Surface decomposition accompanying the perception of transparency.

At the retina, each location can have only one value of luminance or color. When transparency is perceived, however, different surface qualities can be redistributed to two or more apparently superimposed layers. The experiments described here explored the characteristics of this surface decomposition. It is shown that the surface decomposition occurs rapidly, it affects even early stages of visual processing, and it involves attributes such as texture and motion as well as color and brightness. In the first experiment, the recognition advantage for transparent overlapping digits demonstrated that the surface decomposition accompanying transparency occurs within 60 ms. In the second, the separation of overlying orthogonal grids due to surface decomposition was found to influence the strength of the McCollough effect, an effect attributed to early cortical processing. Finally, when a transparent surface appears to extend over areas that are physically identical to the background, qualities of the transparent overlay such as texture and motion, as well as color or brightness (e.g., the neon color effect) appear to spread to the illusory overlay.