If a stock market rally was a colour, what would it be? Strangely, enough there is a group of people on the planet with a condition who might have an idea. Synesthesia occurs in one in 10,000 people and is, at its most basic level - a blending and co-ordinating of the senses. Those with the capacity can literally ‘see’ sounds and ‘taste’ colours. The roll call of famous synesthetes includes Russian painter Kandinksy, physicist Richard Feynman, inventor Nikola Tesla, and founder of Pink Floyd, Syd Barrett.