Visuomotor transformation process in goal-directed prehension: Utilization of online vision during preshaping phase of grasping

Goal-directed prehension is a fundamental human skill and a form of interaction between actor and environment. We reviewed our studies on psychological experiments and computational modeling, examining how online vision affects the control of grasping (in particular, peak grip aperture). In the experiments, we investigated whether online vision in the early phase of movement affects the control of grasping (Experiment 1), and which kinds of visual sources (i.e., visual feedback of the limb/hand, the view of the target) are predominantly relied upon in this early movement phase (Experiment 2). These two experiments demonstrated that the view of the target in the rather early phase of movement is critical for grasping control. Next, we proposed a stochastic predictive control model using the Kalman filter for identifying the mechanism of the visuomotor process revealed in the experiment. The simulation results qualitatively replicated the experimental results, which showed the early phase availability of online vision and the priority of the view of the target on grasping control. Both studies suggest the importance of predictive control in human grasping.