A Large-Sample Study of Sex Differences in Functional Cerebral Lateralization

For practitioners, the importance of sex differences in lateralization lies in their potential prediction of susceptibility to and recovery from hemispheric damage. However, previous literature reviews suggest that sex accounts for only 0.1–1% of the variance in asymmetry scores. Here a large-sample, single-laboratory approach uses tasks requiring the recognition of bargraphs, dichotic words, facial emotions, locations, and visual words, and visual line bisection, each sensitive to lateralization of a separate mental module. The results agree with previous reviews, with sex accounting for a maximum of 0.9% and an average of 0.09% of the variance, suggesting that sex has little predictive clinical utility. However, the strength of relationship between sex and laterality depends on the nature of the lateralized task, presumably because of differences between tasks in underlying lateralized modules. I would like to thank the collaborators and research assistants whose collective efforts resulted in the data included in the laterality database. They include Jeff Baker, Todd Barlow, Joan Barth, Brian Casey, Bruce Cramer, Richard Duffy, Felicia Dugway, Michael Hochlerin, Linda Jaynes, James Kelliher, Mark Law, Stephen Pasquarette, Shari Pucci, and Noel Simpson. I would also like to thank Jamie DeCoster for statistical consulting, and Somer Shandy for her critical comments on the manuscript.