The morphology and syntax of individuals who use AAC: research review and implications for effective practice.

A research review of 31 studies pertaining to the morphology and syntax of individuals who use augmentative and alternative communication (AAC) and who had severe speech and physical impairments (SSPI) was completed. Results suggest that, although many individuals who use AAC exhibit comprehension and expression of a wide range of grammatical structures, these individuals are at risk for experiencing grammar deficits. A wide range of individual differences was noted, both within and across many of the investigations. One of the more robust findings was that individuals tended to produce shorter utterances when they used graphic symbol-based AAC systems than would be expected, based on participant profiles; however, there appeared to be a developmental trend toward using longer utterances. There has been a dearth of research pertaining to the development and evaluation of appropriate assessment tools and intervention techniques to enhance grammar acquisition for individuals who use AAC. Considerations for developing such tools and techniques are discussed.