WHAT IS FUNCTION? HOW CAN IT BE MAINTAINED?
Mary C. Howell
The word function is derived from an Old French word that means "to perform." We use it to denote a human ability or capability--a process that is defined by the effect it causes. This means that we determine the presence of a function by looking for its effect: the function of the sense of sight allows vision, the function of the immune system overcomes infection, the function of eating with utensils results in food being consumed in a certain way, and the function of manual dexterity permits a variety of instrumental activities such as dialing a telephone. Because of this assessment of demonstrable effect, the measurement of function differs from other kinds of measurement (like tests for IQ) in which conclusions are often drawn that go far beyond what is actually observed. The measurement of function is usually direct, simple, and commonsensical.
There is an interesting history to the emphasis on function. Initially, this sort of measurement was proposed in relation to the needs of those who were injured--at the workplace or in war--and who needed assistance, especially in the form of compensation. It was clearly more useful to know that the injured person could not walk, than to know just that there had been a spinal cord injury. The diagnosis told what had happened to or inside the body; the functional assessment told what the whole person could and could not do.
From these beginnings, functional assessment has moved in two directions that are important for those who are both old and mentally retarded. The first direction is a focus on rehabilitation, bringing back lost functions. Assessment in this instance is aimed at specifying all functions (relevant to the discipline or disciplines available for rehabilitation services) that are now impaired or absent, and for which specific services are needed.