Striking individual differences in color perception uncovered by 'the dress' photograph

Abstract

'The dress' is a peculiar photograph: by themselves the dress' pixels are brown and blue, colors associated with natural illuminants, but popular accounts (#TheDress) suggest the dress appears either white/gold or blue/black. Could the purported categorical perception arise because the original social-media question was an alternative-forced-choice? In a free-response survey (N = 1401), we found that most people, including those naïve to the image, reported white/gold or blue/black, but some said blue/brown. Reports of white/gold over blue/black were higher among older people and women. On re-test, some subjects reported a switch in perception, showing the image can be multistable. In a language-independent measure of perception, we asked subjects to identify the dress' colors from a complete color gamut. The results showed three peaks corresponding to the main descriptive categories, providing additional evidence that the brain resolves the image into one of three stable percepts. We hypothesize that these reflect different internal priors: some people favor a cool illuminant (blue sky), discount shorter wavelengths, and perceive white/gold; others favor a warm illuminant (incandescent light), discount longer wavelengths, and see blue/black. The remaining subjects may assume a neutral illuminant, and see blue/brown. We show that by introducing overt cues to the illumination, we can flip the dress color.

Figure 1

Striking differences in color perception of The Dress. (A) Original photograph, reproduced with permission from Cecilia Bleasdale. (B) Pixel chromaticities for the dress. (C) Histogram of color descriptions, for naïve (N=313) and non-naive (N=1088) subjects. Error bars are 95% C.I. (D) Of subjects who reported W/G or B/K (N=1221), the odds of reporting W/G increased by a factor 1.02 per unit age, p=0.0035, 95% C.I. [1.01-1.03] (Table S1). Symbol size denotes number of subjects (largest dot=76; smallest dot=1). (E) Color matches for regions i-iv (panel A), sorted by color description (B/K, left; W/G, right). Symbols show averages (upward triangles, regions i and ii; downward triangles, regions iii and iv), and contain 95% C.I.s of the mean. Grid provides a reference across the B/K and W/G panels. Insets depict color matches for individual subjects in each row, sorted by description. (F) Color matches for region (i) plotted against matches for region (ii) for all subjects (R=0.59, p<0.0001). Contours contain the highest density (25%) of respondents obtained in separate plots (not shown) generated by sorting the data by description (B/K, W/G, B/B). The first principal component of the population matches to (i, iv) defined the y axis (gold/black, “GK”); the first PC of the population matches to (ii, iii) defined the x axis (white/blue, “WB”). Each subject’s (x,y) values are the PC weights for their matches (Supplementary Experimental Procedures). Color scale is number of subjects. (G) Among W/G or B/K respondents, percent of W/G responses increased with image size (N=235, 10%; N=1223, 36%; N=245, 100%; N=215, 150%; p < 0.0001, OR=1.004 [1.002-1.007]). The horizontal dimension of the image was about 2°, 7.2 °, 20°, and 30° of visual angle. Blurring the image biased responses towards B/K (N=1048, image was 41% of original size; image was 260×401pixels with a 0.11° pixel radius Gaussian bl ur; Chi-square, p<0.0001).