Developmental trajectories of young children with autism enrolled in an Intensive Behaviour Intervention Program: What the ABLLS can tell us about their progress

There is an abundance of empirical support for Intensive Behavioural Intervention (IBI) for children with autism. However, intervention studies in autism typically employ a pre-post design with standardized measures of cognitive and adaptive functioning. This type of design often assumes linearity in skill acquisition from intake to discharge, and it is limited to capturing only the broad domains of development covered by standardized measures on a group basis. As a result, the trajectory of skill development for individual children with autism receiving IBI is still unclear.;A three-part study was designed to examine these questions. The first study explores developmental trajectories on the ABLLS for 14 typically developing children between the ages of 5 and 56 months of age. The second study explores inter-rater reliability of the ABLLS among a sample of 5 preschool children with autism, and convergent validity with standardized measures for 83 children (68 with autism and 14 typically developing). Finally, the third part of this study uses the ABLLS, in conjunction with standardized measures of cognitive and adaptive functioning, to explore the developmental trajectories of75 children with autism enrolled in a publicly funded IBI program. Overall, the results indicate that the ABLLS is a valid and reliable tool for detecting changes in development, but the sensitivity of this tool varies by age and skill area. The results highlight predictors of response to IBI, as well as different groups of responders.;One way to clarify the nature of skill acquisition among these children is to use a measure that captures discrete skill development at multiple time points while enrolled in treatment. One such tool, The Assessment of Basic Language and Learning Skills (ABLLS; Partington & Sundberg, 1998) is a detailed language/learning curriculum and assessment tool. It is widely used among educators of children with autism and can be a useful supplement to standardized assessment tools by providing a more fine-grained analysis of skill acquisition. However, the ABLLS has not been standardized on typical children and appropriate psychometric properties, such as reliability and validity, have not been established.