Conference on Cognitive Computational Neuroscience

Lightness illusions demonstrate that how bright an object appears depends on an elaborate constructive process, to the point that the same surface can be perceived as either black or white depending on the context. Why does the biological visual system work this way? Our work examines the degree to which edge-surface reconstruction mechanisms can explain lightness illusions present in complex scenes (e.g., the moon illusion, Anderson & Winawer 2005). First, across two behavioral tasks, 56 participants matched the brightness of a disc presented in a dark or light hazy background to illustrate the effect of the context on lightness perception. Second, we trained a reconstructive U-Net model to output a filled-in image from edge-only inputs, thus computationally solving the same problem of the biological system: going from edges to a filled-in perceptual experience. Surprisingly, we found that, when reconstructing the discs, the U-Net model made systematic errors consistent with lightness illusions measured in people, suggesting a significant role of edge-surface reconstruction for this complex illusion.