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Ego depletion refers to the idea that self-control and other mental processes that require focused conscious effort rely on energy that can be used up. When that energy is low (rather than high), mental activity that requires self-control is impaired. In other words, using one's self-control impairs the ability to control one's self later on. In this sense, the idea of (limited) willpower is correct. In an illustrative experiment on ego depletion, participants who controlled themselves by trying not to laugh while watching a comedian did worse on a later task that required self-control compared to participants who did not have to control their laughter while watching the video.
Much of the early research on ego depletion was performed by Roy Baumeister, Mark Muraven, and their colleagues.
The theory of ego depletion suggests that one’s capacity for self-regulation is a limited resource or energy that can be exhausted (1). Ego depletion itself refers to the case in which the self’s capacity or willingness to take volitional action is temporarily reduced in response to a previous act of volition (1). Such volitional actions include conscious, controlled processing, active choice making, initiating behavior, and overriding responses (1). Volition, which is more commonly known as willpower, is the cognitive process by which an individual decides on and commits to a particular course of action.
Baumeister, Bratslavsky, Muraven, and Tice (1998) have conducted a series of experiments aimed at gathering evidence for the hypothesis of ego depletion. An outline of some of these is provided below.
In the first experiment, a bowl of radishes and a stack of freshly-baked chocolate chip cookies were placed on a table. Subjects in the experiment were instructed to skip a meal in order to induce hunger. Three conditions were established: radish-eating, chocolate-eating, and non-eating. The non-eating condition constituted the control. In the radish condition, subjects were left alone in the room and asked to eat two or three radishes, while avoiding the chocolate. In the chocolate condition, subjects were asked to eat two or three cookies, while avoiding the radishes. The non-eating subjects did not participate in the eating part of the experiment. Following the eating exercise, subjects were instructed to attempt to solve a geometrical drawing puzzle, which unbeknownst to them, was actually impossible to solve. Subjects were also informed that if they wished to quit trying to solve the puzzle, they would be able to do so. Results showed that participants in the radish condition quit sooner on the puzzle task than did participants in either the chocolate condition or the non-eating condition. Also evident was that the chocolate condition did not differ from the no-food control condition in persistence in trying to solve the puzzle. Participants in the radish condition also reported being more tired after the puzzle task than those in the chocolate or non-eating conditions. These findings showed support for the theory of ego depletion. In the radish condition, the subjects’ resistance to the temptation to eat chocolate resulted in the decrease of some psychic energy. The depleted level of this energy resulted in radish-condition subjects to give up more easily on the puzzle task. Conversely, subjects in the chocolate and non-eating conditions did not have their resource taxed, and therefore showed no decrease in persistence in the puzzle task.
The second experiment aimed to study whether ego depletion could impair performance on solvable, rather than unsolvable, tasks. The first part of the study involved having participants watch movies. In the suppress-emotion condition, subjects were asked to try to not show or feel emotions while viewing the movies. On the other hand, participants in the no-regulation condition were instructed to let out their emotions while watching the movies. Half of the subjects in each condition were then shown a positive, humorous clip of video, while the other half were presented with a negative, sad clip of video. Following the viewing, participants were given anagram letter sets that they were asked to solve. The results showed that subjects in the suppress-emotion condition solved significantly fewer anagrams than those in the no-regulation condition. The type of movie that was watched had no affect on the ability to solve anagrams. In this case, self-regulation in the form of emotion suppression was followed by poorer performance in solving anagram puzzles. This provided further evidence that some resource was depleted after an act of volition. Other experiments performed by Baumeister and his colleagues showed that making a responsible decision impaired subsequent self-control and that an initial act of self-control led to increased passivity. The latter can be explained by the fact that activity requires cognitive energy that is presumably depleted after an act of self-control.
Because these experiments provided no direct measure of the limited resource in question, the hypothesis of ego depletion is based on behavioral observations and analyses. As a result, it is important to consider alternative explanations for the behavior. One such alternative view is that the frustration experienced by participants during puzzle tasks could have resulted in negative emotions that would lead to quitting the task. However, Baumeister et al. (1998) measured negative emotion in several parts of the experiments and did not find it to differ among conditions in the experiments. Further, the visual stimuli in Experiment 2, whether positive or negative, did not affect performance in the anagram task. Another alternative explanation for the findings could be that quitting the unsolvable puzzles was actually a volitional act of good self-regulation instead of a sign of self-regulation failure. This interpretation assumes that the subjects were able to recognize that the puzzles were indeed unsolvable and so actively made the decision to not waste any further time on them. However, this alternative explanation was addressed and encountered by Experiment 2, in which solvable anagrams still prompted a decrease in performance.
Ego depletion is an area on ongoing study. Baumeister continues to be one of the most active researchers of this phenomenon. Studies performed by Baumeister and his colleagues have revealed results that provide insight into some of the occurrences that human beings experience in everyday life. Schmeichel, Vohs, and Baumeister (2003) discovered that individuals who experienced ego depletion via experiments similar to those described above were less intelligent and less capable of performing high-level mental tasks (2). Ego depletion did not affect performance on lower-level tasks, such as memorization. This result suggests that acts of volition can result in cognitive performance decrements. The result also suggests that the cognitive resource necessary for volitional acts is also required for high-order mental tasks. Baumeister, Sommer, and Ciarocco (2001) performed experiments which studied the relationship between ego depletion ostracism. Such studies revealed that subjects who followed instructions to avoid conversation with a confederate for 3 minutes later showed decrements in persistence on unsolvable problems (3). Apparently, the act of ostracism also depletes the cognitive resource. Ego depletion has also been found to have implications in consumer behavior. Baumeister (2002) has suggested that depletion of the self-regulatory resource caused by prior exertion or decision making may lead to an inability to resist impulsive purchases that one may regret later on (4).
Generally, Baumeister’s experiments showed that an act of volition, whether a choice or an effort of self-control, can cause a decrease in some sort of resource that is required for further acts of volition. Whatever this resource is, it is clear that it is both very important and very limited. It is apparent that depletion of this resource can affect decision-making and cognitive ability, which thereby can affect the way in which human beings conduct their lives. While there is currently no way of quantitatively measuring the internal resource that is used in decision making and self-regulation, the results of these experiments provide strong evidence for the hypothesis of ego depletion. Ultimately, ego depletion is consistent with the understanding of automatic and controlled processing. Controlled processing depletes the limited resource. As a result, perhaps the vast amount of automatic processing that occurs in the brain has evolved to help conserve this resource. It may be assumed that this resource can be replenished, but the means by which this occurs or factors that would positively or negatively affect replenishment cannot currently be determined.
Baumeister, Roy F. "Ego Depletion: Is the Active Self a Limited Resource?" Journal of Personality and Social Psychology Vol. 7405 1998 1252-1265. 25 Nov 2008.
Baumeister, Roy. "Ego Depletion, Self-Control, and Choice." Handbook of Experimental Existential Psychology. Thomas Pysczcynski. Guilford Press.
Baumeister, Roy. "Yielding to Temptation: Self-Control Failure, Impulsive Purchasing, and Consumer Behavior." Journal of Consumer Behavior Vol. 28 (2002).
Ciarocco, Natalie, Kristin Sommer, Roy Baumeister. "Ostracism and Ego Depletion: The Strains of Silence." Personality and Social Psychology Bulletin Vol. 27(2001): 1156-1163.
Moller, Arlen. C., Deci, Edward. L., & Ryan, Richard. M. (2006). Choice & ego-depletion: A self-determination theory perspective. Personality and Social Psychology Bulletin, 32, 1024-1036.