Discrete vs. continuous visual control of manual aiming

Two experiments were conducted to examine the influence of instructional set and vision on the kinematics and end-point accuracy of a simple target-aiming movement. While instructional set had a large impact on the velocity and acceleration patterns of the movements, the availability of vision before and during the movement was the best predictor of accuracy. Although subjects were more accurate in a full vision condition than in two visually degraded conditions, subjects made no more discrete adjustments to the movement trajectory. These data suggest that the visual control of aiming may occur in a continuous fashion.