DEVELOPMENTAL INSTABILITY AND CEREBRAL LATERALIZATION

On the basis of prior studies of handedness, it was predicted that var iations from modal asymmetry scores on cognitive tasks, in either dire ction from the mean, would be associated with an elevated incidence of classic markers of developmental instability (minor physical anomalie s and fluctuating anatomic asymmetries). University students (N = 146) were administered 4 tasks that typically reveal functional asymmetrie s: the fused rhymed words dichotic listening task, the line bisection task, the chimeric faces task, and the cartoon faces task. A composite measure of developmental instability was computed from minor physical anomalies and fluctuating asymmetries. Participants with greater evid ence of developmental instability had more atypical lateralization sco res, deviating more from the sample mean, in either direction. Directi onal asymmetries were unrelated to developmental instability. These re sults suggest that developmental instability influences variation in t he lateralization of cognitive skills as well as handedness.