Asymmetrical movement overflow in children depends on handedness and task characteristics

Unintentional movement overflow between the hands was examined in 176 right-handed children in grades 2, 4, and 6. A significant multivariate hand difference was observed for contralateral but not for ipsilateral overflow during rapid repetitive movements and discrete finger placement tasks. Individual ANOVAs revealed greater overflow from left to right hands during forearm pronation/supination (a rapid repetitive task) but the reverse during finger-displacement tasks. Hand differences in contralateral overflow were also observed in 19 left-handed children, with greater overflow from right to left hands observed for two tasks. These data support previous reports of asymmetrical overflow, but suggest that the presence and direction of the phenomenon depends on the nature of the intended movement and on handedness.