Transfer of Coordination Skill to the Unpracticed Hand in Immersive Environments

Physical practice with one hand results in performance gains of the other (un-practiced) hand in a unilateral motor task. Yet how it induces performance gains of interlimb coordination in the bimanual movements between trained limb and the opposite, untrained limb is unclear. The present study designed a game-like interactive system for physical practice, in which an avatar’s hands could be controlled itself or by the subject during a bimanual movement task in an immersive virtual reality environment. Participants practiced with the bimanual task by simultaneously drawing non-symmetric three-sided squares (e.g., U and C) to learn limb coordination with the following training strategies: (1) performing and seeing a bimanual task (BH-BH); (2) performing a unimanual task with right hand and seeing a bimanual action (RH-BH); (3) not performing a task but seeing a bimanual action (noH-BH); (4) performing and seeing a unimanual task (RH-RH). We found that the learning performance was better after BH-BH and RH-BH compared with other training strategies. In addition, we examined the effects of virtual hand representations on the learning performance after RH-BH. We found that the performance after training was increased with the realism level of virtual hands. These findings suggest that the proposed approach of RH-BH with realistic virtual hand would result in transfer of coordination skill to the unpracticed hand, which puts forward a new approach for learning and rehabilitation of coordination skill in patients with unilateral motor deficit in immersive environments.