Texture interactions determine perceived contrast.

For a patch of random visual texture embedded in a surrounding background of similar texture, we demonstrate that the perceived contrast of the texture patch depends substantially on the contrast of the background. When the texture patch is surrounded by high-contrast texture, the bright points of the texture patch appear dimmer, and simultaneously, its dark points appear less dark than when it is surrounded by a uniform background. The induced reduction of apparent contrast is greatly diminished when (i) the texture patch and background are filtered into nonoverlapping spatial frequency bands or (ii) the texture patch and background are presented to different eyes. Our results are unanticipated by all current theories of lightness perception and point to a perceptual mechanism for contrast gain control occurring at an early cortical or precortical neural locus.