As research on the ERN has progressed, a major development has been the finding that brain activity like the ERN can happen when people encounter things other than errors. Don Tucker and Phan Luu and their colleagues, for example, found that ERN-like activity can be observed when people see bad things (associated with negative emotions), and they also found that people who score high in negative emotionality produce larger ERNs than control subjects early in task performance. John Allen and his colleagues found that individuals who score low on measures of socialization, a group very much like psychopaths, show reduced ERNs when punished for errors, consistent with psychopaths' inability to stop doing things for which they are punished. A number of other findings have seemed inconsistent with the response-conflict and error-detection views.
Findings like these led us to hypothesize that the anterior cingulate is involved in detecting motivationally salient negative events. Clay Holroyd and his colleagues have proposed a similar view. Their theory emphasizes the role of midbrain dopaminergic systems in generating a response to outcomes that are worse than expected. One example of such an event is the loss of money in a gambling task. We found that losses in a simple gambling task would be were associated with activity similar to the ERN (see Gehring & Willoughby, 2002), even when the subjects made a correct choice (by avoiding other, worse losses). Yanni Liu's dissertation work, however (see Liu and Gehring, 2009), has found that the perceptual characteristics of feedback stimuli can affect the size of the ERN, raising doubts that the FRN is solely concerned with a loss of reward.
Most recently, Nicola Ferdinand showed that positive (rewarding) response feedback will cause an FRN when it is unexpected. This new finding suggests that it is the unexpectedness of a response outcome, rather than its valence, that is important for causing an FRN (Ferdinand et al., in press).