Hitting moving objects - The dependency of hand velocity on the speed of the target

In previous studies, subjects did not hit slowly moving objects as quickly as fast ones, despite being instructed to hit them all as quickly as possib le. In those studies the targets moved at constant but unpredictable veloci ties, and it has been suggested that subjects were unable to adjust the han d's path to suit the velocity of the target. To compensate for this, they a djusted the speed of their hand to that of the target (speed coupling). Acc ording to this hypothesis, speed coupling is necessary only when subjects a re unable to correctly predict the next target velocity and only if they ha ve to be accurate. We show here that decreasing the uncertainty about the u pcoming target's velocity or enlarging the tip of the hitting weapon does n ot make speed coupling disappear. Moreover, there is a negative correlation between hand velocity and strength of speed coupling, whereas the hypothes is predicts a positive correlation. The hypothesis is therefore rejected. W e propose that speed coupling is a result of different speed-accuracy trade offs applying to different target velocities.