The present study investigated the extent to which movement time and practice influenced usage of feedback by subjects to make corrections in the spatial-temporal movement pattern of coincident timing responses. Twenty-four college males and females watched a .01 sec timer and attempted to knock over a barrier at the precise moment that the sweep hand reached a "target position" (250, 500, and 1000 msec). All subjects were given 100 trials of practice at a particular "target position" on each of four consecutive days. Schmidt's (1972) index of preprogramming was calculated for each subject each day in order to estimate the level of feedback involvement in controlling the movement, while the spatial-temporal pattern of the response was characterized by segmental movement time and variability. The results indicated that the index of preprogramming increased as instructed movement time decreased but remained stable throughout all trials. This suggests that movement time and not practice limits the extent to which a response is programmed, with rapid performance more likely to be pre-programmed than slower performance. Likewise, the spatial-temporal pattern of the movement was found to fluctuate as instructed movement time increased but remained stable over practice. Indeed, the 250 and 500 msec movements appeared to be primarily ballistic while the 1000 msec movement appeared to be adjusted in the terminal phase of the response by accelerating or decelerating the rate of movement. Thus, it was assumed that the index of preprogramming was sensitive to changes, as a result of feedback based corrections, in the spatial-temporal pattern of the movement. / Ph. D.