The Anderson-Winawer illusion: it's not occlusion.

In their recent article, Anderson and Winawer (2005) presented a dramatic lightness illusion in which identical texture patches appear to be either black or white. Albert (2007) argued that the Anderson and Winawer (2005) illusion can be explained by a simple theory in which occlusion cues determine the depth relationships of the different surfaces, and determine which stimulus areas are perceived as seen in plain view. Using both modeling and psychophysical methods, however, I show that alterations such as those that Albert used actually reverse the illusion within the range of figure contrasts that Anderson and Winawer (2005) tested. Albert's theory (and any occlusion-based theory), therefore, cannot account for Anderson and Winawer's (2005) data, at least in the lower figure-contrast range. I propose a novel scene-interpretation strategy to account for the effects.