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The reinforcement learning theory suggests that the feedback negativity should be larger when feedback is unexpected. Two recent studies found, however, that the feedback negativity was unaffected by outcome probability. To further examine this issue, participants in the present studies made reward predictions on each trial of a gambling task where objective reward probability was indicated by a cue. In Study 1, participants made reward predictions following the cue, but prior to their gambling choice; in Study 2, predictions were made following their gambling choice. Predicted and unpredicted outcomes were associated with equivalent feedback negativities in Study 1. In Study 2, however, the feedback negativity was larger for unpredicted outcomes. These data suggest that the magnitude of the feedback negativity is sensitive to violations of reward prediction, but that this effect may depend on the close coupling of prediction and outcome.

A two-component event-related brain potential consisting of an error-related negativity (ERN/Ne) and positivity (Pe) has been associated with response monitoring and error detection. Both the ERN and Pe have been source-localized to the anterior cingulate cortex (ACC)Fa frontal structure implicated in both cognitive and affective processing, as well as autonomic nervous system (ANS) modulation. The current study sought to examine the relationships among the ERN, the Pe, two autonomic measures, and behavior. Electroencephalogram (EEG), heart rate (HR), and skin conductance (SC) were recorded while subjects performed a two-choice reaction-time task. In addition to the characteristic ERN-Pe complex, errors were associated with larger SCRs and greater HR deceleration. The ERN correlated with the number of errors, but was unrelated to ANS activity and compensatory behavior. Pe, on the other hand, was correlated significantly with SCR, and both SCR and Pe were significantly correlated with post-error slowing.Descriptors: Error-related negativity (ERN), Event-related brain potential (ERP), Error processing, Heart rate (HR), Skin conductance response (SCR)

The error-related negativity (ERN) is an event-related brain potential observed when subjects receive feedback indicating errors or monetary losses. Evidence suggests that the ERN is larger for unexpected negative feedback. The P300 has also been shown to be enhanced for unexpected feedback, but does not appear to be sensitive to feedback valence. The present study evaluated the role of expectations on the ERN and P300 in two experiments that manipulated the probability of negative feedback (25%, 50%, or 75%) on a trial-by-trial basis in experiment 1, and by varying the frequency of positive and negative feedback across blocks of trials in experiment 2. In both experiments, P300 amplitude was larger for unexpected feedback; however, the ERN was equally large for expected and unexpected negative feedback. These results are discussed in terms of the potential role of expectations in processing errors and negative feedback.