Cerebral deficits in schizophrenia have been associated either with left hemisphere dysfunction, or with impairment in interhemispheric transfer. To test the relative efficacy of the two hypotheses, 63 right-handed subjects (24 paranoid schizophrenics, 21 nonparanoid schizophrenics, and 18 normal controls) were given two auditory lateral tasks: identification of dichotically delivered tonal sequences and digit sets. As the data analyses showed, more correct responses were given by the normal controls than by the patients, and by males than by females. Generally, report (especially from the ear reported second) was better from the right than from the left ear. This right ear advantage (which was more consistent in males than in females) was abnormally large for the paranoid schizophrenics who showed on both tests, relative to normal subjects, a slight decrement in right ear report and a significant decrement in left ear report. The data were interpreted as indicating left hemisphere dysfunction and structural callosal damage in paranoid schizophrenics.
