conclusion, that it is more efficacious to aim intervention at key autistic spectrum disorders deficits that will yield broad changes in collateral behaviors than to address individual behaviors in an isolated fashion (Koegel et al., 1999a).
The approach of the Developmental Intervention Model is based upon the assumption that a child’s symptoms reflect unique biologically based processing difficulties that may involve affect, sensory modulation and processing, motor planing, and symbol formation (Greenspan and Wieder, 1997). Relationships and affective interactions may go awry secondarily, and intervention is aimed at helping a child try to work around the processing difficulties to reestablish affective contact.
By far, the bulk of autistic spectrum disorders intervention research has been conducted from the perspective of applied behavior analysis. An exhaustive review of 19,000 published journal articles revealed that there were 500 papers on applied behavior analysis and autistic spectrum disorders, and 90 of these were studies using single-subject designs to evaluate specific interventions for young children with autistic spectrum disorders (Palmieri et al., 1998). Rather than being tied to specific procedures, applied behavior analysis includes any method that changes behavior in systematic and measurable ways (Sulzer-Azaroff and Mayer, 1991). Historically, the behavioral approaches emphasized acquisition of discrete skills, and interventions were evaluated in terms of whether they produced observable and socially significant changes in children’s behavior (Baer et al., 1968).
Traditional behavioral interventions impose structure in the form of distraction-free environments and presentation of opportunities-to-respond in discrete trials, and appropriate behavior is rewarded when it occurs. Technically sophisticated discrimination training procedures have been derived from years of research in applied behavior analysis. Lovaas’ Young Autism Project, Harris and Handleman’s Douglass Center, and Romanczyk’s Children’s Unit represent classic behavioral interventions, although all now use more naturalistic interventions as children’s basic skills improve.
In an effort to improve the generalization of skills from teaching settings to daily use in the real world, comprehensive behavioral interventions have modified traditional applied behavior analysis techniques in a way that permits instruction in natural environments. The LEAP model was the first to recognize the importance of direct instruction in peer-related social behaviors, and that more natural instructional settings were required to accommodate the presence of typically developing classmates (Strain and Hoyson, 2000; Strain et al., 1985). Walden’s incidental teach-