Event-related brain potentials to high-incentive stimuli in unmedicated schizophrenic patients

Schizophrenic patients have been observed to have a significantly diminished P300 component of the event-related potential (ERP). We investigated whether this result would be obtained with high-incentive stimuli. We presented 14 unmedicated patients and 14 controls with two easily identified visual stimuli under three conditions: (i) a nonincentive condition, (ii) under the condition of $1 payment for each correct identification, and (iii) under the condition of $1 payment for each correct identification within a criterion time. The patients responded accurately but showed a significantly reduced P300 in the incentive conditions. We interpret our results as neurophysiological evidence for possible limbic system dysfunction in schizophrenia.