Jin Hirano¹, Masataka Sawayama², Kiyofumi Miyoshi¹, Shin'ya Nishida¹; ¹Graduate School of Informatics, Kyoto University, Japan, ²Graduate School of Information Science and Technology, The University of Tokyo, Japan

#TheDress has demonstrated significant individual differences in perceived colors, but the specific conditions that lead to similar variability remain unclear. Previous research has highlighted the importance of elongated color distributions along the daylight axis, but #TheShoe questioned the generality of this rule. We examined the effects of color distribution axes on the individual variation in perceived color in various objects. We projected the color distribution of an object image onto a straight line along an arbitrary color axis passing through a white point in the CIE u*v* chromaticity diagram. By shifting the 1D color distribution along this axis, we generated a set of object images with continuously varying colors. A psychophysical experiment with the constant method was conducted with 30 participants, who answered perceived color from three options (e.g., blue, gray, yellow) at two distinct regions of the images. We estimated the magnitude of color shifts at which the response color was switched. This protocol was designed to quantify the state of individual color perception using a color-naming task that encourages surface matching (rather than appearance matching). Stimuli were four types of real-world objects, including Dress and Shoe, and control stimuli consisting of two color patches. There were six chromatic axis conditions, including the daylight axis. The results showed that the individual variation was larger for object images than for control stimuli. Within four objects, Dress and Shoe had larger variations than the other two novel objects. The large individual variation was observed not only for the daylight axis or the major axis of #TheShoe but also for other color axes (e.g., green–purple axis). The daylight axis showed a slightly larger variation, but only for Dress. Our results suggest that the individual difference in color perception is a more general phenomenon in object color perception than previously thought.

Acknowledgements: This work was supported by the KAKENHI Grant Number JP24H00721 and JP20H05957.