Disability as a Difference Between Performance and Demands ​

Formally, any disability can be seen as a difference between the performance possible for a given person and the demands placed on that person by the environment and the society. If the performance is equal to or greater than the demands made, then the person can fulfill a particular function, task, or social role. However, if the difference between the performance and the requirement is negative, then the person fails in the task.

If these are tasks that are considered “normally achievable” by the masses, then the person experiences disability. In Figure 1, this relationship is shown graphically. The person shown on the left, with the size of $5$ units (where here body size is to be considered representative of any physical or mental ability of a person), meets the requirements of the environment. One can look across a wall, which is also $5$ units high, without any problems.

The person shown on the right can only perform to the extent of $3$ units (represented by a body height of $3$ units) and must therefore fail against a “normal height” wall of $5$ units.

The symbol of the wall was deliberately chosen to introduce the generalized term of “barrier”. It should be made clear that a barrier is any obstacle (usually in a figurative sense) that leads to the exclusion of a disabled person or, to be more precise, that makes a person with reduced capacity a disabled person in the first place.

Attribution/Citation ​

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Attribution ​

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Citation ​

Use the following information to cite this book.

• Author: Dr. Wolfgang L. Zagler
• Title: Rehabilitationstechnik
• Date: March 1, 2008
• Location: Vienna, Austria
• Book URL:
• Chapter URL:

List of Figures ​

• Figure 1: Disability is experienced when one's own performance is less than the task set by the environment or society [1].

List of Sources ​

• [1]: Rehabilitationstechnik (Wolfgang L. Zagler - CC-NC-SA 4.0)