critical period

In child language ACQUISITION, the hypothesis that there is a particular time span during which a first LANGUAGE can be most easily acquired. The notion of a critical period is well supported in several areas of child development (e.g. with reference to the development of the mechanism of swallowing), and was felt to be also relevant to the emergence of language. It was argued that the critical period for language ends at puberty, because by this time the brain has become specialized in its functions, and no longer has the adaptability found at earlier stages of biological development. The hypothesis has proved to be extremely difficult to test, and remains controversial. The study of language-deprived children (reared in the wild or by animals – ‘feral children’ – or kept isolated from society – ‘attic children’) provides some support; but studies of adult language learning indicate that the brain is more plastic in adulthood than was once believed and that its language functions are more widely distributed. Adults moreover have certain cognitive abilities which facilitate language acquisition, such as increased motivation and greater METALINGUISTIC awareness.