Motivation and Emotion8
Enduring Issues in Motivation and Emotion
Perspectives on Motivation • Instincts • Drive-Reduction Theory • Arousal Theory • Intrinsic and Extrinsic
Motivation • A Hierarchy of Motives
Hunger and Thirst • Biological and Emotional
Factors • Eating Disorders and Obesity Sex • Biological Factors • Cultural and Environmental
Factors • Patterns of Sexual Behavior
Among Americans • Sexual Orientation
Other Important Motives • Exploration and Curiosity • Manipulation and
Contact • Aggression • Achievement • Affiliation
Emotions • Basic Emotions • Theories of Emotion
Communicating Emotion • Voice Quality and Facial
Expression • How the Brain Reads
the Face • Body Language,
Personal Space, and Gestures
• Gender and Emotion • Culture and Emotion
O V E R V I E W
Understanding Psychology, Ninth Edition, by Charles G. Morris and Albert A. Maisto. Published by Prentice Hall. Copyright © 2010 by Pearson Education, Inc.
Emotion refers to the experience of feelings such as fear, joy, surprise, and anger. Like motives, emotions also activate and affect behavior, but it is more difficult to predict the kind of behavior that a particular emotion will prompt. If a man is hungry, we can be reasonably sure that he will seek food. If, however, this same man experiences a feeling of joy or surprise, we can- not know with certainty how he will act.
The important thing to remember about both motives and emotions is that they push us to take some kind of action whether or not we are aware of it. We do not need to think about feeling hungry to make a beeline for the refrigerator. Similarly, we do not have to realize that we are afraid before stepping back from a growling dog. Moreover, the same moti- vation or emotion may produce different behaviors in different people. Ambition might motivate one person to go to law school and another to join a crime ring. Feeling sad might lead one person to cry alone and another to seek out a friend. On the other hand, the same behavior might arise from different motives or emotions: You may go to a movie because you are happy, bored, or lonely. In short, the workings of motives and emotions are very complex.
In this chapter, we will first look at some specific motives that play important roles in human behavior. Then we will turn our attention to emotions and the various ways they are expressed. We begin our discussion of motivation with a few general concepts.
Classic detective stories are usually studies of motivation andemotion. At the beginning, all we know is that a murder hasbeen committed: After eating dinner with her family, sweet old Amanda Jones collapses and dies of strychnine poisoning. “Now, why would anyone do a thing like that?” everybody wonders. The police ask the same question, in different terms: “Who had a motive for killing Miss Jones?” In a good mystery, the answer is “Practically everybody.”
There is, for example, the younger sister—although she is 75 years old, she still bristles when she thinks of that tragic day 50 years ago when Amanda stole her sweetheart. And there is the next-door neighbor, who was heard saying that if Miss Jones’s poodle trampled his peonies one more time, there would be consequences. Then there is the spendthrift nephew who stands to inherit a fortune from the deceased. Finally, the parlor maid has a guilty secret that Miss Jones knew and had threat- ened to reveal. All four suspects were in the house on the night of the murder, had access to the poison (which was used to kill rats in the basement), and had strong feelings about Amanda Jones. All of them had a motive for killing her.
In this story, motivation and emotion are so closely inter- twined that drawing distinctions between them is difficult. How- ever, psychologists do try to separate them. A motive is a specific need or desire that arouses the organism and directs its behavior toward a goal. All motives are triggered by some kind of stimulus: a bodily condition, a cue in the environment, or a feeling.
ENDURING ISSUES IN MOTIVATION AND EMOTION The heart of this chapter concerns the ways in which motives and emotions affect behavior and are affected by the external environment (person–situation). While discussing those key issues, we will explore the question of whether motives and emotions are inborn or acquired (nature–nurture) and whether they change significantly over the life span (stability–change). We will also consider the extent to which individuals differ in their motives and emotions (diversity–universality) and the ways in which motives and emotions arise from and, in turn, affect biological processes (mind–body).
PERSPECTIVES ON MOTIVATION How can you use intrinsic and extrinsic motivation to help you succeed in college?
Instincts Early in the 20th century, psychologists often attributed behavior to instincts—specific, inborn behavior patterns characteristic of an entire species. In 1890, William James compiled a list of human instincts that included hunting, rivalry, fear, curiosity, shyness, love, shame, and resentment. But by the 1920s, instinct theory began to fall out of favor as an explanation of
motive Specific need or desire, such as hunger, thirst, or achievement, that prompts goal-directed behavior.
emotion Feeling, such as fear, joy, or surprise, that underlies behavior.
instincts Inborn, inflexible, goal-directed behaviors that are characteristic of an entire species.
L E A R N I N G O B J E C T I V E • Compare and contrast instincts,
drive-reduction theory, and arousal theory (including the Yerkes-Dodson law) as explanations of human behavior. Distinguish between primary and secondary drives, intrinsic and extrinsic motivation, and summarize Maslow’s hierarchy of motives.
Understanding Psychology, Ninth Edition, by Charles G. Morris and Albert A. Maisto. Published by Prentice Hall. Copyright © 2010 by Pearson Education, Inc.
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human behavior for three reasons: (1) Most important human behavior is learned; (2) human behavior is rarely rigid, inflexible, unchanging, and found through- out the species, as is the case with instincts; and (3) ascribing every conceivable human behavior to a corresponding instinct explains nothing (calling a person’s propensity to be alone an “antisocial instinct,” for example, merely names the behavior without pinpointing its origins).
Drive-Reduction Theory An alternative view of motivation holds that bodily needs (such as the need for food or the need for water) create a state of tension or arousal called a drive (such as hunger or thirst). According to drive-
reduction theory, motivated behavior is an attempt to reduce this unpleasant state of ten- sion in the body and to return the body to a state of homeostasis, or balance (S. Cooper, 2008). When we are hungry, we look for food to reduce the hunger drive. When we are tired, we find a place to rest.
According to drive-reduction theory, drives can generally be divided into two cate- gories. Primary drives are unlearned, are found in all animals (including humans), and motivate behavior that is vital to the survival of the individual or species. Primary drives include hunger, thirst, and sex. Secondary drives are acquired through learning. For instance, no one is born with a drive to acquire great wealth, yet many people are moti- vated by money.
Arousal Theory Drive-reduction theory is appealing, but it cannot explain all kinds of behavior. It implies, for example, that once drives are reduced, people will do little. They would literally have no motivation. Yet this is obviously not the case. People work, play, do Sudoku puzzles, and do many other things for which there is no known drive that needs to be reduced.
Arousal theory suggests that each of us has an optimum level of arousal that varies over the course of the day and from one situation to another. According to this view, behav- ior is motivated by the desire to maintain the optimum level of arousal for a given moment. Sometimes, as envisioned in drive-reduction theory, that may call for reducing the level of arousal. But other times, behavior appears to be motivated by a desire to increase the state of arousal. For example, when you are bored, you may turn on the television, take a walk, or check for text messages.
Interestingly, overall level of arousal affects performance in different situations but psychologists agree that there is no “best” level of arousal necessary to perform all tasks (Gray, Braver, & Raichle, 2002). Rather, it is largely a question of degree. The Yerkes–Dodson law puts it this way: The more complex the task, the lower the level of arousal that can be tolerated without interfering with performance (Yerkes & Dodson, 1908/2007). Thus, to perform optimally on a simple task, you may need to increase your level of arousal. Conversely, you may need to reduce your level of arousal to perform well on a complex task. (See Figure 8–1.)
Arousal theory has some advantages over drive-reduction theory, but neither one can readily account for some kinds of behavior. For example, many people today participate in activities that are stimulating in the extreme: rock climbing, skydiving, bungee jumping, and hang gliding. Such thrill-seeking activities do not seem to be drive-reducing and do not seem to be done in pursuit of an optimal level of arousal. Zuckerman (1979, 2007a) accounts for such activities by suggesting that sensation seeking is itself a basic moti- vation, at least some aspects of which are inherited and neurologically based (Arnaut, 2006;
Primary drives are, by definition, unlearned. But learning clearly affects howthese drives are expressed: We learn how and what to eat and drink. 1. Given that information, how might you design a research study to
determine what aspects of a given drive, say hunger, are learned and which are not?
2. What steps would you take to increase the likelihood that your results apply to people in general and not just to a small sample of people?
3. Would you have to rely on self-reports or could you directly observe behavior?
arousal theory Theory of motivation that proposes that organisms seek an optimal level of arousal.
Yerkes–Dodson law States that there is an optimal level of arousal for the best performance of any task; the more complex the task, the lower the level of arousal that can be tolerated before performance deteriorates.
drive State of tension or arousal that motivates behavior.
drive-reduction theory States that motivated behavior is aimed at reducing a state of bodily tension or arousal and returning the organism to homeostasis.
homeostasis State of balance and stability in which the organism functions effectively.
primary drives Unlearned drive, such as hunger, that are based on a physiological state.
secondary drives Learned drives, such as ambition, that are not based on a physiological state.
Understanding Psychology, Ninth Edition, by Charles G. Morris and Albert A. Maisto. Published by Prentice Hall. Copyright © 2010 by Pearson Education, Inc.
Motivation and Emotion 261
Zuckerman, 2005). In general, high sensation seekers, compared to low sensation seekers, are more likely to
• prefer dangerous sports (Diehm & Armatas, 2004; Eachus, 2004; Zuckerman, 2007b); • choose vocations that involve an element of risk and excitement (Zuckerman, 2006); • smoke, drink heavily, gamble, and use illicit drugs (D’Silva, Grant-Harrington,
Palmgreen, Donohew, & Pugzles-Lorch, 2001; Gurpegui et al., 2007; Nower, Derevensky, & Gupta, 2004);
• engage in unsafe driving (S. L. Pedersen & McCarthy, 2008; Thiffault & Bergeron, 2003); • have more sexual partners and engage in more varied and dangerous sexual activities
(Berg, 2008: Cohen, 2008); and
• be classified in school as delinquent or hyperactive (though not more aggressive) (Ang & Woo, 2003; Modecki, 2008).
Figure 8–1 The Yerkes–Dodson law. A certain amount of arousal is needed to perform most tasks, but a very high level of arousal interferes with the performance of complicated activities. That is, the level of arousal that can be tolerated is higher for a simple task than for a complex one. Source: After Hebb, 1955.
Low arousal High arousal
High SIMPLE TASK
Low arousal High arousal Low
High COMPLEX TASK
intrinsic motivation A desire to perform a behavior that stems from the enjoyment derived from the behavior itself.
extrinsic motivation A desire to perform a behavior to obtain an external reward or avoid punishment.
Nature–Nurture The Evolutionary Basis of Arousal Seeking Some evolutionary theorists argue that sensation seeking may have an evolutionary basis. For example, Cosmides and Tooby (2000) propose that risk-taking behavior may have played an important adaptive role for our ancestors by providing them with opportunities to develop successful strategies to deal with potentially dangerous situations. Those who took risks, and who were thereby better equipped to cope with danger and turmoil in their environment, improved their social status and sexual competitiveness more than those who did not (Ermer, Cosmides & Tooby, 2008). ■
Intrinsic and Extrinsic Motivation Some psychologists further distinguish between intrinsic and extrinsic motivation. Intrinsic motivation refers to motivation provided by an activity itself. Children climb trees, finger paint, and play games for no other reason than the fun they get from the activity itself. In the same way, adults may solve crossword puzzles, play a musical instrument, or tinker in a workshop largely for the enjoyment they get from the activity. Extrinsic motivation refers to motivation that derives from the consequences of an activity. For example, a child may do chores not because he enjoys them but because doing so earns an allowance, and an adult who plays a musical instrument may do so to earn some extra money.
Whether behavior is intrinsically or extrinsically motivated can have important conse- quences (Deci & Ryan, 2008). For example, if parents offer a reward to their young daughter for writing to her grandparents, the likelihood of her writing to them when rewards are no
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hierarchy of needs A theory of motivation advanced by Maslow holding that higher order motives involving social and personal growth only emerge after lower level motives related to survival have been satisfied.
The same activity might be motivated intrinsically, just for the pleasure of doing it, or extrinsically, by rewards unrelated to the activity itself.
longer available may actually decrease. One analysis of some 128 studies that examined the effect of extrinsic rewards on the behavior of children, adolescents, and adults found that when extrinsic rewards are offered for a behavior, intrinsic motivation and sense of personal responsibility for that behavior are likely to decrease, at least for a short time (Deci, Koestner, & Ryan, 1999, 2001). However, unexpected (as opposed to contrac- tual) rewards do not necessarily reduce intrinsic moti- vation, and positive feedback (including praise) may actually increase intrinsic motivation (Chance, 1992; Deci et al., 1999; Reiss, 2005).
A Hierarchy of Motives Humanistic psychologist Abraham Maslow (1954) arranged motives in a hierarchy, from lower to higher. The lower motives spring from physiological needs
that must be satisfied. As we move higher in Maslow’s hierarchy of needs, the motives have more subtle origins: the desire to live as safely as possible, to connect meaningfully with other human beings, and to make the best possible impression on others. Maslow believed that the highest motive in the hierarchy is self-actualization—the drive to realize one’s full potential. Maslow’s hierarchy of motives is illustrated in Figure 8–2.
According to Maslow’s theory, higher motives emerge only after the more basic ones have been largely satisfied: A person who is starving doesn’t care what people think of her table manners.
Maslow’s model offers an appealing way to organize a wide range of motives into a coherent structure. But recent research challenges the universality of his views. In many societies, people live on the very edge of survival, yet they form strong and meaningful social ties and possess a firm sense of self-esteem (E. Hoffman, 2008; Wubbolding, 2005). As a result of such research findings, many psychologists now view Maslow’s model with a measure of skepticism although it continues to be a convenient way to think of the wide range of human motives.
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Figure 8–2 A pyramid representing Maslow’s hierarchy of needs. From bottom to top, the stages correspond to how fundamental the motive is for survival and how early it appears in both the evolution of the species and the development of the individual. According to Maslow, the more basic needs must largely be satisfied before higher motives can emerge. Source: From Motivation and Personality by Abraham H. Maslow. Copyright © 1970. Reprinted by permission of Pearson Education, Upper Saddle River, NJ.
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We have reviewed some basic concepts about motivation. With these concepts in mind, we now turn our attention to specific motives.
L E A R N I N G O B J E C T I V E S • Identify the areas of the brain that are
involved in hunger and describe the role of glucose, leptin, and ghrelin in determining a biological need for food. Distinguish between the biological need for food and the experience of hunger (including the role of incentives).
• List the symptoms that are used to diagnose anorexia nervosa, bulimia nervosa, muscle dysmorphia, and obesity. Describe the people who are most likely to develop these disorders and the most likely causes of them.
CHECK YOUR UNDERSTANDING
Match the following terms with the appropriate definition.
1. ___ drive 2. ___ drive reduction
3. ___ homeostasis
4. ___ self-actualization
5. ___ intrinsic motivation
6. ___ extrinsic motivation
a. The drive to realize one’s full potential b. state of balance in which the organism
functions effectively c. theory that motivated behavior is focused
on reducing bodily tension d. tending to perform behavior to receive
some external reward or avoid punishment e. state of tension brought on by biological
needs f. motivation arising from behavior itself
Answers:1. e.2. c.3. b.4. a.5. f.6. d.
APPLY YOUR UNDERSTANDING
1. You are home alone and have nothing to do. You find yourself walking around. You look for something to read, but nothing seems quite right. Then you check to see if anything interesting is on TV, but again nothing seems worth watching. Finally, you decide to go jogging. This kind of motivated behavior that increases the state of arousal is a problem for
a. the instinct theory of motivation. b. any theory of motivation. c. the drive-reduction theory of motivation. d. the Yerkes–Dodson law.
2. While you are working on a complex task, your boss stops by your desk and says, “You’ve only got 10 more minutes to finish that up. It’s really important that it be done right. I know you can do it and I’m depending on you.” When you complain that he’s making you nervous and your performance will suffer, he replies, “I’m just trying to motivate you.” Which of the following does your boss apparently not understand?
a. drive-reduction theory b. homeostasis c. extrinsic motivation d. the Yerkes–Dodson law
Answers:1. c.2. d.
HUNGER AND THIRST Why do people usually get hungry at mealtime?
When you are hungry, you eat. If you don’t eat, your need for food will increase but your hunger will come and go. Moreover, shortly after lunch when you have no need for further food, if you pass a bakery and smell the baked goods, you may crave a donut or a scone. In other words, the psychological state of hunger is not the same as the biological need for food, although that need often sets the psychological state in motion.
Thirst also is stimulated by both internal and external cues. Internally, thirst is controlled by two regulators that monitor the level of fluids inside and outside the cells. But we may also become thirsty just seeing a TV commercial featuring people savoring tall, cool drinks in a lush, tropical setting (W. G. Hall, Arnold, & Myers, 2000; Rowland, 2002).
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Biological and Emotional Factors How can external cues influence our desire to eat?
Early research identified two regions in the hypothalamus that served as a kind of “switch” that turned eating on or off. When one of these centers was stimulated, animals began to eat; and when it was destroyed the animals stopped eating to the point of starvation. When the second region was stimulated, animals stopped eating; when it was destroyed, animals ate to the point of extreme obesity. However, recent studies have challenged this simple “on–off” explanation for the control of eating by showing that a number of other areas of the brain are also involved (Olszewski, Cedernaes, Olsson, Levine, & Schiöth, 2008). For example, research has shown that regions of the cortex and spinal cord play an important role in regulating food intake. Moreover, the connections among brain centers that control hunger are now known to be considerably more complex than were once thought (Blundell & Halford, 1998; Brambilla, Monteleono, & Maj,. 2007; Volkow et al., 2003; Woods, Seeley, Porte, & Schwartz, 1998).
How do these various areas of the brain know when to stimulate hunger? It turns out that the brain monitors the blood levels of glucose (a simple sugar used by the body for energy), fats, carbohydrates, and the hormone insulin. (See Figure 8–3.) Changes in the levels of these substances signal the need for food. In addition, fat cells within our body produce the hormone leptin which travels in the bloodstream and is sensed by the hypo- thalamus. High levels of leptin signal the brain to reduce appetite, or to increase the rate at which fat is burned.
The brain also monitors the amount of food that you have eaten. Specialized cells in the stomach and the upper part of the small intestine sense the volume of food in the diges- tive system. When only a small quantity of food is present, these cells release a hormone called ghrelin into the bloodstream. Ghrelin travels to the brain where it stimulates appetite and focuses our thoughts and imagination on food (Näslund & Hellström, 2007; Schmid et al., 2005).
ghrelin A hormone produced in the stomach and small intestines that increases appetite.
Figure 8–3 Physiological factors regulating appetite and body weight. A variety of chemical messengers interact to stimulate and suppress appetite. Among these are insulin, leptin, and ghrelin.
Hypothalamus The brain monitors
levels of glucose, fats, carbohydrates, and hormones
Ghrelin Released by the empty stomach, this hormone stimulates appetite
Insulin Secreted by the pancreas, this hormone keeps glucose levels balanced
Leptin Fat cells secrete this hormone. High levels signal the brain to reduce appetite or to increase metabolism
glucose A simple sugar used by the body for energy.
leptin A hormone released by fat cells that reduces appetite.
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But, as we noted earlier, the biological need for food is not the only thing that can trigger the experience of hunger. For example, a single night of sleep deprivation can leave one feeling hungry by increasing ghrelin levels and decreasing leptin levels (Schmid, Hallschmid, Jauch- Chara, Born, & Schultes, 2008). Moreover, the mere sight, smell, or thought of food causes an increase in insulin production, which, in turn, lowers glucose levels in the body’s cells, mirroring the body’s response to a physical need for food (Logue, 2000). Thus, the aroma from a nearby restaurant may serve as more than an incentive to eat; it may actually cause the body to react as though there is a real biological need for food. Most Americans eat three meals a day at fairly regular intervals. Numer- ous studies with both humans and animals have shown that regularly eating at particular times during the day leads to the release at those times of the hormones and neurotransmitters that cause hunger (Woods, Schwartz, Baskin, & Seeley, 2000). In other words, we get hun- gry around noon partly because the body “learns” that if it’s noon, it’s time to eat.
incentive External stimulus that prompts goal- directed behavior.
Diversity–Universality Hunger and Eating The hunger drive is tied to emotions in complex ways. Some people head for the refrigera- tor whenever they are depressed, bored, anxious, or angry. Others lose all interest in food at these times and complain that they are “too upset to eat.” One student studying for an important exam spends as much time eating as reading; another student studying for the same exam lives on coffee until the exam is over. Under emotionally arousing conditions, what one person craves may turn another person’s stomach.
What people eat when they are hungry also varies greatly as a result of learning and social conditioning. Although most Americans will not eat horsemeat, it is very popular in several European countries. Yet many Americans consume pork, which violates both Islamic and Jewish dietary laws. In some parts of South Asia, Africa, and China, people consider monkey brains a delicacy. And in Cambodia, fried tarantulas are popular and cheap! ■
Eating Disorders and Obesity How can you tell if someone is suffering from anorexia nervosa or bulimia?
Anorexia Nervosa and Bulimia Nervosa “When people told me I looked like someone from Auschwitz [the Nazi concentration camp], I thought that was the highest compliment anyone could give me.” This confession comes from a young woman who as a teenager suffered from a serious eating disorder known as anorexia nervosa. She was 18 years old, 5 feet 3 inches tall, and weighed 68 pounds. This young woman was lucky. She managed to overcome the disorder and has since maintained normal body weight. Many others are less fortunate. In fact, Canadian researchers found that over 10% of the young women with anorexia nervosa between 1981 and 2000 died as a result of the disorder, one of the highest fatality rates for psychiatric disorders affecting young females (Birmingham, Su, Hlynsky, Goldner, & Gao, 2005; Derman & Szabo, 2006; Park, 2007).
The following four symptoms are used in the diagnosis of anorexia nervosa (American Psychiatric Association, 2000; Bulik, Reba, Siega-Riz, & Reichborn-Kjennerud, 2005):
1. Intense fear of becoming obese, which does not diminish as weight loss progresses. 2. Disturbance of body image (for example, claiming to “feel fat” even when emaciated).
How and when you satisfy hunger and thirst depends on social, psychological, environmental, and cultural influences as well as on physiological needs. For example, the Japanese tea ceremony (above) is concerned more with restoring inner harmony than with satisfying thirst. Do you think the office worker (below) is drinking coffee because she is thirsty?
anorexia nervosa A serious eating disorder that is associated with an intense fear of weight gain and a distorted body image.
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3. Refusal to maintain body weight at or above a minimal normal weight for age and height.
4. In females, the absence of at least three consecutive menstrual cycles.
Approximately 1% of all adolescents suffer from anorexia nervosa; about 90% of these are White upper- or middle-class females (Bulik et al., 2006).
Anorexia is frequently compounded by another eating disorder known as bulimia nervosa (Herpertz-Dahlmann, 2009). The following criteria are used for its diagnosis (American Psychiatric Association, 2000):
1. Recurrent episodes of binge eating (rapid consumption of a large amount of food, usually in less than 2 hours).
2. Recurrent inappropriate behaviors to try to prevent weight gain, such as self- induced vomiting.
3. Binge eating and compensatory behaviors occurring at least twice a week for three months.
4. Body shape and weight excessively influencing the person’s self-image. 5. Occurrence of the just-mentioned behaviors at least sometimes in the absence
Approximately 1 to 2% of all adolescent females suffer from bulimia nervosa, though recent evidence suggests this number may be decreasing (Keel, Heatherton, Dorer, Joiner, & Zalta, 2006). Once again, the socioeconomic group at highest risk for bulimia is upper- middle- and upper-class women.
Although anorexia and bulimia are much more prevalent among females than males (Gleaves, Miller, Williams, & Summers, 2000; S. Turnbull, Ward, Treasure, Jick, & Derby, 1996), many more men are affected by these disorders than was once suspected (Gila, Castro, & Cesena, 2005). Both men and women with eating disorders are preoccupied with body image, but men are not necessarily obsessed with losing weight (Ousley, Cordero, & White, 2008). For example, a related phenomenon called muscle dysmorphia appears to be on the increase among young men (Olivardia, 2007). Muscle dysmorphia is an obsessive concern with one’s muscle size. Men with muscle dysmorphia, many of whom are well muscled, are nonetheless distressed at their perceived puniness, and spend an inordinate amount of time fretting over their diet and exercising to increase their muscle mass (C. G. Pope, Pope, & Menard, 2005).
Little is known about the factors that contribute to eating disorders among men (Crosscope-Happel, 2005), though research has shown that muscle dysmorphia is associ- ated with low self-esteem and having been bullied as a child (Wolke & Sapouna, 2008). We know considerably more about the factors that contribute to eating disorders in women (Favaro, Tenconi, & Santonastaso, 2006; Garner & Magana, 2006). On one hand, mass media promote the idea that a woman must be thin to be attractive. In addition, women with bulimia commonly have low self-esteem, are hypersensitive to social interactions, and are more likely to come from families where negative comments are often made about weight (Crowther, Kichler, Sherwood, & Kuhnert, 2002; Zonnevylle-Bender et al, 2004). Many also display clinical depression or obsessive–compulsive disorder (see Chapter 12, “Psychological Disorders”) and have engaged in self-injurious behaviors such as cutting themselves (Herpertz-Dahlmann, 2009; Milos, Spindler, Ruggiero, Klaghofer, & Schnyder, 2002; Paul, Schroeter, Dahme, & Nutzinger, 2002). Finally, there is growing evidence that genetics plays a role in both anorexia nervosa and bulimia nervosa, although the two eating disorders may have a very different genetic basis (Jacobi, Hayward, de Zwaan, Kraemer, & Agras, 2004; Keel & Klump, 2003).
Anorexia and bulimia are notoriously hard to treat, and there is considerable disagree- ment on the most effective approach to therapy (G. T. Wilson, Grilo, & Vitousek, 2007; Yager, 2008). In fact, some psychologists doubt that we can ever eliminate eating disorders in a cul- ture bombarded with the message that “thin is in” (Fairburn, Cooper, Shafran, & Wilson, 2008). Regrettably, in many developing countries such as Taiwan, Singapore, and China, where dieting is becoming a fad, eating disorders, once little known, are now becoming a serious problem (H. Chen & Jackson, 2008; Sing Lee, Chan, & Hsu, 2003).
Does the American obsession with superslimness lead adolescents to become anorexic?
bulimia nervosa An eating disorder characterized by binges of eating followed by self-induced vomiting.
muscle dysmorphia A disorder generally seen in young men involving an obsessive concern with muscle size.
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Obesity and Weight Control According to the U.S. Surgeon General, obesity is the most pressing health problem in America (Chamber- lin, 2008; P. J. Johnson, 2003; Office of the Surgeon General, 2007). Obesity refers to an excess of body fat in relation to lean body mass, while overweight refers to weighing more than a desirable standard, whether from high amounts of fat or being very muscular. Obesity has increased by more than 50% during the past decade, with more than two-thirds of Ameri- cans being either overweight or obese. In con- trast to anorexia nervosa and bulimia nervosa, obesity is more prevalent among Black women than among White women (Y. C. Wang, Colditz, & Kuntz, 2007).
Even more disturbing, the rate of obesity among young people has more than tripled since 1980, with over 9 million overweight adolescents in America today. (See Figure 8–4). This problem is particularly serious since overweight children and adolescents are more likely to become overweight adults who are at an increased risk for serious diseases like hyperten- sion, cardiovascular disease, diabetes, and sleep apnea (American Heart Association, 2009; Nishimura et al., 2003).
Many factors contribute to overeating and obesity (Hebebrand & Hinney, 2009). In some cases, people inherit a tendency to be overweight (Frayling et al., 2007; Ramadori et al., 2008). Neuroimaging studies suggest part of this problem may stem from an inherited tendency in some people to become addicted to compulsive eating (similar to the genetic predisposition toward drug and alcohol addiction). As a result of this predisposition, these individuals are more vulnerable to cravings triggered by food cues in their environment, and less responsive to their body’s internal signaling of satiety (Leutwyler-Ozelli, 2007).
Eating habits established during childhood are also important because they determine the number of fat cells that develop in the body and that number remains fairly constant throughout life. Dieting during adulthood only decreases the amount of fat each cell stores; it doesn’t reduce the total number of fat cells (Spalding et al., 2008).
A sedentary lifestyle also contributes to obesity. Children in the United States today are more likely to watch television and play video games than to play soccer or hockey; and many adults lack adequate physical activity, too. Abundant opportunities and encouragement to overeat in American culture also play a role. Several studies have shown that many obese people eat more than half their calories at night (Mieda, Williams, Richardson, Tanaka, & Yanagisawa, 2006). Portion size has also increased in recent years, as has the constant availability of food from vending machines and fast-food restaurants.
Adding to the medical difficulties accompanying obesity, overweight people often face ridicule and discrimination resulting in significant economic, social, and educational loss (D. Carr & Friedman, 2005; Maranto & Stenoien, 2000). For example, overweight women have reported lowered self-confidence owing to victimization in school and at work because of their weight (C. Johnson, 2002; Rothblum, Brand, Miller, & Oetjen, 1990). And obese male lawyers earn less than male lawyers of normal weight (Saporta & Halpern, 2002). Even children who are overweight display increased rates of behavior problems, including aggression, lack of discipline, immaturity, anxiety, low self-esteem, and depres- sion when compared with their normal-weight peers (Ward-Begnoche et al., 2009; Q. Yang & Chen, 2001).
With all of the problems associated with being overweight, many people are constantly trying to lose weight. There are no quick fixes to weight loss, but the suggestions in “Apply- ing Psychology: The Slow (but Lasting) Fix for Weight Gain” can help people lose weight and keep it off.
Figure 8–4 Rising obesity among American youth. The number of overweight children and adolescents has increased sharply in recent years. From 1980 to 2002, the percentage of overweight adolescents tripled. This trend is particularly disturbing since overweight children and adolescents are likely to become overweight adults, placing them at increased risk for cardiovascular disease, hypertension, and diabetes. Source: CDC/NCHS, NHES, and NHANES.
Notes: Excludes pregnant women starting with 1971–74. Pregnancy status not available for 1963–65 and 1966–70. Data for 1963–65 are for children 6–11 years of age; data for 1966–70 are for adolescents 12–17 years of age, not 12–19 years.
1999–02 2003–061988–94 1976–80 1971–74 1963–70 Pe
Age in years
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The Slow (but Lasting) Fix for Weight Gain
triggering hunger. Many people find that if they do their grocery shopping on a full stomach, it is easier to resist the temptation to buy junk foods.
5. Set realistic goals. Focus at least as much on preventing weight gain as on losing weight. If you must lose weight, try to shed just one pound a week for 2 or 3 months. After that, concentrate on maintaining that new, lower weight for several months before moving on to further weight loss.
6. Reward yourself—in ways unrelated to food—for small improvements. Use some of the behavior-modification techniques described in Chapter 5: Reward yourself not only for each pound of weight lost but also for each day or week that you maintain that weight loss. And remember, numerous studies have shown that losing weight is much easier than keeping weight off (T. Mann et al, 2007). The only way you can keep the weight off is by con- tinuing to adhere to a reasonable diet and exercise plan (Adbel-Hamid, 2003; McGuire, Wing, Klem, Lang, & Hill, 1999).
To learn more about weight control, visit our Web site at www.prenhall.com/morris.
The study of hunger and eating has led tosome compelling insights into the prob-lem of weight control. It appears that our bodies are genetically “set” to maintain a certain weight (Hallschmid, Benedict, Born, Fehm, & Kern, 2004; G. N. Wade, 2004). According to this set point theory, if you consume more calories than you need for that weight, your metabolic rate will increase. As a result, you will feel an increase in energy that will prompt you to be more active, thereby burning more calories. If, however, you eat fewer calories than are needed to maintain your weight, your metabolic rate will decrease; you will feel tired and become less active, thereby burning fewer calories. This mechanism was no doubt helpful dur- ing the thousands of years that our species lived literally hand to mouth, but it is less helpful where food is abundant, as in mod- ern industrialized nations.
An implication of our current under- standing of hunger and weight regulation is that a successful weight-control pro- gram must be long term and must work with, rather than against, the body’s nor- mal tendency to maintain weight. On the basis of studies of the hunger drive and the relationship between eating and body weight, here are our recommendations for weight control:
1. First, check with your doctor before you start. People want quick fixes, so they often go overboard on dieting or exercise, sometimes with disastrous consequences. Make sure your weight loss program will be safe.
2. Increase your body’s metabolism through regular exercise. The most effective metabolism booster is 20–30 minutes of moderate activity several times a week. Although only about 200–300 calories are burned off dur- ing each exercise session, the exercise increases the resting metabolic rate. This means that you burn more calories when not exercising. Thus, exercise is an important part of a weight reduction program (Sarwer, Allison, & Berkowitz, 2004; Wadden, Crerand, & Brock, 2005).
3. Modify your diet. A moderate reduc- tion in calories is beneficial. Also, reduce your consumption of fats (par- ticularly saturated fats) and sugars. Sug- ars trigger an increase in the body’s level of insulin; and high levels of fat and insulin in the blood stimulate hunger.
4. Reduce external cues that encourage you to eat undesirable foods. The mere sight or smell of food can increase the amount of insulin in the body, thus
CHECK YOUR UNDERSTANDING
1. The level of ___________ in the blood signals hunger. 2. Hunger can be stimulated by both ____________ and ____________ cues.
Match the following terms with the appropriate definition. 3. ___ hypothalamus 4. ___ anorexia nervosa 5. ___ bulimia nervosa
a. recurrent episodes of binge eating, followed by vomiting, taking laxatives, or excessively exercising
b. contains both a hunger center and a satiety center c. intense fear of obesity, disturbance of body image, and very little intake of food,
with resulting weight well below normal minimums
Answers:1. glucose.2. internal, external.3. b.4. c.5. a.
set point theory A theory that our bodies are genetically predisposed to maintaining a certain weight by changing our metabolic rate and activity level in response to caloric intake.
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Motivation and Emotion 269
SEX How is the sex drive different from other primary drives?
Sex is the primary drive that motivates reproductive behavior. Like the other primary drives, it can be turned on and off by biological conditions in the body as well as by environmental cues. The human sexual response is also affected by social experience, sexual experience, nutrition, emotions, and age. In fact, just thinking about, viewing, or having fantasies about sex can lead to sexual arousal in humans (Beauregard, Lévesque, & Bourgouin, 2001; Bogaert & Fawcett, 2006). Sex differs from other primary drives in one important way: Hunger and thirst are vital to the survival of the indi- vidual, but sex is vital only to the survival of the species.
Biological Factors How well do we understand the biology of the sex drive?
Biology clearly plays a major role in sexual motivation. At one time, the level of hormones such as testosterone—the male sex hormone—was believed to determine the male sex drive. Today, scientists recognize that hormonal influences on human sexual arousal are considerably more complex (Gades et al., 2008). While moment-to-moment fluctuations in testosterone levels are not directly linked to sex drive, baseline levels of testosterone are associated with the frequency of sexual behavior and satisfaction (Persky, 1978). In addi- tion, testosterone supplements have been shown to increase sex drive in women (Bolour & Braunstein, 2005). However, unlike lower animals, whose sexual activity is tied to the female’s reproductive cycle, humans are capable of sexual arousal at any time.
Many animals secrete substances called pheromones that promote sexual readiness in potential partners (see Chapter 3, “Sensation and Perception”). Some evidence suggests that humans, too, secrete pheromones, in the sweat glands of the armpits and in the geni- tals, and that they may influence human sexual attraction (Boulkroune, Wang, March, Walker, & Jacob, 2007; Keverne, 2004; Lundström, Goncalves, Esteves, & Olsson, 2003). The
APPLY YOUR UNDERSTANDING
1. You are on your way out to a play, and you notice that you are hungry. While you are watching the play, you no longer feel hungry. But when the play is over, you notice that you are hungry again. This demonstrates that
a. the biological need for food causes hunger. b. if you are distracted, primary drives but not secondary drives will decrease. c. hunger does not necessarily correspond to a biological need for food. d. primary drives are unlearned and are essential to survival of the individual or species.
2. You’ve noticed that when you are hungry, eating a carrot doesn’t satisfy you, but eating a chocolate bar does. This is probably because the chocolate bar, to a greater extent than the carrot:
a. increases the amount of glucose in your bloodstream, which in turn reduces hunger. b. reduces your biological need for food. c. is an extrinsic motivator. d. serves as an incentive.
Answers:1. c.2. a.
L E A R N I N G O B J E C T I V E S • Describe how sexual motivation is
both similar to and different from other primary drives. Identify the factors (biological and nonbiological) that affect sexual motivation.
• Describe the sexual response cycle and how it differs for men and women. Briefly explain what is meant by the statement that “research indicates that the sex lives of most Americans differ significantly from media portrayals.”
• Summarize the research evidence for and against a biological basis for sexual orientation.
The Sex Drive
The sex drive is said to have no survival value for the individual; its only valueis the survival of the species. Suppose that humans were capable of repro-ducing, but no longer had a sex drive. How would life be different? In answering that question, would it help to collect data on people alive today who, for one reason or another, have lost their sex drive? Are there ways in which information from such people might not be useful to you?
testosterone The primary male sex hormone.
brain exerts a powerful influence on the sex drive, too. In particular, the limbic system and the insula, located deep within the brain, are involved in sexual excitement (Balfour, 2004; Bianchi-Demicheli & Ortigue, 2007) (see Chapter 2, “Biological Basis of Behavior”).
The biology of sexual behavior is better understood than that of the sex drive itself. Sex researchers William Masters and Virginia Johnson long ago identified a sexual response cycle that consists of four phases: excitement, plateau, orgasm, and resolution (W. H. Masters & Johnson, 1966). In the excitement phase, the genitals become engorged with blood. In the male, this causes erection of the penis; in the female, it causes erection of the clitoris and nipples. This engorgement of the sexual organs continues into the plateau phase, in which sexual tension levels off. During this phase, breathing becomes more rapid and genital secre- tions and muscle tension increase. During orgasm, the male ejaculates and the woman’s uterus contracts rhythmically; and both men and women experience some loss of muscle control. Following orgasm males experience a refractory period, which can last from a few minutes to several hours, during which time they cannot have another orgasm. Women do not have a refractory period, and may, if stimulation is reinitiated, experience another orgasm almost immediately. The resolution phase is one of relaxation in which muscle ten- sion decreases and the engorged genitals return to normal. Heart rate, breathing, and blood pressure also return to normal. Figure 8–5 displays the pattern of sexual responses for men and women.
Cultural and Environmental Factors How does culture influence sexual behavior?
Although hormones and the nervous system do figure in the sex drive, human sexual moti- vation, especially in the early stages of excitement and arousal, is much more dependent on experience and learning than on biology.
What kinds of stimuli activate the sex drive? It need not be anything as immediate as a sexual partner. The sight of one’s lover, as well as the smell of perfume or aftershave lotion, can stimulate sexual excitement. Soft lights and music often have an aphrodisiac effect. One person may be unmoved by an explicit pornographic movie but aroused by a romantic love story, whereas another may respond in just the opposite way. Ideas about what is moral, appro- priate, and pleasurable also influence our sexual behavior. Finally, as shown in Figure 8–6, one global survey of reported sexual activity indicated the rate at which couples have sex varies dramatically around the world (Durex Global Sex Survey, 2005). This survey also revealed that the frequency of sexual activity varies by age, with 35- to 44-year-olds reporting to have sex an average of 112 times a year, 25- to 34-year-olds having sex an average of 108 times per year, and 16- to 20-year-olds having sex 90 times annually.
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Figure 8–5 The sexual response cycle in males and females. As the illustration shows, males typically go through one complete response cycle and are then capable of becoming excited again after a refractory period. Females have three characteristic patterns: one similar to the male cycle, with the added possibility of multiple orgasms (A); one that includes a lengthy plateau phase with no orgasm (B); and a rapid cycle including several increases and decreases of excitement before reaching orgasm (C). Source: Adapted from Masters & Johnson, 1966. Reprinted by permission of The Masters and Johnson Institute.
Cycle in Men
Cycle in Women
sexual response cycle The typical sequence of events, including excitement, plateau, orgasm, and resolution, characterizing sexual response in males and females.
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Gender equality is also an important cultural factor in how much people report enjoy- ing their sex lives. For example, heterosexual couples living in countries where women and men hold equal status are the most likely to report that their sex lives are emotionally and physically satisfying. Conversely, both men and women in countries where men tradition- ally are more dominant report the least satisfying sex lives (Harms, 2006).
Patterns of Sexual Behavior Among Americans Contrary to media portrayals of sexual behavior in publications like Playboy or TV shows like Sex in the City, which depict Americans as oversexed and unwilling to commit to long- term relationships, research indicates that most people are far more conservative in their sex lives. One carefully designed study (Michael, Gagnon, Laumann, & Kolata, 1994) of 3,432 randomly selected people between the ages of 18 and 59 revealed the following patterns in the sexual activity of American men and women:
• About one-third of those sampled had sex twice a week or more, one-third a few times a month, and the remaining third a few times a year or not at all.
• The overwhelming majority of respondents did not engage in kinky sex. Instead, vaginal intercourse was the preferred form of sex for over 90% of those sampled. Watching their partner undress was ranked second, and oral sex, third.
• Married couples reported having sex more often—and being more satisfied with their sex lives—than did unmarried persons (see also Waite & Joyner, 2001).
• The average duration of sexual intercourse reported by most people was approxi- mately 15 minutes.
• The median number of partners over the lifetime for males was 6 and for females 2 (17% of the men and 3% of the women reported having sex with over 20 partners).
• About 25% of the men and 15% of the women had committed adultery. Extensive research has also documented at least four significant differences in sexuality
between American men and women: Men are more interested in sex than are women;