I blurt out whatever is on my mind.
I never allow myself to lose control.
I get carried away by my feelings.
I lose my temper too easily.
I don’t keep secrets very well.
I’d be better off if I stopped to think before acting.
Pleasure and fun sometimes keep me from getting work done.
I am always on time.
After adjusting for any tendency just to tick off socially desirable traits, the researchers combined the responses into a single measure of habitual self-control. They found that the students with higher scores got better grades, had fewer eating disorders, drank less, had fewer psychosomatic aches and pains, were less depressed, anxious, phobic, and paranoid, had higher self-esteem, were more conscientious, had better relationships with their families, had more stable friendships, were less likely to have sex they regretted, were less likely to imagine themselves cheating in a monogamous relationship, felt less of a need to “vent” or “let off steam,” and felt more guilt but less shame.96 Self-controllers are better at perspective-taking and are less distressed when responding to others’ troubles, though they are neither more nor less sympathetic in their concern for them. And contrary to the conventional wisdom that says that people with too much self-control are uptight, repressed, neurotic, bottled up, wound up, obsessive-compulsive, or fixated at the anal stage of psychosexual development, the team found that the more self-control people have, the better their lives are. The people at the top of the scale were the mentally healthiest.
Are people with low self-control more likely to perpetrate acts of violence? Circumstantial evidence suggests they are. Recall from chapter 3 the theory of crime (championed by Michael Gottfredson, Travis Hirschi, James Q. Wilson, and Richard Herrnstein) in which the people who commit crimes are those with the least self-control.97 They opt for small, quick, ill-gotten gains over the longer-term fruits of honest toil, among them the reward of not ending up in jail. Violent adolescents and young adults tend to have a history of misconduct at school, and they tend to get into other kinds of trouble that bespeak a lack of self-control, such as drunk driving, drug and alcohol abuse, accidents, poor school performance, risky sex, unemployment, and nonviolent crimes such as burglary, vandalism, and auto theft. Many violent crimes are strikingly impulsive. A man will walk into a convenience store for some cigarettes and on the spur of the moment pull out a gun and rob the cash register. Or he will react to a curse or insult by pulling out a knife and stabbing the insulter.
To make the case more than circumstantial, one would have to show that the psychologists’ conception of self-control (measured by people’s choice between smaller-sooner and larger-later rewards or by ratings of their own impulsiveness) match up with the criminologists’ conception of self-control (measured by actual outbreaks of violence). Mischel tested children in urban middle schools and in camps for troubled youth and found that the children who waited longer for larger piles of M&Ms were also less likely to get into fights and to pick on their playmates.98 Many studies of teachers’ ratings have confirmed that the children who appear to them to be more impulsive are also the ones who are more aggressive.99 A particularly informative study by the psychologists Avshalom Caspi and Terri Moffitt followed an entire cohort of children born in the New Zealand city of Dunedin from the year of their birth in 1972–73.100 Three-year-old children who were rated as undercontrolled—that is, impulsive, restless, negativistic, distractible, and emotionally fluctuating—grew into twenty-one-year-olds who were far more likely to be convicted of a crime. (The study did not distinguish violent from nonviolent crimes, but later studies on the same sample showed that the two kinds of crime tend to go together.)101 And one of the causes of their greater criminality may have been differences in their anticipation of the consequences of their behavior. In their answers to questionnaires, the less-controlled people gave lower odds that they would get arrested following a string of crimes, and that they would lose the respect of their friends and family if their illegal behavior came to light.
The trajectory of crime in adolescence and young adulthood is related to an increase in self-control, measured in a growing willingness to choose larger late rewards over smaller earlier ones. This change is partly driven by the physical maturation of the brain. The wiring of the prefrontal cortex is not complete until the third decade of life, with the lateral and polar regions developing last.102 But self-control is not the whole story. If delinquency depended only on self-control, young teenagers should become less and less likely to get in trouble as they turn into older teenagers, which is not what happens. The reason is that violence depends not just on self-control but on the urges that self-control has to control.103 Adolescence is also an age that sees the rise and fall of a motive called sensation-seeking, driven by activity in the Seeking system, which peaks at eighteen.104 It also sees an increase in male-against-male competitiveness, driven by testosterone.105 The rise in sensation-seeking and competitiveness can overtake the rise in self-control, making older adolescents and twenty-somethings more violent despite their blossoming frontal lobes. In the long run, self-control gains the upper hand when it is fortified by experience, which teaches adolescents that thrill-seeking and competitiveness have costs and that self-control has rewards. The arc of crime in adolescence is the outcome of these inner forces pushing and pulling in different directions.106
Self-control, then, is a stable trait that differentiates one person from another, beginning in early childhood. No one has done the twin and adoption studies that would be needed to show that performance on standard tests of self-control, such as the marshmallow test or the adult equivalent, are heritable. But it’s a good bet that they are, because pretty much every psychological trait has turned out to be partly heritable.107 Self-control is partly correlated with intelligence (with a coefficient of about 0.23 on a scale from–1 to 1), and the two traits depend on the same parts of the brain, though not exactly in the same way.108 Intelligence itself is highly correlated with crime—duller people commit more violent crimes and are more likely to be the victims of a violent crime—and though we can’t rule out the possibility that the effect of self-control is really an effect of intelligence or vice versa, it’s likely that both traits contribute independently to nonviolence.109 Another clue that self-control is heritable is that a syndrome marked by a shortage of self-control, attention deficit hyperactivity disorder (which is also linked with delinquency and crime), is among the most heritable of personality traits.110
So far all the evidence that violence is released by a lack of self-control is correlational. It comes from the discovery that some people have less self-control than others, and that those people are likelier to misbehave, get angry, and commit more crimes. But the correlation doesn’t prove causation. Perhaps people with low self-control are more crime-prone because they are also less intelligent, or they come from worse environments, or they have some other across-the-board disadvantage. More important, a stable trait that differs from one person to another cannot explain the main thing we’re trying to explain: why rates of violence change over the course of history. To show that, we need to show that individual people, when they let up or clamp down on their self-control, get more or less violent as a result. And we must show that people and societies can cultivate the faculty of self-control over time and thereby drive down their rates of violence. Let’s see if we can find these missing links.
When a person fights an urge, it feels like a strenuous effort. Many of the idioms for self-control invoke the concept of force, such as willpower, force of will, strength of will, and self-restraint. The linguist Len Talmy has noticed that the language of self-control borrows from the language of force dynamics, as if self-control were a homunculus that physically impinged on a stubborn antagonist inside the skull.111 We use the same construction in Sally forced the door to open and Sally forced herself to go to work; in Biff controlled his dog and Biff controlled his te
mper. Like many conceptual metaphors, SELF-CONTROL IS PHYSICAL EFFORT turns out to have a kernel of neurobiological reality.
In a remarkable set of experiments, Baumeister and his collaborators have shown that self-control, like a muscle, can become fatigued. Their laboratory procedure is best introduced by quoting from the Method section of one of their papers:Procedure. Participants signed up for a study on taste perception. Each participant was contacted to schedule an individual session, and at that time the experimenter requested the participant to skip one meal before the experiment and make sure not to have eaten anything for at least 3 hr.
The laboratory room was carefully set up before participants in the food conditions arrived. Chocolate chip cookies were baked in the room in a small oven, and, as a result, the laboratory was filled with the delicious aroma of fresh chocolate and baking. Two foods were displayed on the table at which the participant was seated. One display consisted of a stack of chocolate chip cookies augmented by some chocolate candies. The other consisted of a bowl of red and white radishes.112
The cover story was that the experiment was on sensory memory and that the participants would experience one of two distinctive tastes and have to recall its qualities after a delay. The experimenter told half the participants to eat two or three of the cookies, and the other half to eat two or three of the radishes. She left the room and watched through a one-way mirror to confirm that the participant did not cheat. The article notes: “Several of them did indicate clear interest in the chocolates, to the point of looking longingly at the chocolate display and in a few cases even picking up the cookies to sniff at them.” The experimenter then told them they would have to wait fifteen minutes for the test of their memory of the taste. In the interim, they were to solve some puzzles that required tracing a geometric figure with a pencil without either retracing a line or lifting the pencil off the paper. Compounding the sadism, the experimenters had given them puzzles that were unsolvable, and measured how long the participant persisted before giving up. The ones who had eaten the cookies spent 18.9 minutes and made 34.3 attempts to solve the puzzle. The ones who had eaten the radishes spent 8.4 minutes and made 19.4 attempts. Presumably the radish eaters had depleted so much of their mental strength in resisting the cookies that they had little left to persist in solving the puzzles. Baumeister called the effect ego depletion , using Freud’s sense of ego as the mental entity that controls the passions.
The study raises many objections: maybe the radish eaters were just frustrated, or angry, or in a bad mood, or hungry. But the Baumeister team addressed them and over the following decade accumulated a raft of experiments showing that just about any task that requires an exercise of willpower can impede performance in any other task that requires willpower. Here are a few tasks that can deplete the ego:• Name the color in which a word is displayed (such as the word RED printed in blue ink), ignoring the color it spells out (the Stroop task).
• Track moving boxes on a screen, as if playing a shell game, while ignoring a comedy video on an adjacent screen.
• Write a convincing speech on why tuition fees should be raised.
• Write an essay about the typical day in the life of a fat person without using any stereotypes.
• Watch the scene in Terms of Endearment in which a dying Debra Winger says good-bye to her children, without showing emotion.
• For racially prejudiced people, carry on a conversation with an African American.
• Write down all your thoughts, but don’t think of a polar bear. 113
And here are some of the lapses in willpower that result:• Giving up sooner when squeezing a handgrip, solving anagrams, or watching a movie of a box on a table until something happens.
• Breaking a diet by eating ice cream from a container after rating a spoonful in a taste experiment.
• Drinking more beer in a taste experiment, even when having to take a simulated driving test immediately afterward.
• Failing to stifle sexual thoughts, such as in solving the anagram NISEP as penis rather than as spine.
• Failing to keep up a running conversation while teaching someone how to putt in golf.
• Being willing to pay more for an attractive watch, car, or boat.
• Blowing your payment for participation in the study on gum, candy, Doritos, or playing cards, which the experimenters had mischievously offered for sale.
Various control conditions allowed the psychologists to rule out alternative explanations such as fatigue, difficulty, mood, and lack of confidence. The only common denominator was the need for self-control.
An important implication of the research is that the exercise of self-control can conceal the differences among individual people.114 It’s no coincidence that 1960s popular culture, which denigrated sobriety and self-control, also denigrated conformity, as in the signature motto “Do your own thing.” Everyone has a different thing, but society insists on just one thing, so we must apply self-control to do it. If self-control flattens individuality, one can predict that when the ego is depleted, individuality will pop back up. And that is what the Baumeister group found. In the ice-cream-tasting experiment, when the participants had not been called on to exercise self-control beforehand, the dieters and the indiscriminate eaters consumed the same amount of ice cream. But when their willpower had been exhausted, the dieters ate more. Other individual differences unmasked by depletion of the ego included the degree of stereotyping by prejudiced and unprejudiced people, the amount of beer drunk by tipplers and moderate drinkers, and the amount of small talk made by shy and outgoing people.
The Baumeister group also vindicated the Victorian idea that some people—particularly men—have to exert their will to control their sexual appetites.115 In one study, the psychologists assessed how emotionally close a participant had to feel to another person before engaging in casual sex. People of both sexes differ along that dimension, and there is also a robust difference between the sexes, captured in the movie dialogue in which Diane Keaton says, “I believe that sex without love is a meaningless experience” and Woody Allen replies, “Yes, but as meaningless experiences go, it’s one of the best.” Half the participants in the study went through an ego depletion task (crossing out letters according to shifting rules), and all were then asked to imagine themselves being in a committed romantic relationship and then finding themselves in the hotel room of an attractive acquaintance of the opposite sex. They were then asked whether they imagined themselves succumbing to the temptation. Whether their wills had been tuckered or not, the participants (of both sexes) who had indicated that sex without love was a meaningless experience imagined they would resist the temptation. But a transient weakness of their will affected the ones who were more open to casual sex: if their ego had just been fatigued, their imagined selves were far more likely to say yes.
The pattern for the two sexes was revealing. When the willpower of the participants was fresh, men and women didn’t differ: both were resistant to imaginary cheating. When their wills had been weakened, the women were just as resistant, but the men imagined themselves likely to stray. Another sign that gallantry requires self-control came from an analysis that simply compared people who reported having a lot or a little self-control (ignoring momentary ego depletion). Among those with high self-control, neither the men and nor the women imagined cheating on their partners, but among the people with low self-control, the men imagined that they probably would. The pattern suggests that the exercise of self-control hides a deep difference between men and women. Freed from their own willpower, men are more likely to act as evolutionary psychology predicts.
Baumeister and Gailliot pushed their luck in one more experiment, aiming to show that self-control affects real, not just imagined, sexual activity. They invited couples into the lab who were either sexually experienced or just beginning their relationship, separated them, gave them an ego depletion task (concentrating on a boring video while shutting out distractions), reun
ited them, and invited them to be affectionate with each other for three minutes while the experimenter discreetly left the room. A sense of propriety prevented the experimenters from videotaping the couple or observing them from behind a one-way mirror, so they asked each partner to write a confidential paragraph describing exactly what had gone on between them. Experienced couples, if their wills had been depleted, were a bit less physical, as if sex had switched from a passion to a chore. But ego depletion made the inexperienced couples far more physical. According to the write-up, “They kissed open-mouthed for prolonged periods of time, groped and caressed each other (e.g., on the buttocks and woman’s chest), and even removed articles of clothing to expose themselves.”
According to the theory of the Civilizing Process, a dearth of self-control in medieval Europe underlay many forms of dissoluteness, including slovenliness, petulance, licentiousness, uncouthness, steep discounting of the future, and most important, violence. The science of self-control vindicates the idea that a single capability of mind can counteract many of these forms of dissipation. But it remains to be shown that violence is one of them. We know that people with less self-control are more cantankerous and trouble-prone. But can manipulating self-control in an experiment bring out the beast within?
No one wants a fight to break out in the lab, so Baumeister went to the hot sauce. Hungry participants were asked to take part in a study on the relation between tastes in food and written expression.116 They indicated their favorite and least favorite flavors, wrote an essay expressing their views on abortion, rated the essay of a bogus fellow participant, rated the taste of a food, and finally read their partner’s feedback on their essay. In the taste test, half of them had to rate the taste, texture, and aroma of a donut; half had to rate the taste, texture, and aroma of a radish. But just as they raised the stimulus to their mouth, the experimenter exclaimed, “Wait! I’m sorry; I think I screwed up. This isn’t for you. Please don’t eat the rest of it. Let me go figure out what’s supposed to be next.” He then left the participant alone with the donut or the radish for five minutes. Lest there be any doubt that this was a valid test of self-control, one may note the following passage in the write-up:Participants: Forty undergraduates participated in this study in exchange for course credit. Data from seven participants were discarded from all analyses, four due to expressed suspicion about the feedback and three due to participants having eaten the entire donut.