Demonstration of an illusory limb movement and associated motor activities induced by a moving visual stimulus in man. A descriptive study.

We show that, in man, a moving visual stimulus can induce sensations of movement of the forearm when it is exhibited beneath the hand and part of the forearm. These sensations in the limb are analagous to vection which has been described in the whole body. They are accompanied by involuntary motor activities coherent with the direction of illusory movement. Thus, a sensation of flexion is accompanied by EMG activity in the biceps and a sensation of extension by EMG activity in the triceps. There results make it possible to extend the kinesthetic role of visual information to limb segments entering the visual field, and suggest that vision works within an assistance loop for limb movement.