Kanizsa Triangle

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Kanizsa Triangle Kanizsa Square

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Kanizsa Triangle

Do you perceive edgeless triangle (square)? Does this shape appear brighter than the surrounding background? (Compare this to the Simultaneous Contrast Illusion.) The effect is known as a subjective (or illusory) contour. For a recognizable simlpe shape the brain appears to supply edges. Once edges are used elsewhere the shape becomes less prominent.

References

A. Seckel, The Art of Optical Illusions, Carlton Books, 2002 (#46)
The Mind's Eye, Readings from SCIENTIFIC AMERICAN, W. H. Freeman and Company, 1986

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