The good, the bad and the neutral: electrophysiological responses to feedback stimuli.

The feedback error-related negativity (fERN) is a component of the event-related brain potential elicited in gambling and trial-and-error learning tasks by negative, but not positive, feedback stimuli. Here, we present the results of a series of five experiments that investigated the response of the fERN to the presentation of neutral feedback stimuli. In three of the experiments, the neutral feedback stimuli indicated that the participants did not receive a potential reward nor incur a potential penalty (i.e., they received nothing); and in the remaining two experiments, the neutral feedback stimuli did not convey any meaningful information (i.e., the participants were either successful or unsuccessful on those trials, but the feedback stimuli were uninformative about the outcomes). Across the five experiments, we found that neutral feedback stimuli elicited a fERN about as large as that elicited by negative feedback stimuli. This result is consistent with recent proposals that the evaluative system that produces the fERN classifies outcomes into two categories: those outcomes that indicate that a goal has been satisfied and those that do not.