Age, pupil size differences, and color choices for the "dress" and the "jacket"

The color identification responses to photographs of #thedress (white/gold and blue/black) and a jacket (white/blue and green/black, and teal) reveal obvious individual differences in color perception. To explore possible association between pupil size/retinal illuminance and color perception, we recorded the pupil diameters of participants shown 22 uniformly colored (generated from the RGB values using a laptop LCD display) screens followed by photographs of #thedress and jacket. We analyzed (a) pupil size difference in the color groups and (b) age-related pupil size and/or reflex change and its influence on color perception. The data confirms that the average pupil size of the white/gold group was significantly less than the blue/black group for the dress. The pupil size difference between the color groups is slightly higher in the 21-30-year and 31-55-year age groups but not in the 18-20-year age group, while a similar variance was not observed for the jacket color groups. Interestingly, the average pupil size of both color groups was smaller for the dress compared to the baseline (collected with a gray hue displayed on the screen), whereas an opposite effect was observed for the jacket. The contrasting results for the two photographs do not allow for a strong inference of only pupil size change principal for differences in color perception. But, a probable explanation of the pupil size difference could be the subjective variation in the perceptual interpretation of illumination cues in the photographs.