Filling the preparatory interval with temporal information or visual noise: crossover effect in schizophrenics and controls

Abstract

SYNOPSISThree variants of a simple reaction time task with regular and irregular series of different preparatory intervals (Pls) were presented to schizophrenics and a control group of alcoholics and normals: the visual warning signal (WS) either (1) remained fixed, (2) shrank at a constant rate, or (3) changed in size erratically. Time information provided by shrinking WSs reduced the average reaction time in all groups and attenuated the crossover effect (COE) of schizophrenics, although even here more schizophrenics than controls had COE-scores ≥ 25 msec. Erratically changing WSs introduced the COE in controls. Within groups the COE was not related to general response speed, age, duration of hospitalization, or medication. Results are interpreted as indicating that schizophrenics eschew controlled anticipatory processes on the basis of WS- and PI-information which are crucial for motor preparation when PIs are too long to allow an automatic perceptual grouping of warning and imperative stimulus. This may also occur in controls when time estimation is impeded by distraction.

Manual and saccadic reaction time with constant and variable preparatory intervals in schizophrenia.

“…Most prior studies used a longer maximum PI. However, some previous manual RT studies using a similar range of PIs have found greater regular PI effects in schizophrenia than in controls (Borst & Cohen, 1989; R. Cohen, Hermanutz, & Rist, 1984), but not all (Borst & Cohen, 1987).…”

Context, cortex, and dopamine: A connectionist approach to behavior and biology in schizophrenia.

“…In addition to the Stroop task and the CPT, there are a number of other information-processing paradigms in which schizophrenics exhibit performance deficits that have been related to selective attention, including the span of apprehension task (Neale, 1971), dichotic listening tasks (Spring, 1985; Wielgus & Harvey, 1988), and a variety of reaction time tasks (see Nuechterlein, 1977, for a review of the early literature, and Borst & Cohen, 1989, and R. Cohen, Borst, & Rist, 1989, for more recent work).…”