one odd brain experience frequently linked with artistic genius is synaesthesia - "seeing" sounds, "hearing" colours. some have claimed the cross-referencing of one sense to another as a source of inspiration for creative brilliance. in fact it may be an "ability" any number of us have, artists or not.
the great russian psychologist a r luria spent many years early in this century studying the phenomenal memory of a man called S. in his classic book 'the mind of mnemonist' luria recalls how he first uncovered the key to S's extraordinary abilities. S was recounting a huge table of data - reading off the numbers from a mental image he had created - when someone coughed. S faltered and complained that the cough had shown up as a puff of steam on his mental image and interfered with his ability to recall.
S's experience was a typical example of synaesthesia - he perceived an input in more than one sensory mode. on being presented with a high-pitched tone S said "it looks something like fireworks tinged with a pink-red hue. the strip of colour feels rough and unpleasant, and it has an ugly taste - rather like that of a briny pickle. you could hurt your hand on this."
russian composer alexander scriabin included his experiences of synaesthesia in a work called 'prometheus or the poem of fire', which includes an instrument called a colour organ, whose keyboard projected colours on to a screen. other composers who have used synaesthesia in their work include liszt, rimsky-korsakov, messiaen and scriabin. you may detect synaesthesia in the paintings of kandinsky and hockney. and vladimir nabakov writes about his own and his mother's experience of synaesthesia in his autobiography.
the phenomenon also interested film-maker sergei eisenstein and poets such as rimbaud and baudelaire. but despite the role synaesthesia may have played in creativity and culture, it has been regarded as little more than a psychological curiosity until recently.
over the last few years, however, simon baron-cohen and john harrison of cambridge university have used a mixture of brain imaging and interviews to discover whether synaesthesia is a genuine sensory experience - or just the product of a fertile imagination. you might describe music as 'green' or 'purple' - but that doesn't mean you are actually perceiving colours.
the psychologists presented 100 words to people who experienced synaesthesia and asked them which colours they associated them with. months later they were retested - and came up with the same colours. if you do the same test on people who don't experience synaesthesia, the associations don't persist. the test also showed that there are two sorts of synaesthesia. for some people, the colour depended on what letter the word began with. for others, the colour depended on the word itself.
about one person in 2000 experiences synaesthesia and it is about four times as common in women than in men. surprisingly, there's little evidence that it's commoner in creative people or artists. most synaesthetics had experienced it for as long as they could remember - although they tended to keep it to themselves. indeed it was difficult for synaesthetic subjects to describe the experience at all.
to find out what happens in the brain when someone has a synaesthetic experience, harrison and baron-cohen turned to 'pet' scanning. they found that there is increased blood flow in the parts of the brain concerned with colour perception in subjects with synaesthesia when they are listening to words. control subjects do not show the same pattern of blood flow - which suggests that synaesthesia is a genuine phenomenon taking place in the brain. it may be that people with synaesthesia have extra connections in their brains between areas concerned with auditory and visual perceptions.
now baron-cohen and harrison are extending their studies away from audible colour in the direction of 'coloured smell' and are working with young people to see how the acquisition of synaesthesia may be linked to learning to read. they are also looking into the possibility that synaesthesia has a genetic basis...
