Prior knowledge modulates peripheral color appearance

Color perception deteriorates with increasing eccentricity in the visual field. Here, we investigated peripheral color perception using a painting method, asking how prior knowledge affects color appearance. A professional artist was presented with complex, cluttered images in the visual periphery. The task was to paint as accurately as possible how each image appeared. Eye tracking assured that the image was only viewed in the periphery. The resulting paintings were strongly compromised. After finishing a painting, the target image was freely viewed to acquire knowledge about it. Next, the same image was presented at the same peripheral location and painted again. There were two conditions for the second painting. In the first condition, the image was again masked when not fixating the fixation dot (as during the first presentation). In the second condition, the image was not masked, allowing saccades to the image. In both conditions, the paintings resulting from the first presentation showed clear differences compared to the second presentation. Salient color regions in the images that were not painted during the first presentation, were painted during the second presentation. Color changes were less pronounced in the first than in the second condition. Importantly, several image features were remembered but not painted during the second presentation, showing - in addition to subjective reports – the perceptual nature of the effect. Our results indicate that prior knowledge of peripheral targets strongly shapes perception.