There have been several studies on WCST training in schizophrenia. However, it is still unclear what aspects of the test schizophrenic patients find most difficult: are they failing because of impaired attention, memory or planning, to name a few possibilities? To address this, seven different versions of the WCST were developed, including a range of alternative stimuli and training techniques. The subjects were 24 schizophrenics and 24 elderly controls, divided into eight groups of three pairs (one group merely repeating the standard version), matched on their poor performance of the WCST (<3 categories). Results on retesting with the standard WCST after carrying out a modified version, suggest levels of test performance are not fixed, and that modifications which promote planning, pacing and error detection are the most successful in improving WCST score, especially in schizophrenics. Additionally, performance was improved in controls, but not schizophrenic patients by increasing the verbal information contained in the task. The results indicate that WCST deficits in elderly controls are due to limited capacity, whereas in patient with schizophrenia, the problem may be due to the impaired monitoring of responses.
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