A 14-YEAR-OLD boy who has an IQ of about 130 but consistently fails on a number of simple grammatical tasks may hold the key to understanding how the mind is organised, scientists claim.
The boy, referred to as AZ, formed the focus of discussion at a recent pioneering conference dedicated to specific language impairment (SLI), a little-understood condition in which the grammatical aspects of language are impaired in the apparent absence of any other disability.
Half a million British children are thought to suffer from the condition which makes communication difficult and which hampers education and job prospects.
Organised by Heather van der Lely, a research fellow at Birkbeck College, London, the conference, held near Frankfurt in Germany, brought together some of the world's leading lights in the field who have studied manifestations of SLI in their own languages.
Dr van der Lely, a qualified speech and language therapist, has spent the past decade trying to pinpoint the reasons behind SLI in a bid to develop suitable remediation.
She believes her research on AZ provides strong evidence that it is possible purely for language, as opposed to other cognitive functions, to be impaired. Despite high intelligence and a good grasp of logic, AZ, she says, is unable to perform simple grammatical tasks and to construct anything but the simplest of sentences. "AZ is making some errors in his grammar that three or four-year-olds don't make," she said. "But he also has a very high IQ."
This, believes Dr van der Lely, is evidence that a separate section of the brain governs language.
However, her views have been challenged. Others maintain that the brain's abilities are not specialised prior to birth, instead becoming specialised with experience. Some argue that a child's inability to master grammar, particularly problems with tense endings or other hard-to-hear inflectual sounds, is a result of slow processing ability, rather than a specific language impairment.
Dr van der Lely's earlier work shows the hereditary nature of the condition - children with SLI are highly likely to have a parent and sibling also with a language impairment. She said: "Most people now concede that there is a genetic basis to this problem. Where researchers differ is in how specific the disorder is. AZ has a very high IQ. He's extremely good at logic, but if you give him a sentence, he can't put it in the past tense. He just can't see it."
"In cognitive science, there is a big battle over how the mind is organised and whether it is modular. If a child who has SLI shows only an impairment in this grammatical aspect and we can find no other cognitive impairment, then this is evidence for the modularity of the brain. Language is one of the candidates for a module."
The conference also presented an opportunity for international researchers, in languages as diverse as Inuktitut, Quebec French and Hebrew, to start to assess whether patterns in SLI children's grammar problems occur across the languages.
"If we find a common problem with tense, however it is realised in language, then the evidence points to a modular grammatical problem. Whereas, if children are always leaving off inflectional endings which are hard to hear then perhaps it is more likely to be a processing problem."
Dr van der Lely added: "This is a very exciting area because of its potential to give us insight into some very big issues in cognitive science. I want to further understanding of SLI so there is better therapy, but also because of the potential for science generally."