Role of visual information during playing ball-juggling

Three experiments on ball-juggling were carried out in order to clarify how our brain utilizes visual information in motor control. In Experiment 1, the temporal relation between ball and eye movements were examined. The results suggested that visual information around the top of the trajectory seemed important, and that eye movements were controlled in an active fashion that our brain obtained necessary information in appropriate timing. In Experiment 2, where movement of the left-hand (i.e., catching hand) were analyzed, it was shown that spatial movement to the catching position, catching action and return movement were performed as a continuous movement. Experiment 3 examined how juggling performance was affected by restricting visual information. Results were compared among three conditions, (1) vision was always available, (2) vision around the top of the trajectory was deprived of, and (3) vision of the left eye was always unavailable. The result showed that the performance was impaired a little in the second condition, and further more in the third condition, meaning that binocular information was quite important. A schematic model was proposed for understanding the general structure of control of ball-juggling