Bimanual transfer of visuomotor adaptation is driven by explicit adaptation


Reaching with altered visual feedback of the hand's position in a virtual environment leads to reach adaptation in the trained hand, and also in the untrained hand (Wang & Sainburg, 2002). We asked if reach adaptation in the untrained (right) hand is due to transfer of implicit adaptation (i.e., IA; unconscious) and/or explicit adaptation (i.e., EA; conscious strategy) from the left (trained) hand, and if the transfer of IA and EA change depending on how one is made aware of the visuomotor distortion. Participants (n=60) were divided into 3 groups (Strategy (provided with instructions on how to counteract the visuomotor distortion), No-Strategy (no instructions provided), and Control (EA not assessed)). EA was probed in the Strategy and No-Strategy groups immediately after reaching with a cursor that was rotated 40 deg clockwise relative to hand motion. IA was assessed at a similar time, for all 3 groups. Results revealed that, while EA was greater for the Strategy versus No-Strategy group, EA transferred between hands for both groups. IA in the trained hand was greatest in the No-Strategy group. IA did not significantly transfer between hands, and in fact, the extent of IA observed in the untrained hand was not related to the extent of IA initially observed in the trained hand. These results suggest that while initial EA and IA in the trained hand are dependent on how one is made aware of the visuomotor distortion, transfer of visuomotor adaptation is driven almost exclusively by EA, regardless of instructions provided.

Acknowledgments: Funded by NSERC (Discovery Grant awarded to EKC)