Demonstration of the "rotation freeze illusion" with a rotating pattern: This movie shows a continuous rotation around the gaze axis of the observer. When the computer display is turned back and forth around the same axis while the movie is playing in full screen mode, the perceived rotation speed slows down and may even freeze completely. A similar "motion freeze illusion" for a translating sinusoidal grating was reported by Mesland B.S. and Wertheim A.H. in 1996.

The Duncker Illusion: The motion of the background induces an apparent motion of the physically stationary plane serving as a foreground object. Karl Duncker (1929) was not the first to notice induced motion, but in his thesis he systematically explored induced motion. Amongst other stimuli he also used a circular disk in front of another bigger disk. He determined the rotation speed needed of the inner disk to null the apparent rotation speed induced by rotation of the outer disk. He however did not observe the rotation freeze illusion.

Rotation freeze illusion using an experimental design of K. Duncker to measure induced motion effects. Whereas Duncker was using constant rotation speed of both the central disk and the surround, here the surround is rotating sinusoidally forth and back. The central disk is perceived as slowing down or even freezing when the surround is rotating in the same direction as the center. Physically the central disk is rotating at a constant speed.

In this example where the surround (the greenhouse with its plants) and the center (the airplane) are interleaved into each other the impression of a periodically freezing of the airplane's rotation is particularly strong. In reality the airplane is rolling clockwise at constant rotational speed. The surround is rolling sinusoidally back and forth.

The illusion of freezing rotation does largely not depend on the kind of texture pattern used. Using random dot patterns, there are however subtle differences to the previous examples: when the center and the surround are rotating in the same direction, the center appears to melt into the surround. Than the perceived rotational speed of the center is not approching zero but approaches the speed of the surround (a filling-in phenomen).

Assymmetry between center and surround :  As this movie shows, sinusoidal rotation of the center do not influence the perception of the surround rotational velocity (a constant clockwise roll rotation). This asymmetry persists when the area of the surround is the same as the area of the center (not shown here).