Running on empty: neural signals for self-control failure.

Past research shows that self-control is limited and becomes depleted after initial exertions. This study examined the neural processes underlying self-control failure by testing whether controlled, effortful behavior impairs subsequent attempts at control by depleting the neural system associated with conflict monitoring. Subjects either watched an emotional movie normally or tried to suppress their emotions while watching the movie; they then completed an ostensibly unrelated Stroop task while electroencephalographic activity was recorded. The error-related negativity (ERN)--a waveform associated with activity in the anterior cingulate--was measured to determine whether prior regulatory exertion constrained the conflict-monitoring system. Compared with subjects in the control condition, those who suppressed their emotions performed worse on the Stroop task, and this deficit was mediated by weaker ERN signals. These results offer a neural account for the self-regulatory-strength model and demonstrate the utility of the social neuroscience approach.