Abstract
The distribution of chromaticities in natural scenes is elongated along the blue-yellow axis. Color discrimination thresholds are also poorest along the blue-yellow axis, which may reflect calibration of color vision to the visual environment (Bosten, Beer & MacLeod, 2015). The hypothesis of whether or not color vision can be calibrated within an individual’s lifetime to the content of the scenes they encounter can be tested by comparing individuals who live in chromatically different environments. We compared color discrimination in individuals living in different visual environments (in two cities (Brighton (UK), Quito (Ecuador)) and a rainforest community in Esmeraldas (Ecuador)). Here we developed a psychophysical method of efficiently measuring color discrimination ellipses on a calibrated tablet. Color discrimination thresholds for 8 hues were measured for participants at the three locations. Additionally participants wore calibrated head mounted cameras to capture a representative sample of the natural scenes that they encounter in daily life. All of the images were analysed for their color distributions to characterise the differences in color statistics between the three environments. Discrimination thresholds for all three groups were poorest for the blue-yellow axis (Brighton, t(34), 12.47, p=<.001,Quito, t(20)= 6.129 p=<.001, Esmeraldas, t(25) = 8.23, p=<.001). The distributions of colors in natural scenes were also biased along the blue-yellow axis in all three locations. However, despite differences in the chromatic distributions of scenes at different locations, these differences could not easily account for color discrimination performance.