DIFFICULTY IN DIAGNOSIS
It is deemed necessary before any classification for mental retardation, that he should be evaluated by a team of qualified professionals — including representatives from the social, educational, psychological and medical disciplines. Also, the assessment requires that parents or relatives have been involved in the evaluation process as significant observers, and the person's adaptive behavior has been assessed in relation to his community and family situation, taking into account the cultural norms of his environment.
As indicated above, the diagnosis of mental retardation is made on the basis of two dimensions:
- Measured Intelligence;
- Adaptive Behavior.
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| IQ = Age(Mental)/Age (Actual) x 100 |
1. Measured Intelligence
Intelligence test, of this type are used to sample a wide range of knowledge and skills in order to compare a person's test performance to a standard established for his age level. A person exhibiting knowledge and skills similar to the standard for his age group is considered average. Below and above average performance, therefore, means that a person's test performance is comparable to persons either younger or older than himself.
The most frequently used are the Stanford-Binet Intelligence Scale, the Wechsler Intelligence Scale for Children, and the Wechsler Adult Intelligence Scale. The Stanford-Binet measures a wide range of abilities corresponding to various mental ages, while the Wechsler Scales for Children and Adults are separated into specific skill areas with performance compared to the average abilities of persons at different chronological ages.
Persons attaining IQ's significantly below 100, (100 is considered to be average),are usually classified according to levels of mental retardation as follows:
| Standardized Intelligence Test |
Level of Retardation | Stanford-Binet | Wechsler |
Mild | 52-67 | 55-69 |
Moderate | 36-51 | 40-54 |
Sever | 20-35 | 25-39 |
Profound | Below 20 | Below 25 |
The classification of "borderline mental retardation" is also frequently employed (IQ's of 68-83 and 70-84 on the Stanford-Binet and Wechsler Scales, respectively).
It is important to note that, Basic to the use of intelligence tests is the assumption that the person taking the test has had similar opportunities to learn and shares a common language and culture with those persons on whom the test was standardized.
The classification of mental retardation should be applied only to those persons who, after a comprehensive and appropriate evaluation, continue to function at a significantly subaverage level — even after various attempts at remediation have been made.
2. Adaptive Behavior
The second criterion used in diagnosis of mental retardation is adaptive behavior, Heber (1959) defines adaptive behavior as follows:
"The dimension of adaptive behavior refers primarily to the effectiveness with which the individual copes with the naturaland social demands of his environment. It has two major facets: (1) the degree to which the individual is able to function and maintain himself independently, and (2) the degree to which he meets satisfactorily the culturally-imposed demands of personal and social responsibility"
Thus, maturation would be emphasized during early childhood years in which such skills as sitting, standing, walking, self-feeding, toileting and speech are ordinarily developed. Academic performance would be stressed during school age years, while vocational and social effectiveness would be appropriate topics for adults.
A positive correlation should exist between measured intelligence and adaptive behavior. That is, an individual who ranks relatively high in one dimension would be expected to rank high in the other area as well. Marked discrepancies between measured intelligence and adaptive behavior (e.g., an intelligence quotient within normal limits coupled with a subaverage adaptive behavioral level, and vice versa) would cast serious doubt upon the diagnosis of mental retardation.
Eternal Child
In the diagnostic or evaluative process, there is a danger of approaching the mentally retarded person as an "eternal child". Diagnostic conclusions such as, "This child will always have the mind of a five year old", are overly common. Obviously, this approach places unnecessary limitations on the development of the retarded person — no one "expects" them to progress beyond the dependent stage of childhood. The retarded individual, then, may be treated as a child even during his adult years, preventing development of the independence associated with adult maturity.
It must be remembered that a retarded person's "mental age"does not necessarily reflect his social interests and needs. Thus, while the performance of a mildly retarded adolescent on a standardized intelligence test may approximate that of a non-retarded ten year old, it is likely that his social interests will be similar to those of non-retarded persons in his own chronological age group.
