Date of Award:
Master of Science (MS)
This study investigated the functional significance of cerebral asymmetries. Width measurements of the human brain were derived from computerized tomographic (CT) films and related to intellectual variables as determined by the Wechsler Adult Intelligence Scale Revised (WAIS-R). Subjects were adults of both sexes who had been referred for neurologic examination and were diagnosed as having no abnormalities (N=28). Reasons for referral included headache, dizziness, or to rule out central nervous system damage following various types of trauma. The asymmetry of hemispheric widths (left minus right) in the frontal, temporoparietal, and occipital areas was correlated with Verbal IQ minus Performance IQ scores within subjects. The difference between verbal and performance IQ scores was used because it reflected an IQ imbalance (IQ-I). Correlations obtained were -.30, -.26, and .06 (respectively). None of these correlations were significant by means of a two-tailed test. There were relationships between particular width asymmetries and individual subtest scores (p≤.05). The Verbal 1 (V1) subtest (Information) was correlated -.50, -.39 and -.47 with brain width asymmetries at 25%, 33% and 50% of the AP distance respectively. V1 correlated .39 with width asymmetry at 80%. Verbal 3 (Vocabulary), verbal 4 (Arithmetic) and verbal 5 (Comprehension) correlated .53 .38, and .39 with width asymmetry at 60% of the AP distance. Performance 1 (Picture Completion) correlated .46 with the width asymmetry at 20% of the AP length. In summary, there does appear to be some specific correlation between individual variation in brain asymmetry and cognitive processing. Relative size of the area of the brain that is involved in a key aspect of a particular cognitive processing may be a factor in the effectiveness of that processing. Further research appears warranted to confirm and clarify a possible relation between anatomical asymmetry and patterns of intellectual ability.
McShane, Anne, "A Study of the Relationships Between Hemispheric Asymmetries and Intellectual Abilities" (1987). All Graduate Theses and Dissertations. 6116.