An illusion in which the eye alternately sees two black faces, or a white goblet.
Goblet Illusion
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References
Fineman, M. The Nature of Visual Illusion. New York: Dover, pp. 111 and 115, 1996.Kid's World. "Optical Illusions--2." http://www.frontiernet.net/~docbob/ilusion2.htm.
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Referenced on Wolfram|Alpha
Goblet IllusionCite this as:
Weisstein, Eric W. "Goblet Illusion." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/GobletIllusion.html