Cerebral specialization in young adults with Down syndrome.

Adults with and without Down syndrome performed a rapid unimanual finger-tapping task alone and while sound-shadowing high frequency words. For male subjects, the concurrent speech disrupted right-hand, but not left-hand performance. Females suffered finger-tapping decrements in both hands in the dual-task situation. These results provide no evidence for reverse (right hemisphere) lateralization of speech in individuals with Down syndrome.