Redundancy-associated deficit in schizophrenic reaction time performance.

Abstract

Hospitalized schizophrenic patients, process and reactive as defined by the Elgin Prognostic Rating Scale, were compared with nonschizophrenic psychiatric patient controls and normal controls to assess the effects of redundancy of information on reaction lime performance. The influence of information redundancy was assessed by manipulating the degree of regularity in the presentation of preparatory interval (PI) durations. Runs of two and four identical Pis, defined as low and high redundant sets, respectively, were embedded in an irregular order of trials to test the influence associated with regular presentation. Departing from an observation in the literature that the irregular versus regular presentation condition interacts with PI duration, this study found the interaction for process patients only. This interaction takes the form of a "crossover" in which the regular PI trials yield worse performance than the irregular trials at long PI durations, although the opposite is true for short durations. The findings in the present study show that redundant Pis tended to show an improved performance immediately and then, for the process group only, a progressive loss on successive trials. An interpretation in light of Shakow's "set theory" and an inhibitory process explanation were discussed.

Information processing: a new model for understanding cognitive disturbances in psychiatric patients

“…Concerning the crossover effect, results from various studies have shown that in 47-72% of all process schizophrenics, a typical crossover pattern is manifested (referring now to the Steffy paradigm in which each series of regular preparatory interval trials is embedded in a longer irregular series (78,79)). The crossover pattern has, however, also shown to be highly prevalent in temporal lobe lesion patients, and in some groups of aged patients (48).…”

Relationship between exploratory eye movement, P300, and reaction time in schizophrenia

“…Almost all of the available literature suggests that a high rate of process schizophrenic patients shows the RT-crossover. 6,10,11,14,17 These findings suggest that the crossover phenomenon may be a marker for process schizophrenia.…”

David Shakow and schizophrenia research at Worcester State Hospital: The roots of the scientist‐practitioner model

“…Numerous schizophrenia researchers in subsequent decades have referred to Shakow's findings as solid evidence of reaction time deficits. Moreover, many have relied on this paradigm to study the crossover effect and its implications for the cognitive underpinnings of the disorder (e.g., Bellissimo & Steffy, 1972;Nideffer et al, 1971;Knehr, 1954;Rosenbaum, Taylor, & Minasian, 1997;Tizard & Venables, 1956). And although researchers have offered alternative explanations for Shakow's findings (e.g., Steffy & Galbraith, 1974), they continue to utilize Shakow's work as a starting point.…”