Bimanual Coupling and the Intermanual Speed Advantage

Abstract

This study investigated previously observed differences in speed when completing a two-handed task either bimanually (i.e., the normal, two-handed mode) or intermanually (i.e., when such tasks are performed with different peoples’ hands). When comparing these two manual “coordination modes,” a phenomena referred to as the intermanual speed advantage has been observed. While various research domains have reported the intermanual speed advantage (i.e., a “mode effect”), recent research suggests that the observed difference in performance may depend on fundamental bimanual limitations that are not observed when using the intermanual coordination mode. To investigate the intermanual speed advantage, a task was constructed to exploit a hypothesized bimanual limitation that may underlie this mode effect: bimanual coupling. Results showed a replication of the intermanual speed advantage and higher between-hand coupling during bimanual performance. Subsequent analyses suggests that speed during two-handed tasks may be facilitated by decoupled movement of the limbs, regardless of coordination mode.