The purpose of this study was to investigate the role of visual feedback information in rapid movements. Two experiments were conducted in order to test the minimum visual feedback processing time and the role of visual feedback information.

Experiment I was designed to examine minimum visual feedback processing time. Subjects participated in the experiment were 8 males, 25 years old on the average. The task in experiment I was single target aiming with stylus. The movement amplitude was held constant as 35cm. The data from experiment I was analyzed by 2 x 2 x 4 3-factors within subject
design.

Experiment 2 was designed to examine the role of visual feedback information in movement phase. Subjects were 8 males, 21 years old on the average. The task in experiment 2 was also single target aiming with movement amplitude held 35cm. 30 trials was given tor each subject under each condition in experiments. The data from experiment 2 was analyized by single factor within-subject design.

Analysis of data revealed the following results:

1. The time required to process the visual feedback information is about 120msec.

2. The effect of the visual feedback uncertainty on visual feedback processing time is not significant.

3. The visual information is more important as the hand approaches the target than as the hand moves in intial portion of the target aiming movements.