The Use and Abuse of Mental Tests
- Author:
Carleton Williams, M.R.C.S., L.R.C.P., D.P.H.
Eminent authorities are quoted as saying that mental tests are unnecessary with low grade defectives and of little value with high grade cases, and also that the opinion of an expert after a few minutes’ observation and conversa- tion is of greater value than the records of a series of tests conducted by a tyro who judges by results only.
These statements contain a profound truth, but taken apart from their context, they are sometimes misinterpreted as meaning that mental tests are almost useless.
The first dictum might be compared with the analogy of the stethoscope. It is perfectly true that sometimes the ravages of tubercular disease are so ob- vious that no instrument is needed to detect them, while in very early cases, stethoscopic examination may yield no evidence, though bacteriological methods may make the diagnosis unmistakable. Moreover, there are occasions when the stethoscope reveals nothing definitely abnormal while general obser- vation shows that the patient is seriously ill, and in fact these are only too often the cases where the progress of the disease is particularly disastrous.
In spite of all this, no one would discard the stethoscope in dealing with diseases of the chest; and similarly no one should neglect mental tests in dealing with defectives.
It is often urged that the all important matter in mental deficiency is the conduct. A man needs to be dealt with not because he cannot count back from 20 to i, but because he is inefficient socially. This statement again is true in itself, but unless the certifying officer has the misfortune to be an employer or close relative of the alleged defective, he can seldom see much of the conduct for himself, and most of the evidence as to behaviour must be second-hand and sometimes little better than hearsay.
Social inefficiency is the important manifestation of defect. For definite proof that it is due to intrinsic mental deficiency, it is necessary to employ scientific methods of first-hand mental observation. Without them there have been such absurdities committed as the diagnosis of a girl as mentally defective because her conduct was reported to be grossly immoral, and on examination she was found to have a mis-shapen ear.
Experience has shown the value of serial mental tests. The mental ages are only part of the information obtainable, but even they have been proved by Goddard and others to have a remarkably close correlation to practical cap- acity, and this has been shown also by Tylor Fox at Lingfield even with patients whose efficiency is complicated by epilepsy. (British Journal of Psychology, T924-) In the great majority of ordinary cases, the use of mental tests is essential for the recognition of defect. In the low grade cases in which the defect can be recognised without them, they are of great value both for classification and for the selection of appropriate training.
The term ” imbecile ” may be used by two medical men of high stand- ing with extremely different connotations, whereas if to the designation is added the statement that the defective has a mental age of 5, the description is more exact and of much greater practical value. This was, in fact, one of the reasons which originally led Binet to devise his series of tests.
For the higher grades, some of the tests and especially those depending on academic attainments, may be less appropriate, but those that measure plan- ning, foresight and power of self-criticism are essential aids to a correct diagnosis.
Then again, for all grades, when certification is undertaken, the examiner must cite facts observed by himself, not only because the law insists upon it, but also because to depend on the statements of others which may be biassed or gravely inaccurate, would be ethically wrong. How unreliable such evidence can be is amazing, and is only known to those who have frequently experienced the perversions of parents and others anxious to get rid of a child that is for some reason a discredit to them.
The objector may admit that definite criteria are needed for accurate diagnosis, classification and certification, but still doubt whether an exper- ienced doctor needs to use these monotonous standardised problems and ques- tions. To this objection the answer is two-fold : ?first that it is extraordinarily difficult to know at what level a new test is appropriate and how far the stan- dards are constant: for example, the age at which non-defectives learn to tell the time may vary by 5 years or more?and secondly, that it is particularly the experienced worker who by the repeated application of the same tests, learns the most from the nature of the responses given to them.
THE ABUSE OF TESTS
If then mental tests are so reliable, why are they not all sufficient and why need they be carried out by specialist medical men themselves? It is known that for comparisons between various groups of normal children, accuracy has been obtained by relatively untrained workers, provided that they adhere strictly to the rules and conditions laid down for their guidance. It is thought sometimes that it would be satisfactory for testing to be carried out by ” field workers ” and then for the records to be submitted to an expert who could base his diagnosis upon them. It is a little unfortunate that, as yet, the selec- tion and application of tests for the diagnosis of mental deficiency has not been more distinguished from their use for measuring the intelligence of normal children. Yet these two functions ought to receive separate consideration. Burt (Mental and Scholastic Tests) has some valuable notes, which have not received the attention they merit, on the tests that are particularly diag- nostic of mental defect. His comparisons are based on the differences observed in the results when the tests are applied to ordinary schools and to special (M.D.) schools respectively.
The differences cited were found in those whose mental defect showed itself in lack of capacity for education, rather than social inefficiency. In my own work I have learnt to attach special importance to questions calling for reasoning power, and to problems of a non-verbal type, such as the 5 weights, the Healy A and the ball and field; and to consider as less significant for diag- nosis, some tests such as the rote repetition of digits, the reproduction of designs and the description of pictures; though these tests have their own uses. Then again, the method of applying the tests should be modified. For exact comparisons of normal children it is essential to adhere rigidly to the conditions laid down, including the time limits. In the diagnosis of mental defect however, though these rules mav be maintained for the purpose of estim- atlng the mental age, vet much additional knowledge is obtained by the sub- Sequent introduction of modifications. For example, if a child of ten counts *3 objects by rote successfully, but fails to count out 13 objects from a heap, Particularly if it goes on counting, 13, 14?till the heap is exhausted, its action ls specially suggestive of mental defect.
Similarly, a parrot-like repetition of the months may be accomplished by a feeble-minded child but he has much more difficulty in giving the checks, i.e., the month before August and so on. The qualitative differences between the mentality of the normal and the defective, though not easy to define, are very real and important; to ignore them and to use mental ages like a yard measure or the bed of Procrustes is ridiculous.
American Psychologists at one time suggested that all persons with a mental age of less than 12 were probably morons, that is, high grade defectives, but the investigation of the intelligence of recruits for the United States Army showed that something like one-third of the adult male population of America would, under such an assumption, be held to be defective.
Again, in a large proportion of the cases in which mental inefficiency is suggested, there are complicating factors which make a mechanical type of measurement entirely fallacious. For the deaf it is necessary to employ a special series of tests, the non-verbal type (see Mental Welfare, October, 1926). With the blind, many tests are obviously inapplicable and others need careful mod- ification; while with those suffering from cerebral paralvses, not only must some allowances be made, but also a broad view must be taken involving the application of medical knowledge and special experience. For example, a diplegic child may have a superficial brightness and a fair mental age but show strain and fatigue during the examination, indicating that mental effort can- not be maintained for lone, and that his real capacity for education, training or emolovment is very slight. With severe neuroses or early psychoses, the inapplicability of hard and fast methods is evident; a broad judgment founded on a knowledge of nervous and mental abnormalities is vital.
Malingerers may purposely simulate an inferiority of intelligence which, if accented as real, may lead to unfortunate results. For example, a delinquent trying to escane punishment maintained such an attitude of stupidity that he was actually sent to an institution for defectives. But when he found that he had exchano-ed the orospect of a few weeks in prison for a more lasting loss of libertv. he demanded an interview with the medical officer in charge and told him the correct answers to all the questions which he had previously pretended to be unable to answer. By good fortune this incident did not befall the present writer, but it might happen to any one not on the alert for it. The tests themselves suggest means for its detection, since the fraudulent examinee, not knowing the standards, would fail to solve some easy problems while suc- ceeding with others of much greater difficulty.
In the so-called ” conduct ” cases particularly, the mental age is very far from an absolute criterion. On this basis alone it is not safe to certify those reaching the 9 year old level, but with an absolutely reliable record of in- efficiency confirmed by the subject’s own story and the insight afforded into his mental outlook, it is quite common to find certification justified at higher levels. When, however, there appears to be good general intelligence as shown by tests, coupled with alleged unreasonable conduct, the whole case must be considered with particular care. It may be that the intelligence is rather superficial and that the real deficiency will be revealed only by those tests that estimate qualities such as lack of judgment and foresight. Or on the other hand, it may be that the report of conduct is misleading and the behaviour explicable on other grounds than mental deficiency. An expert examiner who was asked how he could assert that a boy who showed a wild and ” irrational ” dislike of his father, was not mentally defective, answered that he had the advantage of knowing both the boy and the father.
To sum up, it may be said that mental tests form an invaluable means of the direct ascertainment of mental capacity but they must be used with judg- ment; the nature of the responses as well as the results should be observed and interpreted by those who possess sound medical and psychological knowledge, and the findings must be co-ordinated with every other kind of evidence that is available.
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