Adelson’s  “Corrugated Plaid”

from “Visual Phenomena & Optical Illusions

Adelson Brightness Illusion


standard Koffka annulus

Compare the top and bottom gray squares for their brightness. They appear (and, indeed, physically are) equal. Moving the mouse over the image removes the red bars. Now the squares appear in a different context, and lo and behold, they do not look equal anymore.

Comment. When interpreted as a 3-dimensional scene, our visual system immediately estimates a lighting vector and uses this to judge the property of the material.

The explanation is disputed by Todorovic (1997) [thanks to Mark E. McCourt for the pointer]. However, I do not find his counter example (bottom left) completely convincing. See next illusion for a stronger effect.

Source

Adelson EH (1993) Perceptual organization and the judgment of brightness. Science 262:2042–2044

New Demo from Adelson's site

Todorovic D (1997) Lightness and junctions. Percept 26:379–395

Todorovic

 

Created: 2002-Jun-13


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Last update 2013-10-04 by Michael Bach (G+)