The intellectual disability construct and its relation to human functioning.

The American Association on Intellectual and Developmental Disabilities’ (AAIDD) Terminology and Classification Committee has two primary purposes in publishing this Perspective: (a) to share our thinking about the construct underlying the term intellectual disability (henceforth the intellectual disability construct) and its relation to human functioning and (b) to ask for input from the field because the committee is preparing a proposal for the upcoming Definition, Classification and Systems of Supports manual, to be published in 2009 or 2010. The article has three sections. In the first section, we make a distinction between an operational definition, which operationalizes the intellectual disability construct and provides the basis for diagnosis and classification, and a constitutive definition, which explains the underlying construct and provides the basis for theory– model development and planning individualized supports. In the second section, we provide an historical overview of how the construct underlying the term mental retardation (henceforth, the mental retardation construct) differs from the construct underlying intellectual disability. In the third section, we describe the parameters to the proposed AAIDD theoretical framework of human functioning that reflects our current understanding of the multidimensionality of human functioning that underlies the intellectual disability construct and the significant role that individualized supports play in human functioning. The article concludes with a brief discussion of the benefits to the field that accrue from a clear understanding of both the differences between an operational and constitutive definition and the fundamental properties of the intellectual disability construct. Operational Versus Constitutive Definitions