Effect of Practice on the Kinematics of Reaching Movements Made to Moving Targets

Abstract

The purpose of these experiments was to examine the kinematic properties of the trajectories used by human subjects while reaching to moving targets and to determine whether these trajectories are modified with practice. Each subject was asked to reach for a target accelerated to a specified velocity along a horizontal track on twenty successive trials. Three different target speeds were used, and movements made by both the right and left hand were examined. Movements were assessed by determining the changes in the location of infrared emitting diodes located on the shoulder, elbow, wrist and index finger. The data show that movements made to targets of this type consist of several successive curved components and that these components do not vary qualitatively as the movement is practiced. However, when movements were made to faster moving targets and in some cases as movements were practiced, the curvature of the trajectory and the tangential velocity of the distal extremity both increased.