The strength model of self-control was proposed by Roy Baumeister, an eminent social psychologist, to describe how individuals can control their behavior, automatic tendencies, and natural desires in order to achieve long-term goals and conform to socially prescribed codes of behavior and norms. In this model, the terms self-control and self-regulation are used interchangeably to describe the capacity to consciously guide behavior to a desired direction and resist short-term temptations that lure individuals away from their focal goals. The strength model of self-control has achieved a great degree of attention in the psychology literature given that failures to self-control can lead to personal and societal problems (e.g., underachievement in school or work, violence against others).
The ability to self-control is particularly important in terms of engaging in important health behaviors (e.g., regular exercise, healthy diet) and tackling obesity as well as alcohol and substance abuse. Hence, it is not surprising that research based on the strength model of self-control is becoming increasingly popular in the exercise and health psychology literature. In a recent survey of American adults, conducted on behalf of the American Psychological Association, it was revealed that the most frequently reported goals the survey participants had set for 2012 were health-related (e.g., 41% reported a goal to start exercising regularly). However, in the same survey 27% of the respondents reported that poor self-control prevented them from meeting their goals. On a positive note, 71% of them believed that self-control can be improved through practice, which is what research also suggests.
This entry first provides an overview of the strength model of self-control and explains why self-control is a limited resource. It goes on to discuss why self-control is relevant to the promotion of health-related behaviors, and concludes with some practical for strengthening self-control.
Self-Regulatory Strength and Depletion
Following through a New Year’s resolution to engage in regular physical activity (PA) requires not only the motivation to change but also the self-regulatory strength to monitor any discrepancies in meeting this goal and fight against competing interests, priorities, or temptations. This self-regulatory strength is colloquially called willpower. Willpower helps individuals overcome temptations and achieve valued academic, health, financial, interpersonal, and societal goals. Research indicates that the benefits of having high levels of self-control transcend over time; children with high self-control (assessed by both self-reports and adult reports) not only do better at school but grow up to be more successful adults (in their professional and personal lives) than children with lower self-control. These findings hold up if even when differences in socioeconomic status, intelligence, and other potentially confounding variables are taken into account.
Despite the benefits of having high self-control, individuals are often unable to resist temptations and impulses. The playwright Oscar Wilde famously claimed that he could resist anything but temptation. The strength model of self-control explains self-regulatory failures by arguing that self-control is a limited resource resembling a muscle. The more self-control is exercised (irrespective of the nature of the task), the more it gets tired and eventually depleted. This depletion, called ego depletion in the literature (aligned with the Freudian discussion of the self in terms of energy), makes individuals vulnerable to future temptations and can impair their performance in subsequent tasks that require self-control. Research testing the strength model of self-control has found this depleting effect to be robust across a variety of situations, such as when asking individuals to regulate their emotions, make difficult choices, engage in problem solving and logical reasoning, suppress thoughts or stereotypes, and resist temptations. For example, in a study by Kathleen Vohs and Todd Heatherton, chronic dieters and nondieters were asked to sit close to or away from a candy bowl and were told to either help themselves to the candy or not to touch it. For chronic dieters, sitting close to a candy bowl and being told to help themselves to the candy requires the exertion of self-control. The results of the Vohs and Heatherton study showed that the chronic dieters demonstrated less persistence in a subsequent cognitive task and ate more candy compared with the dieters who sat away from the candy bowl. For nondieters, sitting near the bowl did not impair their subsequent self-control performance. This finding indicates that the undermining effects of ego depletion occur only in individuals who have the motivation to achieve a goal. Also, in the same study there was not self-regulatory failure when dieters were told not to eat from the candy bowl. This finding illustrates that willpower depletion does not occur when behavior is constrained by external factors and is not under volitional control.
The depleting effects of self-control might vary as a function of a number of personal or situation factors. For example, individuals high in autonomous motivation to exert self-control, or perceiving others to support their autonomy, are less depleted than those with low autonomous motivation or those pressured by others to self-control. Also, increased positive mood and individuals’ belief that willpower is not a limited resource may reduce levels of ego depletion. In individuals with high reserves of self-control (i.e., high levels of trait self-control), the undermining effects of situational ego depletion on task performance are less pronounced than for individuals who have low trait self-control. Additionally, participants who anticipated a future self-control task showed larger ego depletion than participants who did not expect a future task. Perhaps in the latter case individuals are more strategic in terms of their resource allocation, choosing to conserve resources for the subsequent self-control task. This conservation hypothesis is aligned with Baumeister’s argument that acts of self-control result in partial depletion only, rather than complete exhaustion, because individuals conserve their energy resources for future situations. In fact, research by Vohs, Baumeister, and Brandon Schmeichel has shown that moderately (but not severely) depleted motivated individuals can utilize some of their remaining resources to maintain their performance levels.
The findings from the strength model of self-control literature have implications for exercise and health promotion. First, individuals whose jobs require a great deal of self-regulatory strength and information processing are likely to feel depleted by the end of their working day. If these individuals are on a weight loss program, they might be less able to exert self-control later on in the day in terms of choosing a healthy meal option or engaging in PA when faced with tempting high calorie or sedentary alternatives (unless these individuals are highly motivated to lose weight). Another implication from the findings in the literature is that, since self-control is a limited resource, individuals should try to consolidate a change in a single health behavior first (i.e., make it more habitual so that it requires less self-control) and then move on to another behavior, as opposed to trying to alter multiple behaviors simultaneously. The latter would be more depleting; in fact, exerting self-control toward one behavior might undermine self-control efforts toward the other behavior. This was well illustrated in a study by Ditka Shmueli and Judith Prochaska in which smokers who were asked to resist a highly tempting food were more likely to subsequently smoke compared with smokers who were asked to resist food that was not tempting. The longitudinal evidence suggesting that children with high self-control are more likely to retain their high self-control in adolescence and adulthood, coupled with evidence indicating a negative relation between self-control and overweight or obesity, imply that self-control training programs that aim to promote healthy behaviors should be implemented from a relatively young age. Obviously, the influence of the obesogenic environment and advertising for unhealthy products cannot be discounted. Expecting individuals to exert self-control when unhealthy temptations are readily available throughout the day might not be entirely realistic. However, self-control training could be used in conjunction with changes in policy and legislation to better facilitate health behavior change. The next section discusses some ideas for strengthening self-control.
Odysseus tied himself to the mast of his ship and put wax in his shipmates’ ears to avoid the fatally tempting song of the Sirens. Unlike this Homeric hero, however, many individuals overestimate their ability to resist temptation. People who are perceived to have a high capacity to control their impulses expose themselves to more tempting situations and ultimately engage in more impulsive behavior (perhaps as a result of depletion) than those who perceive a lower capacity for self-control. Thus, an effective way of maintaining self-control, particularly when depleted, is to avoid highly tempting situations. For example, new exercisers who plan to exercise in the evening should avoid watching television first “for a little while” before they start their workout. Self-control can also be boosted by inducing positive mood, promoting autonomous motivation for task engagement, reaffirming long-term goals and higher-order values, and taking breaks or engaging in relaxation between self-control tasks. Further, self-control can be enhanced by making it more automatic. For instance, it has been found that forming implementation intentions (“if–then” plans) can overcome the performance decrements associated with ego depletion. Using again the example of new exercisers who plan to exercise in the evening, these individuals should form a plan so that they are prepared when at the end of the working day they are invited out by their colleagues for “a few drinks.”
Another interesting suggestion that has been made in the literature for boosting self-control is to maintain steady blood glucose levels. This is because self-control might deplete blood glucose, which is important for mental activities. It has been shown that depleted individuals have lower blood glucose levels than nondepleted ones and that by consuming a glucose drink, the effects of depletion can be counteracted. Thus, keeping blood glucose levels steady via consuming glucose-based drinks or regular meals might help individuals’ self-control in tempting situations (e.g., being offered a high calorie cake) when they are in a “hot state” (i.e., hungry). However, such findings have been challenged recently as it has been shown that similar bolstering effects on self-control can be found by simply rinsing the mouth with carbohydrate solutions without actual digestion. Thus, it is possible that the glucose effects are motivational (as opposed to metabolic) in nature.
The muscle metaphor of the strength model implies that self-control, similar to a muscle, can be trained regularly to become stronger. For example, a study by Megan Oaten and Ken Cheng showed that participants enrolled in a 2-month self-regulation program based on regular exercise (which requires self-control) were less depleted in a laboratory task they performed at the end of the program compared to those not enrolled in this program. The self-control training group also self-reported gains in self-control in other healthrelated behaviors (e.g., smoking, alcohol, and caffeine use).
In conclusion, the strength model of self-control has potential as a conceptual framework for explaining how to protect health behavior change from temptations, in particular before the new behavior becomes habitual. Its utility should be further tested outside laboratory settings by recruiting community and clinical samples (e.g., obese individuals) to self-control training programs with objectively assessed outcomes.
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