Eye-hand coordination during motor learning
Numerous studies of motor learning have focused on how hand movements are adapted following visuomotor perturbations that alter the mapping between hand position and visually perceived hand position. However, little is know about gaze behaviour during such learning. To examine this question, examined gaze behaviour in a complex visually guided manual task in which participants were required to learn a novel mapping between hand actions and cursor motion in order to move the cursor to successive targets on a screen.
Participants grasped an object with handles at either end (see A in the figure below) and moved the cursor by applying forces and torques to the handles. Different mappings between these forces and torques and cursor motion could be implemented (see B in the figure).
The following clip shows the cursor (circular dot) and the gaze positions of the two eyes (cross-hairs) during early learning. The box is the target. During this initial exploratory phase of learning, participants made frequent cursor movements but could not control the cursor so as to move it to the target. Note that gaze tends to "chase" the cursor around the screen.
After this exploratory phase – the duration of which varied considerably across participants – participants slowly began to exert control over the cursor. The next clip shows cursor and gaze movements during this phase. In this early "skill acquisition" phase, gaze starts to lead the cursor toward the target but sometimes jumps back to the cursor.
After considerable practice, participants begin to shift their gaze directly to each successive target so that gaze leads the hand. The last clip shows gaze and cursor movements during this "skill refinement" phase.
We have hypothesized that, during the exploratory phase, saccades that chase the cursor may help establish a mapping between hand actions and eye movements in retinal coordinates. Once established, such a map can be used to transform target positions (or eye movements to target positions) into appropriate manual actions.
For more information see: Sailer U, Flanagan JR, Johansson RS (2005) Eye-hand coordination during learning of a novel visuomotor task Journal of Neuroscience 25: 8833-8842.