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Contrast, constancy and measurements of perceived lightness under parametric manipulation of surface
 

Summary:  Contrast, constancy and measurements of perceived
lightness under parametric manipulation of surface
slant and surface reflectance
Sarah R. Allred,1,
and David H. Brainard,1
1
Department of Psychology, University of Pennsylvania,
3401 Walnut Street, 302C, Philadelphia, PA 19104

Corresponding author: sallred@psych.upenn.edu
For perceived surface lightness to be a useful guide to object identity, it should
correlate with surface reflectance. Across illumination changes, local contrast
provides a valid cue to surface reflectance. However, when the surfaces sur-
rounding an object of interest change, local contrast is not necessarily a valid
cue. To generalize beyond theories that rely on local contrast as the sole ex-
planatory construct, we require an empirical account of which stimulus factors
produce effects beyond those explainable in terms of local contrast. A fruit-
ful approach is to hold local contrast fixed while varying other aspects of
the stimulus. Here we adopted this approach to study effects of object slant
in three-dimensional scenes. Observers viewed real, illuminated objects and

  

Source: Allred, Sarah - Department of Psychology, University of Pennsylvania

 

Collections: Biology and Medicine