Performance monitoring in the anterior cingulate cortex (ACC) has largely been viewed as a cognitive, computational process devoid of emotion. A growing body of research, however, suggests that performance is moderated by motivational engagement and that a signal generated by the ACC, the error-related negativity (ERN), may partially reflect a distress response to errors. Although suggestive, this past work is hampered by use of correlational designs or by designs that confound affect and cognitive performance. Here we use the misattribution of arousal paradigm