Multitask analysis of cerebral hemisphere specialization in monozygotic twins discordant for handedness

This study constitutes a multitask appraisal of cerebral hemisphere specialization with 13 monozygotic (MZ) twin pairs discordant for handedness. Tasks included dichotic listening, finger tapping with concurrent loads, two tachistoscopic visual half-field tests, and a free-vision face test. Overall, MZ twins showed similar performance asymmetries on most tasks. Different asymmetries, however, were observed on the finger tapping with anagram load and visual half-field with chair stimuli. In these instances, asymmetries for left- and right-handed MZ twins were more similar to patterns reported in the literature for left- and right-handed singletons, respectively, than for opposite-handed co-twins.