Movement time as a determiner of timing accuracy.

In a task in which 5s tried to move a slide so that an attached pointer hit a moving target, movement time was varied by having move at maximal or at moderate speed, by changing the starting position so that S moved IS, 30, 45, or 60 cm., and by adding or not adding an additional load. One hundred and sixty male right-handed Ss were assigned to one treatment combination in a 2 X 4 X 2 design, and 20 trials with knowledge of results were given. Absolute timing error was decreased by maximal speed instructions when the movements were unloaded, by shorter movement distances under all conditions of speed and load, and by the added load when the movements were at maximal speed, supporting the hypothesis that factors affecting movement time partially determine timing accuracy. Evidence indicated that the responses were preprogrammed, and that 5s tended to hold movement time constant and correct the error on the previous trial by adjusting starting time.