especially true for women, who bear the larger part of the burden of raising the children and taking care of the house, despite the fact they increasingly also work and have careers.

Despite the challenges of early and middle adulthood, the majority of middle-aged adults are not unhappy. These years are often very satisfying, as families have been established, careers have been entered into, and some percentage of life goals has been realized (Eid & Larsen, 2008).

References

Amato, P. R. (1994). Father-child relations, mother-child relations, and offspring psychological well-being in adulthood. Journal of Marriage and the Family, 56, 1031–1042.

Avis, N. E., & Crawford, S. (2008). Cultural differences in symptoms and attitudes toward menopause. Menopause Management, 17(3), 8–13.

Baumrind, D. (1996). The discipline controversy revisited. Family Relations, 45(4), 405–414.

Burt, S. A., Barnes, A. R., McGue, M., & Iacono, W. G. (2008). Parental divorce and adolescent delinquency: Ruling out the impact of common genes. Developmental Psychology, 44(6), 1668–1677.

Claes, M., Perchecb, C., Mirandac, D., Benoita, A., Bariaudb, F., Lanzd, M., Martad, E., & Lacoursea, É. (2011). Adolescents’ perceptions of parental practices: A cross-national comparison of Canada, France, and Italy. Journal of Adolescence, 34 (2), 225–238.

DePaulo, B. M. (2006). Singled out: How singles are stereotyped, stigmatized and ignored, and still live happily ever after. New York, NY: St. Martin’s Press.

Eid, M., & Larsen, R. J. (Eds.). (2008). The science of subjective well-being. New York, NY: Guilford Press.

Ekéus, C., Christensson, K., & Hjern, A. (2004). Unintentional and violent injuries among pre-school children of teenage mothers in Sweden: A national cohort study. Journal of Epidemiology and Community Health, 58(8), 680–685.

Gallagher, M., & Waite, L. J. (2001). The case for marriage: Why married people are happier, healthier, and better off financially. New York, NY: Random House.

Ge, X., Natsuaki, M. N., & Conger, R. D. (2006). Trajectories of depressive symptoms and stressful life events among male and female adolescents in divorced and nondivorced families. Development and Psychopathology, 18(1), 253–273.

Goodwin, P. Y., Mosher, W. D., Chandra A. (2010, February). Marriage and cohabitation in the United States: A statistical portrait based on Cycle 6 (2002) of the National Survey of Family Growth. [PDF] Vital Health Statistics 23(28), 1–45. Retrieved from National Center for Health Statistics, Centers for Disease Control and Prevention, website: http://www.cdc.gov/nchs/data/series/sr_23/sr23_028.pdf

Grolnick, W. S., & Ryan, R. M. (1989). Parent styles associated with children’s self-regulation and competence in school. Journal of Educational Psychology, 81(2), 143–154.

Lacher-Fougëre, S., & Demany, L. (2005). Consequences of cochlear damage for the detection of inter-aural phase differences. Journal of the Acoustical Society of America, 118, 2519–2526.

Liu, H., & Umberson, D. (2008). The times they are a changin’: Marital status and health differentials from 1972 to 2003. Journal of Health and Social Behavior, 49, 239–253.

Minkin, M. J., & Wright, C. V. (2004). A woman’s guide to menopause and perimenopause. New Haven, CT: Yale University Press.

Moore, M. R., & Brooks-Gunn, J. (2002). Adolescent parenthood. In M. H. Bornstein (Ed.), Handbook of parenting: Being and becoming a parent (2nd ed., Vol. 3, pp. 173–214). Mahwah, NJ: Lawrence Erlbaum Associates.

Panno, J. (2004). Aging: Theories and potential therapies. New York, NY: Facts on File Publishers.

Pluess, M., & Belsky, J. (2010). Differential susceptibility to parenting and quality child care. Developmental Psychology, 46(2), 379–390.

Rohner, R. P., & Veneziano, R. A. (2001). The importance of father love: History and contemporary evidence. Review of General Psychology, 5(4), 382–405.

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Long Descriptions

Figure 7.9 long description: Parenting Styles

	High Demands	Low Demands
High Responsiveness	Authoritative parenting	Permissive parenting
Low Responsiveness	Authoritarian parenting	Rejecting-neglecting parenting

[Return to Figure 7.9]

We have seen that, over the course of their lives, most individuals are able to develop secure attachments; reason cognitively, socially, and morally; and create families and find appropriate careers. Eventually, however, as people enter into their 60s and beyond, the aging process leads to faster changes in our physical, cognitive, and social capabilities and needs, and life begins to come to its natural conclusion, resulting in the final life stage, beginning in the 60s, known as late adulthood.

Despite the fact that the body and mind are slowing, most older adults nevertheless maintain an active lifestyle, remain as happy as they were when younger — or are happier — and increasingly value their social connections with family and friends (Angner, Ray, Saag, & Allison, 2009). Kennedy, Mather, and Carstensen (2004) found that people’s memories of their lives became more positive with age, and Myers and Diener (1996) found that older adults tended to speak more positively about events in their lives, particularly their relationships with friends and family, than did younger adults.

Cognitive Changes During Aging

The changes associated with aging do not affect everyone in the same way, and they do not necessarily interfere with a healthy life. Former Beatles drummer Ringo Starr celebrated his 70th birthday in 2010 by playing at Radio City Music Hall, and Rolling Stones singer Mick Jagger (who once supposedly said, “I’d rather be dead than singing ‘Satisfaction’ at 45”) continues to perform even as he turned 70 in 2013. The golfer Tom Watson almost won the 2010 British Open golf tournament at the age of 59, playing against competitors in their 20s and 30s. And people such as the financier Warren Buffett; Jim Pattison, a prominent Vancouver philanthropist; Hazel McCallion, mayor of Mississauga in Ontario for over 35 years; and actress Betty White, all in their 80s or 90s, all enjoy highly productive and energetic lives.

Researchers are beginning to better understand the factors that allow some people to age better than others. For one, research has found that the people who are best able to adjust well to changing situations early in life are also able to better adjust later in life (Rubin, 2007; Sroufe, Collins, Egeland, & Carlson, 2009). Perceptions also matter. People who believe that the elderly are sick, vulnerable, and grumpy often act according to such beliefs (Nemmers, 2005), and Levy, Slade, Kunkel, and Kasl (2002) found that the elderly who had more positive perceptions about aging also lived longer.

Research on the influence of cultural values and beliefs on aging attitudes has been dominated by comparisons between Eastern/Asian versus Western cultures. This belief is inspired by the idea that Asian societies are influenced by Confucian values of filial piety and the practice of ancestor worship, which are thought to promote positive views of aging and high esteem for older adults (Davis, 1983; Ho, 1994; Sher, 1984). Western societies, in contrast, were thought to be youth-oriented and to hold more negative views about the aging process and the elderly (Palmore, 1975). Empirical evidence for the proposed East-West differences is scarce. Although some studies have found support for the notion that aging attitudes are more positive in Asian as compared to Western cultures (Levy & Langer, 1994; Tan, Zhang, & Fan, 2004), others report effects in the opposite direction (Giles et al., 2000; Harwood et al., 2001; Sharps, Price-Sharps, & Hanson, 1998; Zhou, 2007), or fail to find any marked cultural differences (Boduroglu, Yoon, Luo, & Park, 2006; Ryan, Jin, Anas, & Luh, 2004).

Whereas it was once believed that almost all older adults suffered from a generalized memory loss, research now indicates that healthy older adults actually experience only some particular types of memory deficits, while other types of memory remain relatively intact or may even improve with age. Older adults do seem to process information more slowly — it may take them longer to evaluate information and to understand language, and it takes them longer, on average, than it does younger people, to recall a word that they know, even though they are perfectly able to recognize the word once they see it (Burke, Shafto, Craik, & Salthouse, 2008). Older adults also have more difficulty inhibiting and controlling their attention (Persad, Abeles, Zacks, & Denburg, 2002), making them, for example, more likely to talk about topics that are not relevant to the topic at hand when conversing (Pushkar et al., 2000).

But slower processing and less accurate executive control do not always mean worse memory, or even worse intelligence. Perhaps the elderly are slower in part because they simply have more knowledge. Indeed, older adults have more crystallized intelligence — that is, general knowledge about the world, as reflected in semantic knowledge, vocabulary, and language. As a result, adults generally outperform younger people on measures of history, geography, and even on crossword puzzles, where this information is useful (Salthouse, 2004). It is this superior knowledge combined with a slower and more complete processing style, along with a more sophisticated understanding of the workings of the world around them, that gives the elderly the advantage of wisdom over the advantages of fluid intelligence — the ability to think and acquire information quickly and abstractly — which favour the young (Baltes, Staudinger, & Lindenberger, 1999; Scheibe, Kunzmann, & Baltes, 2009).

The differential changes in crystallized versus fluid intelligence help explain why the elderly do not necessarily show poorer performance on tasks that also require experience (i.e., crystallized intelligence), although they show poorer memory overall. A young chess player may think more quickly, for instance, but a more experienced chess player has more knowledge to draw on. Older adults are also more effective at understanding the nuances of social interactions than younger adults are, in part because they have more experience in relationships (Blanchard-Fields, Mienaltowski, & Seay, 2007).

Dementia and Alzheimer’s Disease

Some older adults suffer from biologically based cognitive impairments in which the brain is so adversely affected by aging that it becomes very difficult for the person to continue to function effectively. Dementia is defined as a progressive neurological disease that includes loss of cognitive abilities significant enough to interfere with everyday behaviours, and Alzheimer’s disease is a form of dementia that, over a period of years, leads to a loss of emotions, cognitions, and physical functioning, and that is ultimately fatal. Dementia and Alzheimer’s disease are most likely to be observed in individuals who are 65 and older, and the likelihood of developing Alzheimer’s doubles about every five years after age 65. After age 85, the risk reaches nearly 8% per year (Hebert et al., 1995). Dementia and Alzheimer’s disease both produce a gradual decline in functioning of the brain cells that produce the neurotransmitter acetylcholine. Without this neurotransmitter, the neurons are unable to communicate, leaving the brain less and less functional, as shown in Figure 7.10.

Dementia and Alzheimer’s are in part heritable, but there is increasing evidence that the environment also plays a role. And current research is helping us understand the things that older adults can do to help them slow down or prevent the negative cognitive outcomes of aging, including dementia and Alzheimer’s (Pushkar, Bukowski, Schwartzman, Stack, & White, 2007). Older adults who continue to keep their minds active by engaging in cognitive activities, such as reading, playing musical instruments, attending lectures, or doing crossword puzzles, who maintain social interactions with others, and who keep themselves physically fit have a greater chance of maintaining their mental acuity than those who do not (Cherkas et al., 2008; Verghese et al., 2003). In short, although physical illnesses may occur to anyone, the more people keep their brains active and the more they maintain a healthy and active lifestyle, the more healthy their brains will remain (Ertel, Glymour, & Berkman, 2008).

Social Changes During Aging: Retiring Effectively

Because of increased life expectancy in the 21st century, elderly people can expect to spend approximately a quarter of their lives in retirement. Leaving one’s career is a major life change and can be a time when people experience anxiety, depression, and other negative changes in the self-concept and in self-identity. On the other hand, retirement may also serve as an opportunity for a positive transition from work and career roles to stronger family and community member roles, and the latter may have a variety of positive outcomes for the individual. Retirement may be a relief for people who have worked in boring or physically demanding jobs, particularly if they have other outlets for stimulation and expressing self-identity.

Psychologist Mo Wang (2007) observed the well-being of 2,060 people between the ages of 51 and 61 over an eight-year period and made the following recommendations to make the retirement phase a positive one:

1. Continue to work part-time past retirement in order to ease into retirement status slowly.
2. Plan for retirement — this is a good idea financially, but also making plans to incorporate other kinds of work or hobbies into post-employment life makes sense.
3. Retire with someone — if the retiree is still married, it is a good idea to retire at the same time as a spouse, so that people can continue to work part-time and follow a retirement plan together.
4. Have a happy marriage — people with marital problems tend to find retirement more stressful because they do not have a positive home life to return to and can no longer seek refuge in long working hours. Couples that work on their marriages can make their retirements a lot easier.
5. Take care of physical and financial health — a sound financial plan and good physical health can ensure a healthy, peaceful retirement.
6. Retire early from a stressful job — people who stay in stressful jobs for fear that they will lose their pensions or won’t be able to find work somewhere else feel trapped. Toxic environments can take a severe emotional toll on an employee. Leaving an unsatisfying job early may make retirement a relief.
7. Retire “on time” — retiring too early or too late can cause people to feel “out of sync” or to feel they have not achieved their goals.

Whereas these seven tips are helpful for a smooth transition to retirement, Wang also notes that people tend to be adaptable, and that no matter how they do it, retirees will eventually adjust to their new lifestyles.

Death, Dying, and Bereavement

Living includes dealing with our own and our loved ones’ mortality. In her book On Death and Dying (1997), Elisabeth Kübler-Ross describes five phases of grief through which people pass in grappling with the knowledge that they or someone close to them is dying:

1. Denial: “I feel fine.” “This can’t be happening; not to me.”
2. Anger: “Why me? It’s not fair!” “How can this happen to me?” “Who is to blame?”
3. Bargaining: “Just let me live to see my children graduate.” “I’d do anything for a few more years.” “I’d give my life savings if…”
4. Depression: “I’m so sad, why bother with anything?” “I’m going to die. What’s the point?” “I miss my loved ones — why go on?”
5. Acceptance: “I know my time has come; it’s almost my time.”

Despite Kübler-Ross’s popularity, there are a growing number of critics of her theory who argue that her five-stage sequence is too constraining because attitudes toward death and dying have been found to vary greatly across cultures and religions, and these variations make the process of dying different according to culture (Bonanno, 2009). As an example, Japanese Americans restrain their grief (Corr, Nabe, & Corr, 2009) so as not to burden other people with their pain. By contrast, Jews observe a seven-day, publicly announced mourning period. In some cultures the elderly are more likely to be living and coping alone, or perhaps only with their spouse, whereas in other cultures, such as the Hispanic culture, the elderly are more likely to be living with their sons and daughters and other relatives, and this social support may create a better quality of life for them (Diaz-Cabello, 2004).

Margaret Stroebe and her colleagues (2008) found that although most people adjusted to the loss of a loved one without seeking professional treatment, many had an increased risk of mortality, particularly within the early weeks and months after the loss. These researchers also found that people going through the grieving process suffered more physical and psychological symptoms and illnesses and used more medical services.

The health of survivors during the end of life is influenced by factors such as circumstances surrounding the loved one’s death, individual personalities, and ways of coping. People serving as caretakers to partners or other family members who are ill frequently experience a great deal of stress themselves, making the dying process even more stressful. Despite the trauma of the loss of a loved one, people do recover and are able to continue with effective lives. Grief intervention programs can go a long way in helping people cope during the bereavement period (Neimeyer, Holland, Currier, & Mehta, 2008).

References

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Baltes, P. B., Staudinger, U. M., & Lindenberger, U. (1999). Life-span psychology: Theory and application to intellectual functioning. Annual Review of Psychology, 50, 471–506.

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Boduroglu, A., Yoon, C., Luo, T., & Park, C.D. (2006). Stereotypes about young and old adults: A comparison of Chinese and American Cultures. Gerontology, 52, 324–333.

Bonanno, G. (2009). The other side of sadness: What the new science of bereavement tells us about life after a loss. New York, NY: Basic Books.

Burke, D. M., Shafto, M. A., Craik, F. I. M., & Salthouse, T. A. (2008). Language and aging. In The handbook of aging and cognition (3rd ed., pp. 373–443). New York, NY: Psychology Press.

Cherkas, L. F., Hunkin, J. L., Kato, B. S., Richards, J. B., Gardner, J. P., Surdulescu, G. L.,…Aviv, A. (2008). The association between physical activity in leisure time and leukocyte telomere length. Archives of Internal Medicine, 168, 154–158.

Corr, C. A., Nabe, C. M., & Corr, D. M. (2009). Death and dying: Life and living (6th ed.). Belmont, CA: Wadsworth.

Davis D. (1983). Long lives: Chinese elderly and the Communist revolution. Cambridge, MA: Harvard University Press.

Diaz-Cabello, N. (2004). The Hispanic way of dying: Three families, three perspectives, three cultures. Illness, Crisis, & Loss, 12(3), 239–255.

Ertel, K. A., Glymour, M. M., & Berkman, L. F. (2008). Effects of social integration on preserving memory function in a nationally representative U.S. elderly population. American Journal of Public Health, 98, 1215–1220.

Giles, H., Noels, K., Ota, H., Ng, S.H., Gallois, C., Ryan, E.B., et al. (2000). Age vitality across eleven nations. Journal of Multilingual and Multicultural Development, 21, 308–323.

Harwood, J., Giles, H., McCann, R.M., Cai, D., Somera, L.P., Ng, S.H., et al. (2001). Older adults’ trait ratings of three age-groups around the Pacific rim. Journal of Cross-Cultural Gerontology,16, 157–171.

Hebert, L. E., Scherr, P. A., Beckett, L. A., Albert, M. S., Pilgrim, D. M., Chown, M. J.,…Evans, D. A. (1995). Age-specific incidence of Alzheimer’s disease in a community population. Journal of the American Medical Association, 273(17), 1354–1359.

Ho, D.Y. (1994). Filial Piety, authoritarian moralism, and cognitive conservatism in Chinese societies. Genetic, Social, and General Psychology Monographs, 120, 347–365.

Kennedy, Q., Mather, M., & Carstensen, L. L. (2004). The role of motivation in the age-related positivity effect in autobiographical memory. Psychological Science, 15, 208–214.

Kübler-Ross, E. (1997). On death and dying. New York, NY: Scribner.

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Development begins at conception when a sperm from the father fertilizes an egg from the mother, creating a new life. The resulting zygote grows into an embryo and then a fetus.

Babies are born prepared with reflexes and cognitive skills that contribute to their survival and growth.

Piaget’s stage model of cognitive development proposes that children learn through assimilation and accommodation and that cognitive development follows specific sequential stages: sensorimotor, preoperational, concrete operational, and formal operational.

An important part of development is the attainment of social skills, including the formation of the self-concept and attachment.

Adolescence involves rapid physical changes, including puberty, as well as continued cognitive changes. Moral development continues in adolescence. In Western cultures, adolescence blends into emerging adulthood, the period from age 18 until the mid-20s.

Muscle strength, reaction time, cardiac output, and sensory abilities begin to slowly decline in early and middle adulthood. Fertility, particularly for women, also decreases, and women eventually experience menopause.

Most older adults maintain an active lifestyle — remaining as happy as they were when they were younger, or happier — and increasingly value their social connections with family and friends.

Although older adults have slower cognitive processing overall (fluid intelligence), their experience in the form of crystallized intelligence, or existing knowledge about the world and the ability to use it, is maintained and even strengthened during aging. A portion of the elderly suffer from age-related brain diseases, such as dementia and Alzheimer’s disease.

The topic of this chapter is learning — the relatively permanent change in knowledge or behaviour that is the result of experience. Although you might think of learning in terms of what you need to do before an upcoming exam, the knowledge that you take away from your classes, or new skills that you acquire through practice, these changes represent only one component of learning. In fact, learning is a broad topic that is used to explain not only how we acquire new knowledge and behaviour but also how we acquire a wide variety of other psychological processes, including the development of both appropriate and inappropriate social behaviours, and even how a person may acquire a debilitating psychological disorder such as PTSD.

Learning is perhaps the most important human capacity. Learning allows us to create effective lives by being able to respond to changes. We learn to avoid touching hot stoves, to find our way home from school, and to remember which people have helped us in the past and which people have been unkind. Without the ability to learn from our experiences, our lives would be remarkably dangerous and inefficient. The principles of learning can also be used to explain a wide variety of social interactions, including social dilemmas in which people make important, and often selfish, decisions about how to behave by calculating the costs and benefits of different outcomes.

The study of learning is closely associated with the behaviourist school of psychology, in which it was seen as an alternative scientific perspective to the failure of introspection. The behaviourists, including John B. Watson and B. F. Skinner (Figure 8.1), focused their research entirely on behaviour, to the exclusion of any kinds of mental processes. For behaviourists, the fundamental aspect of learning is the process of conditioning — the ability to connect stimuli (the changes that occur in the environment) with responses (behaviours or other actions).

But conditioning is just one type of learning. We will also consider other types, including learning through insight, as well as observational learning (also known as modelling). In each case we will see not only what psychologists have learned about the topics but also the important influence that learning has on many aspects of our everyday lives. And we will see that in some cases learning can be maladaptive — for instance, when a person like P. K. Philips continually experiences disruptive memories and emotional responses to a negative event.

References

Philips, P. K. (2010). My story of survival: Battling PTSD. Anxiety Disorders Association of America. Retrieved from http://www.adaa.org/living-with-anxiety/personal-stories/my-story-survival-battling-ptsd

Image Attributions

Figure 8.1: “B.F. Skinner” (http://commons.wikimedia.org/wiki/File:B.F._Skinner_at_Harvard_circa_1950.jpg) is licensed under the CC BY 3.0 license (http://creativecommons.org/licenses/by/3.0/deed.en). “John Broadus Watson” (http://en.wikipedia.org/wiki/File:John_Broadus_Watson.JPG) is in the public domain.

Pavlov Demonstrates Conditioning in Dogs

In the early part of the 20th century, Russian physiologist Ivan Pavlov (1849-1936), shown in Figure 8.2, was studying the digestive system of dogs when he noticed an interesting behavioural phenomenon: the dogs began to salivate when the lab technicians who normally fed them entered the room, even though the dogs had not yet received any food. Pavlov realized that the dogs were salivating because they knew that they were about to be fed; the dogs had begun to associate the arrival of the technicians with the food that soon followed their appearance in the room.

With his team of researchers, Pavlov began studying this process in more detail. He conducted a series of experiments in which, over a number of trials, dogs were exposed to a sound immediately before receiving food. He systematically controlled the onset of the sound and the timing of the delivery of the food, and recorded the amount of the dogs’ salivation. Initially the dogs salivated only when they saw or smelled the food, but after several pairings of the sound and the food, the dogs began to salivate as soon as they heard the sound. The animals had learned to associate the sound with the food that followed.

Pavlov had identified a fundamental associative learning process called classical conditioning. Classical conditioning refers to learning that occurs when a neutral stimulus (e.g., a tone) becomes associated with a stimulus (e.g., food) that naturally produces a behaviour. After the association is learned, the previously neutral stimulus is sufficient to produce the behaviour.

As you can see in Figure 8.3, “4-Panel Image of Whistle and Dog,” psychologists use specific terms to identify the stimuli and the responses in classical conditioning. The unconditioned stimulus (US) is something (such as food) that triggers a naturally occurring response, and the unconditioned response (UR) is the naturally occurring response (such as salivation) that follows the unconditioned stimulus. The conditioned stimulus (CS) is a neutral stimulus that, after being repeatedly presented prior to the unconditioned stimulus, evokes a similar response as the unconditioned stimulus. In Pavlov’s experiment, the sound of the tone served as the conditioned stimulus that, after learning, produced the conditioned response (CR), which is the acquired response to the formerly neutral stimulus. Note that the UR and the CR are the same behaviour — in this case salivation — but they are given different names because they are produced by different stimuli (the US and the CS, respectively).

Conditioning is evolutionarily beneficial because it allows organisms to develop expectations that help them prepare for both good and bad events. Imagine, for instance, that an animal first smells a new food, eats it, and then gets sick. If the animal can learn to associate the smell (CS) with the food (US), it will quickly learn that the food creates the negative outcome and will not eat it the next time.

The Persistence and Extinction of Conditioning

After he had demonstrated that learning could occur through association, Pavlov moved on to study the variables that influenced the strength and the persistence of conditioning. In some studies, after the conditioning had taken place, Pavlov presented the sound repeatedly but without presenting the food afterward. Figure 8.4, “Acquisition, Extinction, and Spontaneous Recovery,” shows what happened. As you can see, after the initial acquisition (learning) phase in which the conditioning occurred, when the CS was then presented alone, the behaviour rapidly decreased — the dogs salivated less and less to the sound, and eventually the sound did not elicit salivation at all. Extinction refers to the reduction in responding that occurs when the conditioned stimulus is presented repeatedly without the unconditioned stimulus.

Although at the end of the first extinction period the CS was no longer producing salivation, the effects of conditioning had not entirely disappeared. Pavlov found that, after a pause, sounding the tone again elicited salivation, although to a lesser extent than before extinction took place. The increase in responding to the CS following a pause after extinction is known as spontaneous recovery. When Pavlov again presented the CS alone, the behaviour again showed extinction until it disappeared again.

Although the behaviour has disappeared, extinction is never complete. If conditioning is again attempted, the animal will learn the new associations much faster than it did the first time.

Pavlov also experimented with presenting new stimuli that were similar, but not identical, to the original conditioned stimulus. For instance, if the dog had been conditioned to being scratched before the food arrived, the stimulus would be changed to being rubbed rather than scratched. He found that the dogs also salivated upon experiencing the similar stimulus, a process known as generalization. Generalization refers to the tendency to respond to stimuli that resemble the original conditioned stimulus. The ability to generalize has important evolutionary significance. If we eat some red berries and they make us sick, it would be a good idea to think twice before we eat some purple berries. Although the berries are not exactly the same, they nevertheless are similar and may have the same negative properties.

Lewicki (1985) conducted research that demonstrated the influence of stimulus generalization and how quickly and easily it can happen. In his experiment, high school students first had a brief interaction with a female experimenter who had short hair and glasses. The study was set up so that the students had to ask the experimenter a question, and (according to random assignment) the experimenter responded either in a negative way or a neutral way toward the students. Then the students were told to go into a second room in which two experimenters were present and to approach either one of them. However, the researchers arranged it so that one of the two experimenters looked a lot like the original experimenter, while the other one did not (she had longer hair and no glasses). The students were significantly more likely to avoid the experimenter who looked like the earlier experimenter when that experimenter had been negative to them than when she had treated them more neutrally. The participants showed stimulus generalization such that the new, similar-looking experimenter created the same negative response in the participants as had the experimenter in the prior session.

The flip side of generalization is discrimination — the tendency to respond differently to stimuli that are similar but not identical. Pavlov’s dogs quickly learned, for example, to salivate when they heard the specific tone that had preceded food, but not upon hearing similar tones that had never been associated with food. Discrimination is also useful — if we do try the purple berries, and if they do not make us sick, we will be able to make the distinction in the future. And we can learn that although two people in our class, Courtney and Sarah, may look a lot alike, they are nevertheless different people with different personalities.

In some cases, an existing conditioned stimulus can serve as an unconditioned stimulus for a pairing with a new conditioned stimulus — a process known as second-order conditioning. In one of Pavlov’s studies, for instance, he first conditioned the dogs to salivate to a sound and then repeatedly paired a new CS, a black square, with the sound. Eventually he found that the dogs would salivate at the sight of the black square alone, even though it had never been directly associated with the food. Secondary conditioners in everyday life include our attractions to things that stand for or remind us of something else, such as when we feel good on a Friday because it has become associated with the paycheque that we receive on that day, which itself is a conditioned stimulus for the pleasures that the paycheque buys us.

The Role of Nature in Classical Conditioning

As we have seen in Chapter 1, “Introducing Psychology,” scientists associated with the behaviourist school argued that all learning is driven by experience, and that nature plays no role. Classical conditioning, which is based on learning through experience, represents an example of the importance of the environment. But classical conditioning cannot be understood entirely in terms of experience. Nature also plays a part, as our evolutionary history has made us better able to learn some associations than others.

Clinical psychologists make use of classical conditioning to explain the learning of a phobia — a strong and irrational fear of a specific object, activity, or situation. For example, driving a car is a neutral event that would not normally elicit a fear response in most people. But if a person were to experience a panic attack in which he or she suddenly experienced strong negative emotions while driving, that person may learn to associate driving with the panic response. The driving has become the CS that now creates the fear response.

Psychologists have also discovered that people do not develop phobias to just anything. Although people may in some cases develop a driving phobia, they are more likely to develop phobias toward objects (such as snakes and spiders) or places (such as high locations and open spaces) that have been dangerous to people in the past. In modern life, it is rare for humans to be bitten by spiders or snakes, to fall from trees or buildings, or to be attacked by a predator in an open area. Being injured while riding in a car or being cut by a knife are much more likely. But in our evolutionary past, the potential for being bitten by snakes or spiders, falling out of a tree, or being trapped in an open space were important evolutionary concerns, and therefore humans are still evolutionarily prepared to learn these associations over others (Öhman & Mineka, 2001; LoBue & DeLoache, 2010).

Another evolutionarily important type of conditioning is conditioning related to food. In his important research on food conditioning, John Garcia and his colleagues (Garcia, Kimeldorf, & Koelling, 1955; Garcia, Ervin, & Koelling, 1966) attempted to condition rats by presenting either a taste, a sight, or a sound as a neutral stimulus before the rats were given drugs (the US) that made them nauseous. Garcia discovered that taste conditioning was extremely powerful — the rat learned to avoid the taste associated with illness, even if the illness occurred several hours later. But conditioning the behavioural response of nausea to a sight or a sound was much more difficult. These results contradicted the idea that conditioning occurs entirely as a result of environmental events, such that it would occur equally for any kind of unconditioned stimulus that followed any kind of conditioned stimulus. Rather, Garcia’s research showed that genetics matters — organisms are evolutionarily prepared to learn some associations more easily than others. You can see that the ability to associate smells with illness is an important survival mechanism, allowing the organism to quickly learn to avoid foods that are poisonous.

Classical conditioning has also been used to help explain the experience of post-traumatic stress disorder (PTSD), as in the case of P. K. Philips described in the chapter opener. PTSD is a severe anxiety disorder that can develop after exposure to a fearful event, such as the threat of death (American Psychiatric Association, 2000). PTSD occurs when the individual develops a strong association between the situational factors that surrounded the traumatic event (e.g., military uniforms or the sounds or smells of war) and the US (the fearful trauma itself). As a result of the conditioning, being exposed to or even thinking about the situation in which the trauma occurred (the CS) becomes sufficient to produce the CR of severe anxiety (Keane, Zimering, & Caddell, 1985).

PTSD develops because the emotions experienced during the event have produced neural activity in the amygdala and created strong conditioned learning. In addition to the strong conditioning that people with PTSD experience, they also show slower extinction in classical conditioning tasks (Milad et al., 2009). In short, people with PTSD have developed very strong associations with the events surrounding the trauma and are also slow to show extinction to the conditioned stimulus.

References

American Psychiatric Association. (2000). Diagnostic and statistical manual of mental disorders (4th ed., text rev.). Washington, DC: Author.

Garcia, J., Ervin, F. R., & Koelling, R. A. (1966). Learning with prolonged delay of reinforcement. Psychonomic Science, 5(3), 121–122.

Garcia, J., Kimeldorf, D. J., & Koelling, R. A. (1955). Conditioned aversion to saccharin resulting from exposure to gamma radiation. Science, 122, 157–158.

Keane, T. M., Zimering, R. T., & Caddell, J. M. (1985). A behavioral formulation of posttraumatic stress disorder in Vietnam veterans. The Behavior Therapist, 8(1), 9–12.

Lewicki, P. (1985). Nonconscious biasing effects of single instances on subsequent judgments. Journal of Personality and Social Psychology, 48, 563–574.

LoBue, V., & DeLoache, J. S. (2010). Superior detection of threat-relevant stimuli in infancy. Developmental Science, 13(1), 221–228.

Milad, M. R., Pitman, R. K., Ellis, C. B., Gold, A. L., Shin, L. M., Lasko, N. B.,…Rauch, S. L. (2009). Neurobiological basis of failure to recall extinction memory in posttraumatic stress disorder. Biological Psychiatry, 66(12), 1075–82.

Öhman, A., & Mineka, S. (2001). Fears, phobias, and preparedness: Toward an evolved module of fear and fear learning. Psychological Review, 108(3), 483–522.

Image Attributions

Figure 8.2: Ivan Pavlov (http://commons.wikimedia.org/wiki/File:Ivan_Pavlov_LIFE.jpg) is in the public domain.

In classical conditioning the organism learns to associate new stimuli with natural biological responses such as salivation or fear. The organism does not learn something new but rather begins to perform an existing behaviour in the presence of a new signal. Operant conditioning, on the other hand, is learning that occurs based on the consequences of behaviour and can involve the learning of new actions. Operant conditioning occurs when a dog rolls over on command because it has been praised for doing so in the past, when a schoolroom bully threatens his classmates because doing so allows him to get his way, and when a child gets good grades because her parents threaten to punish her if she doesn’t. In operant conditioning the organism learns from the consequences of its own actions.

How Reinforcement and Punishment Influence Behaviour: The Research of Thorndike and Skinner

Psychologist Edward L. Thorndike (1874-1949) was the first scientist to systematically study operant conditioning. In his research Thorndike (1898) observed cats who had been placed in a “puzzle box” from which they tried to escape (“Video Clip: Thorndike’s Puzzle Box”). At first the cats scratched, bit, and swatted haphazardly, without any idea of how to get out. But eventually, and accidentally, they pressed the lever that opened the door and exited to their prize, a scrap of fish. The next time the cat was constrained within the box, it attempted fewer of the ineffective responses before carrying out the successful escape, and after several trials the cat learned to almost immediately make the correct response.

Observing these changes in the cats’ behaviour led Thorndike to develop his law of effect, the principle that responses that create a typically pleasant outcome in a particular situation are more likely to occur again in a similar situation, whereas responses that produce a typically unpleasant outcome are less likely to occur again in the situation (Thorndike, 1911). The essence of the law of effect is that successful responses, because they are pleasurable, are “stamped in” by experience and thus occur more frequently. Unsuccessful responses, which produce unpleasant experiences, are “stamped out” and subsequently occur less frequently.

When Thorndike placed his cats in a puzzle box, he found that they learned to engage in the important escape behaviour faster after each trial. Thorndike described the learning that follows reinforcement in terms of the law of effect.

Watch: “Thorndike’s Puzzle Box” [YouTube]: http://www.youtube.com/watch?v=BDujDOLre-8

The influential behavioural psychologist B. F. Skinner (1904-1990) expanded on Thorndike’s ideas to develop a more complete set of principles to explain operant conditioning. Skinner created specially designed environments known as operant chambers (usually called Skinner boxes) to systematically study learning. A Skinner box (operant chamber) is a structure that is big enough to fit a rodent or bird and that contains a bar or key that the organism can press or peck to release food or water. It also contains a device to record the animal’s responses (Figure 8.5).

The most basic of Skinner’s experiments was quite similar to Thorndike’s research with cats. A rat placed in the chamber reacted as one might expect, scurrying about the box and sniffing and clawing at the floor and walls. Eventually the rat chanced upon a lever, which it pressed to release pellets of food. The next time around, the rat took a little less time to press the lever, and on successive trials, the time it took to press the lever became shorter and shorter. Soon the rat was pressing the lever as fast as it could eat the food that appeared. As predicted by the law of effect, the rat had learned to repeat the action that brought about the food and cease the actions that did not.

Skinner studied, in detail, how animals changed their behaviour through reinforcement and punishment, and he developed terms that explained the processes of operant learning (Table 8.1, “How Positive and Negative Reinforcement and Punishment Influence Behaviour”). Skinner used the term reinforcer to refer to any event that strengthens or increases the likelihood of a behaviour, and the term punisher to refer to any event that weakens or decreases the likelihood of a behaviour. And he used the terms positive and negative to refer to whether a reinforcement was presented or removed, respectively. Thus, positive reinforcement strengthens a response by presenting something pleasant after the response, and negative reinforcement strengthens a response by reducing or removing something unpleasant. For example, giving a child praise for completing his homework represents positive reinforcement, whereas taking Aspirin to reduce the pain of a headache represents negative reinforcement. In both cases, the reinforcement makes it more likely that behaviour will occur again in the future.

Table 8.1 How Positive and Negative Reinforcement and Punishment Influence Behaviour.

[Skip Table]
Operant conditioning term	Description	Outcome	Example
Positive reinforcement	Add or increase a pleasant stimulus	Behaviour is strengthened	Giving a student a prize after he or she gets an A on a test
Negative reinforcement	Reduce or remove an unpleasant stimulus	Behaviour is strengthened	Taking painkillers that eliminate pain increases the likelihood that you will take painkillers again
Positive punishment	Present or add an unpleasant stimulus	Behaviour is weakened	Giving a student extra homework after he or she misbehaves in class
Negative punishment	Reduce or remove a pleasant stimulus	Behaviour is weakened	Taking away a teen’s computer after he or she misses curfew

Reinforcement, either positive or negative, works by increasing the likelihood of a behaviour. Punishment, on the other hand, refers to any event that weakens or reduces the likelihood of a behaviour. Positive punishment weakens a response by presenting something unpleasant after the response, whereas negative punishment weakens a response by reducing or removing something pleasant. A child who is grounded after fighting with a sibling (positive punishment) or who loses out on the opportunity to go to recess after getting a poor grade (negative punishment) is less likely to repeat these behaviours.

Although the distinction between reinforcement (which increases behaviour) and punishment (which decreases it) is usually clear, in some cases it is difficult to determine whether a reinforcer is positive or negative. On a hot day a cool breeze could be seen as a positive reinforcer (because it brings in cool air) or a negative reinforcer (because it removes hot air). In other cases, reinforcement can be both positive and negative. One may smoke a cigarette both because it brings pleasure (positive reinforcement) and because it eliminates the craving for nicotine (negative reinforcement).

It is also important to note that reinforcement and punishment are not simply opposites. The use of positive reinforcement in changing behaviour is almost always more effective than using punishment. This is because positive reinforcement makes the person or animal feel better, helping create a positive relationship with the person providing the reinforcement. Types of positive reinforcement that are effective in everyday life include verbal praise or approval, the awarding of status or prestige, and direct financial payment. Punishment, on the other hand, is more likely to create only temporary changes in behaviour because it is based on coercion and typically creates a negative and adversarial relationship with the person providing the reinforcement. When the person who provides the punishment leaves the situation, the unwanted behaviour is likely to return.

Creating Complex Behaviours through Operant Conditioning

Perhaps you remember watching a movie or being at a show in which an animal — maybe a dog, a horse, or a dolphin — did some pretty amazing things. The trainer gave a command and the dolphin swam to the bottom of the pool, picked up a ring on its nose, jumped out of the water through a hoop in the air, dived again to the bottom of the pool, picked up another ring, and then took both of the rings to the trainer at the edge of the pool. The animal was trained to do the trick, and the principles of operant conditioning were used to train it. But these complex behaviours are a far cry from the simple stimulus-response relationships that we have considered thus far. How can reinforcement be used to create complex behaviours such as these?

One way to expand the use of operant learning is to modify the schedule on which the reinforcement is applied. To this point we have only discussed a continuous reinforcement schedule, in which the desired response is reinforced every time it occurs; whenever the dog rolls over, for instance, it gets a biscuit. Continuous reinforcement results in relatively fast learning but also rapid extinction of the desired behaviour once the reinforcer disappears. The problem is that because the organism is used to receiving the reinforcement after every behaviour, the responder may give up quickly when it doesn’t appear.

Most real-world reinforcers are not continuous; they occur on a partial (or intermittent) reinforcement schedule — a schedule in which the responses are sometimes reinforced and sometimes not. In comparison to continuous reinforcement, partial reinforcement schedules lead to slower initial learning, but they also lead to greater resistance to extinction. Because the reinforcement does not appear after every behaviour, it takes longer for the learner to determine that the reward is no longer coming, and thus extinction is slower. The four types of partial reinforcement schedules are summarized in Table 8.2, “Reinforcement Schedules.”

Table 8.2 Reinforcement Schedules.

[Skip Table]
Reinforcement schedule	Explanation	Real-world example
Fixed-ratio	Behaviour is reinforced after a specific number of responses.	Factory workers who are paid according to the number of products they produce
Variable-ratio	Behaviour is reinforced after an average, but unpredictable, number of responses.	Payoffs from slot machines and other games of chance
Fixed-interval	Behaviour is reinforced for the first response after a specific amount of time has passed.	People who earn a monthly salary
Variable-interval	Behaviour is reinforced for the first response after an average, but unpredictable, amount of time has passed.	Person who checks email for messages

Partial reinforcement schedules are determined by whether the reinforcement is presented on the basis of the time that elapses between reinforcement (interval) or on the basis of the number of responses that the organism engages in (ratio), and by whether the reinforcement occurs on a regular (fixed) or unpredictable (variable) schedule. In a fixed-interval schedule, reinforcement occurs for the first response made after a specific amount of time has passed. For instance, on a one-minute fixed-interval schedule the animal receives a reinforcement every minute, assuming it engages in the behaviour at least once during the minute. As you can see in Figure 8.6, “Examples of Response Patterns by Animals Trained under Different Partial Reinforcement Schedules,” animals under fixed-interval schedules tend to slow down their responding immediately after the reinforcement but then increase the behaviour again as the time of the next reinforcement gets closer. (Most students study for exams the same way.) In a variable-interval schedule, the reinforcers appear on an interval schedule, but the timing is varied around the average interval, making the actual appearance of the reinforcer unpredictable. An example might be checking your email: you are reinforced by receiving messages that come, on average, say, every 30 minutes, but the reinforcement occurs only at random times. Interval reinforcement schedules tend to produce slow and steady rates of responding.

In a fixed-ratio schedule, a behaviour is reinforced after a specific number of responses. For instance, a rat’s behaviour may be reinforced after it has pressed a key 20 times, or a salesperson may receive a bonus after he or she has sold 10 products. As you can see in Figure 8.6, “Examples of Response Patterns by Animals Trained under Different Partial Reinforcement Schedules,” once the organism has learned to act in accordance with the fixed-ratio schedule, it will pause only briefly when reinforcement occurs before returning to a high level of responsiveness. A variable-ratio schedule provides reinforcers after a specific but average number of responses. Winning money from slot machines or on a lottery ticket is an example of reinforcement that occurs on a variable-ratio schedule. For instance, a slot machine (see Figure 8.7, “Slot Machine”) may be programmed to provide a win every 20 times the user pulls the handle, on average. Ratio schedules tend to produce high rates of responding because reinforcement increases as the number of responses increases.

Complex behaviours are also created through shaping, the process of guiding an organism’s behaviour to the desired outcome through the use of successive approximation to a final desired behaviour. Skinner made extensive use of this procedure in his boxes. For instance, he could train a rat to press a bar two times to receive food, by first providing food when the animal moved near the bar. When that behaviour had been learned, Skinner would begin to provide food only when the rat touched the bar. Further shaping limited the reinforcement to only when the rat pressed the bar, to when it pressed the bar and touched it a second time, and finally to only when it pressed the bar twice. Although it can take a long time, in this way operant conditioning can create chains of behaviours that are reinforced only when they are completed.

Reinforcing animals if they correctly discriminate between similar stimuli allows scientists to test the animals’ ability to learn, and the discriminations that they can make are sometimes remarkable. Pigeons have been trained to distinguish between images of Charlie Brown and the other Peanuts characters (Cerella, 1980), and between different styles of music and art (Porter & Neuringer, 1984; Watanabe, Sakamoto & Wakita, 1995).

Behaviours can also be trained through the use of secondary reinforcers. Whereas a primary reinforcer includes stimuli that are naturally preferred or enjoyed by the organism, such as food, water, and relief from pain, a secondary reinforcer (sometimes called conditioned reinforcer) is a neutral event that has become associated with a primary reinforcer through classical conditioning. An example of a secondary reinforcer would be the whistle given by an animal trainer, which has been associated over time with the primary reinforcer, food. An example of an everyday secondary reinforcer is money. We enjoy having money, not so much for the stimulus itself, but rather for the primary reinforcers (the things that money can buy) with which it is associated.

References

Cerella, J. (1980). The pigeon’s analysis of pictures. Pattern Recognition, 12, 1–6.

Kassin, S. (2003). Essentials of psychology. Upper Saddle River, NJ: Prentice Hall. Retrieved from Essentials of Psychology Prentice Hall Companion Website: http://wps.prenhall.com/hss_kassin_essentials_1/15/3933/1006917.cw/index.html

Porter, D., & Neuringer, A. (1984). Music discriminations by pigeons. Journal of Experimental Psychology: Animal Behavior Processes, 10(2), 138–148.

Thorndike, E. L. (1898). Animal intelligence: An experimental study of the associative processes in animals. Washington, DC: American Psychological Association.

Thorndike, E. L. (1911). Animal intelligence: Experimental studies. New York, NY: Macmillan. Retrieved from http://www.archive.org/details/animalintelligen00thor

Watanabe, S., Sakamoto, J., & Wakita, M. (1995). Pigeons’ discrimination of painting by Monet and Picasso. Journal of the Experimental Analysis of Behaviour, 63(2), 165–174.

Image Attributions

Figure 8.5: “Skinner box” (http://en.wikipedia.org/wiki/File:Skinner_box_photo_02.jpg) is licensed under the CC BY SA 3.0 license (http://creativecommons.org/licenses/by-sa/3.0/deed.en). “Skinner box scheme” by Andreas1 (http://en.wikipedia.org/wiki/File:Skinner_box_scheme_01.png) is licensed under the CC BY SA 3.0 license (http://creativecommons.org/licenses/by-sa/3.0/deed.en)

Figure 8.6: Adapted from Kassin (2003).

Figure 8.7:  “Slot Machines in the Hard Rock Casino” by Ted Murpy (http://commons.wikimedia.org/wiki/File:HardRockCasinoSlotMachines.jpg) is licensed under CC BY 2.0. (http://creativecommons.org/licenses/by/2.0/deed.en).

John B. Watson and B. F. Skinner were behaviourists who believed that all learning could be explained by the processes of conditioning — that is, that associations, and associations alone, influence learning. But some kinds of learning are very difficult to explain using only conditioning. Thus, although classical and operant conditioning play a key role in learning, they constitute only a part of the total picture.

One type of learning that is not determined only by conditioning occurs when we suddenly find the solution to a problem, as if the idea just popped into our head. This type of learning is known as insight, the sudden understanding of a solution to a problem. The German psychologist Wolfgang Köhler (1925) carefully observed what happened when he presented chimpanzees with a problem that was not easy for them to solve, such as placing food in an area that was too high in the cage to be reached. He found that the chimps first engaged in trial-and-error attempts at solving the problem, but when these failed they seemed to stop and contemplate for a while. Then, after this period of contemplation, they would suddenly seem to know how to solve the problem: for instance, by using a stick to knock the food down or by standing on a chair to reach it. Köhler argued that it was this flash of insight, not the prior trial-and-error approaches, which were so important for conditioning theories, that allowed the animals to solve the problem.

Edward Tolman studied the behaviour of three groups of rats that were learning to navigate through mazes (Tolman & Honzik, 1930). The first group always received a reward of food at the end of the maze. The second group never received any reward, and the third group received a reward, but only beginning on the 11th day of the experimental period. As you might expect when considering the principles of conditioning, the rats in the first group quickly learned to negotiate the maze, while the rats of the second group seemed to wander aimlessly through it. The rats in the third group, however, although they wandered aimlessly for the first 10 days, quickly learned to navigate to the end of the maze as soon as they received food on day 11. By the next day, the rats in the third group had caught up in their learning to the rats that had been rewarded from the beginning.

It was clear to Tolman that the rats that had been allowed to experience the maze, even without any reinforcement, had nevertheless learned something, and Tolman called this latent learning. Latent learning refers to learning that is not reinforced and not demonstrated until there is motivation to do so. Tolman argued that the rats had formed a “cognitive map” of the maze but did not demonstrate this knowledge until they received reinforcement.

Observational Learning: Learning by Watching

The idea of latent learning suggests that animals, and people, may learn simply by experiencing or watching. Observational learning (modelling) is learning by observing the behaviour of others. To demonstrate the importance of observational learning in children, Bandura, Ross, and Ross (1963) showed children a live image of either a man or a woman interacting with a Bobo doll, a filmed version of the same events, or a cartoon version of the events. As you can see in “Video Clip: Bandura Discussing Clips From His Modelling Studies,” the Bobo doll is an inflatable balloon with a weight in the bottom that makes it bob back up when you knock it down. In all three conditions, the model violently punched the clown, kicked the doll, sat on it, and hit it with a hammer.

Take a moment to see how Albert Bandura explains his research into the modelling of aggression in children.

Watch: “Bandura Discussing Clips from His Modelling Studies” [YouTube]: http://www.youtube.com/watch?v=jWsxfoJEwQQ&feature=youtu.be

The researchers first let the children view one of the three types of modelling, and then let them play in a room in which there were some really fun toys. To create some frustration in the children, Bandura let the children play with the fun toys for only a couple of minutes before taking them away. Then Bandura gave the children a chance to play with the Bobo doll.

If you guessed that most of the children imitated the model, you would be correct. Regardless of which type of modelling the children had seen, and regardless of the sex of the model or the child, the children who had seen the model behaved aggressively — just as the model had done. They also punched, kicked, sat on the doll, and hit it with the hammer. Bandura and his colleagues had demonstrated that these children had learned new behaviours simply by observing and imitating others.

Observational learning is useful for animals and for people because it allows us to learn without having to actually engage in what might be a risky behaviour. Monkeys that see other monkeys respond with fear to the sight of a snake learn to fear the snake themselves, even if they have been raised in a laboratory and have never actually seen a snake (Cook & Mineka, 1990). As Bandura put it,

the prospects for [human] survival would be slim indeed if one could learn only by suffering the consequences of trial and error. For this reason, one does not teach children to swim, adolescents to drive automobiles, and novice medical students to perform surgery by having them discover the appropriate behaviour through the consequences of their successes and failures. The more costly and hazardous the possible mistakes, the heavier is the reliance on observational learning from competent learners. (Bandura, 1977, p. 212)

Although modelling is normally adaptive, it can be problematic for children who grow up in violent families. These children are not only the victims of aggression, but they also see it happening to their parents and siblings. Because children learn how to be parents in large part by modelling the actions of their own parents, it is no surprise that there is a strong correlation between family violence in childhood and violence as an adult. Children who witness their parents being violent or who are themselves abused are more likely as adults to inflict abuse on intimate partners or their children, and to be victims of intimate violence (Heyman & Slep, 2002). In turn, their children are more likely to interact violently with each other and to aggress against their parents (Patterson, Dishion, & Bank, 1984).

References

Anderson, C. A., & Bushman, B. J. (2001). Effects of violent video games on aggressive behavior, aggressive cognition, aggressive affect, physiological arousal, and prosocial behavior: A meta-analytic review of the scientific literature. Psychological Science, 12(5), 353–359.

Anderson, C. A., Berkowitz, L., Donnerstein, E., Huesmann, L. R., Johnson, J. D., Linz, D.,…Wartella, E. (2003). The influence of media violence on youth. Psychological Science in the Public Interest, 4(3), 81–110.

Bandura, A. (1977). Self-efficacy: Toward a unifying theory of behavior change. Psychological Review, 84, 191–215.

Bandura, A., Ross, D., & Ross, S. A. (1963). Imitation of film-mediated aggressive models. The Journal of Abnormal and Social Psychology, 66(1), 3–11.

Bushman, B. J., & Anderson, C. A. (2002). Violent video games and hostile expectations: A test of the general aggression model. Personality and Social Psychology Bulletin, 28(12), 1679–1686.

Cantor, J., Bushman, B. J., Huesmann, L. R., Groebel, J., Malamuth, N. M., Impett, E. A.,…Singer, J. L. (Eds.). (2001). Some hazards of television viewing: Fears, aggression, and sexual attitudes. Thousand Oaks, CA: Sage.

Cook, M., & Mineka, S. (1990). Selective associations in the observational conditioning of fear in rhesus monkeys. Journal of Experimental Psychology: Animal Behavior Processes, 16(4), 372–389.

Coyne, S. M., & Archer, J. (2005). The relationship between indirect and physical aggression on television and in real life. Social Development, 14(2), 324–337.

Henry J. Kaiser Family Foundation. (2003, Spring). Key facts: TV Violence [PDF]. Menlo Park, CA: Author. Retrieved from https://kaiserfamilyfoundation.files.wordpress.com/2013/01/key-facts-tv-violence.pdf

Heyman, R. E., & Slep, A. M. S. (2002). Do child abuse and interparental violence lead to adulthood family violence? Journal of Marriage and Family, 64(4), 864–870.

Köhler, W. (1925). The mentality of apes (E. Winter, Trans.). New York, NY: Harcourt Brace Jovanovich.

Patterson, G. R., Dishion, T. J., & Bank, L. (1984). Family interaction: A process model of deviancy training. Aggressive Behavior, 10(3), 253–267.

Schulenburg, C. (2007, January). Dying to entertain: Violence on prime time broadcast television, 1998 to 2006 [PDF]. Los Angeles, CA: Parents Television Council. Retrieved from http://www.parentstv.org/PTC/publications/reports/violencestudy/DyingtoEntertain.pdf

Seymour, B., Yoshida, W., & Dolan, R. (2009) Altruistic learning. Frontiers in Behavioral Neuroscience, 3, 23.

Tolman, E. C., & Honzik, C. H. (1930). Introduction and removal of reward, and maze performance in rats. University of California Publications in Psychology, 4, 257–275.

Long Descriptions

Figure 8.8 long description: Effect of Violent and Non-violent Video Games

	Non-violent video game	Violent video game
Do/say	3.0	4.8
Think	1.8	2.5
Feel	5.5	7.0

[Return to Figure 8.8]

The principles of learning are some of the most general and most powerful in all of psychology. It would be fair to say that these principles account for more behaviour using fewer principles than any other set of psychological theories. The principles of learning are applied in numerous ways in everyday settings. For example, operant conditioning has been used to motivate employees, to improve athletic performance, to increase the functioning of those suffering from developmental disabilities, and to help parents successfully toilet train their children (Azrin & Foxx, 1974; McGlynn, 1990; Pedalino & Gamboa, 1974; Simek & O’Brien, 1981). In this section we will consider how learning theories are used in advertising, in education, and in understanding competitive relationships between individuals and groups.

Using Classical Conditioning in Advertising

Classical conditioning has long been, and continues to be, an effective tool in marketing and advertising (Hawkins, Best, & Coney, 1998). The general idea is to create an advertisement that has positive features such that the ad creates enjoyment in the person exposed to it. The enjoyable ad serves as the unconditioned stimulus (US), and the enjoyment is the unconditioned response (UR). Because the product being advertised is mentioned in the ad, it becomes associated with the US, and then becomes the conditioned stimulus (CS). In the end, if everything has gone well, seeing the product online or in the store will then create a positive response in the buyer, leading him or her to be more likely to purchase the product.

Can you determine how classical conditioning is being used in these commercials?

Watch: “Television Ads” [YouTube]: http://www.youtube.com/v/dsESVrArhbk

A similar strategy is used by corporations that sponsor teams or events. For instance, if people enjoy watching a university basketball team playing basketball, and if that team is sponsored by a product, such as Pepsi, then people may end up experiencing positive feelings when they view a can of Pepsi. Of course, the sponsor wants to sponsor only good teams and good athletes because these create more pleasurable responses.

Advertisers use a variety of techniques to create positive advertisements, including enjoyable music, cute babies, attractive models, and funny spokespeople. In one study, Gorn (1982) showed research participants pictures of different writing pens of different colours, but paired one of the pens with pleasant music and the other with unpleasant music. When given a choice as a free gift, more people chose the pen colour associated with the pleasant music. And Schemer, Matthes, Wirth, and Textor (2008) found that people were more interested in products that had been embedded in music videos of artists that they liked and less likely to be interested when the products were in videos featuring artists that they did not like.

Another type of ad that is based on principles of classical conditioning is one that associates fear with the use of a product or behaviour, such as those that show pictures of deadly automobile accidents to encourage seatbelt use or images of lung cancer surgery to discourage smoking. These ads have also been found to be effective (Das, de Wit, & Stroebe, 2003; Perloff, 2003; Witte & Allen, 2000), due in large part to conditioning. When we see a cigarette and the fear of dying has been associated with it, we are hopefully less likely to light up.

Taken together then, there is ample evidence of the utility of classical conditioning, using both positive as well as negative stimuli, in advertising. This does not, however, mean that we are always influenced by these ads. The likelihood of conditioning being successful is greater for products that we do not know much about, where the differences between products are relatively minor, and when we do not think too carefully about the choices (Schemer et al., 2008).

Reinforcement in Social Dilemmas

The basic principles of reinforcement, reward, and punishment have been used to help understand a variety of human behaviours (Bandura, 1977; Miller & Dollard, 1941; Rotter, 1945). The general idea is that, as predicted by principles of operant learning and the law of effect, people act in ways that maximize their outcomes, where outcomes are defined as the presence of reinforcers and the absence of punishers.

Consider, for example, a situation known as the commons dilemma, as proposed by the ecologist Garrett Hardin (1968). Hardin noted that in many European towns there was at one time a centrally located pasture, known as the commons, which was shared by the inhabitants of the village to graze their livestock. But the commons was not always used wisely. The problem was that each individual who owned livestock wanted to be able to use the commons to graze his or her own animals. However, when each group member took advantage of the commons by grazing many animals, the commons became overgrazed, the pasture died, and the commons was destroyed.

Although Hardin focused on the particular example of the commons, the basic dilemma of individual desires versus the benefit of the group as a whole can also be found in many contemporary public goods issues, including the use of limited natural resources, air pollution, and public land. In large cities, most people may prefer the convenience of driving their own car to work each day rather than taking public transportation. Yet this behaviour uses up public goods (the space on limited roadways, crude oil reserves, and clean air). People are lured into the dilemma by short-term rewards, seemingly without considering the potential long-term costs of the behaviour, such as air pollution and the necessity of building even more highways.

A social dilemma such as the commons dilemma is a situation in which the behaviour that creates the most positive outcomes for the individual may in the long term lead to negative consequences for the group as a whole. The dilemmas are arranged in such a way that it is easy to be selfish, because the personally beneficial choice (such as using water during a water shortage or driving to work alone in one’s own car) produces reinforcements for the individual. Furthermore, social dilemmas tend to work on a type of time delay. The problem is that, because the long-term negative outcome (the extinction of fish species or dramatic changes in the earth’s climate) is far away in the future and the individual benefits are occurring right now, it is difficult for an individual to see how many costs there really are. The paradox, of course, is that if everyone takes the personally selfish choice in an attempt to maximize his or her own outcomes, the long-term result is poorer outcomes for every individual in the group. Each individual prefers to make use of the public goods for himself or herself, whereas the best outcome for the group as a whole is to use the resources more slowly and wisely.

One method of understanding how individuals and groups behave in social dilemmas is to create such situations in the laboratory and observe how people react to them. The best known of these laboratory simulations is called the prisoner’s dilemma game (Poundstone, 1992). This game represents a social dilemma in which the goals of the individual compete with the goals of another individual (or sometimes with a group of other individuals). Like all social dilemmas, the prisoner’s dilemma assumes that individuals will generally try to maximize their own outcomes in their interactions with others.

In the prisoner’s dilemma game, the participants are shown a payoff matrix in which numbers are used to express the potential outcomes for each of the players in the game, given the decisions each player makes. The payoffs are chosen beforehand by the experimenter to create a situation that models some real-world outcome. Furthermore, in the prisoner’s dilemma game, the payoffs are normally arranged as they would be in a typical social dilemma, such that each individual is better off acting in his or her immediate self-interest, and yet if all individuals act according to their self-interests, then everyone will be worse off.

In its original form, the prisoner’s dilemma game involves a situation in which two prisoners (we’ll call them Frank and Malik) have been accused of committing a crime. The police believe that the two worked together on the crime, but they have only been able to gather enough evidence to convict each of them of a more minor offence. In an attempt to gain more evidence, and thus be able to convict the prisoners of the larger crime, each of the prisoners is interrogated individually, with the hope that he will confess to having been involved in the more major crime in return for a promise of a reduced sentence if he confesses first. Each prisoner can make either the cooperative choice (which is to not confess) or the competitive choice (which is to confess).

The incentives for either confessing or not confessing are expressed in a payoff matrix such as the one shown in Figure 8.10, “The Prisoner’s Dilemma.” The top of the matrix represents the two choices that Malik might make (to either confess that he did the crime or not confess), and the side of the matrix represents the two choices that Frank might make (also to either confess or not confess). The payoffs that each prisoner receives, given the choices of each of the two prisoners, are shown in each of the four squares.

If both prisoners take the cooperative choice by not confessing (the situation represented in the upper left square of the matrix), there will be a trial, the limited available information will be used to convict each prisoner, and they each will be sentenced to a relatively short prison term of three years. However, if either of the prisoners confesses, turning “state’s evidence” against the other prisoner, then there will be enough information to convict the other prisoner of the larger crime, and that prisoner will receive a sentence of 30 years, whereas the prisoner who confesses will get off free. These outcomes are represented in the lower left and upper right squares of the matrix. Finally, it is possible that both players confess at the same time. In this case there is no need for a trial, and in return the prosecutors offer a somewhat reduced sentence (of 10 years) to each of the prisoners.

The prisoner’s dilemma has two interesting characteristics that make it a useful model of a social dilemma. For one, the prisoner’s dilemma is arranged in such a way that a positive outcome for one player does not necessarily mean a negative outcome for the other player. If you consider again the matrix in Figure 8.10, “The Prisoner’s Dilemma,” you can see that if one player takes the cooperative choice (to not confess) and the other takes the competitive choice (to confess), then the prisoner who cooperates loses, whereas the other prisoner wins. However, if both prisoners make the cooperative choice, each remaining quiet, then neither gains more than the other, and both prisoners receive a relatively light sentence. In this sense, both players can win at the same time.

Second, the prisoner’s dilemma matrix is arranged so that each individual player is motivated to take the competitive choice because this choice leads to a higher payoff regardless of what the other player does. Imagine for a moment that you are Malik, and you are trying to decide whether to cooperate (don’t confess) or to compete (confess). And imagine that you are not really sure what Frank is going to do. Remember the goal of the individual is to maximize outcomes. The values in the matrix make it clear that if you think that Frank is going to confess, you should confess yourself (to get 10 rather than 30 years in prison). And it is also clear that if you think Frank is not going to confess, you should still confess (to get no time in prison rather than three years). So the matrix is arranged so that the “best” alternative for each player, at least in the sense of pure reward and self-interest, is to make the competitive choice, even though in the end both players would prefer the combination in which both players cooperate to the one in which they both compete.

Although initially specified in terms of the two prisoners, similar payoff matrices can be used to predict behaviour in many different types of dilemmas involving two or more parties and including choices of helping and not helping, working and loafing, and paying and not paying debts. For instance, we can use the prisoner’s dilemma to help us understand roommates living together in a house who might not want to contribute to the housework. Each of them would be better off if they relied on the other to clean the house. Yet if neither of them makes an effort to clean the house (the cooperative choice), the house becomes a mess and they will both be worse off.

References

Azrin, N., & Foxx, R. M. (1974). Toilet training in less than a day. New York, NY: Simon & Schuster.

Bandura, A. (1977). Social learning theory. New York, NY: General Learning Press.

Baumeister, R. F., Campbell, J. D., Krueger, J. I., & Vohs, K. D. (2003). Does high self-esteem cause better performance, interpersonal success, happiness, or healthier lifestyles? Psychological Science in the Public Interest, 4, 1–44.

Das, E. H. H. J., de Wit, J. B. F., & Stroebe, W. (2003). Fear appeals motivate acceptance of action recommendations: Evidence for a positive bias in the processing of persuasive messages. Personality & Social Psychology Bulletin, 29(5), 650–664.

Emurian, H. H. (2009). Teaching Java: Managing instructional tactics to optimize student learning. International Journal of Information & Communication Technology Education, 3(4), 34–49.

Gershoff, E. T. (2002). Corporal punishment by parents and associated child behaviors and experiences: A meta-analytic and theoretical review. Psychological Bulletin, 128(4), 539–579.

Gorn, G. J. (1982). The effects of music in advertising on choice behavior: A classical conditioning approach. Journal of Marketing, 46(1), 94–101.

Hardin, G. (1968). The tragedy of the commons. Science, 162, 1243–1248.

Hawkins, D., Best, R., & Coney, K. (1998). Consumer Behavior: Building Marketing Strategy (7th ed.). Boston, MA: McGraw-Hill.

Hulleman, C. S., Durik, A. M., Schweigert, S. B., & Harackiewicz, J. M. (2008). Task values, achievement goals, and interest: An integrative analysis. Journal of Educational Psychology, 100(2), 398–416.

Kohn, A. (1993). Punished by rewards: The trouble with gold stars, incentive plans, A’s, praise, and other bribes. Boston, MA: Houghton Mifflin and Company.

Lepper, M. R., Greene, D., & Nisbett, R. E. (1973). Undermining children’s intrinsic interest with extrinsic reward: A test of the “overjustification” hypothesis. Journal of Personality & Social Psychology, 28(1), 129–137.

McGlynn, S. M. (1990). Behavioral approaches to neuropsychological rehabilitation. Psychological Bulletin, 108, 420–441.

Miller, N., & Dollard, J. (1941). Social learning and imitation. New Haven, CT: Yale University Press.

Pedalino, E., & Gamboa, V. U. (1974). Behavior modification and absenteeism: Intervention in one industrial setting. Journal of Applied Psychology, 59, 694–697.

Perloff, R. M. (2003). The dynamics of persuasion: Communication and attitudes in the 21st century (2nd ed.). Mahwah, NJ: Lawrence Erlbaum Associates.

Poundstone, W. (1992). The prisoner’s dilemma. New York, NY: Doubleday.

Rotter, J. B. (1945). Social learning and clinical psychology. Upper Saddle River, NJ: Prentice Hall.

Ryan, R. M., & Deci, E. L. (2002). Overview of self-determination theory: An organismic-dialectical perspective. In E. L. Deci & R. M. Ryan (Eds.), Handbook of self-determination research (pp. 3–33). Rochester, NY: University of Rochester Press.

Schemer, C., Matthes, J. R., Wirth, W., & Textor, S. (2008). Does “Passing the Courvoisier” always pay off? Positive and negative evaluative conditioning effects of brand placements in music videos. Psychology & Marketing, 25(10), 923–943.

Simek, T. C., & O’Brien, R. M. (1981). Total golf: A behavioral approach to lowering your score and getting more out of your game. New York, NY: Doubleday & Company.

Skinner, B. F. (1965). The technology of teaching. Proceedings of the Royal Society B Biological Sciences, 162(989): 427–43.

Watson, J. B. (1930). Behaviorism (Rev. ed.). New York, NY: Norton.

Witte, K., & Allen, M. (2000). A meta-analysis of fear appeals: Implications for effective public health campaigns. Health Education & Behavior, 27(5), 591–615.

Image Attributions

Figure 8.9: Adapted from Lepper, Greene, & Nisbett (1973).

Long Descriptions

Figure 8.9 long description: Undermining intrinsic interest.

	First Session	Second Session
Expected award	17	8
No award	15	16
Unexpected award	17	17

[Return to Figure 8.9]

Figure 8.10 long description: The prisoner’s Dilemma. If both Malik and Frank don’t confess, they each get three years in prison. If only one of them confesses, the confessor gets no years in prison while the person who did not confess gets 30 years in prison. If they both confess, they each get 10 years in prison. [Return to Figure 8.10]

Classical conditioning was first studied by physiologist Ivan Pavlov. In classical conditioning, a person or animal learns to associate a neutral stimulus (the conditioned stimulus, or CS) with a stimulus (the unconditioned stimulus, or US) that naturally produces a behaviour (the unconditioned response, or UR). As a result of this association, the previously neutral stimulus comes to elicit the same or similar response (the conditioned response, or CR).

Classically conditioned responses show extinction if the CS is repeatedly presented without the US. The CR may reappear later in a process known as spontaneous recovery.

Organisms may show stimulus generalization, in which stimuli similar to the CS may produce similar behaviours, or stimulus discrimination, in which the organism learns to differentiate between the CS and other similar stimuli.

Second-order conditioning occurs when a second CS is conditioned to a previously established CS.

Psychologist Edward Thorndike developed the law of effect: the idea that responses that are reinforced are “stamped in” by experience and thus occur more frequently, whereas responses that are punished are “stamped out” and subsequently occur less frequently.

B. F. Skinner expanded on Thorndike’s ideas to develop a set of principles to explain operant conditioning.

Positive reinforcement strengthens a response by presenting something pleasant after the response, and negative reinforcement strengthens a response by reducing or removing something unpleasant. Positive punishment weakens a response by presenting something unpleasant after the response, whereas negative punishment weakens a response by reducing or removing something pleasant.

Shaping is the process of guiding an organism’s behaviour to the desired outcome through the use of reinforcers.

Reinforcement may be either partial or continuous. Partial-reinforcement schedules are determined by whether the reward is presented on the basis of the time that elapses between rewards (interval) or on the basis of the number of responses that the organism engages in (ratio), and by whether the reinforcement occurs on a regular (fixed) or unpredictable (variable) schedule.

Not all learning can be explained through the principles of classical and operant conditioning. Insight is the sudden understanding of the components of a problem that makes the solution apparent, and latent learning refers to learning that is not reinforced and not demonstrated until there is motivation to do so.

Learning by observing the behaviour of others and the consequences of those behaviours is known as observational learning. Aggression, altruism, and many other behaviours are learned through observation.

Learning theories can be and have been applied to change behaviours in many areas of everyday life. Some advertising uses classical conditioning to associate a pleasant response with a product.

Rewards are frequently and effectively used in education but must be carefully designed to be contingent on performance and to avoid undermining interest in the activity.

Social dilemmas, such as the prisoner’s dilemma, can be understood in terms of a desire to maximize one’s outcomes in a competitive relationship.

Canada has had its share of memories being introduced into legal cases with devastating results: Thomas Sophonow was accused of murdering a young waitress who worked in a donut shop in Winnipeg, Manitoba. Several eyewitnesses testified against Sophonow but there were problems with each one. For example, the photo array shown to a number of witnesses contained a picture of Sophonow, which was significantly different than the other men in the array.

Dubious allegations of repressed memories forced Michael Kliman, a teacher at James McKinney Elementary School in Richmond, B.C.,  to endure three trials before his ultimate acquittal. His world came crashing down when he was accused of molesting a Grade 6 student some 20 years earlier, a student who “recovered” her memories 17 years after the abuse allegedly happened. According to an article in the Vancouver Sun (Brook, 1999): “In 1992, after years of psychiatric treatment, she ‘recovered’ long-lost memories of a year-long series of assaults by Kliman and, encouraged by the  Richmond RCMP, laid charges.”

The two subjects of this chapter are memory, defined as the ability to store and retrieve information over time, and cognition, defined as the processes of acquiring and using knowledge. It is useful to consider memory and cognition in the same chapter because they work together to help us interpret and understand our environments.

Memory and cognition represent the two major interests of cognitive psychologists. The cognitive approach became the most important school of psychology during the 1960s, and the field of psychology has remained in large part cognitive since that time. The cognitive school was greatly influenced by the development of the electronic computer, and although the differences between computers and the human mind are vast, cognitive psychologists have used the computer as a model for understanding the workings of the mind.

We will begin the chapter with the study of memory. Our memories allow us to do relatively simple things, such as remembering where we parked our car or the name of the current prime minister of Canada, but also allow us to form complex memories, such as how to ride a bicycle or to write a computer program. Moreover, our memories define us as individuals — they are our experiences, our relationships, our successes, and our failures. Without our memories, we would not have a life.

At least for some things, our memory is very good (Bahrick, 2000). Once we learn a face, we can recognize that face many years later. We know the lyrics of many songs by heart, and we can give definitions for tens of thousands of words. Mitchell (2006) contacted participants 17 years after they had been briefly exposed to some line drawings in a lab and found that they still could identify the images significantly better than participants who had never seen them.

For some people, memory is truly amazing. Consider, for instance, the case of Kim Peek, who was the inspiration for the Academy Award-winning film Rain Man (Figure 9.1 “Kim Peek” and “Video Clip: Kim Peek”). Although Peek’s IQ was only 87, significantly below the average of about 100, it is estimated that he memorized more than 10,000 books in his lifetime (Wisconsin Medical Society, n.d.; Kim Peek, 2004). The Russian psychologist A. R. Luria (2004) has described the abilities of a man known as “S,” who seems to have unlimited memory. S remembers strings of hundreds of random letters for years at a time, and seems in fact to never forget anything.
You can view an interview with Kim Peek and see some of his amazing memory abilities at this link.

Watch: “Kim Peek” [YouTube]: http://www.youtube.com/watch?v=dhcQG_KItZM

In this chapter we will see how psychologists use behavioural responses (such as memory tests and reaction times) to draw inferences about what and how people remember. And we will see that although we have very good memories for some things, our memories are far from perfect (Schacter, 1996). The errors that we make are due to the fact that our memories are not simply recording devices that input, store, and retrieve the world around us. Rather, we actively process and interpret information as we remember and recollect it, and these cognitive processes influence what we remember and how we remember it. Because memories are constructed, not recorded, when we remember events we don’t reproduce exact replicas of those events (Bartlett, 1932).

In the last section of the chapter we will focus primarily on cognition, with a particular consideration for cases in which cognitive processes lead us to distort our judgments or misremember information. We will see that our prior knowledge can influence our memory. People who read the words “dream, sheets, rest, snore, blanket, tired, and bed” and then are asked to remember the words often think that they saw the word sleep even though that word was not in the list (Roediger & McDermott, 1995). And we will see that in other cases we are influenced by the ease with which we can retrieve information from memory or by the information that we are exposed to after we first learn something.

Although much research in the area of memory and cognition is basic in orientation, the work also has profound influence on our everyday experiences. Our cognitive processes influence the accuracy and inaccuracy of our memories and our judgments, and they lead us to be vulnerable to the types of errors that eyewitnesses such as Jennifer Thompson may make. Understanding these potential errors is the first step in learning to avoid them.

References

Bahrick, H. P. (2000). Long-term maintenance of knowledge. In E. Tulving & F. I. M. Craik (Eds.), The Oxford handbook of memory (pp. 347–362). New York, NY: Oxford University Press.

Bartlett, F. C. (1932). Remembering. Cambridge, MA: Cambridge University Press.

Brook, P. (1999, December 15). Accused falls victim to a legal nightmare. The Vancouver Sun, p. A19.

Chatham, C. (2007, March 27). 10 important differences between brains and computers. Developing Intelligence. Retrieved from http://scienceblogs.com/developingintelligence/2007/03/27/why-the-brain-is-not-like-a-co/

Innocence Project. (n.d.). Ronald Cotton. Retrieved from  http://www.innocenceproject.org/Content/72.php.

Kim Peek: Savant who was the inspiration for the film Rain Man. (2004, December 23). The Times. Retrieved from http://www.timesonline.co.uk/tol/comment/obituaries/article6965115.ece

Luria, A. (2004). The mind of a mnemonist: A little book about a vast memory. Cambridge, MA: Harvard University Press.

Mitchell, D. B. (2006). Nonconscious priming after 17 years: Invulnerable implicit memory? Psychological Science, 17(11), 925–928.

Roediger, H. L., & McDermott, K. B. (1995). Creating false memories: Remembering words not presented in lists. Journal of Experimental Psychology: Learning, Memory, and Cognition, 21(4), 803–814.

Schacter, D. L. (1996). Searching for memory: The brain, the mind, and the past (1st ed.). New York, NY: Basic Books.

Thompson, J. (2000, June 18). I was certain, but I was wrong. New York Times. Retrieved from http://faculty.washington.edu/gloftus/Other_Information/Legal_Stuff/Articles/News_Articles/Thompson_NYT_6_18_2000.html

Wells, G. L., Memon, A., & Penrod, S. D. (2006). Eyewitness evidence: Improving its probative value. Psychological Science in the Public Interest, 7(2), 45–75.

Wisconsin Medical Society. (n.d.). Retrieved from http://www.wisconsinmedicalsociety.org/_SAVANT/_PROFILES/kim_peek/_media/video/expedition/video.html.

Image Attributions

Figure 9.1: Kim Peek by Darold A. Treffert, MD, and the Wisconsin Medical Society (http://commons.wikimedia.org/wiki/File:Peek1.jpg) used under CC BY license.