By Matt Harrington, BCBA · Behaviorist Book Club · Research-backed answers for behavior analysts
The 1987 study published by Ivar Lovaas reported the outcomes of young children with autism who received intensive behavioral treatment through the UCLA Young Autism Project. The high-intensity treatment group, which received 40 or more hours per week of behavioral intervention, showed substantially better outcomes than comparison groups, with approximately 47% achieving outcomes described as indistinguishable from typically developing peers. This finding was considered significant because it provided evidence that intensive behavioral intervention could produce substantial developmental gains for children with autism — a claim that was highly controversial at the time and transformative for the field of ABA and for autism policy.
The Lovaas model, as implemented in the UCLA Young Autism Project, is an intensive early behavioral intervention approach characterized by high treatment intensity (40 or more hours per week), systematic use of discrete trial training to teach foundational skills, a developmental skill sequence progressing from basic attending and imitation through language and social skills, a strong parent involvement and training component, and one-on-one delivery in the child's home and later in school settings. Contemporary ABA programs have evolved from this foundation, incorporating more naturalistic teaching approaches, greater emphasis on child choice and motivation, and goals that emphasize meaningful social participation alongside or above normalization.
Common myths include the claim that the Lovaas model was primarily based on aversive procedures — in fact, positive reinforcement was the primary therapeutic mechanism, though aversives were used in some cases, a practice that the field has since moved away from. Another myth is that the 1987 outcomes are reliably reproducible for any child who receives 40 hours per week of ABA — in fact, outcomes are highly variable and the study's design limits the certainty with which its findings can be generalized. A third myth is that the Lovaas model is identical to all ABA for autism — in fact, it was a specific program developed in a specific context, and contemporary ABA practice has evolved substantially.
Dr. Ronald Leaf is a behavioral psychologist who was a central figure in the UCLA Young Autism Project, working directly with Ivar Lovaas during the development and implementation of the intensive behavioral treatment program. He is a co-founder of the Autism Partnership Foundation, which has continued to develop and disseminate evidence-based behavioral intervention for autism. Dr. Leaf's first-person account of the UCLA project, as featured in this course, provides historical context and clinical perspective that distinguishes the actual practices and intentions of the project from the myths and simplifications that have accumulated around it.
Contemporary ABA intervention for autism has evolved substantially from the primarily DTT-based intensive model of the UCLA project. Current best practices generally involve a blend of structured discrete trial instruction and naturalistic environment teaching, greater emphasis on child motivation and choice in the instructional process, more explicitly social and communicative intervention goals, stronger integration with family routines and natural environments, increased collaboration with speech-language pathology and occupational therapy, and a growing engagement with autistic perspectives on the goals and procedures of intervention. The move away from aversive procedures and toward positive, evidence-based approaches is the most ethically significant evolution.
The research generally supports intensive early intervention as more effective than lower-intensity approaches for many young children with ASD, consistent with the original Lovaas findings. However, the evidence on optimal intensity is more complex than a simple dose-response relationship. The quality of intervention hours matters as much or more than the quantity; the optimal balance of structured and naturalistic teaching varies by child; the involvement of family members in implementing intervention is a strong predictor of outcomes; and the age at which intervention begins, the child's initial skill level, and the specific goals of intervention all influence the relationship between intensity and outcomes.
BCBAs should communicate about expected outcomes honestly, accurately, and individualistically. This means sharing what the research shows about the range of outcomes for children with similar presentations while being explicit about the uncertainty in predicting outcomes for any specific child. It means explaining that intensive ABA can produce substantial gains and that outcomes vary significantly across children. It means not promising outcomes indistinguishable from typical development as a standard expectation, even though this outcome has been achieved by some children. And it means prioritizing goals that are meaningful to the family and child over goals that primarily satisfy normalization criteria.
The neurodiversity perspective questions whether the primary goal of early intensive behavioral intervention should be to produce outcomes indistinguishable from typical development, arguing that this goal frames autism as a defect to be corrected rather than a form of human neurological variation. Neurodiversity advocates have also raised concerns about interventions that prioritize behavioral compliance, suppress autistic social behaviors like stimming, or require children to mask their natural behavioral repertoire to appear neurotypical. BCBAs engaging with this perspective should consider whether the specific goals of an intervention program genuinely serve the individual's wellbeing and expressed interests or primarily serve others' expectations.
Parent involvement was a central and substantive component of the original UCLA Young Autism Project, not a peripheral add-on to clinic-based services. Parents received extensive behavioral training and were expected to implement intervention in the home throughout the child's waking hours, not only during formal therapy sessions. This intensive parent involvement is considered one of the key features of the model that contributed to its outcomes, and subsequent research has consistently identified parent-implemented behavioral intervention as one of the strongest predictors of positive outcomes in early intensive programs. Contemporary programs that minimize parent involvement may be departing from one of the model's most clinically significant elements.
Engaging honestly with the history of the Lovaas model teaches contemporary BCBAs several important lessons: that the field's most influential findings are surrounded by myths and simplifications that obscure instructive historical complexity; that the evolution of ABA practice has been driven by both accumulating evidence and evolving ethical standards, both of which should continue to shape the field; that first-person accounts from practitioners who were present offer qualitatively different and complementary knowledge to published research; and that the foundation of evidence for intensive early behavioral intervention, while complex, remains strong and provides a basis for confident, appropriately humble clinical practice.
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Ronald Leaf, Ph.D | The Lovaas Model: Love It, Hate It, But At Least Understand It | 1 Hour — Autism Partnership Foundation · 1 BACB General CEUs · $0
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All behavior-analytic intervention is individualized. The information on this page is for educational purposes and does not constitute clinical advice. Treatment decisions should be informed by the best available published research, individualized assessment, and obtained with the informed consent of the client or their legal guardian. Behavior analysts are responsible for practicing within the boundaries of their competence and adhering to the BACB Ethics Code for Behavior Analysts.