An illusion studied by the psychologist Walter Ehrenstein in which the sides of a square placed inside a pattern of concentric circles take an apparent curved shape. The name Ehrenstein is also associated with one of the illusory contour figures.
Ehrenstein Illusion
See also
Hering Illusion, Illusory Contour Figures, Orbison's Illusion, Wundt IllusionThis entry contributed by Margherita Barile
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References
A Special Place. Optical Illusions. "Square in a Circle." http://www.aspecialplace.net/illusions/square_circle.htm.Nagoya Visual illusion Experts Group. "Ehrenstein Illusion." http://humanities.lit.nagoya-u.ac.jp/~illusion/gallery/NVEG/standard/Ehrenstein01_e.html.Referenced on Wolfram|Alpha
Ehrenstein IllusionCite this as:
Barile, Margherita. "Ehrenstein Illusion." From MathWorld--A Wolfram Web Resource, created by Eric W. Weisstein. https://mathworld.wolfram.com/EhrensteinIllusion.html