Transfer of Visuomotor Adaptation to Unpractised Hands and Sensory Modalities

Abstract

A recent model (Bock, 2013) predicts that sensorimotor adaptation, achieved while pointing at visual targets, will transfer fully to acoustic targets. The model further predicts that visual-to-acoustic transfer is not diminished even if the left and right arms have adapted to a different distortion. To scrutinize these predictions, we asked subjects to point at visual targets with their right hands under a +30 deg rotation of visual feedback (group “single”), or alternately, with their right hands under a +30 deg and with their left hands under a −30 deg rotation of visual feedback. Aftereffects were registered for each hand and for visual as well as acoustic targets, in counterbalanced order. We found that acoustic aftereffects were only about 66% of visual ones, which violates the first prediction and calls for an amendment of the model. We further found that acoustic aftereffects were of similar magnitude in both groups, which supports the second prediction. Finally, we observed an intermanual transfer of only about 29%. These findings suggest that unpractised acoustic inputs are weighted somewhat lower than practised visual ones, and that outputs to the unpractised left hand are weighted substantially lower than those to the practised right hand.