AFFERENT INFORMATION FOR MOTOR CONTROL - THE ROLE OF VISUAL INFORMATION IN DIFFERENT PORTIONS OF THE MOVEMENT

The question addressed in the present study was whether subjects (N = 24) can use visual information about their hand, in the first half of an aiming movement, to ensure optimal directional accuracy of their ai ming movements. Four groups of subjects practiced an aiming task in ei ther a complete vision condition, a no-vision condition, or in a condi tion in which their hand was visible for the first half [initial visio n condition (IV)] or the second half of the movement [final vision con dition (FV)]. Following 240 trials of acquisition, all subjects were s ubmitted to a transfer test that consisted of 40 trials performed in a no-vision condition. The results indicated that seeing the hand early in movement did not help subjects to optimize either directional or a mplitude accuracy. On the other hand, when subjects viewed their hand closer to the target, movements resulted that were as accurate as thos e performed under a complete vision condition. In transfer, withdrawin g vision did not cause any increase in aiming error for the IV or the no-vision conditions. These results replicated those of Carlton (1981) and extended those of Bard and colleagues (Bard, Hay, & Fleury, 1985) in that they indicated that the kinetic visual channel hypothesized b y Paillard (1980; Paillard & Amblard, 1985) appeared to be inoperative beyond 40 degrees of visual angle.