there are many different developmental programs, a common feature of developmental approaches is that they are child-directed. The environment is arranged to provide opportunities for communication, the child initiates the interaction or teaching episode, and the teacher or communicative partner follows the child’s lead by being responsive to the child’s communicative intentions, and imitating or expanding the child’s behavior. Although the empirical support for developmental approaches is more limited than for behavioral approaches, there are several treatment studies that provide empirical support for language outcomes using specific strategies built on a developmental approach (Lewy and Dawson, 1992; Hwang and Hughes, 2000; Rogers and DiLalla, 1991; Rogers and Lewis, 1989) and many case studies, with Greenspan and Wieder (1997) providing the largest case review. Developmental approaches share many common active ingredients with contemporary naturalistic behavioral approaches and are compatible along most dimensions (Prizant and Wetherby, 1998).
Gains in speech and language outcomes for children with autism have been documented using a variety of behavioral and developmental intervention approaches. Numerous studies have investigated methods of teaching specific receptive and expressive language skills. Most of these studies have used a behavioral method ranging from discrete-trial to naturalistic. Studies have reported good outcomes for teaching specific language content, such as single-word vocabulary, describing objects and pictures, responding to questions, and increasing speech intelligibility (see Goldstein, 1999; Koegel et al., 1998; Krantz et al., 1981). Very positive outcomes have been reported by McGee and colleagues (1999) through natural reinforcers of vocalization, speech shaping, and incidental teaching. They reported that 36 percent of the toddlers studied used verbalizations at program entry with a mean age of 2 years 5 months, and 82 percent were verbalizing meaningful words 1 year later. Most other programs have reported about children entering at 3 years of age or later, and therefore, the impressive treatment outcomes may be related to the young age at entry of treatment.
Research that has documented changes in the communication skills of children with autism falls into three major categories organized by the goal of the intervention: functional communication training to replace challenging behavior, increases in initiation of verbal and nonverbal communication, and increases in the core communication skills.