The selective attention deficit in schizophrenia. Limited resources or cognitive fatigue?

The Stroop Word-Color Test was used to study selective attention deficits in schizophrenic and nonschizophrenic psychiatric patients, compared with nonpsychiatric control subjects. Parts of the Weschler Memory Test and a shortened version of the Stroop Test were administered to test the hypotheses that the attentional deficit could be explained by problems of memory or cognitive fatigue. All patients showed deficits on all of the Stroop scales, but closer analysis of the results permitted discrimination of schizophrenic from nonschizophrenic patients. Schizophrenic patients showed as much difficulty as nonschizophrenic subjects on a limited-duration selective-attention task, but deteriorated significantly more when selective attention had to be maintained. The results could not be attributed to memory problems in the schizophrenic group. The results support the existence of two separable selective attention deficits in schizophrenic patients: a difficulty in selectively attending to the salient aspect of a complex stimulus, a difficulty shared with nonschizophrenic subjects, and a difficulty in maintaining selective attention over time that seems to be more marked in schizophrenic subjects.