Evan C. Carter

A series of meta-analytic tests of the depletion effect: self-control does not seem to rely on a limited resource

Failures of self-control are thought to underlie various important behaviors (e.g., addiction, violence, obesity, poor academic achievement). The modern conceptualization of self-control failure has been heavily influenced by the idea that self-control functions as if it relied upon a limited physiological or cognitive resource. This view of self-control has inspired hundreds of experiments designed to test the prediction that acts of self-control are more likely to fail when they follow previous acts of self-control (the depletion effect). Here, we evaluated the empirical evidence for this effect with a series of focused, meta-analytic tests that address the limitations in prior appraisals of the evidence. We find very little evidence that the depletion effect is a real phenomenon, at least when assessed with the methods most frequently used in the laboratory. Our results strongly challenge the idea that self-control functions as if it relies on a limited psychological or physical resource.

Publication bias and the limited strength model of self-control: has the evidence for ego depletion been overestimated?

Few models of self-control have generated as much scientific interest as has the limited strength model. One of the entailments of this model, the depletion effect, is the expectation that acts of self-control will be less effective when they follow prior acts of self-control. Results from a previous meta-analysis concluded that the depletion effect is robust and medium in magnitude (d = 0.62). However, when we applied methods for estimating and correcting for small-study effects (such as publication bias) to the data from this previous meta-analysis effort, we found very strong signals of publication bias, along with an indication that the depletion effect is actually no different from zero. We conclude that until greater certainty about the size of the depletion effect can be established, circumspection about the existence of this phenomenon is warranted, and that rather than elaborating on the model, research efforts should focus on establishing whether the basic effect exists. We argue that the evidence for the depletion effect is a useful case study for illustrating the dangers of small-study effects as well as some of the possible tools for mitigating their influence in psychological science.

After a pair of self-control-intensive tasks, sucrose swishing improves subsequent working memory performance

BackgroundThe limited strength model of self-control predicts that acts of self-control impair subsequent performance on tasks that require self-control (i.e., “ego depletion”), and the majority of the published research on this topic is supportive of this prediction. Additional research suggests that this effect can be alleviated by manipulating participants’ motivation to perform—for instance, by having participants swish a drink containing carbohydrates, which is thought to function as a reward—or by requiring participants to complete two initial acts of self-control rather than only one.MethodsHere, we explore both the effect of having participants perform two initial tasks thought to require self-control (versus two less self-control-intensive tasks) and the effect of swishing a drink containing sucrose (compared to control drinks) on subsequent self-control. Outcomes were analyzed using standard null hypothesis significance testing techniques (e.g., analysis of variance, t-tests). In some cases, test statistics were transformed into Bayes factors to aid in interpretation (i.e., to allow for acceptance of the null hypothesis).ResultsWe found that performing two self-control-intensive tasks actually improved subsequent self-control when participants swished a drink containing sucrose between tasks. For participants who swished control drinks, we found no evidence of ego depletion.ConclusionsWe conclude that claims that self-control failure is caused by the depletion of a resource (or that it functions as if it relies on a limited resource) merit greater circumspection. Our results—all of which were either null or contrary to predictions from the limited strength model—are important for researchers interested in patterns of self-control failure.

Explaining the relationship between religiousness and substance use: Self-control matters

Religiousness is reliably associated with lower substance use, but little research has examined whether self-control helps explain why religiousness predicts lower substance use. Building on prior theoretical work, our studies suggest that self-control mediates the relationship between religiousness and a variety of substance-use behaviors. Study 1 showed that daily prayer predicted lower alcohol use on subsequent days. In Study 2, religiousness related to lower alcohol use, which was mediated by self-control. Study 3 replicated this mediational pattern using a behavioral measure of self-control. Using a longitudinal design, Study 4 revealed that self-control mediated the relationship between religiousness and lower alcohol use 6 weeks later. Study 5 replicated this mediational pattern again and showed that it remained significant after controlling for trait mindfulness. Studies 6 and 7 replicated and extended these effects to both alcohol and various forms of drug use among community and cross-cultural adult samples. These findings offer novel evidence regarding the role of self-control in explaining why religiousness is associated with lower substance use.

Conciliatory gestures promote forgiveness and reduce anger in humans.

Significance Conflict is a common feature of social life among group-living animals, but many social relationships often retain value even after conflicts have occurred. Consequently, natural selection has likely endowed humans and other animal species with cognitive systems that motivate reconciliation with interaction partners that they perceive as valuable and nonthreatening, notwithstanding prior conflict. In a large sample of people who had recently been harmed by an interaction partner, we found that conciliatory gestures, such as apologies and offers of compensation, accelerated forgiveness and reduced anger toward transgressors, largely by altering victims’ perceptions of their transgressors’ relationship value and exploitation risk. These results give insight into the design logic behind the cognitive systems that motivate human postconflict reconciliation. Conflict is an inevitable component of social life, and natural selection has exerted strong effects on many organisms to facilitate victory in conflict and to deter conspecifics from imposing harms upon them. Like many species, humans likely possess cognitive systems whose function is to motivate revenge as a means of deterring individuals who have harmed them from harming them again in the future. However, many social relationships often retain value even after conflicts have occurred between interactants, so natural selection has very likely also endowed humans with cognitive systems whose function is to motivate reconciliation with transgressors whom they perceive as valuable and nonthreatening, notwithstanding their harmful prior actions. In a longitudinal study with 337 participants who had recently been harmed by a relationship partner, we found that conciliatory gestures (e.g., apologies, offers of compensation) were associated with increases in victims’ perceptions of their transgressors’ relationship value and reductions in perceptions of their transgressors’ exploitation risk. In addition, conciliatory gestures appeared to accelerate forgiveness and reduce reactive anger via their intermediate effects on relationship value and exploitation risk. These results strongly suggest that conciliatory gestures facilitate forgiveness and reduce anger by modifying victims’ perceptions of their transgressors’ value as relationship partners and likelihood of recidivism.

The Mediating Role of Monitoring in the Association of Religion With Self-Control

Religiosity is related to a variety of positive outcomes and the nature of this relationship has long been a topic of inquiry. Recently, it was proposed that an important piece of this puzzle may be the propensity for religious beliefs to promote self-control, a trait that is linked to a range of benefits. How religion translates into self-control, however, remains unclear. We examined the extent to which religiosity’s relationship with self-control is mediated by self-monitoring, perceived monitoring by God, and perceived monitoring by other people. Results revealed that more religious people tended to monitor their standing regarding their goals (self-monitoring) to a greater degree, which in turn related to more self-control. Also, religious people tended to believe that a higher power was watching them, which related to greater self-monitoring, which in turn was related to more self-control.

Rats value time differently on equivalent foraging and delay-discounting tasks.

All organisms have to consider consequences that vary through time. Theories explaining how animals handle intertemporal choice include delay-discounting models, in which the value of future rewards is discounted by the delay until receipt, and foraging models, which predict that decision-makers maximize rate of reward. We measured the behavior of rats on a 2-option delay-discounting task and a stay/go foraging task that were equivalent for rate of reward and physical demand. Despite the highly shared features of the tasks, rats were willing to wait much longer on the foraging task than on the delay-discounting task. Moreover, choice performance by rats was less optimal in terms of total reward received on the foraging task compared to the delay-discounting task. We applied a suite of intertemporal choice models to the data but found that we needed a novel model incorporating interactions of decision-making systems to successfully explain behavior. Our findings (a) highlight the importance of factors that historically have been seen as irrelevant and (b) indicate the inadequacy of current general theories of intertemporal choice. (PsycINFO Database Record

Reassessing intertemporal choice: human decision-making is more optimal in a foraging task than in a self-control task.

Many contemporary concerns (e.g., addiction, failure to save) can be viewed as intertemporal choice problems in which the consequences of choices are realized at different times. In some laboratory paradigms used to study intertemporal choice, non-human animals demonstrate a preference for immediacy (impulsive choice) that results in failures to maximize the amount of reward received. There is evidence, however, suggesting that such non-optimal impulsive choice may be due to a mismatch between the standard presentation of options in the laboratory (e.g., a “larger-later” and a “smaller-sooner” option) and the way that options occur in natural settings (e.g., foraging). We present evidence that human impulsive choice is similarly affected: in two experiments, decisions were more optimal when options were presented in a format sharing features with the evolutionarily important problem of foraging compared to when options were presented in the standard format. These findings suggest a more nuanced view of intertemporal choice and support the adoption of ideas from foraging theory into the study of human decision making.

A Simple, Principled Approach to Combining Evidence From Meta-Analysis and High-Quality Replications

Recent discussions of the influence of publication bias and questionable research practices on psychological science have increased researchers’ interest in both bias-correcting meta-analytic techniques and preregistered replication. Both approaches have their strengths: For example, meta-analyses can quantitatively characterize the full body of work done in the field of interest, and preregistered replications can be immune to bias. Both approaches also have clear weaknesses: Decisions about which meta-analytic estimates to interpret tend to be controversial, and replications can be discounted for failing to address important methodological heterogeneity. Using the experimental literature on ego depletion as a case study, we illustrate a principled approach to combining information from meta-analysis with information from subsequently conducted high-quality replications. This approach (a) compels researchers to explicate their beliefs in meta-analytic conclusions (and also, when controversy arises, to defend the basis for those beliefs), (b) encourages consideration of practical significance, and (c) facilitates the process of planning replications by specifying the sample sizes necessary to have a reasonable chance of changing the minds of other researchers.