Clad in a dark suit and sunglasses, Derek Paravicini makes a beeline for the sound of my voice and links his arm into mine. "Hello, Celeste. Where have you come from today?" I reply and his response is immediate: "From Holborn?" He repeats the word several times, savouring each syllable. "Hol-born, Hol-born, Hooool-bbooorn. Where's Hoollll-booorn?" As our conversation continues, the substance of much of what I say does not seem to sink in, but the sounds themselves certainly do, with Mr Paravicini lingering over and repeating particularly delightful syllables. "Meewww-zick. The pi-aan-o."
Such touching and immediate friendliness is not quite what I expected from my first meeting with the 29-year-old, blind musical savant, but his obsession with reproducing sounds certainly makes sense, given his talent. Mr Paravicini can play just about any piece of music you request, entirely from memory, with formidable technical ability, despite having severe learning difficulties that mean he needs constant support in everyday life. And as I find out an hour later, he constantly improvises the pieces he has learnt by ear, rather than simply copying as you might expect.
Mr Paravicini is a prodigious savant - someone with a dazzling talent in one or two fields, normally music, maths, art or memory, but who also has some kind of a disability, such as autism. Psychologists have puzzled long and hard over savant skills, which confound their traditional understanding of intelligence. "What makes savants so interesting is this jarring juxtaposition of ability and disability in the same person," says Darold Treffert, a psychiatrist based in Fond Du Lac, Wisconsin who was a consultant for the film Rain Man. "We are used to seeing skills that are consistent with each other."
But now researchers are beginning to unearth clues as to how savants' formidable brains work, and that in turn is changing our view of what it means to be a savant. In the past, savants were considered rare, solitary figures capable of mind-boggling skills that appeared as if by magic. "There have almost been suggestions that their skills appear like the birth of Venus in Botticelli - fully formed," says the psychologist Richard Cowan, who studies savants at the Institute of Education, University of London.
A flurry of research published this year in the journal Philosophical Transactions of the Royal Society B paints a very different picture. It turns out that these skills are far more common than previously thought. They may even arise from traits found in the general population, implying that savants are not fundamentally different from the rest of us. What is more, these skills may blossom only after years of obsessive practice, raising the question of whether many more people might cultivate similar skills, if only they had the motivation.
One of the biggest clues to the origins of savant talent lies in the fact that savants are far more common within the autistic population than among people with other mental difficulties. "When you talk about savants, you have to talk about autism," says Greg Wallace, who studies savants at the National Institute of Mental Health in Bethesda, Maryland. "In many ways they are inextricably linked." Previously, about one in 10 people with autism was thought to have a special ability but in April, Patricia Howlin at the Institute of Psychiatry at King's College London found a much higher figure in the autistic adults she surveyed for savant skills or an exceptional cognitive ability. Those with an exceptional cognitive ability scored higher than the general population on at least one aspect of an intelligence test, which included arithmetic, spatial and motor skills, and memory span. Savant skills included more fully developed talents, such as being able to name the elevation of both the sun and the moon at any time of day, on any specified date; being able to name the day of the week for any date in the distant past or future (a talent known as calendrical calculation); and perfect pitch.
But while highlighting the link between autism and savantism, Dr Howlin's results did not offer any further clues as to why the two are so entwined. To investigate the nature of this link, Francesca Happé, also at the Institute of Psychiatry, and her colleagues decided to test which aspects of autism predispose people to talent, and whether these traits also occured in the general population, albeit less commonly.
Her team sent a questionnaire called the Childhood Asperger Syndrome Test to the parents of more than 6,000 autistic and non-autistic eight-year-olds, along with a questionnaire assessing the child's special abilities in maths, musical ability, art and memory. On analysing the results, one trait in particular emerged as the biggest indicator of talent. Children who "notice details that other people miss", or "remember details that other people miss" were twice as likely to have a special gift than those without these attributes.
But how could such an unremarkable trait give rise to a gift? For musical savants like Mr Paravicini, Dr Happé suggests that a bias towards small details might have led their developing brains to focus more on the exact notes than the overall melody, leading to perfect pitch and an exceptional musical memory. In art, a focus on small regions of a picture could lead to accurate perspective drawing.
Other clues might lie in the work of Simon Baron-Cohen, from the University of Cambridge, which suggests that people with autism are "hypersensitive" to sensory information. He now proposes that such acute sensitivity might predispose people with autism to pick out differences that would escape the rest of us, fostering an unusual focus on detail that leads to the development of savant skills. Daniel Tammet, a prodigious savant who has memorised pi to 22,514 digits, believes his talents have arisen from a special ability to connect different pieces of information together. "Savant abilities are linked to a highly associative type of thinking, an extreme form of a kind that everyone does - examples would include daydreaming, puns and the use of metaphors," he says.
In fact, it seems the remaining mystery is not so much how savants achieve their talents, but what drives them in the first place. One person who has something of an inside view on what contributes to savant ability is Mr Paravicini's mentor, Adam Ockelford, a professor of music at Roehampton University in London, who has watched Mr Paravicini's talent blossom since the age of four. When they first met, Mr Paravicini was entirely self-taught and bashed at his plastic keyboard with his fists and elbows to reproduce the sounds he was hearing. It was only after years of practice that his technical skills developed.
But as researchers such as Dr Wallace have suggested, Mr Paravicini seemed motivated way beyond the average music student. In fact, he seemed to be playing as if his life depended on it, and Prof Ockelford thinks it is this that truly sets savants apart from their peers. "The survival instinct gets turned with extraordinary force into something else - in Derek's case music," says Prof Ockelford. "When people see Derek, they think it is amazing, almost religious. But to me, it's mainly just hard work."