NDLI: A scaling analysis of the snake lightness illusion

Content Provider	Springer Nature Link
Author	Logvinenko, Alexander D. Petrini, Karin Maloney, Laurence T.
Copyright Year	2008
Abstract	Logvinenko and Maloney (2006) measured perceived dissimilarities between achromatic surfaces placed in two scenes illuminated by neutral lights that could differ in intensity. Using a novel scaling method, they found that dissimilarities between light surface pairs could be represented as a weighted linear combination of two dimensions, “surface lightness” (a perceptual correlate of the difference in the logarithm of surface albedo) and “surface brightness” (which corresponded to the differences of the logarithms of light intensity across the scenes). Here we attempt to measure the contributions of these dimensions to a compelling lightness illusion (the “snake illusion”). It is commonly assumed that this illusion is a result of erroneous segmentation of the snake pattern into regions of unequal illumination. We find that the illusory shift in the snake pattern occurs along the surface lightness dimension, with no contribution from surface brightness. Thus, even if an erroneous segmentation of the snake pattern into strips of unequal illumination does happen, it reveals itself, paradoxically, as illusory changes in surface lightness rather than as surface brightness. We conjecture that the illusion strength depends on the balance between two groups of illumination cues signaling the true (uniform) illumination and the pictorial (uneven) illumination.
Starting Page	828
Ending Page	840
Page Count	13
File Format	PDF
ISSN	00315117
Journal	Perception & Psychophysics
Volume Number	70
Issue Number	5
e-ISSN	15325962
Language	English
Publisher	Springer-Verlag
Publisher Date	2008-01-01
Publisher Place	New York
Access Restriction	Subscribed
Subject Keyword	Cognitive Psychology
Content Type	Text
Resource Type	Article
Subject	Experimental and Cognitive Psychology Sensory Systems Psychology

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