When Turner daubed a red buoy in his seascape Helvoetsluys, what did he mean? In nature, red may repel or attract, signalling toxicity or ripeness, anger, ruddy health or sexual readiness. For Turner, the red created contrast, and in making that mark, he meant to generate salience and arouse interest, to dominate his rivals and draw in his admirers. Colour has long excited emotions and intellectual debate, not only for visual art, but also in philosophy, psychology and physiology. In contemporary vision science studies, colour helps people find objects faster, discern material properties, learn, conceptualise and memorise. Yet colour is made in the mind, not out there in the world. It is a subjective phenomenon, a personal possession, one that varies between individual eyes, and one that people cling to with ardour when challenged: witness the public divide over the 'blue/black', 'white/gold' dress. So the question is not only what does colour mean, in life and in art, but how does it mean anything? How does the human brain create colour, stabilise it, and make its meaning? And why does it evoke emotion and aesthetic appreciation?
