Functional hemispheric differences in schizophrenia: interhemispheric transfer deficit or selective hemisphere dysfunction?

Two hypotheses concerning functional hemispheric organization in schizophrenic patients were examined in two experiments. In the first experiment 35 chronic schizophrenics and 35 normal controls performed tactile-visual matchings with each hand. The results showed that the performance level of the schizophrenics was inferior to that of the normal controls, but did not show any hand difference. In the second experiment chronic schizophrenics and normal controls made intermanual matchings and intramanual matchings with successively presented nonmeaningful shapes. The results revealed that the intermanual matchings of the schizophrenics were significantly inferior to those of the controls but there was no subject group difference in the intramanual matchings. These results did not lend support to the hypothesis that schizophrenics have selective left hemisphere impairment, but suggest that there may be an interhemisphere interaction deficit in schizophrenic patients.