On the Rate of Progress of the Mentally Defective
- Author:
Drummond, M.D., F.R.C.P. (Edin.), Medical Superintendent,
Baldovan Institution for Feeble-minded Children, by Dundee.
In Mr. Cyril Burt’s valuable?or invaluable?work on “The Distribution and Relations of Educational Abilities,” the following rule is laid down (p. 11):? ‘ ‘The educational progress of ‘ ‘defectives’’ follows an average rate of about half a class (grade or standard) per annum?a rate of progress which is about half that of ordinary elementary school children. With defectives, educational development is not only slower; it also seems to slacken and cease towards the end of the school career. Many doubtless arrive prematurely at the limit of their mental growth.’ ‘ This rule is of practical value as a guide to the regulation of the curriculum of special schools and the average standard of attainment which may fairly be expected in successive classes. However, it should be remembered that the rule is based upon an examination of the children in special schools in London, and is not necessarily applicable to schools where the basis of selection is different. A few pages further on (p. 16) Mr. Burt says: “The educational attainments of a so-called mentally defective child correspond on an average to those of an ordinary child of just over half his age… . We have thus a simple rule for predicting the most probable degree of educational deficiency for any special school child of a given age.”
Thus expressed, the rule seems to me to be somewhat lacking in caution. Perhaps the statement is literally correct (i.e., of London special school children) inasmuch as any child of unknown mentality is more likely to be near the average of his group than to be an extreme deviate, but the reader who is less familiar with averages than Mr. Burt may fail to notice that the generalisation is really inapplicable to individuals especially when the individual belongs to a group in which variations are so numerous and extreme as is the case among defectives. The only safe rule which may be used for predicting the probable educational efficiency (or deficiency) of a given child must be one which is based upon an examination of that child.
Possibly the best foundation we can lay for such prediction is the ascertain- merit of the Intelligence Quotient. Dr. Kuhlmann*, Director of Research at the Minnesota School for the Feeble-minded, writes; “On the whole the I.Q. for a given case remains constant, with a slight tendency on the average to decrease after the ages of about nine or ten. To this general rule there are quite a number of individual exceptions.”
This rule does not quite agree with Mr. Burt’s, even if we assume that edu- cational development and mental development keep pace. Obviously, if a child has an Intelligence Quotient of 0.5 his progress will be at the rate of one year in two, but if his Intelligence Quotient is in the neighbourhood of 0.33 his progress will be only one year in three.
That the I.Q. does remain fairly constant during the developing period is, I believe, true of a considerable proportion of cases, but when intelligence has reached, or is approaching, its maximum development the rule naturally ceases to apply. According to Dr. Ballard, intelligence ceases to develop, in the case of normal children, at or before the age of sixteen. In a large proportion of cases, the maximum development is reached by thirteen years of age. It may safely be assumed that among the mentally defective, the intelligence reaches its maximum development on the average at an earlier age than among normal children. After the age of twelve or thirteen, or sooner, we may expect the rate of mental development to slow down and finally to cease.
Terman lays down the rule that in calculating the I.Q. of any person over the age of 16 years, the denominator is to be taken as 16. For example, if a man of 60 has a mental age of 12 years, his I.Q. is 12-^-16=0.75. A few examples may be given of the constancy of the I.Q. in the case of men- tally defective children. R.D. born 29/6/07. Examined 24/2/17. I.Q. .55 do. do. 30/5/20. I.Q. .5 W.R. born 26/5/05. do. 10/10/17. I.Q. .43. do. do. 13/4/19. I.Q. .41. A.W. born 16/8/06. do. 16/3/16. I.Q. .67. do. do. 15/2/19. I.Q. .64.
As Dr. Kuhlmann states, however, exceptions are numerous. Not only are they numerous; they are at times of great extent and occur in both directions. In the case of children admitted to an institution, it may be found a year or two later that the I.Q. has increased or that it has diminished. W.D., born 22/8/08 had a mental age of VII on 23/11/18, equivalent to an I.Q. of .68. On 20/6/20 his Mental Age was still VII and his I .Q. .59. In this case a boy examined at the age of ten years three months was found nineteen months later to have made no progress in mental development. The result was a little surprising, as the child had improved greatly in his general conduct.
Another boy, W.K., born 27/3/04, had a mental age of VII and an I.Q. of .53 on 28/2/18. Two years and four months later his mental age was slightly over VII (7|) and his I .Q. was .45. His progress was thus at the rate of one year in six. This lad appears to be an instance of the premature arrest of mental development which is common among defectives. His physical development has undergone a similar arrest. Although he is now 17 years of age, his height is that of an average boy of 10 years.
Terman retested a group of children at an interval of two to four years. He found that the average difference in the I.Q. was only 4 per cent, and the greatest difference was only 8 per cent. Quoted by Hollingworth: “The Psychology of Subnormal Children.” Macmillan, 1920. ~ i
A few examples may now be given of an increase in the I.Q. W.C., born 4/2/04. Tested 8/9/16. M.A I.Q. .36. do. do. 25/11/18. M.A. 6+ I.Q. .46. J.C. do. do. do. J.MeG., born 17/4/08. do. do. (W.R., born 23/1/07. do. do. 8/9/16. M.A. 4|. I.Q. .36. 16/5/18. M.A. 6. I.Q. .42. 18/6/16. M.A. 6. I.Q. .73. 1/2/19. M.A. 9f. I.Q. .87. 9/4/17. M.A. 7?. I.Q. .76. 9/6/18. M.A. 9. I.Q. .78.)
It will be noted that the rate of progress in these cases was approximately as follows: The first advanced one year in a little less, and the second in a little more than one year. The third advanced at the rate of one year in six months. The fourth advanced at the rate of one year in a year or slightly less, but although his progress was practically at the normal rate, the period was too short to show any significant increase in his I.Q.
The first two of these cases are twin boys. They were wild, mischievous boys, very open to suggestion, and quite without regard for consequences, who lived a very free life until a house-breaking adventure got them into serious trouble with the police. In the Institution they were very troublesome, un- disciplined lads till Handwork laid its spell upon them, when they became much more amenable to law and order, and might even be found darning stockings in bed instead of plotting mischief for the morrow.
While these two lads belong to the imbecile group the third may be classed as feeble-minded, approximating to the normal standard. He came from a country village where he must have led a somewhat vegetative existence with neither home nor educational advantages. Institution life with all its drawbacks must have provided for him a comparatively stimulating environment. The fourth case is a high grade feeble-minded boy who was admitted as a moral imbecile. In his home surroundings he was well known to the police as an expert boy-thief.
The improvement in the I.Q. of these children was probably greater than the figures indicate. The tests were made with the ordinary Binet-Simon Scale, not with the Stanford revision. It is admitted that some of the earlier tests in the ordinary scale are too easy (i.e., are placed too high on the scale) and that some of the later are too difficult (i.e., are placed too low). The result is that a child whose progress is really normal will show an apparent fall in his I.Q. in suc- cessive testings.
According to Terman, the true border-line case will test approximately as follows: At age 5?I.Q., 90 (apparently nearly normal). At age 9?I.Q., 75 (border-line). At age 14?I.Q., 65 (moral deficiency).
On the other hand, retests by the Stanford revision yield almost identical intelligence quotients. The increased I .Q.’s. in the cases cited above are therefore more significant than appears at first sight.
These cases are few in number, but they are sufficient to show that mentally defective children, after admission to an Institution, may for a time develop as rapidly or even more rapidly than the average normal child. I think the explana- tion is that in such cases the child, in addition to being mentally defective, has also been retarded. A child’s mind does not develop in vacuo, but in response to stimuli, and if the child’s environment does not supply the necessary stimuli the child’s innate capacities will not develop as rapidly nor as fully as they ought to do. The Binet tests have been criticised on the ground that while they claim to test native ability, they imply school knowledge and experience. That is the case with many of the tests; but then the school experience implied is only that which may be taken for granted in the case of practically all children. Binet himself lays down the rule that if a child is retarded by several years we may be justified in suspecting mental deficiency, but we must not make our diagnosis until we have eliminated other possible causes of retardation.
Now if a child of normal intellectual endowment may be retarded in his development, the same may?indeed must?be true of the mentally defective. The defective child is less capable than the normal child of seeking, of finding, of creating those stimuli which are necessary for his own development. The defec- tive baby requires to be taught most of the things which every normal baby teaches himself. Consequently, if he is neglected, if he is not played with, talked to, encouraged and encouraged to do every little thing for himself, he will suffer not merely from the innate weakness of his mental powers, but from the retardation consequent upon these powers not being developed even to the limited extent of which they are capable.
From what I have seen of the Montessori method both in ordinary nursery schools and in our own school for defective children, I think the part of the directress should be decidedly more active in the latter than in the former. I also think that in the case of mentally defective children, the Montessori environ- ment requires to be supplemented in various ways.
Doubtless institution life itself requires supplementing in the case of certain children. I believe that the very environment which has proved stimulating at a certain stage of development, may be found lacking at a later stage. Indeed it may even have a deadening effect, e.g., by failing to provide sufficient variety and sufficient scope and encouragement for initiative. Perhaps the case of J. McG. cited above may be an example of this, for this boy has advanced at a much slower rate since 1919 than he did between 1916 and 1919.
The conclusion we have reached, then, is that the safest forecast we can make of the future progress of a mentally defective child is based upon his intelligence quotient . This should be ascertained by means of the Stanford revision of the Binet scale, though it has not yet been proved that the Stanford tests are as suitable for British as they are for American children. Other tests, such as the Porteus maze tests, also help us to arrive at a reliable forecast.
When we have ascertained the I.Q. we have still to take into account the past history, and the present condition of the child. If the child has had less than the usual advantages, we may hope that a low I.Q. may be in part the indication of a simple retardation which will become less when the pupil is placed in a suitable environment and in charge of experienced teachers. For example, the one-room child about whom Sir Leslie McKenzie has written so eloquently is almost certain to be mentally retarded to a greater degree than should be attri- buted to innate deficiency, especially if he is an only child whose father is out all day, and whose mother is the type of woman who never speaks when she can avoid it. “Let your words be counted” may be a good rule for the Montessori school when the children are busy, but it is a bad rule for the home, where the child has to learn his mother tongue.
Again the health and vigour of the child, the acuity of his senses, his interest and his capacity for attention are all elements which need to be taken into account in our prognosis. If our one-room child is anaemic and rachitic, if he is languid and irresponsive, an improved environment will do little for his mental develop- ment till his health has improved.
Sometimes in the course of an examination one may come to the conclusion that other factors are of greater importance in the case than the intelligence quotient as ordinarily ascertained. Recently I examined a boy of nearly eleven years of age, and found him to have a mental age of 4|, and an I .Q. of (apparently) 4. But the examination revealed the phenomenon of scattering in a marked degree. Thus he failed in tests involving school knowledge, though he had attended school. He also failed in tests which involve the use of language. He did not reply to the question “are you a little boy or a little girl?” He could not repeat a sentence of ten syllables. He could not name colours. Yet his practical abilities were evidently good. When told to count thirteen pennies he immediately gathered them up in his hand, then laid them down one by one counting correctly as he did so. He not only drew the square and the diamond very well indeed, but he secured a pass in the ten-year test of reproducing two diagrams from memory. These results were easily accounted for by the obvious fact that the boy was hard of hearing?deaf enough to be unable to pick up inciden- tal instruction in school. Accordingly I asked the headmaster of a school for the deaf and dumb to examine him, and he agreed with me that the boy should have the opportunity of being educated by methods suited for deaf mutes.
There must be defective children whose deafness is less apparent than in this case, yet is sufficient to cause a certain amount of retardation. The lesson of the case, therefore, is that we should pay attention to the acuity of the senses in each case we have to deal with, and perhaps that all children who are admitted to a special school at a sufficiently early age should receive a greater amount of systematic sense training than is always provided for.
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