Movements of the eyes and hands are coordinated by a common predictive strategy

Although attempts to intercept a ball in flight are often preceded by predictive gaze behavior, the relationship between the predictive control of gaze and the effector is largely unexplored. The present study was designed to investigate the influence of the spatiotemporal demands of the task on a switch to the predictive control. Ten subjects immersed in a virtual environment attempted to intercept a ball that disappeared for 500 ms of its parabolic approach. The timing of the blank was varied through manipulation of the post-blank duration prior to the ball's arrival, and the shape of the trajectory was manipulated through variation of the pre-blank duration. Results reveal that the gaze movement trajectory during the blank was curvilinear, appropriately scaled to the curvature of the invisible moving ball, and the gaze vector was within 4° of the ball upon reappearance, despite 10° to 13° of ball movement. The timing of the blank did not influence the accuracy of predictive positioning of the paddle at the time of ball reappearance, indicated by the distance of the paddle relative to the ball's eventual passing location. However, analysis of trial-by-trial covariations revealed that, when the gaze vector more accurately predicted the ball's trajectory at reappearance, the paddle was also held closer to the ball's eventual passing location. This suggests that predictive strategies for paddle placement are more strongly mediated by the accuracy of gaze behavior than by the observed range of trajectories, or the timing of the blank.