Nonverbal working memory deficits in schizophrenia patients: evidence of a supramodal executive processing deficit

BACKGROUND: Although there have been several investigations of spatial working memory performance in schizophrenia patients, there have been considerably fewer studies of object working memory. The purpose of the present investigation was to evaluate the domain specificity of nonverbal working memory impairment in schizophrenia patients. METHODS: Delayed match-to-sample tasks involving spatial, identity and affective information were administered to schizophrenia and schizophrenia-spectrum patients (n=36) and normal controls (n=29). RESULTS: Using visual stimuli that can be considered prototypical of object vision, namely, faces we observed that schizophrenia patients perform poorly on working memory tasks that are based on the identity and/or features of the stimulus (i.e., object-based working memory tasks) as well as on a working memory task based on the spatial location of the stimulus. We observed significant associations between global ratings of negative symptoms and working memory performance. CONCLUSIONS: These data demonstrate that the working memory deficit displayed by schizophrenia and schizophrenia-spectrum patients extends to nonspatial visual domains.