Single cone photoreceptors experience global image statistics through gaze shifts

Our visual experience does not merely reflect a static view of the world but is a dynamic consequence of our actions, most notably our continuously shifting gaze. These shifts determine the spectral diet of any individual cone photoreceptor. The aim of this study was to characterize that diet and its relationship to scene adaptation. Gaze shifts were recorded from observers freely viewing scenes outdoors for five minutes. Hyperspectral images of the scenes were also recorded from the eye position of observers. As a control, gaze shifts were also recorded from observers viewing the images on a computer-controlled display in the laboratory. From the hyperspectral data, spatially local histograms of estimated excitations in long-, medium-, and short-wavelength-sensitive cones were accumulated over time at different retinal locations. A global illuminant change was then introduced to test how well local retinal adaptation discounted its effects. The results suggest that over short periods individual cones tend to experience the statistics of full scenes, with local adaptation compensating for illumination changes almost as well as global adaptation. This compensation may help to maintain our stable local perception of scene colour despite changes in scene illumination.