Coordination of gaze and hand movements for tracking and tracing in 3D

In addition, we have studied the coordination of eye and hand movements in 3D by measuring binocular eye movements while subjects move the finger along a curved path. The results show that the directional component and finger position almost superimpose when subjects track a target moving in 3D. However, the vergence component of gaze leads finger position by about 250 msec. For drawing (tracing) the path of a visible 3D shape, the directional component of gaze leads finger position by about 225 msec, and the vergence component leads finger position by about 400 msec. These results are compatible with the idea that gaze leads hand position during drawing movement to assist prediction and planning of hand position in 3D space.