Contributed talks II: Environmental calibration of perceived white.

It has been proposed that colour perception is calibrated to the chromatic statistics of the environment. Here we investigate whether perceived white is calibrated to the chromatic statistics of the local current 'visual diet'. We compare achromatic settings for participants in Norway living above (Tromsø, N = 165) or below (Oslo, N = 158) the Arctic Circle and across seasons. To capture the local visual diets we used images from colour-calibrated head-mounted cameras worn during daily life. For each image we computed average chromaticity (L/(L+M) and S/(L+M)) and the amount of blue-yellow bias in the distribution of chromaticities. We find that perceived white is warmer (higher L/(L+M) and lower S/(L+M)), and more blue-yellow biased for observers living in Oslo compared to Tromsø. However, visual diets were warmer and more blue-yellow biased in Tromsø compared to Oslo. Perceived white did not vary significantly with season, yet visual diets were warmest in the winter. In order to explore the effects of visual environment in early life, we also investigate how perceived white varies with latitude of birth and season of birth for participants living in Tromsø. Perceived white was lower in S/(L+M) (yellower) for adults born below the Arctic Circle than adults born above, and was higher in L/(L+M) (redder) for adults born in the summer. Combined, the findings suggest a possible link between colour perception and visual diet, and we discuss potential mechanisms.