Why can pushing on an eye make the visual scene appear to move?

When you push on your eye with your finger, the visual scene appears to move because your brain relies on motor-nerve signals—rather than sensory feedback from eye muscles—to determine whether your eyes or the environment are in motion.1

Normally, when you move your eyes voluntarily, your brain receives a motor discharge that informs it of the movement. This signal allows the brain to perform "psychological compensation," adjusting your perception so that stationary objects remain fixed in space despite the shifting retinal image.12

However, when your eye is moved passively by an external force like your finger, this expected motor discharge is absent. Because the brain does not receive the signal that the eye is being moved intentionally, it interprets the resulting changes in the retinal image as movement of the external scene itself. This phenomenon highlights that our perception of stability depends on the brain's internal monitoring of voluntary motor commands rather than purely sensory input from the eye's position.12