Ego depletion

Ego depletion refers to the idea that self-control or willpower draw upon a limited pool of mental resources that can be used up.[1] 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.

The word “ego” in “ego depletion” is used in the psychological sense rather than the colloquial sense.

American social psychologist 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. Multiple experimental findings show support for this muscle model of self-control and ego depletion.[2]

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.[1] 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. Multiple experiments have connected self-control depletion to reduced blood glucose, and that self-control performance could be replenished by consuming glucose (e.g., lemonade).[3] However, some (but not all) of the findings were questioned.[4] Several recent experiments have found that resource depletion effects can be reversed by simply tasting (but not swallowing or consuming) sweet beverages,[5][6][7] which can have rewarding properties.[8] Others have suggested that the taste of sugar (but not artificial sweetener) has psycho-physiological signaling effects.

An experiment by Segertrom (2007) and Solberg Nes, has shown that HRV (heart rate variability) is a marker for both ego depletion, and an index for self-control power before the task. [1]

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.[9] 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.[10]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.[9] These findings demonstrate preliminary evidence that depletion experienced after exerting self-control, can weaken neural mechanisms responsible for conflict monitoring.
The majority of ego depletion studies have been carried out on university students, which raises concerns about how generalizable the results really are. The effects of age are unknown, but maybe younger people are 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.[11]

Although self-control has traditionally been thought of as a limited resource that can be depleted, some researchers disagree with this model[2]. While multiple studies provide support for the ego depletion effect, there is currently no direct measure of ego depletion, and studies mainly observe it by measuring how long people persist at a second task after performing a self-control task (the depleting task).[1] 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. 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.

Many 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.[1]

Process model

In contrast to the original most known model of self-control, Michael Inzlicht and Brandon J. Schmeichel propose an alternative model of depletion, which they refer to as the process model.[26] 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.

Reproducibility controversy and conflicting meta analyses

A 2010 meta analysis found the effect significant. Even after accounting for possible unpublished failed studies, the analysis concluded that it is extremely unlikely that the effect is untrue. [27] In 2015, another meta analysis argued that more strict meta analysis and different statistical models show no effect. [28][29] Others, however questioned the statistical analysis used in this analysis.[30]

In 2016, a major study carried out at two dozen labs across the world using a single protocol failed to find any evidence for ego depletion.[31][32]

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