Prior time uncertainty reduction of foreperiod duration under two different levels of event uncertainty in process and reactive schizophrenia.

Abstract

Process and reactive schizophrenic Ss judged stimulus durations of .50 and .55 seconds. Stimulus was 1, 3 or 5 dark dots and was preceded by variable foreperiod duration of 1, 3 or 5 seconds. Judgment of stimulus duration was found to be a monotonically increasing function of foreperiod duration. When pitch of the auditory warning signal was correlated with foreperiod duration so that it functioned as prior time information, such monotonic function was eliminated for process schizophrenics only when the numerosity of dots was constant from trial to trial. The effect of prior time information that concerned foreperiod duration was negligible for both process and reactive schizophrenics when the numerosity of dots was variable from trial to trial. Uniqueness of process schizophrenia was shown to be associated with prior time uncertainty reduction of foreperiod duration in the context of minimal event uncertainty of stimulus.