Twenty-three inpatients and two outpatients (20 male, 5 female) at New York State Psychiatric Institute were recruited for the study, excluding left-handed individuals and those with a history of neurological illness or substance abuse. Five male patients did not provide sufficient correct, artifact-free trials for stable ERP waveforms (more than 15 for new or old items) and were removed from the study. The patients included in the final patient sample met DSM-IV (American Psychiatric Association, 1994) criteria for schizophrenia (paranoid, n = 11; undifferentiated, n = 4), schizoaffective disorder (bipolar type, n = 3), or psychosis not otherwise specified (n = 2).1 Diagnoses were based on clinical interviews by psychiatrists and a semistructured interview (Nurnberger et al., 1994) including items from commonly-used instruments (e.g., SCID-P, Spitzer et al., 1990; SANS, SAPS, Andreasen 1983, 1984). Symptom ratings were obtained using the Positive and Negative Syndrome Scale (PANSS; Kay et al., 1992). The total BPRS score indicated that patients were mildly-to-moderately disturbed (Table 1). Most patients (n = 11) did not receive antipsychotic medications for at least 14 days before testing. Nine
