Adaptation for Discrimination
Light reflected = r * I Light reflected = r * I
Adaptation for Discrimination
Adaptation for Discrimination
Adaptation for Discrimination
Adaptation for Discrimination
IT1
IT1
IT2
Discrimination Thresholds
Pedestal Contrast
Response Function
IT1
IT2
Discrimination Thresholds
Boynton et al., 1999
Discrimination Thresholds
Discrimination Thresholds
Light reflected = r * I Light reflected = r * I
Adaptation for Appearance
Adaptation for Appearance
Adaptation for Appearance
Adaptation for Appearance
See Hillis and Brainard (2005; under review)
Discrimination Thresholds
See Hillis and Brainard (2005; under review)
Discrimination Thresholds
See Hillis and Brainard (2005; under review)
Thresholds & Appearance
See Hillis and Brainard (2005; under review)
See Hillis and Brainard (2005; under review)
Summary• Both threshold and appearance measurements can
be linked (by hypothesis) to an underlying response function.
• Studying change in response function with viewing context is one way to characterize adaptation.
• For simple context changes (intensity of uniform backgrounds, unstructured contrast), both threshold and appearance data are consistent with a common mechanism of adaptation. [This is not true in general.]
“PAINT”
x x
“SHADOW”
x x
(Adopted, with permission, from Adelson’s checkerboard illusion)
“Paint”
“Shadow”
“Paint”
“Shadow”