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--an experimental paradigm that pilot research shows can dissociate affect from cognitive performance--to investigate the extent to which the ERN has arousal properties. Forty university students completed a misattribution of arousal paradigm by consuming a beverage they believed would either increase their anxiety or would have no side effects and then completed a go/no-go task while we recorded ERNs. Results indicate that participants who were given the opportunity to misattribute arousal exhibited a reduced ERN compared with participants who were not given any misattribution cues. This occurred despite no measurable differences in performance on the go/no-go task. In addition, correlations between the ERN and behavior were observed only for participants who did not misattribute their arousal to the placebo beverage. Taken together, these results suggest that the ERN is dissociable from cognitive performance but not negative affect. (Contains 2 figures, 1 table and 5 footnotes.)