INTELLIGENCE 17, 461-474 (1993) Quantitative Analysis of Gender Differences in the Effects of Lateralized Lesions on Verbal and Performance IQ ERIC TURKHEIMER ELANA FARACE University of Virginia RONALD A. YEO University of New Mexico ERIN D. BIGLER i Brigham Young University Previous studies and meta-analyses have demonstratedthat males have larger differences between Verbal IQ (VIQ) and PerformanceIQ (PIQ) followingunilateralbrain lesions. Several theories have been proposed as an explanation of this finding, including a greater degree of functional lateralization in males, gender differences in the organizationof language centers within the left hemisphere, and differencesin problem-solving strategy for PIQ. We apply quantitativemethods for analysisof relationsbetween lesion location and behaviorto a sample of 64 males and females with unilateral brain lesions. Statistical tests conducted in LISREL-VIIsuggest that in females, a single model can describe the relationshipsbetweenlesion locationand VIQ and PIQ, with left-hemispherelesionspro- ducing more severe deficits on both measures. In males, separate models of the relation- ships between lesion location and VIQ and PIQ are required. Gender differences in the effects of unilateral lesions have been described since Lansdell (1962). Although sometimes viewed in the clinical context of the inter- pretation of intelligence test profiles (Lawson & Inglis, 1983), in recent years the study of gender differences in structure and function of brain organization has expanded rapidly and become more concerned with the basic scientific issue of gender differences in the functional asymmetry of the cerebral hemispheres (e.g., McGlone, 1980; Witelson, 1989, 1991a, 1991b). Two major findings were suggested by early studies. Subjects with left- hemisphere lesions have smaller Verbal IQ (VIQ) minus Performance IQ (PIQ) score (VIQ - PIQ) differences than subjects with right-hemisphere lesions, and this difference is greater for males than for females. Correspondence and requests for reprints should be sent to Eric Turkheimer, Departmentof Psy- chology, Universityof Virginia, Gilmer Hall, Charlottesville, VA 22903-2477. 461