The WHO (World Health Organization) introduced in 1980 a classification of functional limitation in people; the ICIDH (International Classification Impairment, Disability and Handicap). In this classification a difference is made between illness, limitations and handicap.
This reference model was created to facilitate international communication. The model was presented on the one hand to offer a reference framework for policy makers and on the other hand, to offer a reference framework for doctors diagnosing people suffering from the consequences of illness.
Why this reference framework? It arose with the aim of trying to improve and increase the participation of people with long-term limited abilities. Two aims are mentioned:
- the rehabilitation perspective, i.e., the reintegration of people into society, whether this means work, school, household, etc.
- the prevention of illness and where possible the consequences of illness e.g., disability and handicap.
As of January 1st, 1994 the classification is official. The activities that have followed, are widespread and especially concerned with issues such as: information and educational measures for specific groups; regulations for the protection of workers; or, for instance, demands that companies should employ, for example, at least 5 per cent of workers with a disability. The classification itself leads in the long term to integration and non-discrimination.
Illness strikes each of us. Certain illnesses can be prevented, others not. Certain illnesses can be cured, others not. Where possible illness should be prevented and if possible cured.
Impairment means every absence or abnormality of a psychological, physiological or anatomic structure or function.
Being born with three fingers instead of five does not have to lead to disability. The capabilities of the individual, and the degree of manipulation possible with the three fingers, will determine whether or not the person is disabled. When, however, a fair amount of signal processing is not possible on a central level in the brain, then impairment will certainly lead to disability as at present there is no method to “cure” (solve) this problem for the patient.
Disability describes the functional level of an individual having difficulty in task performance e.g., difficulty standing up from their chair. These difficulties are of course related to the impairment, but also to the circumstances surrounding it. A person who uses a wheelchair and lives in a flat country like the Netherlands has more possibilities for self-transportation than the same person living in a mountainous area like Tibet.
When the problems are placed on a handicap level, it can be determined in which field the main problems are effective e.g., immobility or physical dependency. These can affect work performance; for example the person may not be able to get themselves to work; or, once at work, might need assistance in personal hygiene, etc.
A handicap shows the negative consequences of disability and can only be solved by taking the negative consequences away.
Summary and conclusions
The above-mentioned classification and the policies thereof offer a well defined international workable framework. Any discussion on designing for specific groups will need such a framework in order to define our activities and try to implement these thoughts in design.