Manual and Attentional Asymmetries in Goal-Directed Movements in Adults with Down Syndrome

The present study was designed to investigate attentional processes and performance asymmetries in goal-directed aiming in individuals with Down syndrome (DS; n = 6 in each group). Using the right and left hands, young adults with and without DS completed rapid aiming movements to small targets in ipsilateral and contralateral space. On some trials, a visual distractor was present. As attention and action were assumed to be coupled, the impact of distractors on reaction time (RT) and movement kinematics was examined. The performance of individuals with DS was quantitatively and qualitatively different from nonaffected participants, suggesting that participants in the two groups used different strategies to complete the task. Individuals with DS exhibited movement time (MT) interference when a distractor was present. This finding is consistent with an action-centered framework of attention.