As mentioned, intellectual disabilities (ID, formerly mental retardation) have two key diagnostic criteria. These are intellectual functioning (IQ) and adaptive functioning. Tests of adaptive functioning evaluate the social and emotional maturity of a child, relative to his or her peers. They also help to evaluate life skills and abilities. Commonly used tests of adaptive functioning are described below:
Woodcock-Johnson Scales of Independent Behavior: This test measures independent behavior in children.
Vineland Adaptive Behavior Scale (VABS): This test measures the social skills of people from birth to 19 years of age. This test is not administered directly to the child. Instead, questions are directed to primary caregivers and other people familiar with the child. The test contains four sections. These are communication; daily living skills; socialization; and motor skills. This test is also used for children with behavioral disorders, and physical handicaps.
The Diagnostic Adaptive Behavior Scale (AAIDD, 2013): This test measures adaptive behavioral skills. There are three main categories of these skills. This includes conceptual, social, and practical life skills. This test is very helpful for determining the intensity and types of supports needed to maximize independent functioning and quality of life. However, a more useful and appropriate test for that purpose is the Supports Intensity Scale (AAIDD, 2004).
Tests of IQ and adaptive functioning form the basis for making a diagnosis of intellectual disability. Other tests (e.g., neuropsychological tests) may provide further detail. However, these additional tests are not needed for diagnosis. All relevant information into account before a diagnosis is made. This includes interviews, observations, and medical history. Diagnosticians have some discretion. The test scores are weighted heavily. However, test scores are not the sole basis for diagnosis. For instance, some children appear to be smarter or higher functioning than the testing indicates. These observations are also taken into account along with all the other data. The diagnostician then compares all the data to the diagnostic criteria for intellectual disabilities. These diagnostic criteria are discussed in the next section.