Doctoral Dissertations

Date of Award


Degree Type


Degree Name

Doctor of Philosophy



Major Professor

R. Steve McCallum

Committee Members

Thomas George, Charles Hargis, William Calhoun, Bruce A. Bracken


Data consisting of 3,861 participants from the Universal Nonverbal Intelligence Test (UNIT) standardization and validity studies samples were used to examine the effects of increased socioeconomic refinement on cultural and racial mean difference scores. Groups were equated not only on age, sex, and highest parent education level, as reported in the UNIT manual, but on two additional socioeconomic status (SES) indicators: community setting and both parent education levels. Results suggest that additional refinement on socioeconomic variables does little to further reduce mean score IQ differences in UNIT Standard FSIQ scores between African Americans and Whites (n=168 in each group; mean difference = 8.51, effect size= .55); however, the 8.51 mean difference is considerably smaller than the 15-point difference typically observed between African American and Whites and is lower than the 11 point difference shown for WISC-III FSIQ scores, even after SES matching. There were no significant mean IQ score differences (n=162, p>.05) between Hispanics and Non Hispanics indicating that additional socioeconomic status refinement does contribute to reductions in mean score differences in IQ between these populations. In fact, Hispanics scored higher than their Non Hispanic counterparts on several subscales. Findings offer support for the use of the UNIT with diverse populations, as this measure of intelligence may limit the influence of irrelevant cultural factors in assessment. Future research on the use of nonverbal intelligence measures to predict minority student achievement, progressive conceptualizations of intelligent behavior, and exploration of within racial-ethnic group factors that contribute to or inhibit cognitive growth and academic achievement in minorities is warranted.

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