Abstract
Lightness and darkness induction have been independently investigated in a large number of classic and contemporary psychophysical experiments. A common finding of these studies is that lightness and darkness induction behave asymmetrically. For example, Wallach(1) demonstrated the brightness of a test disk was depressed by the presence of a surround ring of higher luminance (darkness induction) and that test brightness depended strictly on the luminance ratio, or contrast, between the disk and its surround. Heinemann(2) performed a similar experiment using a bright test and a dark surround (lightness induction) and reported an assimilation effect rather than a contrast effect. That is, raising the luminance of the surround increased, rather than decreased, the brightness of the test. In recent experiments, brightness judgments have been carried out in the context of more realistic scenes consisting of checkerboard and Mondrian patterns(3,4,5). The results of these experiments are generally consistent with the idea that the brightness of regions within the display are judged relative to the highest luminance in the scene and that the highest luminance appears white(6). Thus, as originally shown by Gelb(7), increasing the highest luminance darkens the rest of the scene, but decreasing the lowest luminance does not lighten the rest of the scene. These asymmetries between lightness induction and darkness induction will be discussed and quantitatively investigated in the context of theory of edge integration based on a neural filling-in mechanism, which was first presented at last year's ARVO meeting(8,9,10). New lightness and darkness induction data based on replications of the classic Wallach and Heinemann experiments will be presented and quantitatively modeled on the basis of the theory.
(1)
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(2)
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BrunoN.BernardisP.SchirilloJ.(1997). Lightness, equivalent backgrounds, and anchoring. Perception and Psychophysics, 59,
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SchirilloJ. A.(1999). Surround articulation. I. Brightness judgments. Journal of the Optical Society of America A, 16,
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(8)
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