Ego depletion refers to the idea that self-control or willpower draw upon a limited pool of mental resources that can be used up. When the energy for mental activity is low, self-control is typically impaired, which would be considered a state of ego depletion. In particular, experiencing a state of ego depletion impairs the ability to control oneself later on. A depleting task requiring self-control can have a hindering effect on a subsequent self-control task, even if the tasks are seemingly unrelated. Self-control plays a valuable role in the functioning of the self on both individualistic and interpersonal levels. Ego depletion is therefore a critical topic in experimental psychology, specifically social psychology, because it is a mechanism that contributes to the understanding of the processes of human self-control.
Key experimental evidence 
Roy Baumeister and his colleagues proposed a model that relates self-control to a muscle, which can become both strengthened and fatigued. Initial use of the “muscle” of self-control will cause a decrease in strength, or ego depletion, for subsequent tasks. Various experimental findings support this muscle model of self-control and ego depletion.
A key experiment by Roy Baumeister, Ellen Bratslavsky, Mark Muraven and Dianne Tice in 1998, demonstrated some of the first evidence that ego depletion has effects in many diverse contexts or situations. They showed that people who initially resisted the temptation of chocolates were subsequently less able to persist on a difficult and frustrating puzzle task. They attributed this effect to ego depletion, which resulted from the prior resisting of a tempting treat. Additionally, it was demonstrated that when people voluntarily gave a speech that included beliefs contrary to their own, they were also less able to persist on the difficult puzzle, indicating a state of ego depletion. Interestingly, this effect was not nearly as strong when individuals were not given a choice and were "forced" to write a counter-attitudinal speech. Thus, it is believed that both the act of choice and counter-attitudinal behaviors draw upon the same pool of limited resources. While giving a counter-attitudinal speech is expected to produce ego depletion, introducing the element of choice further increases the level of experienced depletion. These findings demonstrated the effects of ego depletion in differential situations and emphasized that ego depletion is not context specific. This experiment was critical in that the researchers synthesized ideas proposed by prior studies that had suggested evidence for a strength model of willpower. With this study, Baumeister and his colleagues therefore provided the first direct experimental evidence of ego depletion, and initiated research interest on the subject.
Physiological correlates 
The role of glucose as a specific form of energy needed for self-control has been explored. Glucose, a sugar found in many foods, is a vital fuel for the body and the brain. Even though minor fluctuations in glucose levels do not significantly affect most cognitive processes, the process of self-control seems strongly influenced by glucose levels. Gailliot and his colleagues found a significant drop in blood glucose levels following an act of self-control. Furthermore, low levels of glucose after an initial self-control task predicted a hindered ability to perform subsequent self-control tasks. Thirdly, boosting an individual’s glucose levels improved subsequent self-control performance. Therefore, poor self-control can be attributed to drops in glucose level, and consuming glucose can replenish a depleted individual’s self-control resources.
The underlying neural processes associated with self-control failure have been recently examined using neurophysiological techniques. According to cognitive and neuroscientific models of mental control, a "conflict-monitoring/error-detection system" identifies discrepancies between intended goals and actual behaviors. Error-related negativity (ERN) signals are a waveform of event-related potentials, which appear to be generated in the anterior cingulate cortex when individuals commit errors in various psychological tasks. Using electroencephalography (EEG) recordings, Inzlicht and Gutsell found that individuals who had undergone an emotion-suppression task displayed weaker ERN signals compared to individuals who had not undergone emotion-suppression tasks. These findings demonstrate preliminary evidence that depletion experienced after exerting self-control, can weaken neural mechanisms responsible for conflict monitoring.
Influences and factors 
In a recent experiment, it was shown that inducing a positive mood can buffer the impairing effects of ego depletion on subsequent performance. Positive mood was induced by getting individuals to watch comedy videos or by giving them a surprise gift. Positive mood seemed to allow people to recover faster from ego depletion and furthermore, improved their ability to self-regulate. There is no claim that positive mood can provide a general benefit to people who had not previously engaged in self-regulatory tasks; rather, positive mood can restore depleted individuals’ capacity to self-regulate. Furthermore, this experimental work does not consider in depth the mechanisms by which performance is restored. It is not known whether positive mood counteracts ego depletion or whether positive mood merely motivates an individual to persist in a task, despite their depleted state.
Ego depletion has also been implicated in guilt and prosocial behavior. The feeling of guilt, while unpleasant, is necessary to facilitate adaptive human interactions. The experience of guilt is dependent on one’s ability to reflect on past actions and behaviors. Ego depletion has been shown to hinder the ability to engage in such reflection, thereby making it difficult to experience guilt. Since guilt typically leads to prosocial behavior, ego depletion will therefore reduce the good deeds that often result from a guilty conscience. In the study by Xu and colleagues, some participants were required to suppress their emotions while watching a movie about butchering animals, which resulted in a depleted state. Participants were then induced to feel guilty by playing a game in which an opponent player was blasted with loud, unpleasant noises when they made errors. At the end of the experiment, participants were given a chance to leave money for a subsequent participant and were also given the choice of making a charitable donation. These were the measures of pro-social behavior. The results of this study indicated that people who experienced ego depletion felt less guilty and donated less money than non-depleted people. This demonstrates that ego depletion has an indirect effect on prosocial behavior by decreasing one’s ability to experience guilt.
Perceived levels of fatigue 
An individual’s perceived level of fatigue has been shown to influence their subsequent performance on a task requiring self-regulation, independent of their actual state of depletion. This effect is known as illusory fatigue. This was shown in an experiment in which participants engaged in a task that was either depleting or non-depleting, which determined each individual’s true state of depletion. Ultimately, when participants were led to believe their level of depletion was lower than their true state of depletion, they performed much better on a difficult working memory task. This indicates that an increased perceived level of fatigue can hinder self-regulatory performance independent of the actual state of depletion.
Motivation and beliefs 
Ego depletion has been shown to have some rather debilitating consequences, most notably self-regulation impairments. These effects can, however, be temporarily buffered by external motivations and beliefs in unlimited willpower. An example of such an external motivator was demonstrated by Boucher and Kofos in 2012, where depleted participants who were reminded of money performed better on a subsequent self-control task.
An experiment by Carol Dweck and subsequent work by Roy Baumeister and Kathleen Vohs has shown that beliefs in unlimited self control helps mitigate ego depletion for a short while, but not for long. Participants that were led to believe that they will not get fatiguede performed well on a second task but were fully depleted on a third task. 
The majority of ego depletion studies have been carried out on university students, which raises concerns about how generalizable the results really are. Younger people may simply be more susceptible to the effects of ego depletion, given that the areas of the brain involved in self-control continue to develop until the mid 20s. For example, a recent study found that people over the age of 40 did not become ego depleted following a typical depletion manipulation, whereas younger, university students did.
Real-life implications 
In a state of ego depletion, an individual’s impaired ability to self-regulate can be implicated in a wide range of undesirable and maladaptive behaviors, such as acts of aggression. Knowledge and strategies to counteract ego depletion would therefore, be highly beneficial in various real-life situations.
An experiment performed by Kathleen Vohs and Todd Heatherton demonstrated how ego depletion is particularly relevant when considering chronic dieters compared to non-dieters. Chronic dieters constantly work at resisting their cravings and limiting their food intake. Vohs and Heatherton showed that the task of regulating food intake could be undermined in the face of tempting snacks, especially when the individual was experiencing a state of ego depletion. Both dieters and non-dieters to suppress their emotional responses while watching a movie. Afterwards, participants were required to consume ice cream in order to engage in a taste-test. The major finding was that dieters who suppressed their emotional responses to the movie experienced more ego depletion than those who were not required to suppress their emotions. Additionally, those individuals subsequently ate much more ice cream in the taste-testing task. Non-dieters did not show the same self-regulatory failures as dieters in these tasks. Therefore, it seems that the act of dieting itself is a form of resource expenditure. Dieters spend so much energy trying to limit their food intake, but these efforts are likely to be undermined when faced with overwhelming temptation.
Athletic performance 
Research has found that competitive athletes’ mental determination can be hindered after completing a difficult cognitive task more than after completing an easy cognitive task. This indicates that the hindering effects of ego depletion can be applied not only to subsequent performance on cognitive tasks, but on physical tasks, as well.
Consumer behavior 
In the world of consumerism, individuals are faced with decisions and choices that require the use of valuable energy resources in order to make informed purchases while resisting temptation of impulsive or unnecessary purchases. Consumers are constantly bombarded with a broad range of options. In order to make the best choice, one must compare the many different aspects of various products. The complexity of consumer decisions in itself can result in ego depletion. This, in turn, could impact any subsequent decisions consumers must make. When consumers are depleted, they are more likely to become passive, and make more impulsive decisions that may not fall in line with their true values.
Theoretical explanations 
Conservation hypothesis 
The conservation hypothesis is a partial explanation of ego depletion. It suggests that there are two sorts of depletion:
- when one is completely depleted and unable to self control.
- When one is not fully depleted, but partly. Still, one reduces his self control efforts to avoid complete exhaustion.
According to this view, when people feel depleted, there might still exists a reserve store of energy to be used in extreme, high priority situations that could be encountered in the future. This can be adaptive to the extent that expending any more resources at a given time might render an individual fully depleted of their resources in an unexpected situation requiring self-regulation or other self-monitoring behaviours. The existence of a spare reservoir of mental energy ultimately explains why various motivators can buffer the effects of mild or moderate ego depletion. In a state of low resources, an individual lacks motivation to exert any more energy, but if motivation is presented, there are still extra resources that can be used up. Thus, ego depletion could be conceptualized as a psychological constraint necessary to safeguard precious resources that might be needed in emergency situations in the future. Under mild depletion, people still have a small amount of energy left in their "tank", which they do not have access to under normal circumstances.
Challenges and alternative explanations 
Although self-control has traditionally been thought of as a limited resource that can be depleted, research on cognition, motivation, and affect has begun to challenge this picture. Many studies discuss and provide support for ego depletion, but there is no currently direct measures of ego depletion, and studies see how long people persist at a second task to measure their depletion level . The theory of ego depletion relies on the inner workings of an individual's volition, which can only be indirectly tested; therefore, only inferences can be made.[original research?] Another challenge facing research on ego depletion is the influence of the overall mental conditions of individuals being studied. There is speculation that results may be disrupted in individuals who report experiencing depression and already possess high levels of ego depletion prior to the study.[original research?]
Many of ego depletion studies, however, have shown that mood is not relevant to the results. In fact, many of the earlier experiments have tested for the effects of mood and saw no effect of mood whatsoever. Furthermore, the study and measurement of ego depletion may be affected by the confounding effect of cognitive dissonance. Researchers have questioned whether subjects are truly experiencing ego depletion, or whether the individuals are merely experiencing cognitive dissonance in the psychological tasks.
The process model of depletion 
In contrast to the existing popularized model of self-control, Michael Inzlicht and Brandon J. Schmeichel propose an alternative model of depletion, which they refer to as the process model. This process model holds that initial exertions of willpower lead an individual's motivation to shift away from control, and towards gratification. As a part of this process, one's attention shifts away from cues that signal the need for control, and towards cues that signal indulgence. Inzlicht and Schmeichel argue that the process model provides a starting point for understanding self-control and that more research examining these cognitive, motivational, and affective influences on self-control is needed.
See also 
- Baumeister, R. F.; Bratslavsky, E.; Muraven, M.; Tice, D. M. (1998). "Ego depletion: Is the active self a limited resource?". Journal of Personality and Social Psychology 74: 1252–1265. doi:10.1037/0022-3522.214.171.1242.
- Baumeister, R. F. (2002). Ego depletion and self-control failure: an energy model of the self’s executive function. Psychology Press.
- Gailliot 2007, p. 326
- Gailliot, M. T.; Baumeister, R. F.; DeWall, C. N.; Maner, J. K.; Plant, E. A.; Tice, D. M.; Schmeichel, B. J. (2007). "Self-control relies on glucose as a limited energy source: Willpower is more than a metaphor.". Journal of Personality and Social Psychology 92: 325–336. doi:10.1037/0022-35126.96.36.1995. PMID 17279852.
- Inzlicht, M.; Gutzell, J. N. (2007). "Running on empty: Neural signals for self-control failure.". Psychological Science 18: 933–937. doi:10.1111/j.1467-9280.2007.02004.x.
- Holroyd, C. B.; Coles, M. G. H. (2002). "The Neural Basis of Human Error Processing: Reinforcement Learning, Dopamine, and the Error-related Negativity". Psychological Review 209: 679–709. doi:10.1037//0033-295X.109.4.679.
- Tice, D. M.; Baumeister, R. F.; Schmueli, D.; Muraven, M. (2007). "Restoring the self: Positive affect helps improve self-regulation following ego depletion". Journal of Experimental Social Psychology 43: 379–384. doi:10.1016/j.jesp.2006.05.007.
- Baumeister, R. F.; Stillwell, A. M.; Heatherton, T. F. (1994). "Guilt: An interpersonal approach". Psychological Bulletin 115: 243–267. doi:10.1037/0033-2909.115.2.243.
- Xu, H.; Begue, L.; Bushman, B. J. (2012). "Too fatigued to care: Ego depletion, guilt, and prosocial behavior". Journal of Experimental Social Psychology 43: 379–384. doi:10.1016/j.jesp.2012.03.007.
- Clarkson, J. J.; Hirt, E. R.; Chapman, A. D.; Jia, L. (2010). "The impact of illusory fatigue on executive control: Do perceptions of depletion impair working memory capacity?". Social Psychological and Personality Science 2: 231–238. doi:10.1177/1948550610386628.
- Boucher, H. C.; Kofos, M. N. (2012). "The idea of money counteracts ego depletion effects". Journal of Experimental Social Psychology 48: 804–810. doi:10.1016/j.jesp.2012.02.003.
- Vohs, K. D.; Baumeister, R. F.; Schmeichel, B. J. (2012). "Motivation, personal beliefs, and limited resources all contribute to self-control". Journal of Experimental Social Psychology 48: 943–947. doi:10.1016/j.jesp.2012.03.002.
- Dahm T, Neshat-Doost HT, Golden A-M, Horn E, Hagger M, et al. (2011) Age Shall Not Weary Us: Deleterious Effects of Self-Regulation Depletion Are Specific to Younger Adults. PLoS ONE 6(10): e26351. doi:10.1371/journal.pone.0026351
- Vohs, K. D.; Heatherton, T. F. (2000). "Self-regulatory failure: A resource-depletion approach". Psychological Science 11: 249–254.
- Dorris, D. C.; Power, D. A.; Kenefick, E. (2011). "Investigating the effects of ego depletion on physical exercise routines of athletes". Psychology of Sport and Exercise 13: 118–125.
- Baumeister, R. F.; Sparks, E. A.; Stillman, T. F.; Vohs, K. D. (2008). "Free will in consumer behavior: Self-control, ego depletion, and choice". Journal of Consumer Psychology 18: 4–13. doi:10.1016/j.jcps.2007.10.002.
- Baumeister, R. F.; Vohs, K. D. (2007). "Self-regulation, ego depletion, and motivation". Social and Personality Psychology Compass 1: 115–128. doi:10.1111/j.1751-9004.2007.00001.x.
Further reading 
- Baumeister, R.F.; Dewall, C.N.; Ciarocco, N.J.; Twenge (2005). "Social Exclusion Impairs Self-Regulation" (PDF). Journal of Personality and Social Psychology 88: 589–604.
- Hagger, Martin S.; Wood, Chantelle; Stiff, Chris; Chatzisarantis, Nikos L. D. (2010). "Ego Depletion and the Strength Model of Self-Control: A Meta-Analysis". Psychological Bulletin (American Psychological Association) 136 (4): 495–525. doi:10.1037/a0019486. ISSN 0033-2909. PMID 20565167
- Inzlicht, M.; Schmeichel, B. J. (2012). "What is ego depletion? Toward a mechanistic revision of the resource model of self-control". Perspectives on Psychological Science 7: 450–463. doi:10.1177/1745691612454134.
- Muraven, M.; Baumeister, R. F. (2000). "Self-regulation and depletion of limited resources: Does self-control resemble a muscle?". Psychological Bulletin 126: 247–259.
- Muraven, M.; Tice, D. M.; Baumeister, R. F. (1998). "Self-control as a limited resource: Regulatory depletion patterns". Journal of Personality and Social Psychology 74: 774–789.