Adaptive Functioning

History

Adaptive behavior or adaptive functioning is most often considered when assessing whether an individual meets criteria for an intellectual disability and for the level of severity specified within the diagnosis. Adaptive behavior is not a new concept. As early as the Renaissance period, laws and language defined mental retardation in terms of an individual’s ability to take care of himself. However, with the development of intelligence tests in the early 1900s, diagnosis of mental retardation shifted solely to reliance on low IQ scores for many decades.

In the 1930s, Edgar Doll, who is considered the father of adaptive behavior assessment, openly criticized the use of IQ alone to justify diagnosis and proposed that one’s social competence and independent skills were as important, if not more important, than IQ alone. In 1961, Rick Heber revised the American Association of Mental Deficiency (AAMD)’s definition of intellectual disability to include adaptive behavior, using the terms maturation, learning, and social adjustment.

The Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), published in 2013, specifies in its criteria for a diagnosis of intellectual disability that, in addition to deficits in intellectual functioning, there also must be deficits in adaptive functioning in one or more areas, such as communication and social participation, across multiple types of settings. In 2002, the American Association of Mental Retardation (now the American Association on Intellectual and Developmental Disabilities [AAIDD]) identified the three domains that constitute adaptive behavior as conceptual, social, and practical. These remain in the DSM-5 to define severity levels for intellectual [Page 28]disability, as it is an individual’s level of adaptive functioning that determines the level of supports that she requires.

It should be noted that assessment of adaptive behavior is required for regulatory agencies considering classification of intellectual disabilities for purposes of school services, Social Security, and Medicaid requirements. However, the concept and use of adaptive behavior is certainly not limited to understanding and defining intellectual disabilities. In fact, it is becoming more and more common for psychologists, social workers, school teams, and medical professionals to use measurement of adaptive behavior to inform supports and services.

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