NUMBERS OF PRECEDING NONTARGETS DIFFERENTIALLY AFFECT RESPONSES TO TARGETS IN NORMAL VOLUNTEERS AND PATIENTS WITH SCHIZOPHRENIA - A STUDY OF EVENT-RELATED POTENTIALS

This event-related potential study systematically varied the number of nontargets (1, 3, 5, 7, 9) preceding the target tone in an oddball experiment and examined the effect of this on N-2, P-3, and reaction time measures in schizophrenic patients and normal volunteers. Schizophrenic patients were found to have reduced P-3 amplitudes, but this reduction was restricted to series when the targets followed an intermediate number (3-7) of nontargets, and not when targets followed a short (1) or long series (9) of nontargets. Although other interpretations of this finding are possible, the pattern of results could be explained by the hypothesis that the refractory period governing the generation of the P-3 component was prolonged in schizophrenia.