Sex differences and hemispheric organization in cognitive functioning

Abstract

The literature review concludes that despite inadequacies in the evidence and the need to qualify current generalizations, the existence of sex differences in the verbal and spatial domains, especially the latter, is well documented. In contrast, the available experimental
and clinical neuropsychological data provide only slender
support for the idea that the sexes differ in patterns of functional cerebral specialization.
A series of studies of cognitive skills provide evidence of a male superiority on certain spatial tasks (mental rotation, water-level prediction), but no evidence of a sex difference on verbal tasks (word fluency, letter detection). Pilot experiments on perceptual laterality effects (dichotic listening,· divided visual-field presentation and dichaptic stimulation) are next reported. In the final study, 80 right-handed adults completed a battery of standard tests of verbal and spatial ability and three tests of perceptual laterality, each involving either verbal or spatial stimulus materials. The results indicate that cognitive test scores are related to the degree of asymmetry manifest on perceptual laterality tasks. For instance, males showing the greatest ear asymmetry during dichotic listening also achieved the highest scores on spatial tests. However, the nature of the relationship varies depending on the sex of the subject, the particular verbal or spatial task employed, and the particular laterality task used.
A factor analysis of accuracy scores on both the ability and laterality tests provided only partial confirmation of assumptions about the cognitive skills tapped by these tests. It is argued that the study of variations in solution strategy will further our understanding of individual differences in cognitive ability and perceptual laterality.