UNDER THE MICROSCOPE:ALTHOUGH SAVANT syndrome is not an officially recognised medical diagnosis, Darold Treffert, an American research psychiatrist, who was a consultant for the film Rain Man, defines the savant syndrome as "a rare condition in which persons with developmental disorders have one or more areas of expertise, ability or brilliance that are in contrast with the individual's overall limitations".
John Langdon Down (1828-1896) was the first to describe the savant syndrome (he is also known for his description of Down syndrome). Down used the term “idiot savant” to describe the condition and this terminology was used until well into the 20th century. Back then, the term “idiot” was accepted within the scientific community to describe a person with an IQ below 20. That term is now unacceptable because it offends personal dignity, but it is also technically incorrect, since almost all cases of savant syndrome have IQs above 40.
About half those diagnosed with savant syndrome are autistic and the term “autistic savant” was also used in the past, but no longer. About 10 per cent of autistic people have savant skills. Also, male savants are six times more common than female savants. Although it is extremely rare, some savants show no evidence of abnormalities accompanying their unique abilities.
Derek Paravicini is a typical example of savant syndrome (described by Celeste Biever in New Scientist, Issue 2711, June 2009). He is a 29-year-old musical savant. Derek has severe general learning difficulties and needs everyday support. Yet he can play on the piano any musical piece you request, entirely from memory and with considerable technical skill. He doesn't simply regurgitate music he has heard, but constantly improvises the pieces.
Many readers will have seen the 1988 film Rain Man, starring Tom Cruise and Dustin Hoffman. Hoffman plays autistic savant Raymond Babbit, who can remember everything he reads and do lightening-fast calculations in his head. The character was based on real-life Kim Peek who lives in Salt Lake City. Peek is a savant who is not autistic. He probably suffers from Opitz-Kaveggia syndrome, a genetic syndrome linked to the X chromosome that causes developmental delays and physical anomalies. Peek has a photographic memory. He reads a book in about an hour and remembers almost everything he reads. He can recall the content of more than 12,000 books.
Savant syndrome is poorly understood. The latest research is published in the Philosophical Transactions of the Royal Society B,Vol 364, 2009. It used be thought that the amazing talents displayed by savants emerge fully formed, but it is now believed that such skills are more common than previously thought and may even arise from traits found in the general population. Furthermore, savant skills may develop only after years of obsessive practice.
Since half of all savants are autistic, autism must hold some clues to the origins of the special talents. One study has identified the capacity of “remembering details that other people miss” as the biggest indicator of special talent in autistic children. This eye for detail seems to give one a “foothold into talent”. Biever speculates that, in the case of musical savants such as Paravicini, a bias towards noticing small details could lead their developing brains to home in on the exact notes more than the overall melody, encouraging outstanding musical memory and perfect pitch. In general, people with autism are hypersensitive to sensory information.
Biever describes studies that have shown that savant brains are physically somewhat different from average brains. These differences may not be innate, rather they may develop with practice. Some London taxi drivers have an encyclopaedic knowledge of the layout of 25,000 streets and thousands of places of interest. Studies have shown differences between their brain structures and the brains of adults who do not drive taxis. These differences become less pronounced after the drivers retire. It seems that they start out with typical brains that then develop with training and practice to accommodate the special skill.
Many things no doubt make essential contributions to the development of savant skills. It seems that one of these things, overlooked in the past, is motivation. Autistic savants obsessively practice their skills. Adam Ockelford (quoted by Biever), a professor of music, has watched Paravicini’s talent develop since the age of four. At first, Paravicini was entirely self-taught and bashed at a plastic keyboard with fists and elbows to reproduce the sounds he heard. His technical skills developed only after years of practice. But he was motivated far beyond the average music student and practised “as if his life depended on it”. Hard work seems to play an essential part in the development of savant skills.
William Reville is associate professor of biochemistry and public awareness of science officer at University College Cork – http://understandingscience.ucc.ie
