Separate sources of spatial information for distance and location in rapid aiming movements

The purpose of this research was to examine the role of distance and location information in the production of rapid aiming movements. Participants performed an aiming task consisting of horizontal left-handed elbow flexion movements that translated to movements of a cursor on an oscilloscope screen. The location of the home position and the target on the oscilloscope screen were fixed but the initial angle of the elbow was varied randomly. Participants were informed that the required distance was always constant. Initial impulse and error correction phases were analyzed to examine whether separate spatial codes for distance and position were used in the control of these two movement phases. The results indicated that initial impulse endpoints and the final positions of the limb overshot the target from the leftmost starting positions, while they undershot the target from the rightmost starting positions. Also, varying the initial angle of the elbow had a greater influence on the final position of the limb than initial impulse endpoints.