March 23, 2006
Chikaku (Perception) Colloquium 2006 in Takayama, Japan

Luminance-gradient-dependent brightness contrast

Akiyoshi Kitaoka
(Department of Psychology, Ritsumeikan University)

Access since March 22, 2006


I propose a new brightness illusion that depends on luminance gradients. Here I discuss this illusion in terms of brightness contrast, lightness constancy, and Gilchrist's theories.

Kitaoka, A. (2006) Ilusions of brightness or lightness. Professor Alan Gilchrist's talk in Ritsumeikan, March 17, 2006.
Presentation (html), Program

"Illusory staircase yellow Gelb effect"

The rightmost square appears to be yellow. It seems there is the highest yellowishness rule!

Copyright Akiyoshi .Kitaoka 2006 (March 22)

Illusory staircase Gelb effect vs. Illusory staicase reverse Gelb effect

The Gelb effect refers to a phenomenon that in a homogeneously dark room an intensely lit black card appears to be gray or white. The card suddenly appears to be black when another white card is placed in the visual field (= lightness constancy).

The staircase Gelb effect is the striking demonstration of the Gelb effect exhibited by Professor Alan Gilchrist, Rutgers University. He used five cards of different luminances in the invited lecture held in Tokyo (March 14, 2006).  Related lecture 

Cataliotti J and Gilchrist A (1995) Local and global processes in surface lightness perception. Perception and Psychophysics, 57, 125-135.

Gilchrist A, Kossyfidis C, Bonato F, Agostini T, Cataliotti J, Li X, Spehar B, Annan V, Economou E.. (1999) An anchoring theory of lightness perception. Psychological Review, 106, 795-834.

Thank you

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