Visual control of reaching

Usually we look where we want to reach, but at other times we reach for an object without moving our eyes toward it, while fixating our gaze elsewhere; for example, when we turn on the radio or the fan in a car while driving. Thus, although eye and hand movements are usually coordinated in the sense that they are frequently both directed to the object of interest, this coordination is not obligatory. However, vision plays a major role in the control of hand movements: Even if we do not move the eyes, there is a major difference between reaching with eyes open and groping in the dark. I review here the results of pertinent psychophysical, neuropsychological, and neurophysiological studies concerning visually directed reaching. The anatomic pathways involved in this function have been reviewed by Humphrey (1979), and pertinent studies of visuomotor coordination in normal and brain-damaged subjects have been discussed by Jeannerod (1986)