A target gray spot looks darker on a white background than on a black one: the contrast illusion. If the target is embedded in a context consisting of black spots on the white background and white spots on the black background, the effect reverses: the dungeon illusion. Whether the dungeon figure produces contrast or contrast reversal depends on which of its three parts (target, context, and background) is gray, black, or white. In some variants, the effect further depends on whether the figures are themselves surrounded by larger white and black regions, implying that even the illumination and wall color of the laboratory might be critical. Here, the various versions of the dungeon illusion are presented and explained with the help of the double-anchoring theory of lightness—that computes the gray shade of objects by “anchoring” them both to their context and to the brightest region in the scene.

The dungeon illusion

BRESSAN, PAOLA;KRAMER, PETER
2017

Abstract

A target gray spot looks darker on a white background than on a black one: the contrast illusion. If the target is embedded in a context consisting of black spots on the white background and white spots on the black background, the effect reverses: the dungeon illusion. Whether the dungeon figure produces contrast or contrast reversal depends on which of its three parts (target, context, and background) is gray, black, or white. In some variants, the effect further depends on whether the figures are themselves surrounded by larger white and black regions, implying that even the illumination and wall color of the laboratory might be critical. Here, the various versions of the dungeon illusion are presented and explained with the help of the double-anchoring theory of lightness—that computes the gray shade of objects by “anchoring” them both to their context and to the brightest region in the scene.
2017
The Oxford Compendium of Visual Illusions
9780199794607
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11577/2478079
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