BRAIN AND COGNITION 8, 275-290 (1988) The Relationship between Cerebral Lateralization and Cognitive Ability: Suggested Criteria for Empirical Tests RICHARD S. LEWIS Pomona College AND LAUREN JULIUS HARRIS Michigan Stare University Many recent investigations in cognitive neuropsychology have been devoted to a fundamental question: are individual differences in cerebral lateralization reliably associated with differences in cognitive ability? The results have been highly inconsistent and inconclusive, with some studies showing a relationship, others not. We propose that research on this question has been hampered by inadequate clarification of the criteria required for a proper test. We suggest what these criteria should be, and, for purposes of illustration, we evaluate representative tests of the lateralization-cognition hypothesis in light of these criteria. We conclude that studies that meet our criteria lend at least a modest measure ofiupport for the hypothesis. 0 1988 Academic Press, Inc. INTRODUCTION Neuropsychological research on human beings has focused, to date, to a great extent on the analysis of the functions of the cerebral hemispheres. The result has been abundant documentation for what is now regarded as a basic scientific principle of human biology, namely, that the hem- ispheres are remarkably asymmetric in functional organization. The left hemisphere is specialized for verbal, analytical, and temporal-sequential Preparation of this manuscript was supported, in part, by a National Institute of Mental Health, National Research Service Award, MH09255, to R.S.L., and by a grant from the Michigan State University Foundation to L.J.H. We are grateful to Sheri A. Berenbaum, Douglas F. Carlson, and Peter J. Snyder for their comments on an earlier version of this paper. Address correspondence and reprint requests to Richard S. Lewis, Department of Psychology, Pomona College, Claremont, CA 91711. 275 0278-2626/88 $3.00 Copyright 0 1988 by Academic Press. Inc. All rights of reproduction in any form reserved.