capacity), there are only a few studies that have documented intervention effects on these core deficits. Most of the comprehensive programs do not present data targeting improvement in these skills. Exceptions are Rogers and Lewis (1989), who documented improvements in symbolic play as a result of a structured, developmentally based program (see Chapter 6) and studies of symbolic play with pivotal response treatment (Thorp and Schreibman, 1995; Stahmer, 1995). Other studies that have documented improvement in these core communication deficits have demonstrated increases in gaze to regulate interaction, shared positive affect, use of conventional gestures, and joint attention. Lewy and Dawson (1992) compared the effects of a child-directed teaching strategy in which the adult imitated the child’s behavior with an adult-directed teaching strategy in a group comparison study. They demonstrated that the imitation strategy improved gaze, turn-taking, object use, and joint attention in children with autism, while the adult-directed strategy did not lead to these communicative gains. More recent studies have used single-subject designs to provide systematic evidence of naturalistic language teaching techniques that improve joint attention skills in children with autism (Buffington et al., 1998; Hwang and Hughes, 2000; Pierce and Schriebman, 1995). Thus, naturalistic behavioral or structured developmental methods appear to be an effective way to address the core communication deficits of autism.
For children with autism who do not acquire functional speech or have difficulty processing and comprehending spoken language, augmentative and alternative communication (AAC) and assistive technology (AT) can be useful components of an educational program. There is disagreement about whether to use AAC to train speech and language for young children with autistic spectrum disorders. There is relatively little rigorous, systematic research to elucidate characteristics of children and the components of AAC and AT that may interact to produce effective (or ineffective) intervention. However, available findings are summarized in some detail here to provide a snapshot of this emerging area.
AAC is defined as “an area of clinical practice that attempts to compensate (either temporarily or permanently) for the impairment and disability patterns of individuals with severe expressive communication disorders” (American Speech-Language-Hearing Association, 1989:7). AAC may involve supporting existing speech or developing independent use of a nonspeech symbol system, such as sign language, visual symbols (pictures and words) displayed on communication boards, and voice output devices with synthesized and digitized speech. AT is any commer-