What the eye tells the hand.

The information flow necessary to coordinate hand movements with vision is summarized. A series of experiments was performed which quantitatively examined and confirmed the summary. In general, an information-theoretic approach was used. It was confirmed that the speed and accuracy of hand movements are in a reciprocal relationship. The accuracy of a movement is more sensitive to a loss of visual information than the pacing mechanism. Both speed and accuracy are sensitive to withdrawal of information to maintain posture. It is suggested that the retrieval of a movement pre-program is disturbed by afferent "noise." The contribution of visual information to controlling standing posture, arm and shoulder movement, and wrist movement were investigated.