Available information is reviewed on defining features and diagnostic issues related to autism and related developmental disorders. Controversies over both the boundaries and the heterogeneity within the autism syndrome are evaluated. Diagnostic rating instruments for expediting systematic sample selection are critiqued. (Author/DB)

A cluster analytic study was conducted to derive behaviorally homogeneous subtypes of pervasive developmental disorders (PDD) based on a range of behavioral symptoms that characterize autism. Analysis of data on 34 children with PDD, 27 of whom met criteria for autism, indicated 4 distinct groups differing on independent measures of social,…

Evaluation of 26 children (ages 24-55 months) with pervasive developmental disorder (PDD) while interacting with either the mother, a familiar female teacher, and an unfamiliar male doctor. PDD subjects were most severely impaired during the mother episode. During the teacher episode, PDD subjects were twice as variable in interpersonal response…