Humans see colour differently in the summer
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. Humans identify four unique hues – blue, green, yellow and red – that do not appear to contain mixtures of other colours. Unique yellow is particularly interesting to scientists as it is stable across large populations – everyone agrees what unique yellow looks like despite the fact that people’s eyes are often very different. The researchers in the Department of Psychology wanted to discover why this colour is so stable and what factors might make it change. The researchers tested 67 men and women in January and June 2015. Participants were placed in a darkened room, allowed to adjust to the light and then (on a machine called a colorimeter) asked to adjust a dial backwards and forwards until they felt they had reached the point where it had reached unique yellow – with no hint of a green or red. They found that in June volunteers adjusted more green out of yellow than in January, and added more in January to get back to yellow, suggesting that their eyes were viewing the colours differently. Lead author Lauren Welbourne highlights how “this is the first time natural changes in the environment have been shown to affect our perception of colour. For me as a vision scientist it is fascinating as it is telling us more about how visual processing works. Although there’s no disorder that this can fix, the more we learn about how vision and colour in particular is processed, the better we can understand exactly how we see the world. This can have knock on effects on the way we diagnose and treat visual disorders”. We are blessed with four very distinct seasons in this country; each with its own character, charm, and idiosyncrasies and this study reveals for perhaps the first time how we visually adapt to this seasonal cycle.