Healthy Adults (n=32)

Schizophrenic Patients (n=66)

Surface potential topographies of right-handed healthy adults (n=32) and schizophrenic patients (n=66) for target stimuli during tonal (complex tones) and phonetic (consonant-vowel syllables) oddball tasks. At the peak of N2 amplitude (200 ms), healthy adults showed greater negativity over right frontotemporal sites for complex tones, and over left parietotemporal sites for syllables. Similar task-related asymmetries were seen for P3 (300-500 ms). Schizophrenic patients showed marked reductions of early negativities (N1, N2), but did not show reduced P3 amplitude, particularly in the tonal task. Task-related asymmetries of the N2/P3 complex were similar in healthy adults and schizophrenic patients.