Ego Depletion : Encyclopedia of Social Psychology

The model of ego depletion suggests that individuals have a fixed amount of resource to exert selfcontrol or perform other effortful and willful acts of the self. This resource, called ego strength, is required for any and all self-directed efforts (in particular, selfcontrol and making choices that are relevant to the self). This ego strength is consumed or depleted in the process of self-control, however. In addition, this ego strength is recovered slowly, so that it remains depleted for some time after the exertion itself. Thus, the process of exerting self-control or making choices reduces the amount of ego strength available for future self-control efforts. Moreover, the success of selfcontrol depends on ego strength: When ego strength is depleted, self-control is more likely to fail. Hence, individuals whose ego strength has been depleted through the previous exertion of the self's will are more likely to suffer a loss of self-control, because the success of self-control depends on having enough strength to fight off the temptation. In short, the exertion of self-control can lead to poorer self-control subsequently, through the exhaustion of self-control strength, a process known as ego depletion.