Matthew T. Gailliot

Self-control relies on glucose as a limited energy source: Willpower is more than a metaphor.

The present work suggests that self-control relies on glucose as a limited energy source. Laboratory tests of self-control (i.e., the Stroop task, thought suppression, emotion regulation, attention control) and of social behaviors (i.e., helping behavior, coping with thoughts of death, stifling prejudice during an interracial interaction) showed that (a) acts of self-control reduced blood glucose levels, (b) low levels of blood glucose after an initial self-control task predicted poor performance on a subsequent self-control task, and (c) initial acts of self-control impaired performance on subsequent self-control tasks, but consuming a glucose drink eliminated these impairments. Self-control requires a certain amount of glucose to operate unimpaired. A single act of self-control causes glucose to drop below optimal levels, thereby impairing subsequent attempts at self-control.

The Physiology of Willpower: Linking Blood Glucose to Self-Control

Past research indicates that self-control relies on some sort of limited energy source. This review suggests that blood glucose is one important part of the energy source of self-control. Acts of self-control deplete relatively large amounts of glucose. Self-control failures are more likely when glucose is low or cannot be mobilized effectively to the brain (i.e., when insulin is low or insensitive). Restoring glucose to a sufficient level typically improves self-control. Numerous self-control behaviors fit this pattern, including controlling attention, regulating emotions, quitting smoking, coping with stress, resisting impulsivity, and refraining from criminal and aggressive behavior. Alcohol reduces glucose throughout the brain and body and likewise impairs many forms of self-control. Furthermore, self-control failure is most likely during times of the day when glucose is used least effectively. Self-control thus appears highly susceptible to glucose. Self-control benefits numerous social and interpersonal processes. Glucose might therefore be related to a broad range of social behavior.

Depletion Makes the Heart Grow Less Helpful: Helping as a Function of Self-Regulatory Energy and Genetic Relatedness

Often people are faced with conflict between prosocial motivations for helping and selfish impulses that favor not helping. Three studies tested the hypothesis that self-regulation is useful for managing such motivational conflicts. In each study, depleted self-regulatory energy reduced willingness to help others. Participants who broke a habit, relative to participants who followed a habit, later reported reduced willingness to help in hypothetical scenarios (e.g., donating food or money; Studies 1 and 3). Controlling attention while watching a video, relative to watching it normally, reduced volunteering efforts to help a victim of a recent tragedy— but drinking a glucose drink undid this effect (Study 2). Depleted energy reduced helping toward strangers but it did not reduce helping toward family members (Study 3). Helping requires self-regulatory energy to manage conflict between selfish and prosocial motivations—a metabolically expensive process—and thus depleted energy reduces helping and increased energy (glucose) increases helping.

Self-regulatory processes defend against the threat of death : Effects of self-control depletion and trait self-control on thoughts and fears of dying

Nine studies (N = 979) demonstrated that managing the threat of death requires self-regulation. Both trait and state self-control ability moderated the degree to which people experienced death-related thought and anxiety. Participants high (vs. low) in self-control generated fewer death-related thoughts after being primed with death, reported less death anxiety, were less likely to perceive death-related themes in ambiguous scenes, and reacted with less worldview defense when mortality was made salient. Further, coping with thoughts of death led to self-regulatory fatigue. After writing about death versus a control topic, participants performed worse on several measures of self-regulation that were irrelevant to death. These results suggest that self-regulation is a key intrapsychic mechanism for alleviating troublesome thoughts and feelings about mortality.

Can't Take My Eyes off You: Attentional Adhesion to Mates and Rivals

In 3 experiments, mating primes interacted with functionally relevant individual differences to guide basic, lower order social perception. A visual cuing method assessed biases in attentional adhesion--a tendency to have ones attention captured by particular social stimuli. Mate-search primes increased attentional adhesion to physically attractive members of the opposite sex (potential mates) among participants with an unrestricted sociosexual orientation but not among sexually restricted participants (Studies 1 and 2). A mate-guarding prime increased attentional adhesion to physically attractive members of ones own sex (potential rivals) among participants who were concerned with threats posed by intrasexual competitors but not among those less concerned about such threats (Study 3). Findings are consistent with a functionalist approach to motivation and social cognition and highlight the utility of integrating evolutionary and social cognitive perspectives.

Self-Regulation and Sexual Restraint: Dispositionally and Temporarily Poor Self-Regulatory Abilities Contribute to Failures at Restraining Sexual Behavior

Nonsexual deficiencies in self-control may contribute to inappropriate or objectionable sexual behaviors, as shown by survey questionnaires, autobiographical narratives, and experimental manipulations. People with low overall trait self-control and/or whose self-control strength had been depleted by recent, nonsexual acts were less likely than other people to stifle inappropriate sexual thoughts and to resist the temptation to engage in sexual activities with someone other than their primary relationship partner. They also engaged in more extensive sexual activity in the laboratory with their dating partner and they reported more undercontrolled or impulsive sexual behavior generally. Furthermore, there was some evidence that the effects of diminished self-control were strongest among those with the strongest sexual desires (men and sexually unrestricted individuals) and among couples with less sexual experience.

Increasing Self-Regulatory Strength Can Reduce the Depleting Effect of Suppressing Stereotypes:

Three longitudinal studies and one correlational study tested the hypothesis that increasing self-regulatory strength by regular self-regulatory exercise would reduce the intrapsychic costs of suppressing stereotypes. Participants tried to resist using stereotypes while describing or talking to a stimulus person. Participants whose habitual motivation to suppress stereotypes was low exhibited impaired Stroop and anagram performance after the suppression task, presumably because of self-regulatory depletion (i.e., a reduction of self-regulatory strength following prior use). Two weeks of self-regulation exercises (such as using one’s nondominant hand or refraining from cursing) eliminated this effect. These findings indicate that self-regulatory exercise can improve resistance to self-regulatory depletion and, consequently, people can suppress stereotypes without suffering subsequent decrements in task performance.

Terror Management Theory and Self-Esteem Revisited: The Roles of Implicit and Explicit Self-Esteem in Mortality Salience Effects

Three studies tested the roles of implicit and/or explicit self-esteem in reactions to mortality salience. In Study 1, writing about death versus a control topic increased worldview defense among participants low in implicit self-esteem but not among those high in implicit self-esteem. In Study 2, a manipulation to boost implicit self-esteem reduced the effect of mortality salience on worldview defense. In Study 3, mortality salience increased the endorsement of positive personality descriptions but only among participants with the combination of low implicit and high explicit self-esteem. These findings indicate that high implicit self-esteem confers resilience against the psychological threat of death, and therefore the findings provide direct support for a fundamental tenet of terror management theory regarding the anxiety-buffering role of self-esteem.

Mortality Salience Increases Adherence to Salient Norms and Values

Four studies indicate that mortality salience increases adherence to social norms and values, but only when cultural norms and values are salient. In Study 1, mortality salience coupled with a reminder about cultural values of egalitarianism reduced prejudice toward Blacks among non-Black participants. In Studies 2 through 4, a mortality salience induction (e.g., walking through a cemetery) increased self-reported and actual helping behavior only when the cultural value of helping was salient. These results suggest that people may adhere to norms and values so as to manage awareness of death.

Intrasexual Vigilance: The Implicit Cognition of Romantic Rivalry

Four experiments tested the hypothesis that concerns about infidelity would lead people, particularly those displaying high chronic levels of romantic jealousy, to display a functionally coordinated set of implicit cognitive biases aimed at vigilantly processing attractive romantic rivals. Priming concerns about infidelity led people with high levels of chronic jealousy (but not those low in chronic jealousy) to attend vigilantly to physically attractive same-sex targets at an early stage of visual processing (Study 1), to strongly encode and remember attractive same-sex targets (Study 2), and to form implicit negative evaluations of attractive same-sex targets (Studies 3 and 4). In each case, effects were observed only for same-sex targets who were physically attractive-individuals who can pose especially potent threats to a persons own romantic interests. These studies reveal a cascade of implicit, lower order cognitive processes underlying romantic rivalry and identify the individuals most likely to display those processes. At a broader conceptual level, this research illustrates the utility of integrating social cognitive and evolutionary approaches to psychological science.