Stereokinetic Depth


In stereokinetic depth, rotary movement enhances the impression of depth seen in patterns of concentric rings. Typically, rotation creates a vivid impression of a wobbly protruding cone or receding tunnel, or both, as in this demonstration. The effect indicates that the visual system has an in-built assumption that shapes tend to be rigid, and interprets the changing rings as a rigid 3-D shape moving in depth, rather than as an ameoba-like form changing shape.
Stereokinetic depth was actually first described by Musatti (1924; see Zanforlin, 1988). It was also used in the 1920's by the artist Marcel Duchamp, who called his spinning wobbly discs 'rotoreliefs'.
Clara, E., Regolin, L., Zanforlin, M., & Vallortigara, G. (2006). Domestic chicks perceive stereokinetic illusions. Perception, 35, 983-992.
Shearer, R.R., & Gould, S.J. (1999) Of two minds and one nature. Science, 286, 1093-1094.
Wilson, J., Robinson, J., & Piggins, D. (1983) Wobble cones and wobble holes: the stereokinetic effect revisited. Perception, 12, 187-193.
Zanforlin, M. (1988) The height of a stereokinetic cone: A quantitative determination of a 3-D effect from 2-D moving patterns without a "rigidity assumption". Psychological Research, 50, 162-172.