EXCEPTIONAL LANGUAGE-DEVELOPMENT IN MENTAL-RETARDATION - NATURAL EXPERIMENTS IN LANGUAGE MODULARITY

Recent data on mentally retarded subjects with exceptional language ca pacities are summarized and discussed in relation with so-called ''cog nition-drives-language'' theories such a Piaget's and the competition theory recently proposed by Bates and MacWhinney. It is suggested that those and similar theories cannot account in principle for the except ional cases documented. Such cases provide support for the Chomskian n otion of the autonomy of grammar, and for the distinction between the computational and conceptual aspects of language. Additional empirical indications from studies on language pathology and the neurolinguisti c literature are analyzed in support of a modular account of language organization.