Cognitive subprocesses and schizophrenia. A. Reaction-time decomposition

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