Visual Feedback Control of Hand Movements

TLDR

Early movements rely mainly on motion cues, while endpoint control depends more on position cues. The study examined which visual cues—motion or position—drive online hand movement control. Participants performed reaching tasks in a virtual environment with a moving virtual fingertip, and the fingertip was perturbed behind an occluder to isolate motion and position feedback. Both motion and position visual signals contribute to feedback control, with responses to combined perturbations matching a model that optimally integrates noisy, delayed motion and position feedback.

Abstract

We investigated what visual information contributes to on-line control of hand movements. It has been suggested that motion information predominates early in movements but that position information predominates for endpoint control. We used a perturbation method to determine the relative contributions of motion and position information to feedback control. Subjects reached to touch targets in a dynamic virtual environment in which subjects viewed a moving virtual fingertip in place of their own finger. On some trials, we perturbed the virtual fingertip while it moved behind an occluder. Subjects responded to perturbations that selectively altered either motion or position information, indicating that both contribute to feedback control. Responses to perturbations that changed both motion and position information were consistent with superimposed motion-based and position-based control. Results were well fit by a control model that optimally integrates noisy, delayed sensory feedback about both motion and position to estimate hand state.