Color from invisible patterns

Human pattern resolution is limited by optical blurring as well as neural filtering by a cascade of retinal and cortical sites with progressively lower resolution limits. Curiously, pattern structure can influence perceived color: a high-contrast, monochromatic (single wavelength) pattern appears desaturated (closer to white) relative to a uniform field of the same wavelength. Here we show that this desaturation is evident even when the pattern's frequency is too high for conscious perception, implicating a nonlinear process--namely light adaptation--at the level of single cone photoreceptors. We propose a neural mechanism in which fast, involuntary eye movements serve to shift control over perception between two competing cone populations, each operating at different levels of adaptation.