Neeranuch Kittikiatkumjorn¹ (), Waragon Phusuwan^1,2, Anantaporn Sena¹, Arp-Arpa Kasemsantitham^1,3, Sedthapong Chunamchai¹; ¹Cognitive Clinical & Computational Neuroscience Lab, Chula Neuroscience Center, King Chulalongkorn Memorial Hospital, ²Medical Science, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand, ³Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand

Humans perceive color images through different wavelengths of light interacting with retinal cells, generating signals for the visual system, and subsequently creating color perception. However, prolonged exposure to a single color typically results in negative afterimages, or opponent colors, when the stimulus is removed. Whether these negative afterimages originate solely from retinal or jointly with cortical processes is still debated (Dong et al., 2017). One theory explains this phenomenon by retinal cone cell fatigue, where opposing pairs of cone cells inhibit the perception of the opposing color, resulting in the illusory perception of opponent colors after extended exposure to one color; meanwhile, statistical learning processes theorize the color illusions arise from the visual system's adaptation to prolonged exposure. Here, we investigated whether negative afterimages depend on the physical properties of color or on perceived colors influenced by color constancy — a phenomenon enabling varying color perceptions of the same physical color under different environmental conditions. We presented images of a Rubik's Cube with multiple-color squares illuminated by different lights; a grey square was placed alongside other colored squares to evoke perceptions of color constancy (yellow, blue, red, and green). After viewing these images followed by a white Rubik's Cube, eleven participants identified the afterimage color seen in the probe location. We found that the afterimage color of the grey square varied significantly based on color constancy (F = 23.86, p < 0.001). The colored squares that matched the light source color— appearing whitish due to color constancy – also resulted in a consistent white and black afterimage across different trials, demonstrating that the perceived afterimage color is more influenced by perceived color than by the actual physical color properties. These findings suggest that negative afterimage perception is driven more by cortical processes and statistical learning, rather than solely by retinal cell fatigue.