Tuesday, April 14, 2009
Savant skills may be widespread in people with autism
Daniel Paul Tammet is a British high-functioning autistic savant gifted with a facility for mathematical and natural language learning.
By Celeste Biever - New Scientist
Savant-like skills, such as astounding memory, perfect pitch or the ability to multiply very high numbers together, may be much more common among people with autism than previously thought.
A new study of about 100 adults with autism shows that one third have skills that stand out, both in comparison with their other abilities and with the skills of the general population. Previous studies put the prevalence of savantism in autistic people as around 1 in 10.
"People often focus on the things people with autism can't do," says Patricia Howlin of the Institute of Psychiatry at King's College in London, who led the study. "One of the things our study illustrates is that these are people who do have special skills but they are not being used."
The notion of the savant – someone who has a skill that is exceptional both compared to the general population and to that person's other skills – has long captured the imagination of cognitive scientists and the general public alike. But despite this fascination, the connection between autism and savantism remains mysterious.
Some studies indicate that there are more savants within the autistic population than among the general population and among the populations of people with other mental difficulties. Putting an exact figure on the prevalence of such special skills among people with autism, however, has proved difficult.
In an attempt to quantify this, Howlin's team looked at two different measures of exceptional ability in a group of people with autism – all now adults – who the team have been studying periodically since they were first diagnosed between 1950 and 1985. They found that 39 met criteria for either what they call a "savant skill" or an "exceptional cognitive skill".
To identify savant skills, the researchers sent the parents of the autistic adults a questionnaire asking them to identify and describe, using specific examples, any outstanding skills and talents that were present "at a level that would be unusual even for normal people".
Of almost 100 parents who replied, about half (45) claimed that their child had a special skill. But only 24 of the hundred met the researchers' tough criteria for what constitutes a savant skill: both exceptional in terms of population norms and above the individual's overall level of ability.
Relying on parents' anecdotal reports of skills could be risky. However, Francesca Happe, also at the Institute of Psychiatry but not involved in the study, says that the team's criteria were "pretty strict": "They didn't count anything that could conceivably be considered a normal skill. I don't think the parental reports are inflated."
Searching for savants
Among those skills considered at the savant level were: 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 fairly common savant ability known as calendrical calculation); perfect pitch; and the ability to say, from a single chord, which piece of music it came from.
To identify exceptional cognitive ability, Howlin's team also examined the volunteers' scores on standard intelligence tests consisting of a range of subtests aimed at different aspects of IQ, such as arithmetic, spatial and motor skills and memory span. They found that 23 had an ability on at least one of these subtests that was well above the general population's average score on that subtest.
Eight of these 23 had also been identified as a mathematical or calendrical savant according to the first criteria, and the team concludes that overall 28.5% – or almost one third – of their volunteers had either a savant skill or an exceptional cognitive ability.
"I think it is a surprisingly high number, but believable," says Happe. She says that the study opens a window into the mind of a child with autism and recommends using these isolated, exceptional abilities as a way to motivate people with autism to learn other skills – such as social or communication ones – that might not come as easily.
One in ten?
Darold Treffert, a psychiatrist based in Fond du Lac, Wisconsin who studies savants, says that he sticks by an earlier estimate of the prevalence of savantism as being one in ten among people with autism. This is based on previous studies and backed up by his own observations.
He says this is partly because he is mistrustful of parental reports, and partly because he does not think that the peak ability in the intelligence subtests qualifies someone as a savant. "Some autistic savants do well on IQ subtests, but not all autistic persons who do well on IQ subtests are savant."
But he says the study is interesting, because it underscores the failings of IQ tests to measure overall intelligence.
"We are all made up of a series of intelligences, especially the savant, and IQ measures one component," he says. "Savants starkly challenge our definition of 'intelligence' and require us to look for ways to measure other 'intelligences'."
"We need a more reliable definition of savant syndrome, and a more reliable definition of intelligence," he adds.
Please share this news with friends, family and also with your contact list on Facebook and MySpace.