Factors influencing online control of video-aiming movements performed without vision of the cursor.

A modulation of the primary impulse of manual/video-aiming movements performed without visual feedback has been reported. In the present study, we show that this modulation is modified (a) with increased practice, (b) the use of an aligned visual display, and (c) the availability of visual feedback on alternated trials. However, this modulation was not as efficient as that observed in a normal vision condition, which underlines the primary role of vision to ensure endpoint accuracy. Moreover, this modulation was observed only on the extent component of the task. This last observation indicates that proprioception can be used to modulate the extent component of goal-directed movements but that vision is necessary to modulate their direction.