Cognitive subprocesses and schizophrenia. A. Reaction-time decomposition

Objective: The aim of the study is to demonstrate that deficits of information processing in schizophrenic patients can be isolated with reaction-time (RT) decomposition paradigms. Method: Three types of visually presented tasks were applied: simple, disjunctive and choice RT-tasks. RT were split into movement latency and time necessary to execute movements. Comparisons of three samples of schizophrenic patients (295.3) with individually matched (age, sex, education and handedness) healthy controls are presented: Sample 1:10 drug-naive first-onset patients, Sample 2:10 neuroleptically treated first-onset patients, Sample 3:10 neuroleptically treated chronically ill patients. Results: Findings indicate that schizophrenia affects primarily subprocesses in which percepts are translated into appropriate actions (response-selection). Neuroleptic treatment improves processing at this stage but is accompanied by slowing of movement execution. Conclusion: Response-selection is selectively impaired in first-onset patients. This disturbance, which might be specific for schizophrenia, can be regarded as indication of a disconnection between frontal and posterior areas.