PERCEPTUAL AND ATTENTIONAL ASYMMETRIES IN SCHIZOPHRENIA - FURTHER EVIDENCE FOR A LEFT-HEMISPHERE DEFICIT

Increasing evidence suggests the presence of a lateralizing attentiona l deficit in schizophrenia. In the present study, 23 unmedicated patie nts with schizophrenia (mean age = 32.1 years) and 14 age- and sex-mat ched normal subjects were studied with the Global/Local Task to provid e converging evidence for the presence of a left-hemisphere-associated attentional deficit in schizophrenia. This task is sensitive to the i ntegrity of mechanisms involved in discriminating local and global ele ments of stimuli. Previous research has linked the discrimination of l ocal targets to left hemispheric processes and the discrimination of g lobal targets to right hemispheric processes. As predicted, patients w ere impaired in the detection of local level targets, consistent with a left hemispheric deficit. The degree of impairment correlated with t he patient's level of auditory hallucinations. These results are consi stent with previous studies showing an asymmetrical attentional defici t in schizophrenia and left hemispheric dysfunction. The correlation b etween this deficit and auditory hallucinations is consistent with a h ypothesized relationship between this symptom in schizophrenia and lef t temporal pathology.