Color Constancy for an Unseen Surface

Abstract

The illumination of a scene strongly affects our perception of objects in that scene, e.g., the pages of a book illuminated by candlelight will appear quite yellow relative to other types of artificial illuminants. Yet at the same time, the reader still judges the pages as white, their surface color unaffected by the interplay of paper and illuminant. It has been shown empirically that we can indeed report two quite different interpretations of "color": one is dependent on the constant surface spectral reflectance of an object (surface color) and the other on the power of light of different wavelengths reflected from that object (reflected color). How then are these two representations related? The common view, dating from Aristotle, is that our experience of surface color is derived from reflected color or, in more familiar terms, that color perception follows from color sensation. By definition, color constancy requires that vision "discounts the illuminant"; thus, it seems reasonable that vision begins with the color of objects as they naively appear and that we infer from their appearances their surface color. Here, we question this classic view. We use metacontrast-masked priming and, by presenting the unseen prime and the visible mask under different illuminants, dissociate two ways in which the prime matched the mask: in surface color or in reflected color. We find that priming of the mask occurs when it matches the prime in surface color, not reflected color. It follows that color perception can arise without prior color sensation.

No watershed for overflow: Recent work on the richness of consciousness

“…However, such a claim would need to confront recent evidence that color can be perceptually represented outside of consciousness, even when the latter is measured objectively. In particular, using a metacontrast masking paradigm, Norman et al (2014) found priming effects implicating surface color representations (implying constancy based perception) despite d` not differing significantly from zero. In Phillips (forthcoming-a), I discuss whether such cases of perceptual representation amount to perception of the same fundamental kind as ordinary conscious perception by the individual.…”

Fame in the predictive brain: a deflationary approach to explaining consciousness in the prediction error minimization framework

“…For example, subjects fail to detect subliminal primes even in controlled settings, but such stimuli can still drive behavioral responses (see e.g. Norman et al 2014;Faivre et al 2014; see also Ansorge et al 2014 for a review). On the other hand, several studies have shown that percepts which were not consciously registered by the subjects can later be brought into consciousness by attentional cues directed at the location of the stimulus after its disappearance (Kentridge 2013;Sergent et al 2013;Thibault et al 2016).…”

The nature of shape constancy mechanisms as revealed by shape priming

“…The central question we address here is whether the same is true of shape constancy. This question is of some importance because the extant data suggest that shape constancy appears to operate in ways that are different from those that Norman et al (2014) found for color constancy.…”

“…The present series of experiments arose through consideration of a recent paper by Norman, Akins, Heywood, and Kentridge (2014). In a series of metacontrast masking experiments, they found that color constancy can be achieved unconsciously and with extraordinary speed.…”