Modeling Effects of Edge Classification and Perceptual Organization on the Appearance of Disk/Annulus Stimuli

In classical theories of sensory psychophysics, appearance matches conducted with simple stimuli consisting of disks surrounded by annuli were posited to probe low-level contrast mechanisms in the visual pathways that computed the approximate luminance ratio between the disk and annulus for the purpose of achieving lightness constancy (Wallach, 1948). Subsequent models have explained such matches on the basis of neural edge integration (Shapley & Reid, 1985; Rudd & Zemach, 2004). Here, I demonstrate that appearances matches made in the disk/annulus paradigm are influenced by at least two types of top-down effects involving edge classification and perceptual organization. I present a neural edge integration model of achromatic color computation that accounts for these top-down effects by assuming the existence of cortical feedback mechanisms that adjust the neural gains applied to edges at multiple stages of cortical processing to influence judgments of the disk brightness (perceived luminance), lightness (perceived reflectance), and brightness contrast (the perceived disk/annulus luminance relationship).