Time and Space-Time Movement Accuracy

Abstract

In this article, we report on the relation between spatial error and timing error in human performance as a function of a range of space-time movement con- ditions. The effect of time on the space-time movement accuracy of an elbow flexion movement task was examined over three ranges of motion (l0, 30, and 50 deg.) and eight time durations (from 100 ms to 3 sec) in two experiments. Counter to traditional accounts of the movement speed-accuracy trade-off in human performance, shorter movement time durations decreased the variabil- ity of both spatial and timing error. The spatial error and timing error func- tions were complementary in a function consistent with a space-time model of the speed-accuracy relation. The findings also confirm that the function for the movement speed-accuracy relation is dependent in part on the frame of reference used to measure movement error in the performance context.