Kaleidoscopic motion and velocity illusions

A novel class of vivid motion and velocity illusions for contrast-defined shapes is presented and discussed. The illusions concern a starlike wheel that, physically, rotates with constant velocity between stationary starlike inner and outer shapes but that, perceptually, shows pulsations, jolts backwards, jolts forwards, and accelerations, each time it aligns with the inner and outer shapes. These dynamic effects turn from one into another when contrasts in the image change gradually, and seem to be caused by colour assimilation and ambiguous figure-ground segregation.