IMAGES: Opening Doors of Perception

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Science  11 Oct 2002:
Vol. 298, Issue 5592, pp. 329
DOI: 10.1126/science.298.5592.329a

The two middle squares in this image appear to be different shades of gray, but they are actually the same. Researchers in the Perceptual Science Group at the Massachusetts Institute of Technology exploit such trickery to illuminate the workings of the visual system. The group's online tutorials provide some clever examples of how we can learn from deceptive appearances.

Simple animations explore 11 tricks of light. We might fall for the simultaneous contrast illusion above, for example, because cells in the retina inhibit their neighbors. Thus the interior square at left looks relatively light against the dark pattern, and the right one looks relatively dark against the light background. Check out other deceptions that involve shadows and oscillating ellipses. Or for the nitty-gritty on perception, read papers by lab members that probe the lightness illusions or present the basics of image processing.

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