Self-regulation refers to people's ability to regulate their own thoughts and actions, and override them when necessary. Measures of self-regulation have been observed to correlate with a number of important outcomes, including academic achievement and job performance (Cleary, 2006; Gailliot, 2008; Mischel, Shoda, & Peake, 1988). Nevertheless, there is still debate about how best to conceptualize self-regulation. Does self-regulation draw on ability or motivation? This debate has been discussed, in recent years, in the context of a finding referred to as the ego-depletion effect. This effect has typically been demonstrated using a two-task procedure (e.g., Muraven, Tice, & Baumeister, 1998). In a depletion condition, participants perform a task that presumably places a high demand on self-regulation, whereas in a control condition, participants perform a non-regulatory task. All participants then complete a demanding regulatory task. In a number of studies, participants in the depletion condition have performed worse on the second task than participants in the control condition. One prominent explanation of ego-depletion is the resource depletion account. The basic idea of this account is that self-regulation draws on a limited resource that becomes even more limited after engaging in self-regulation; this negatively affects subsequent self-regulatory behavior. Thus, according to this account, ego-depletion reflects an inability to continue regulating effectively. There are several limitations of the resource account of ego-depletion and alternative explanations are possible. Specifically, a motivation account suggests that ego-depletion reflects an unwillingness to perform the second task rather than an inability to do so. That is, it could be that individuals who have previously exerted more effort may be less inclined to exert effort thereafter without sufficient motivation. In this dissertation, I conducted five studies to investigate this possibility. In the first study, I performed a meta-analysis and found a relationship between the depletion effect and ratings of effort and difficulty on the first task. In the second study, I found a depletion-like effect after two initial non-regulatory tasks that required different levels of effort exertion. In the third and fourth studies, I found depletion-like effects using motivation manipulations--even when, across conditions, participants' resource was presumably depleted to the same degree. In the fifth study, I investigated whether the role of effort and motivation extended to a three-task conservation procedure (see Muraven, Shmeuli, & Burkley, 2006). While I did not find evidence for conservation, I did find some evidence that motivation continues to impact performance after two demanding regulatory tasks. Together, these findings suggest that motivated effort allocation has a significant impact on ego-depletion. Specifically, the results suggest that individuals are less inclined to exert effort after prior exertion. If sufficiently motivated, however, participants can and will exert effort.
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