Early intensive behavioral intervention (EIBI) has been shown to effectively remediate some cases of autism. However, few studies have evaluated the importance of various factors, such as the effect of treatment intensity on treatment outcomes, and how these outcomes vary by age.

The objective of this study was to evaluate the relationship of treatment hours and participant age with the rate of learning within an early intensive behavioral intervention program. The present study evaluated treatment progress for 245 children receiving EIBI services. Regression analyses were conducted to predict treatment progress based upon the number of monthly treatment hours received and the participant’s age. Each of these variables were significant predictors and accounted for considerable portions of the observed variance. Further, the younger participants showed a greater benefit from increased treatment hours when compared to older participants.

These data indicate that for children between 2 and 7 years of age, there was a significant increase in new skill acquisition with increased treatment hours. Further, there was not a point of diminishing-returns.