A Twin Study of Individual Differences in Perceptual Asymmetry

Abstract

Individual differences in perceptual asymmetry have been associated with individual differences in cognitive abilities, personality characteristics, and psychiatric symptoms, for which between-person variation appears to be genetically influenced. Perceptual asymmetry scores are also associated with direction of handedness, for which between-person variation does not appear to be genetically influenced. To assess whether between-person variation of perceptual asymmetry scores is genetically influenced, we examined asymmetry on a freevision task of face processing, the Chimeric Faces Task (CFT), in a sample of 31 monozygotic (MZ) and 20 same-sex dizygotic (DZ) twin pairs. MZ and DZ within twin-pair resemblances were compared to assess genetic and familial influences on asymmetric hemispheric function. We found that twins within a pair were no more likely to resemble each other than were unrelated individuals. The results suggest that the between-person variation in CFT perceptual asymmetry is not influenced by genes or shared environment.