Effects of cerebral hemispheric laterality on the span of apprehension of schizophrenic and healthy subjects.

The effects of hemispheric laterality on a forced-choice Span of Apprehension (SoA) task were investigated. Forty-eight adult schizophrenic inpatients were recruited. A control group of healthy subjects was put together using the matched-pairs method with age, gender, and education as control variables. SoA performance was determined separately for the left and right visual field (VF), respectively. No SoA group differences were found; in both groups, the hit percentage was higher in the right VF. However, in the schizophrenic group, the left VF performance showed significant negative correlations with psychopathologic symptoms (especially auditory verbal hallucinations). In a subsample of patients receiving atypical neuroleptic drugs, the daily dosage correlated negatively with left VF performance. In general, young subjects performed better than old subjects (both VFs), males performed better than females, and subjects with high education performed better than subjects with low education (right VF).