Abstract
Sensorimotor recalibration in response to discrepant visual feedback occurs for goal-directed tasks like walking and pointing, and generalization across tasks can be used to infer the locus of adaptation. In this study, we distinguish two potential factors in generalization: the functional type of control task (locomotion vs pointing) and the specific limbs and movements that execute the actions (legs vs arm). To distinguish functional and motor specificity, we created a hand locomotion task: subjects used pointing movements to simulate self-motion in virtual reality. Experiment 1 first tested whether adaptation of walking direction generalizes to pointing, using a sinusoidal perturbation method (Hudson & Landy, 2012). Subjects walked toward a target in virtual reality and the mapping from physical to visual heading was varied over time. Interspersed with walking, subjects pointing toward targets without feedback to test generalization. Walking direction showed a damped and delayed response to the perturbations, but this adaptation did not generalize to pointing, consistent with previous studies using virtual reality. Experiment 2 tested generalization between hand locomotion and pointing using a similar method. Sinusoidal perturbations were applied to either the visual heading direction or the visual location of the hand, which produced adaptation, and generalization across tasks was measured with interspersed test trials. When self-motion was controlled by a pointing movement rather than walking, there was partial generalization from locomotion to pointing, and from pointing to locomotion. Experiment 3 tested generalization between hand locomotion and walking, and similarly observed partial generalization in both directions. Even though the tasks involved different limbs and motor actions, there was partial generalization between the two locomotion tasks. Our results demonstrate that visuomotor adaptation can generalize based on either shared functional task or shared motor actions. This suggests that adaptation involves both function-specific and motor-specific components.
Meeting abstract presented at VSS 2017