Peter van der Helm: Kaleidoscopic motion and velocity illusions | The brain and illusions |

The illusions presented here occur in stimuli with the following layout:

Between stationary starlike inner and outer shapes, a starlike wheel rotates with constant velocity about its own center. It rotates partly behind the inner shape and partly in front of the outer shape, but at regular intervals, it precisely fills the space between the stationary shapes. At these moments, various motion and velocity illusions occur, for both the rotating wheel and the inner stationary shape