Acquisition and extension of syntactic repertoires by severely mentally retarded youth.

This study investigated the conditions that contribute to generalized language learning in severely mentally retarded children. Matrix-training strategies were used to teach three mentally retarded children syntactic rules for combining known words into two- and three-word utterances. The children applied these rules subsequently to learn unknown words. Generalized learning of responses not taught directly was shown to be under experimental control using a multiple baseline design across submatrices. Training only a limited number of responses was sufficient to promote recombinative generalization in the trained modality and transfer to untrained responses in the opposite modality. Teaching receptive and expressive language responses while simultaneously promoting untrained responding through matrix training provides an economical and efficient training approach for mentally retarded individuals.