Color Vision

Humans See Colour Differently in the Summer

Colour perception changes between seasons with humans seeing yellow as more green in the summertime

Sarah Kanpton | August 5, 2015

Humans see colour differently in the summer with yellow seeming more green than in the winter months, scientists have shown for the first time
The researchers at York University looked at how colour perception changes between seasons and in particular how humans process the colour known as unique yellow.
Humans identify four unique hues – blue, green, yellow and red – that do not appear to contain mixtures of other colours.

<more at http://www.telegraph.co.uk/news/science/science-news/11783155/Humans-see-colour-differently-in-the-summer.html; http://phys.org/news/2015-08-differently-winter-summer.html (Why we see things differently in winter compared with summer. August 5, 2015) and http://phys.org/news/2013-10-bright-eyes-reindeers-colour-arctic.html (Bright eyes: Study finds reindeers' eyes change colour with Arctic seasons. October 29, 2013); further: https://www.york.ac.uk/news-and-events/news/2015/research/colours-eyes-psychology/ (Seeing the sunnier side of life – scientists bring a whole new meaning to winter blues. Scientists at the University of York have shed new light on how humans process colour – revealing that we see things differently in winter compared with summer. August 4, 2015) and http://www.cell.com/current-biology/abstract/S0960-9822(15)00724-1 Lauren E. Welbourne, Antony B. Morland, Alex R. Wade. [http://dx.doi.org/10.1016/j.cub.2015.06.030] [Abstract: Humans identify four ‘unique hues’ — blue, green, yellow and red — that do not appear to contain mixtures of other colours. Unique yellow (UY) is particularly interesting because it is stable across large populations: participants reliably set a monochromatic light to a stereotypical wavelength. Individual variability in the ratio of L- and M-cones in the retina, and effects of ageing, both impact unique green (UG) settings, but cannot predict the relatively small inter-individual differences in UY. The stability of UY may arise because it is set by the environment rather than retinal physiology. Support for this idea comes from studies of long-term, artificial chromatic adaptation, but there is no evidence for this process in natural settings. Here, we measured 67 participants in York (UK) in both the winter and summer, and found a significant seasonal change in UY settings. In comparison, Rayleigh colour matches that would not be expected to exhibit environmentally driven changes were found to be constant. The seasonal shift in UY settings is consistent with a model that reweights L- and M-cone inputs into a perceptual opponent colour channel after a small, seasonally-driven change in mean L:M cone activity.]>