Perceptual discrimination and reaction time in hallucinatory schizophrenics.

Perceptual discrimination tasks were administered to a group of normal control subjects and the following three groups of schizophrenic subjects: those currently experiencing auditory hallucinations, those who experienced auditory hallucinations in the past but not at present, and those who never experienced auditory hallucinations. No one who ever experienced visual hallucinations was included. Reaction times (RTs) and accuracy in an auditory and in a visual perceptual discrimination task were recorded. The normal subjects were generally more accurate and had faster RTs than the schizophrenic groups. Among the schizophrenic groups, the currently hallucinatory group was generally most accurate. Also, their RTs early in the session were faster than those of the other schizophrenic subjects in the auditory, but not the visual, task. Unlike the other schizophrenic subjects, the currently hallucinatory group displayed faster auditory, as compared with visual, RTs throughout the session. The results point to altered processing of auditory information during the time schizophrenic subjects experience auditory hallucinations.