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”