Prior time uncertanity reduction of foreperiod duration under two different levels of event uncertainty in schizophrenia

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Schizophrenic and alcoholic 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 both foreperiod duration and numerosity of dots. When pitch of sound, which functioned as a warning signal, was correlated with numerosity of dots, the monotonic relation between numerosity of dots and estimation of stimulus duration was eliminated for alcoholics, but not for schizophrenics, only when foreperiod duration was constant from trial to trial. The effect of prior information as to numerosity of dots was negligible for both schizophrenics and alcoholics when foreperiod duration was variable from trial to trial.

Prior event uncertainty reduction under two different levels of time uncertainty of foreperiod duration in schizophrenia

Mo¹,

Kersey²,

Lowe³

1977

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

Mo¹,

Kersey²,

Lowe³

1977

Self Cite

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.

Weakness and instability of time expectancy in schizophrenia

Mo¹,

Kersey²,

Huang³

1978

Duration of a tachistoscopically presented dark dot was estimated by schizophrenics and alcoholics. The dot was preceded by the auditory warning signal of viariable duration of up to 9 seconds. The duration of the warning signal constituted foreperiod duration. Estimation was a monotonically increasing function of foreperiod duration for both schizophrenics and alcoholics when the probability distribution of foreperiods was constant. However, this monotonicity was eliminated when changes in foreperiod duration became infrequent. When intrusion of extraneous stimulus accompanied such infrequent changes, the effect of foreperiod duration on estimation of stimulus duration became curvilinear, with the maximum estimation at the mid-range. For alcoholics, the monotonically increasing effect of foreperiod duration was independent of relative frequency of foreperiod changes and intrusion of extraneous stimulus. Weakness and instability of time expectancy as characteristics unique to schizophrenia were demonstrated.