Intellectual disability is the currently preferred term for the disability historically referred to as mental retardation. Although the preferred name is intellectual disability, the authoritative definition and assumptions put forth by the American Association on Intellectual and Developmental Disabilities (AAIDD) remain the same as those found in the Mental Retardation: Definition, Classification and Systems of Supports manual (Luckasson et al., 2002).
The term intellectual disability covers the same population of individuals who were diagnosed previously with mental retardation in number, kind, level, type, and duration of the disability and the need of people with this disability for individualized services and supports.
Intellectual disability is diagnosed by looking at two main things. These are:
- the ability of a person's brain to learn, think, solve problems, and make sense of the world (called IQ or intellectual functioning); and
- whether the person has the skills he or she needs to live independently (called adaptive behavior, or adaptive functioning).
Intellectual functioning, or IQ, is usually measured by a test called an IQ test. The average score is 100. People scoring below 70 to 75 are thought to have an intellectual disability. To measure adaptive behavior, professionals look at what a child can do in comparison to other children of his or her age. Certain skills are important to adaptive behavior. These are:
- daily living skills, such as getting dressed, going to the bathroom, and feeding one's self;
- communication skills, such as understanding what is said and being able to answer;
- social skills with peers, family members, adults, and others.
To diagnose an intellectual disability, professionals look at the person's mental abilities (IQ) and his or her adaptive skills. Both of these are highlighted in the definition provided in the Individuals with Disabilities Education Act (IDEA). The IDEA is the federal law that guides how schools provide early intervention and special education and related services to children with disabilities.
IDEA's Definition of "Mental Retardation"
Our nation's special education law, the IDEA, defines mental retardation as . . .
". . . significantly subaverage general intellectual functioning, existing concurrently with deficits in adaptive behavior and manifested during the developmental period, that adversely affects a child's educational performance." [34 Code of Federal Regulations §300.8(c)(6)]
Providing services to help individuals with an intellectual disability has led to a new understanding of the disability. After the initial diagnosis of intellectual disability is made, we look at a person's strengths and weaknesses. We also look at how much support or help the person needs to get along at home, in school, and in the community. This approach gives a realistic picture of each individual. It also recognizes that the "picture" can change. As the person grows and learns, his or her ability to get along in the world grows as well.