[6] American social psychologist Roy Baumeister and his colleagues proposed a model that described self-control like a muscle, which can become both strengthened and fatigued.
The researchers proposed that initial use of the “muscle” of self-control could cause a decrease in strength, or ego depletion, for subsequent tasks.
[2] A key experiment by Baumeister, Ellen Bratslavsky, Mark Muraven, and Dianne Tice in 1998, demonstrated some of the first evidence that ego depletion had effects in 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.
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.
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.
[8] However, several recent experiments have found that resource depletion effects can be reversed by simply tasting (but not swallowing or consuming) sweet beverages,[9][10][11] which can have rewarding properties.
[12] A 2007 experiment by Segertrom and Nes found HRV (heart rate variability) to be a marker for ego depletion as well as an index for self-control power before the task.
According to cognitive and neuroscientific models of mental control, a "conflict-monitoring/error-detection system" identifies discrepancies between intended goals and actual behaviors.
[14] 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.
[14] These findings demonstrate preliminary evidence that depletion experienced after exerting self-control can weaken neural mechanisms responsible for conflict monitoring.
[18] 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.
[18] 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.
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 indicates that an increased perceived level of fatigue can hinder self-regulatory performance independent of the actual state of depletion.
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.
[20] An experiment by Carol Dweck and subsequent work by Roy Baumeister and Kathleen Vohs have shown that beliefs in unlimited self-control help mitigate ego depletion for a short while, but not for long.
[21] 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.
[citation needed] An experiment performed by Kathleen Vohs and Todd Heatherton demonstrated how ego depletion is particularly relevant when considering chronic dieters compared to non-dieters.
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.
A recent experiment showed that inducing a positive mood can buffer the impairing effects of ego depletion on subsequent performance.
The existence of a spare reservoir of mental energy ultimately explains why various motivators can buffer the effects of mild or moderate ego depletion.
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.
[32] This process model holds that initial exertions of willpower lead an individual's motivation to shift away from control, and towards gratification.
[40] In 2016, a major multi-lab replication study (2141 participants) carried out at two dozen labs across the world using a single protocol failed to find any evidence for ego depletion.