The discrimination, acquisition, and retention of aiming movements made with and without elastic resistance

Two experiments were conducted to compare the discrimination, acquisition, and retention of movements made with and without elastic resistance. Using methods from psychophysics, Experiment 1 revealed that a discrete 800-mm movement could be discriminated equally precisely when it was performed with and without elastic resistance. Similarly, there was no difference in the spatial accuracy of a discrete aiming movement made with and without elastic resistance when extended practice with knowledge of results (KR) was provided in Experiment 2. Contrary to expectation, when KR about the outcome of the movement was removed on a retention test given 24 h after practice, the accuracy of the movements made with elastic resistance declined much more rapidly than those made without resistance. These findings question the common assumption that elastic resistance is a desirable characteristic of a control mechanism. Actual or potential applications of this research include the design of control mechanisms that facilitate performance under a variety of task and environmental conditions.