Working memory in schizophrenia: A systematic study of specific modalities and processes

Although many researchers agree that working memory (WM) impairments are a core symptom of schizophrenia, it remains unclear how the disturbances on specific WM components relate to one another. In this study, we presented a Delayed-Matching-To-Sample task to 24 schizophrenia patients and 24 healthy controls, matched on demographical variables. Verbal and visuospatial WM performance was investigated with pseudowords and Chinese characters as stimuli, respectively. Processing demands (maintenance and manipulation, measured with delay and mental rotation) were low or high. Reaction time and accuracy were recorded. All experimental factors had significant effects. In general, patients were slower and less accurate than controls. Patients were especially slower on verbal tasks but they were not less accurate. Accuracy differences did not increase when either maintenance or manipulation demands increased alone but they did when both maintenance and manipulation demands increased simultaneously. These findings indicate that performance impairment in patients was non-specific and that no specific deficit of any WM component was observed.