Perceptual Organization and the Judgment of Brightness

Edward H. Adelson

Published in
Science, vol. 262, pp. 2042-2044 (1993).
The perceived brightness of a grey patch depends on the surrounding context. For example, a middle grey patch appears darker when placed on a bright background and brighter when placed on a dark background. Models to explain these effects are usually based on simple low-level mechanisms such as the lateral inhibition that occurs in the retina, whereby cells in one region inhibit cells in adjacent regions. A new set of brightness illusions cannot be explained by such models. In these new illusions the brightness percept is strongly influenced by the perceptual organization of the stimuli. Simple modifications of the stimuli that should have little effect on low-level mechanisms greatly alter the strength of the illusion. These effects may be ascribed to more complex mechanisms occuring later in the visual system.