Hypnosis Lets Regular People See Numbers as Colors
Psychologists have used hypnosis to give people the ability to see numbers as colors.
That form of synesthesia is naturally possessed by roughly one in 1,000 people, among them such historical luminaries as physicist Richard Feynman and writer Vladimir Nabokov, who saw "q as browner than k, while s is not the light blue of c, but a curious mixture of azure and mother-of-pearl."