MODULARITY1
The hypothesis that language is a separate faculty, supported by general cognition but not dependent upon it. It is especially associated with the nativist view that language is genetically transmitted.
Arguments in favour of modularity include the fact nearly every infant manages to achieve full linguistic competence, regardless of variations in intelligence and in ability to perform other cognitive functions. There are also forms of impairment where language and general intelligence seem dissociated:
In specific language impairment, sufferers show signs of normal cognitive development but their language remains incomplete in certain important features (particularly inflections and function words).
Williams Syndrome presents the opposite symptoms. Sufferers show signs of cognitive impairment, including low IQs. However, language is spared; indeed Williams sufferers are often extremely communicative and their vocabulary and speaking skills may be above normal at early ages.
A remarkable case has been identified of a savant named Christopher who was diagnosed as brain-damaged and has to live in care but who is able to translate into and out of sixteen languages.
However, contrary evidence comes from other forms of impairment such as Down’s Syndrome, where both language and mental capacity are impaired. Likewise, autism presents symptoms of cognitive and social impairment which affect all forms of communication.
Incompatible with the modularity hypothesis is the view of some neuroscientists that language maps on to operations of the brain which originally served other cognitive functions. Evidence from brain imaging is cited which shows that language operations are widely distributed throughout the brain. An explanation given for the Williams symptoms is that certain parts of the brain are affected but that those which subserve language are spared. There is also an evolutionary argument which suggests that it is more likely that language adapted to the brain than that the brain adapted to language.
See also: Brain: localisation, Evolution of language, Nativism
Further reading: Bishop (1997); Crain and Lillo-Martin (1999: 61–70); Pinker (1994b)
