Yellow gets greener in summer

Remember winter, when everything was cold and grey? Right now, when all around is lush and green, the contrast couldn't be greater. But is everything really as it seems? New research shows that we see things differently in winter compared with summer.

Our eyes perceive four pure, unmixed colours - blue, green, red and yellow. People often find it hard to agree exactly what shade pure blue, green and red are, but curiously we tend to see pure yellow the same way, despite having different eyes. Lauren Welbourne, a psychologist at the University of York, wondered if that was because yellow is influenced more by the world around us than the biology of our eyes.