Language acquisition: the acquisition of linguistic structure in normal and special populations.

This review examines how language learners master the formal structure of their language. Three possible routes to the acquisition and mastery of linguistic structure are investigated: (a) the use of prosodic and phonological information, which is imperfectly correlated with syntactic units and linguistic classes; (b) the use of function words to syntactically classify co-occurring words and phrases, and the effect of location of function-word processing on structural mastery; and (c) the use of morphology internal to lexical items to determine language structure, and the productive recombination of these subunits in new items. Evidence supporting these three routes comes from normal language acquirers and from several special populations, including learners given impoverished input, learners with Williams syndrome, specific language-impaired learners, learners with Down syndrome, and late learners of first and second languages. Further evidence for the three routes comes from artificial language acquisition experiments and computer simulations.