Photorealism aftereffect.

This study reports a novel visual aftereffect for photorealism judgments. Participants observed image sequences where a photograph was gradually transformed into an artificial image (a painting or a sketch). Their task was to choose the image that was the category boundary between the photograph and the artificial image among the frames of each image sequence. This task was performed before and after observing photographs or artificial images for 1 min. The chosen images were less photorealistic after the observation of artificial images, suggesting an aftereffect for photorealism judgments. However, observation of photographs did not induce an aftereffect. It is known that the observation of the norms for perceptual judgments (e.g., the prototypical face for facial judgments) does not induce aftereffects. Thus, these results suggest that photorealistic images serve as the norm for the perceptual judgment of photorealism. The human visual system may represent the photorealism of artificial images as a deviation from photorealistic images.