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

Imaging depletion: fMRI provides new insights into the processes underlying ego depletion*

'Ego depletion' refers to the phenomenon of diminished ability to enact self-regulation with repeated efforts. Several models offer process accounts of how ego depletion works, but few studies directly investigate these processes. A study in this issue of Social, Cognitive, & Affective Neuroscience by Wagner and Heatherton is among the first to do so. Their results substantiate one possible mechanism of ego depletion and, more broadly, illustrate how neuroscience data can further social psychological theory.

The Sweet Taste of Success

According to the resource-depletion model, self-control is a limited resource that is depleted after a period of exertion. Evidence consistent with this model indicates that self-control relies on glucose metabolism and glucose supplementation to depleted individuals replenishes self-control resources. In five experiments, we tested an alternative hypothesis that glucose in the oral cavity counteracts the deleterious effects of self-control depletion. We predicted a glucose mouth rinse, as opposed to an artificially sweetened placebo rinse, would lead to better self-control after depletion. In Studies 1 to 3, participants engaging in a depleting task performed significantly better on a subsequent self-control task after receiving a glucose mouth rinse, as opposed to participants rinsing with a placebo. Studies 4 and 5 replicated these findings and demonstrated that the glucose mouth rinse had no effect on self-control in nondepleted participants. Results are consistent with a neural rather than metabolic mechanism for the effect of glucose supplementation on self-control.

Motivational versus metabolic effects of carbohydrates on self-control

Self-control is critical for achievement and well-being. However, people's capacity for self-control is limited and becomes depleted through use. One prominent explanation for this depletion posits that self-control consumes energy through carbohydrate metabolization, which further suggests that ingesting carbohydrates improves self-control. Some evidence has supported this energy model, but because of its broad implications for efforts to improve self-control, we reevaluated the role of carbohydrates in self-control processes. In four experiments, we found that (a) exerting self-control did not increase carbohydrate metabolization, as assessed with highly precise measurements of blood glucose levels under carefully standardized conditions; (b) rinsing one's mouth with, but not ingesting, carbohydrate solutions immediately bolstered self-control; and (c) carbohydrate rinsing did not increase blood glucose. These findings challenge metabolic explanations for the role of carbohydrates in self-control depletion; we therefore propose an alternative motivational model for these and other previously observed effects of carbohydrates on self-control.

What Is Ego Depletion? Toward a Mechanistic Revision of the Resource Model of Self-Control

According to the resource model of self-control, overriding one’s predominant response tendencies consumes and temporarily depletes a limited inner resource. Over 100 experiments have lent support to this model of ego depletion by observing that acts of self-control at Time 1 reduce performance on subsequent, seemingly unrelated self-control tasks at Time 2. The time is now ripe, therefore, not only to broaden the scope of the model but to start gaining a precise, mechanistic account of it. Accordingly, in the current article, the authors probe the particular cognitive, affective, and motivational mechanics of self-control and its depletion, asking, “What is ego depletion?” This study proposes a process model of depletion, suggesting that exerting self-control at Time 1 causes temporary shifts in both motivation and attention that undermine self-control at Time 2. The article highlights evidence in support of this model but also highlights where evidence is lacking, thus providing a blueprint for future research. Though the process model of depletion may sacrifice the elegance of the resource metaphor, it paints a more precise picture of ego depletion and suggests several nuanced predictions for future research.

Self-regulatory depletion increases emotional reactivity in the amygdala

The ability to self-regulate can become impaired when people are required to engage in successive acts of effortful self-control, even when self-control occurs in different domains. Here, we used functional neuroimaging to test whether engaging in effortful inhibition in the cognitive domain would lead to putative dysfunction in the emotional domain. Forty-eight participants viewed images of emotional scenes during functional magnetic resonance imaging in two sessions that were separated by a challenging attention control task that required effortful inhibition (depletion group) or not (control group). Compared to the control group, depleted participants showed increased activity in the left amygdala to negative but not to positive or neutral scenes. Moreover, whereas the control group showed reduced amygdala activity to all scene types (i.e. habituation), the depletion group showed increased amygdala activity relative to their pre-depletion baseline; however this was only significant for negative scenes. Finally, depleted participants showed reduced functional connectivity between the left amygdala and ventromedial prefrontal cortex during negative scene processing. These findings demonstrate that consuming self-regulatory resources leads to an exaggerated neural response to emotional material that appears specific to negatively valenced stimuli and further suggests a failure to recruit top-down prefrontal regions involved in emotion regulation.

Pain catastrophizing: an updated review

Pain catastrophizing has been described for more than half a century which adversely affects the pain coping behavior and overall prognosis in susceptible individuals when challenged by painful conditions. It is a distinct phenomenon which is characterized by feelings of helplessness, active rumination and excessive magnification of cognitions and feelings toward the painful situation. Susceptible subjects may have certain demographic or psychological predisposition. Various models of pain catastrophizing have been proposed which include attention-bias, schema-activation, communal-coping and appraisal models. Nevertheless, consensus is still lacking as to the true nature and mechanisms for pain catastrophizing. Recent advances in population genomics and noninvasive neuroimaging have helped elucidate the known determinants and neurophysiological correlates behind this potentially disabling behavior.

"Pause and plan" includes the liver: self-regulatory effort slows alcohol metabolism for those low in self-control

During self-regulatory effort, a series of potentially energy-saving changes occur in the heart and immune system. The present study tested the possibility that one function of the liver, alcohol metabolism, also slows in the presence of self-regulatory effort. Young men (N=19) received a small dose of alcohol and performed either self-regulatory tasks or identical tasks without a self-regulatory component, counterbalanced across two sessions. There was no main effect of condition on alcohol metabolism; however, trait self-control moderated the effect of condition such that those with higher trait self-control metabolized alcohol at similar rates across conditions, whereas those with lower trait self-control experienced a slowing of alcohol metabolism in the high self-regulation condition compared with the low self-regulation condition. This finding adds changes in liver metabolism to the "pause and plan" profile of self-regulation and suggests that trait self-control reduces the effort associated with self-regulatory tasks.

Working in our sleep

A large body of sleep physiology research highlights a broad array of effects of sleep on human functioning. Until recently, this literature has been completely isolated from the organizational psychology literature. The purpose of this paper is to further extend the sleep literature into the organizational psychology literature, with a focus on self-regulation in the workplace. I summarize the sleep literature into a model of sleep self-regulation. Next, I highlight initial research in organizational psychology which has drawn from basic sleep physiology research. Following this, I generate new propositions linking sleep to work withdrawal, goal level, incivility, and defection in workplace social dilemmas. Finally, I close with a discussion of methods for conducting sleep research in organizational psychology, as well as some promising areas for future research.

Achieving the same for less: improving mood depletes blood glucose for people with poor (but not good) emotion control

Previous studies have found that acts of self-control like emotion regulation deplete blood glucose levels. The present experiment investigated the hypothesis that the extent to which people's blood glucose levels decline during emotion regulation attempts is influenced by whether they believe themselves to be good or poor at emotion control. We found that although good and poor emotion regulators were equally able to achieve positive and negative moods, the blood glucose of poor emotion regulators was reduced after performing an affect-improving task, whereas the blood glucose of good emotion regulators remained unchanged. As evidence suggests that glucose is a limited energy resource upon which self-control relies, the implication is that good emotion regulators are able to achieve the same positive mood with less cost to their self-regulatory resource. Thus, depletion may not be an inevitable consequence of engaging in emotion regulation.

The Regulatory Easy Street: Self-Regulation Below the Self-Control Threshold Does not Consume Regulatory Resources

We present and test a theory in which self-control is distinguished from broader acts of self-regulation when it is both effortful and conscious. In two studies, we examined whether acts of behavioral management that do not require effort are exempt from resource depletion. In Study 1, we found that a self-regulation task only reduced subsequent self-control for participants who had previously indicated that completing the task would require effort. In Study 2, we found that participants who completed a self-regulation task for two minutes did not evidence the subsequent impairment in self-control evident for participants who had completed the task for four or more minutes. Our results support the notion that self-regulation without effort falls below the self-control threshold and has different downstream consequences than self-control.

Psychological processes and stimulant use among men who have sex with men

BACKGROUND

Prior research established that psychological factors are associated with the frequency of stimulant (i.e., cocaine, crack, and methamphetamine) use among substance-using men who have sex with men (MSM). The present investigation examined whether and how psychological factors are associated with engagement in any stimulant use in the broader population of MSM.

METHODS

A probability sample of 879 MSM residing in San Francisco was obtained using random digit dialing from May of 2002 through January of 2003. Of these, 711 participants (81%) completed a mail-in questionnaire that assessed psychological factors and substance use. After accounting for demographic factors, a multiple logistic regression analysis examined correlates of any self-reported stimulant use during the past 6 months. Path analyses examined if the use of alcohol or other substances to avoid negative mood states (i.e., substance use coping) mediated the associations of sexual compulsivity and depressed mood with stimulant use.

RESULTS

Younger age (adjusted OR [AOR]=0.58; 95% CI=0.47-0.70), HIV-positive serostatus (AOR=2.55; 95% CI=1.61-4.04), greater depressed mood (AOR=1.26; 95% CI=1.05-1.52) and higher sexual compulsivity (AOR=1.46; 95% CI=1.18-1.80) were independently associated with increased odds of stimulant use. Substance use coping partially mediated the associations of sexual compulsivity (β(indirect)=0.11, p<.001) and depressed mood (β(indirect)=0.13, p<.001) with stimulant use.

CONCLUSIONS

Clinical research is needed to examine if interventions targeting sexual compulsivity and emotion regulation reduce stimulant use among MSM.

Reducing self-control by weakening belief in free will

Believing in free will may arise from a biological need for control. People induced to disbelieve in free will show impulsive and antisocial tendencies, suggesting a reduction of the willingness to exert self-control. We investigated whether undermining free will affects two aspects of self-control: intentional inhibition and perceived self-control. We exposed participants either to anti-free will or to neutral messages. The two groups (no-free will and control) then performed a task that required self-control to inhibit a prepotent response. No-free will participants showed less intentional inhibitions than controls, suggesting a reduction of self-control. We assessed perceived self-control by asking participants whether the response resulted from a deliberate intention or from an impulsive reaction. Perceived self-control was lower in the no-free will group than in control group. Our findings show that undermining free will can degrade self-control and provide insights into how disbelieving in free will leads to antisocial tendencies.

Muscle or motivation? A stop-signal study on the effects of sequential cognitive control

Performance on cognitive control tasks deteriorates when control tasks are performed together with other control tasks, that is, if simultaneous cognitive control is required. Surprisingly, this is also observed if control tasks are preceded by other control tasks, that is, if sequential cognitive control is required. The typical explanation for the latter finding is that previous acts of cognitive control deplete a common resource, just like a muscle becomes fatigued after repeated usage. An alternative explanation, however, is that previous acts of cognitive control reduce motivation to match allocated resources to required resources. In this paper we formalize these muscle and motivation accounts, and show that they yield differential predictions regarding the interaction between simultaneous and sequential cognitive control. These predictions were tested using a paradigm where participants had to perform multiple stop-signal tasks, which varied in their demands on simultaneous and sequential control. Results of two studies supported predictions derived from the motivation account. Therefore, we conclude that the effects of sequential cognitive control are best explained in terms of a reduction of motivation to match allocated to required resources.

Continuous glucose monitoring: a review for behavioral researchers

OBJECTIVE

Continuous glucose monitoring (CGM) systems collect and store glucose data in an ongoing fashion for several days at a time. The main advantage of CGM is that it can help identify fluctuations and trends that would otherwise go unnoticed with other glucose measures. Here, we provide a review of CGM for behavioral researchers.

METHODS

We begin with a brief review of diabetes and glucose measurement and then describe what CGM is and reference the commercial CGM systems currently available. We discuss the challenges involved in using CGM in behavioral research. We then present a broad overview of CGM in behavioral research, including data from ours and others' research programs. Finally, we cover some practical issues to be considered when using CGM, suggest reporting guidelines for the behavioral researcher, and offer suggestions for future research.

RESULTS

Only a handful of behavioral researchers are using CGM, although its use is increasing. The main ways that CGM is being used in behavioral research is to investigate basic biobehavioral processes, to assess the effects of behavioral interventions on diabetes control, and to use CGM itself as a behavior modification and teaching tool in diabetes self-management interventions.

CONCLUSIONS

Continuous glucose monitoring holds promise to help behavioral researchers unravel the complex relationships among glucose and intrapersonal, interpersonal, and contextual factors. However, the uptake of CGM for this purpose is limited, and the possibilities for its use are largely unmet. We encourage behavioral researchers to implement CGM in their protocols and to do so in a way that maximizes its explanatory power.

Circadian rhythms in executive function during the transition to adolescence: the effect of synchrony between chronotype and time of day

To explore the influence of circadian rhythms on executive function during early adolescence, we administered a battery of executive function measures (including a Go-Nogo task, the Iowa Gambling Task, a Self-ordered Pointing task, and an Intra/Extradimensional Shift task) to Morning-preference and Evening-preference participants (N = 80) between the ages of 11 and 14 years who were tested in the morning or afternoon. Significant Chronotype × Time of Day interactions (controlling for amount of sleep the previous night) revealed that adolescents tested at their optimal times of day performed better than those tested at their nonoptimal times. Implications for our understanding of physiological arousal, sleep, and executive function during adolescence are discussed.

Self-control: limited resources and extensive benefits

Successful self-control has many benefits for individuals and society as a whole. Self-regulation relies on a limited resource. After one act of self-control, this resource is reduced, thereby impairing future acts of self-control. Self-control resources can be managed and conserved for future tasks. Recent research on perceived self-control (in the self and others), self-control in interpersonal interactions, and the physiological basis of the limited resource model point to promising areas for future self-control research. WIREs Cogn Sci 2012, 3:419-423. doi: 10.1002/wcs.1173 For further resources related to this article, please visit the WIREs website.

A theoretical account of cognitive effects in delay discounting

Although delay discounting, the attenuation of the value of future rewards, is a robust finding, the mechanism of discounting is not known. We propose a potential mechanism for delay discounting such that discounting emerges from a search process that is trying to determine what rewards will be available in the future. In this theory, the delay dependence of the discounting of future expected rewards arises from three assumptions. First, that the evaluation of outcomes involves a search process. Second, that the value is assigned to an outcome proportionally to how easy it is to find. Third, that outcomes that are less delayed are typically easier for the search process to find. By relaxing this third assumption (e.g. by assuming that episodically-cued outcomes are easier to find), our model suggests that it is possible to dissociate discounting from delay. Our theory thereby explains the empirical result that discounting is slower to episodically-imagined outcomes, because these outcomes are easier for the search process to find. Additionally, the theory explains why improving cognitive resources such as working memory slows discounting, by improving searches and thereby making rewards easier to find. The three assumptions outlined here are likely to be instantiated during deliberative decision-making, but are unlikely in habitual decision-making. We model two simple implementations of this theory and show that they unify empirical results about the role of cognitive function in delay discounting, and make new neural, behavioral, and pharmacological predictions.

The social psychology of perception experiments: hills, backpacks, glucose, and the problem of generalizability

Experiments take place in a physical environment but also a social environment. Generalizability from experimental manipulations to more typical contexts may be limited by violations of ecological validity with respect to either the physical or the social environment. A replication and extension of a recent study (a blood glucose manipulation) was conducted to investigate the effects of experimental demand (a social artifact) on participant behaviors judging the geographical slant of a large-scale outdoor hill. Three different assessments of experimental demand indicate that even when the physical environment is naturalistic, and the goal of the main experimental manipulation was primarily concealed, artificial aspects of the social environment (such as an explicit requirement to wear a heavy backpack while estimating the slant of a hill) may still be primarily responsible for altered judgments of hill orientation.

Your Love Lifts Me Higher! The Energizing Quality of Secure Relationships

Three studies tested and confirmed the hypothesis that secure attachment relationships lead to feelings of security and energy, as well as willingness to explore. In Study 1, priming a secure attachment relationship increased felt security and energy. In Studies 2 and 3, felt energy mediated the effect of (primed) secure attachment relationships on willingness to explore. In Study 3, the effect of (primed) secure attachment relationships on felt energy and willingness to explore was independent of general positive affect. Secure attachments energize partners, thus enabling exploration.

Executive functions and self-regulation

Self-regulation is a core aspect of adaptive human behavior that has been studied, largely in parallel, through the lenses of social and personality psychology as well as cognitive psychology. Here, we argue for more communication between these disciplines and highlight recent research that speaks to their connection. We outline how basic facets of executive functioning (working memory operations, behavioral inhibition, and task-switching) may subserve successful self-regulation. We also argue that temporary reductions in executive functions underlie many of the situational risk factors identified in the social psychological research on self-regulation and review recent evidence that the training of executive functions holds significant potential for improving poor self-regulation in problem populations.

Self-Control and Aggression

Psychological science has largely neglected the role of self-control in studying aggression. Fortunately, the past half decade has witnessed a surge of research on this long-neglected topic, including two self-control-informed integrative theories of aggression. Robust experimental evidence demonstrates that self-control failures frequently predict aggression and, conversely, that bolstering self-control decreases aggression. Research on rumination also suggests that maladaptive anger regulation decreases self-control and, consequently, increases aggression. Advances from social-affective and cognitive neuroscience suggest that the neural mechanisms involved in emotion regulation and cognitive control mediate the relationship between deficient self-control and aggression.

Development and validation of the Delaying Gratification Inventory

Deficits in gratification delay are associated with a broad range of public health problems, such as obesity, risky sexual behavior, and substance abuse. However, 6 decades of research on the construct has progressed less quickly than might be hoped, largely because of measurement issues. Although past research has implicated 5 domains of delay behavior, involving food, physical pleasures, social interactions, money, and achievement, no published measure to date has tapped all 5 components of the content domain. Existing measures have been criticized for limitations related to efficiency, reliability, and construct validity. Using an innovative Internet-mediated approach to survey construction, we developed the 35-item 5-factor Delaying Gratification Inventory (DGI). Evidence from 4 studies and a large, diverse sample of respondents (N = 10,741) provided support for the psychometric properties of the measure. Specifically, scores on the DGI demonstrated strong internal consistency and test-retest reliability for the 35-item composite, each of the 5 domains, and a 10-item short form. The 5-factor structure fit the data well and had good measurement invariance across subgroups. Construct validity was supported by correlations with scores on closely related self-control measures, behavioral ratings, Big Five personality trait measures, and measures of adjustment and psychopathology, including those on the Minnesota Multiphasic Personality Inventory-2-Restructured Form. DGI scores also showed incremental validity in accounting for well-being and health-related variables. The present investigation holds implications for improving public health, accelerating future research on gratification delay, and facilitating survey construction research more generally by demonstrating the suitability of an Internet-mediated strategy.

Passionate Thinkers Feel Better

The present study tested a possible explanation for the positive relationship between the motivation to engage in cognitive endeavors (need for cognition, NFC) and indicators of affective adjustment (e.g., higher self-esteem, lower depression) that has been demonstrated in previous studies. We suggest that dispositional self-control capacity mediates this relationship, since NFC has been found to be related to self-control capacity, and self-control capacity is crucial for adjustment. NFC, dispositional self-control capacity, self-esteem, habitual depressive mood, and tendency to respond in a socially desirable manner were measured among 150 university students via self-report. Regression analyses and Sobel tests revealed that self-control capacity was a potential mediator of the positive relationship between NFC and affective adjustment. The findings were robust in terms of social desirability.

Manipulations of attention enhance self-regulation

Successful goal-directed behavior requires self-regulation to override competing impulses. Emerging evidence suggests that attention may mediate such acts, but little is known about the specific operations through which attention might influence self-regulation. Here we test this often-implicit assumption by manipulating attention mechanisms in two ways: one controlling the inhibition of inappropriate responses; the other controlling the breadth of attention. Participants significantly improved their performance on a self-regulation task after practice on a response inhibition task (Experiment 1) and after the induction of a broad focus of attention in a visual discrimination task (Experiment 2). We propose that such manipulations enhance self-regulation by engaging mechanisms that enhance the salience of goal-related representations and reduce the activation of competing goal-irrelevant neural representations. By more efficiently resolving conflict among the signals vying to drive behavior, pre-engaging attention may also help to conserve resources needed for continued self-regulation.

Being Active and Impulsive: The Role of Goals for Action and Inaction in Self-Control

Although self-control often requires behavioral inaction (i.e., not eating a piece of cake), the process of inhibiting impulsive behavior is commonly characterized as cognitively active (i.e., actively exerting self-control). Two experiments examined whether motivation for action or inaction facilitates self-control behavior in the presence of tempting stimuli. Experiment 1 used a delay discounting task to assess the ability to delay gratification with respect to money. Experiment 2 used a Go/No-Go task to assess the ability to inhibit a dominant but incorrect motor response to the words "condom" and "sex". The results demonstrate that goals for inaction promote self-control, whereas goals for action promote impulsive behavior. These findings are discussed in light of recent evidence suggesting that goals for action and inaction modulate physiological resources that promote behavioral execution.

Emotion and perception: the role of affective information

Visual perception and emotion are traditionally considered separate domains of study. In this article, however, we review research showing them to be less separable than usually assumed. In fact, emotions routinely affect how and what we see. Fear, for example, can affect low-level visual processes, sad moods can alter susceptibility to visual illusions, and goal-directed desires can change the apparent size of goal-relevant objects. In addition, the layout of the physical environment, including the apparent steepness of a hill and the distance to the ground from a balcony can both be affected by emotional states. We propose that emotions provide embodied information about the costs and benefits of anticipated action, information that can be used automatically and immediately, circumventing the need for cogitating on the possible consequences of potential actions. Emotions thus provide a strong motivating influence on how the environment is perceived. WIREs Cogni Sci 2011 2 676-685 DOI: 10.1002/wcs.147 This article is categorized under: Psychology > Emotion and Motivation.

How addiction happens, how change happens, and what social workers need to know to be effective facilitators of change

During the last two decades, neuroscience research has proliferated examining brain mechanisms that explain why some people are compelled to pursue drugs and alcohol. The findings suggest that addiction is independent of pleasure, and that drug seeking can be triggered outside of conscious awareness (Berridge, Robinson, & Aldridge, 2009; Goldstein et al., 2009; Kalivas, Volkow, & Seamans, 2005). The observations and conclusions from this research can be used to advantage in treating addiction. The use of social psychological principles, in the context of motivational interviewing, offers a platform for taking advantage of these new insights. After a brief sketch of the latest understanding of the physiological forces operating in addiction, the author examines those ways to interact with substance dependent clients that promote change without provoking resistance in this article. Action plans are later described that can supplant automatic, addiction-induced behaviors (Gollwitzer, Fujita, & Oettingen, 2004). Mechanisms such as building coping skills are discussed, that help in maintaining new behaviors. Some of these mechanisms are efficacious because they bolster the brain's self-regulatory capacity (Baumeister, Vohs, & Tice, 2007; Littrell, 2010). Thus, for every step in the change process, from resistance to change maintenance, validated guidelines for altering the outcome from addiction will be provided.