Perceptual asymmetries in schizophrenia: subtype differences in left hemisphere dominance for dichotic fused words.

ABSTRACT

OBJECTIVE: Dichotic listening techniques have been used to study hemispheric dominance for language in schizophrenia. The authors' goal was to compare subjects with paranoid and undifferentiated subtypes of schizophrenia. METHOD: The Fused Rhymed Words Test was used to compare perceptual asymmetries in 16 patients with paranoid schizophrenia, 28 patients with undifferentiated schizophrenia, and 29 healthy comparison subjects. RESULTS: Patients with paranoid schizophrenia had the largest left hemisphere advantage and patients with undifferentiated schizophrenia had the smallest. The asymmetry of healthy subjects was intermediate. Hemisphere advantage varied as a function of gender only in the patients with undifferentiated schizophrenia. CONCLUSIONS: The findings support the hypotheses that undifferentiated schizophrenia is associated with underactivation of left hemisphere resources for verbal processing and that paranoid schizophrenia is characterized by preserved left hemisphere processing.