Lightness constancy in visual artists

Research to date has produced widely divergent findings in terms of the degree of lightness constancy shown by individuals, and there are hosts of competing models of lightness processing in the brain. We argue here that visual artists–especially painters of representational works–are a useful cohort for investigations of lightness perception because the task of creating representational paintings would appear to require artists to judge natural scene luminance (what artists call “value”) accurately in the face of visual system efforts to normalize perceived intensity. Here we investigate the ability to judge illusory luminance differences in a Craik-O'Brien-Cornsweet stimulus in artists with varying expertise. In a 2AFC staircase design, professional realist painters (N = 2) show lower overall PSE (point of subjective equality) with respect to real luminance differences, compared to student artists (N = 3) and non-artists (N = 9) considered together. For artists vs. non-artists, this result holds at 2 of 3 levels of illusory contrast (i.e., the contrast of the luminance ramp in the center of the illusory stimulus). In addition, there is an inverse correlation between the subjects' reported number of hours spent painting or drawing per week and PSE for the same two illusory contrasts (R2 ≥ .18). Artistic training regimes–and perhaps innate endowments–that lead to the putative ability to judge luminance accurately may be seen as analogous to those that allow superior pitch judgment (e.g., absolute or relative pitch) in musicians, and therefore we provisionally term superior luminance judgment as absolute (or relative) value. Artists with this ability are of interest to vision science, much as musicians with superior pitch perception have long been studied by audition researchers to elucidate neural processing of acoustic tone. Tests aimed at determining the factors involved in artists' ability to judge luminance and tests quantifying luminance judgment in naturalistic conditions are also described.