Randomized checkerboard contrast illusion: theoretical implications on Gestalt principles in brightness perception M Hudak1, J Geier2 |
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1Dept. Gen. Psych, Pazmany Peter Catholic University, Hungary |
| The checkerboard contrast illusion comprises two identical grey squares, one substituting a white square, while the other a black square of a black-white checkerboard. The grey square surrounded by four white squares seems brighter than the one surrounded by black squares, contrary to the simultaneous contrast illusion [De Valois & De Valois, 1988, Spatial Vision. New York, Oxford University Press]. The anchoring theory attributes this phenomenon to the belongingness of the grey squares to the diagonal set of uniform black or white squares, within which the highest luminance rule is applied to explain the illusion [Gilchrist et al, 1999, An anchoring theory of lightness perception, Psychological Review, 106(4), 795-834]. We eliminated the diagonal sets by randomizing the location of the black and white squares. However, the illusion persists. Therefore, the illusion cannot be explained by grouping the grey squares to the diagonal sets of uniform squares. Since grouping and regularity of the pattern are not necessary conditions for the illusion, another explanation should be sought. We suggest a filling-in type of explanation, whose computer simulation will be presented to show that the checkerboard contrast illusion can be explained at a low level. |
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