A Shift from a Categorical to a Functional Definition.
Initially, the federal definition of developmental disabilities and mental retardation placed the emphasis on the condition or label. This is called a "categorical approach". Thanks in large part to the understandings developed with the principle of normalization, it came to be more widely recognized that categorical labels do not tell much about the person that is useful for support.
Labels, whether medical or cruel, stigmatize and isolate the individual. The change in the federal definition moved the focus away from the label to a concern with specific functional limitations that the individual experiences. This is called the "functional approach".
The 1978 federal definition of developmental disabilities eliminated references to specific disability categories and focused instead on the development of severe functional impairments. Over the years, specific functional areas were identified – self care, language, learning, mobility, self direction, capacity for independent living, and economic self sufficiency.
"Train, Don't Test" for Life in the Real World
In the early 1970s, Marc Gold began to shift the understanding of the capacities of people with severe disabilities. Gold was very much aware of how I.Q. testing, assessments, and school curriculum limited people with disabilities. Such tests, Gold insisted, simply tell you the least a person can do; they can never tell you the most.
Marc Gold's strategy was straightforward – "Train, don't test".
"We who work with the handicapped have a continuing responsibility not to accept labels, and not to accept characteristics that are 'hanging tools' that we can use to make sure that the individual stays functioning at the same level why don't we believe that (people with autism) all have receptive language, and stop telling them, even in an indirect way, all the ways we expect them to behave; stop discussing all the things they do that you or I consider to be 'autistic' I think that diagnosis is useless, and that prediction or prognosis is fatal."
This kind of analysis informed the development of ideas such as school inclusion, facilitated communication, and supported employment.