The Definition and Diagnosis of Mental Deficiency
Part II. I / :Auhtor: Cyril Burt, M.A., Psychologist to the London County Council.
DIAGNOSIS OF TEMPERAMENTAL DEFICIENCY. —————————————-Suspected deficiency of temperament, which provides by far the more perplexing problems, we may perhaps consider first. It is here that the psychographic scheme need’s to be followed with great thoroughness and to be filled in with greatest detail. With these cases the question as to degree of deficiency resolves itself into two issues: how unstable is the patient, and what amount of instability is necessary to form a ground for his certification? If, with some authorities, we restrict mental defect to defect of intelligence alone, then it might seem that the criterion for temperamental or moral defect was given in the statutory clause relating to the moral imbecile. The instability, it may foe urged, is certifiable as deficiency when it is so extreme as to issue in incorrigible vice or crime. But, unfortunately for this interpretation, icious and criminal propensities, however violent and refractory they may be, form, according to the statute, no ground for certification, unless coupled with signs of early and permanent defect. Hence, if mental defect implies inadequacy of intelligence alone, the diagnosis after all will turn upon the question. is the patient s intellectual inadequacy sufficientlv profound to be characterised as deficiency* If, however, as I have urged, the term mental defect be extended to cover deficiencies of temperament, as well as of intelligence, then temperamental instability is not to be identified merely with moral imbecility : it falls also under the definition of feeblemindedness. To be certifiable, such instability need not of necessity include vicious or criminal behaviour. It need only be so pronounced as to necessitate care and control in the interests of the patient and the community.
This being so, I suggest that the same developmental level be adopted for the temperamental defective as I shall presently propose for the intellectual defective, namely, a mental age of about 8 or 9. This limit relates to institutional cases in adult life, that is, to persons who have passed the calendar age of sixteen. For younger persons the same ratio may be adopted, namely, about half the actual age; and for supervision cases a level proportionately higher. A boy, therefore, of fourteen who is so unstable in temperament as to -need the t>ame control and supervision as a child of seven or less, is, so far as degree of instability is concerned, prima facie, a defective in the technical sense.
It must, however, be demonstrated that the apparent defect is genuinely mental, by which I understand that it should be both inborn and also pretty general. A child’s delinquency may arise as a reaction to friction at home, or as a transitory phase of adolescence; or it may affect one instinct only, for example, acquisitiveness or sex; I should not then cons:der the child mentally defective. That the defect is inborn may be presumed, as the Act suggests, from the fact that it emerged early and appears permanent,?the rough test of permanence being indifference to punishment, and, I would add, to other.available modes of rational treatment; but more cogent evidence, such as may be gained by mental analysis or by mental tests, is always desirable. That the defect is general can hardly, indeed, be shown at all without such analysis and tests. But upon this second qualification?the generality of the defect?some, it is true, would not insist. I should, however, argue briefly as follows. First, on theoretical grounds: if only one instinct or emotion is affected, even if the affection be inborn, it yet can hardly ibe described as a defect of temperament; and if it is not a defect of temperament, it is not a mental defect in the sense in which I understand the phrase, that is, a defect which affects some general aspect of the mind as a whole. Secondly, upon practical grounds: if the defect affects one instinct or emotion alone, then in the present state of scientific knowledge regarding those several tendencies, we can hardly affirm with certainty that it is, in any particular case, inborn or permanent; and, indeed, the balance of probability would usually be that it was not.
What tests and methods are available, then, for diagnosing the presence and measuring the intensity of inborn general instability ?
The methods are numerous, but not reliable. In the psychological laboratory the degree of emotional instability can be estimated in quantitative form by recording various physical and mental responses to standard emotional stimuli. Changes in pulse or respiration, slight involuntary movements or slight secretions of sweat, induced by the report of a pistol or the application of a pin, can be accurately registered and measured. These records have of late been used with practical success in the selection of candidates for the air-force. Individuals showing reactions beyond a certain limit have been rejected as of too unsteady a temperament. In the diagnosis of hysterical and neurotic tendencies, experiments upon associative reactions and with the so-called psycho-galvanic reflex have afforded valuable results. All these investigations, however, are still in their infancy,. It would be impossible to formulate the borderline for normality in terms of an average galvanic duration. Further, the technique requires special apparatus and special experience, which are not at the command of all. The Porteus Maze tests, although designed originally to measure practical intelligence, throw much light upon temperamental difficulties. They require only the simplest materials, and are too little known in this country. On the whole, however, for the diagnosis of temperamental deficiency the best guide is expert judgment and methodical observation.
The chief symptoms of instability to be noted1 in children I have enumerated at length elsewhere * Here I need only recapitulate the principal headings and rubrics.
Observations may best be directed1 in order to two main levels of activity, hereditary instincts and emotions, and acquired sentiments and complexes. The former include the various manifestations of fear, of anger (pugnacity, destruo tiveness, violent or sulky temper), of curiosity (including the hunting and wandering instincts), of disgust (often in defectives conspicuously absent), of affection (love, in the sense of tenderness), of pride (in the sense of assertiveness, vanity and self-display), of humility (submissiveness, and certain suggestibility), of sex, of sociability (gregariousness, the herd-instinct, response to the presence of persons), of joy and laughter, of sorrow and crying, and1 perhaps of the acquisitive instinct (hoarding, pilfering, etc.), and the constructive instinct. The strength, the ease, the mode, with which each of these is exhibited, should be observed. The average strength of the whole may be taken as indicating the patient’s general emotionality. But specific tendencies should also be remarked.
It should be noted whether the emotionality, though inwardly strong, is suppressed, and whether the predominant emotions are of the weak, negative, asthenic type (fear, sorrow, and the like) ; or whether the emotionality is unrcpressed, and the instincts predominating are of the aggressive type (anger, vanity, assertiveness, and so forth). The acquired sentiments or interests should then be analysed : those for persons?for self, father, mother, and other individuals within the family and without (brothers, sisters, teachers, playfellows) ; those for concrete but impersonal objects and institutions (toys, clothes, money, Possessions, school, etc.), and, finally?if the child’s intellect is sufficiently advanced for such to have been formed?sentiments for more abstract objects and ideals (work, duty, virtue, authority, reputation, religion, the community as a whole, etc.). It should be discovered whether these sentiments are repressed (forming ‘complexes ‘) or unrepressed; whether they are sentiments of love, of hatred, or perhaps ambivalent; and whether they are well co-ordinated; and whether they are perhaps systematically organised around some master passion, good or bad, that may serve at once to consolidate the entire character, to give Purpose to the entire mental life, and to harmonise and sublimate the various instincts, so that they are no longer discrete impulses, but subdued to some higher aim. Nett strength of character or will may then be expressed as the ratio of the stability of the controlling sentiments to the instability of the several instincts and emotions.
Such analyses of character may seem elaborate; but they are indispensable. Indeed, it can hardly be reiterated too often that the mere fact of abnormal conduct is not in itself a sufficient proof of mental defect. Its basis must be probed and explored. A child may be an ingrained vagrant or a habitual thief; he may have causeless fits of violence or show himself inconceivably cruel; he may be utterly beyond his parents’ control, or have been convicted of repeated; sexual or even murderous assaults ; punishments and rewards may have no * See Child. Study, Ice. tit suf. ‘ The Unstable Child.’ influence whatever upon his vicious habits and criminal propensities; and yet a close study and a careful treatment of his case may at length reveal that these tendencies were phases only, often fully explained by his environment and his history, and neither permanent in themselves, nor the outcome of any inborn general deficiency of intellect or temperament!.
It is to be remembered that a large proportion of individuals of all ages among the poorer classes, and a large proportion of adolescents among all classes, display tendencies which, in the “eyes of those accustomed only to the society of cultured adults, strongly suggest instability. Hence, criteria likely to convict of temperamental deficiency an appreciable percentage of the population?say, more than one-half per cent.?must be rejected. And, personally, in the absence of any concomitant approach to intellectual deficiency, I should not be eager to consider a person temperamentally defective, unless the instability was associated with causal indications, clearly pronounced and fairly permanent,?symptoms, for example, of chorea, of epilepsy, of hyperthyroidism, or marked psycho-pathic or neuro-pathic tendencies, occurring either in the patient himself, or among his immediate relatives.
One other problem under this head has still to be decided. A person may show a definite instability of temperament, but a normal or nearly normal intellect. Should such a case be certified as mental defective in the legal sense? ? Those who have to deal with delinquents, where the alternatives are usually a prison or reformatory, on the one hand, and a home or guardianship, on the other, will generally be disposed to certify. Those who have to examine children as they enter or leave the special schools, will usually be inclined to refrain. Upon theoretical grounds, the former course is no doubt justifiable. But, upon practical grounds, I had rather err, if error is unavoidable, in the latter direction. To accommodate side by side, whether in a school or an institution, a few highly unstable children with a group of ordinary defectives or imbeciles, who are often excitable and almost always suggestible, is to risk undoubted harm to both parties: such an association cannot fail to impair the intelligence of the one and the moral character of the other. The law has always been intellectualistic. It has been framed upon the assumption that human conduct and efficiency are dependent solely upon reason and intelligence. The excuse of the over-emotional, the plea of the victim of temperament, Video meliora proboque, Deteriora sequor, i finds no echo of sympathy or comprehension in the statute book. Until the social menace of the unstable is more clearly realised, until, to those whose disabilities are temperamental rather than intellectual, legal recognition and institutional accommodation are more freely accorded, any procedure must of necessity be but a makeshift.
Fortunately the problem of purely temperamental deficiency confronts the certifying officer only upon rare occasions. With intellectual deficiency diagnosis is simpler. By the use of tests of intelligence a decision can be reached with far greater certainty and far greater speed. As before, acquired capacities are to be carefully discriminated from those which are inborn. Poor attainments do not always indicate poor abilities; and, while the dull are usually backward, the backward are not necessarily dull.
Tests of acquired attainments will be chiefly scholastic in character, although tests of general information and out-of-scliool knowledge are often highly suggestive. The best plan is to assemble ten questions for every age?ten words that can be read, ten words that can be spelt, ten mental sums that can be worked ?by average or median* children of each year of school age. Attainments can thus be measured in terms either of standards or of an educational age. Inborn general intelligence and acquired scholastic attainments are, as a rule, closely correlated. The normal school standard can be deduced from the child’s calendar age by the equation:?Standard = Age?6. A child of ten, therefore, who is working in Standard II., and, not being promoted thither merely for age or size, is able to do the work of Standard II., is not likely (except possibly oai rarer grounds of character), to be defective, though he is very probably backward. On the other hand, through absence, ill-health, slow promotion, or other cause, a child’s apparent attainments may be much below the level of his intelligence. For these cases, some scheme designed for the measurement of inborn ability is necessary. The most useful is the Binet-Simon scale. The tests are far from perfect; and need drastic revision before they can be legitimately applied to English children.f Intelligence is measured by this scale in terms of mental age. A deviation from the normal is expressed as a backwardness of so many years, that is as so many years of retardation behind the average. The child’s method of attacking the test-problems is even more significant than the mere correctness of his replies. But it is convenient to have a single summary measure.
Of all those proposed, the most convenient expressions, for both ability andl attainment, are those which may be termed the child’s educational and mental ratios. The mental ratio is obtained by dividing the child’s mental age by his chronological age. Thus, a child aged 12 years 6 months, with a mental age of 7-5 years has a mental ratio, or intelligence quotient, of 60 per cent. The educational ratio is computed similarly. On the average, as investigation will show, this ratio tends to be constant throughout school life. Thus, if at the age of 5 a child has a mental age of 4, and, therefore, a mental ratio of 80 per cent., then at the age of 10 he will probably have a mental age of 8, and have reached Standard II.; at the age of 15 he will have a mental age of 12, and1, having left school somewhat low in Standard V., will probably, throughout his adult life, progress little if at all beyond this level.
What degree of backwardness is to be taken as indicative of mental deficiency? ?This question is most easily resolved iby a statistical survey, by a psychological census, as it were, of all the children in a typical group of schools, special and ordinary elementary. Such a survey I have carried out, both for educational and for general intelligence:, in a representative London area!.} The’ results * For the rough standardisation of tests it is not necessary to test all the children in a given age-group, but only the middle children in the middle class : e.g., for age 10, only those of that age left in Standard IV., after eliminating, say, the ten highest and ten dullest in that class.
t A revised version of this scale, including a set of scholastic tests, prepared with the assistance of Dr Simon and a number of London school teachers, will, I hope, shortly be issued by the London County Council.
t The Distribution and Relations of Educational Abilities. P. S. King and Sons, 2s. 6d. shortieSU*tS ^ *uvest*Sat’on uPon distribution of general intelligence will be publishei reveal a striking overlap between so-called normals and so-called defectives. The brightest children in the special schools are distinctly brighter than the dullest children in the ordinary schools. Apart from a few rare exceptions belonging to a definite pathological type, there is between normals and defectives no clear distinction; ho hiatus, no gulf, no gap. The one group merges into the other by insensible gradations, as night into day. The point of demarcation, therefore, is purely a matter of convenience and convention, as artificial and as arbitrary as the moment we term midnight or the hour we select for lighting up.
Where is this point to be fixed? The replies to this question conflict and differ almost beyond belief. In the report of an American Census for 1910 the proportion of defectives, both within and without institutions, was put at 0.2 per cent. Binet, on the other hand, assessed the percentage as ” somewhere in the neighbourhood of 5.0 per cent. ” ; and a group of American psychologists have more recently given a figure almost as large. One estimate thus recognises twenty-five times as many defectives as another. Upon what scale is an education authority, such as that for the County of London, to provide when one calculation would declare that between the ages contemplated, 22,500 wTill be defective, and another only 900?
Considerations, based upon current practice and’ confirmed by actual experience, concur with a priori inferences to suggest that, in the case of children, the most convenient borderline to adopt is that indicated by a mental ratio of 70 per cent. A child who has less than seven-tenths of the abilities possessed by average children of his age is to be regarded as mentally defective; thus, a child aged 10 who is backward by more than three years, and is, therefore, below the mental level of an average child of 7, is a fit candidate for a special school. A child who is backward by less than this amount should be educated in a class for backward children in the ordinary school. A child whose ratio is under 40 per cent, proves, as a rule, to be ineducable. But again the borderline is purely artificial.
This is equivalent, at any rate in an industrial town, to cutting off the lowest 15 per mille. of the school population. And for such an area my definition of the intellectually defective child would be one who for intelligence ranks among the lowest per cent, of his age group. The definition should doubtless vary from one type of area to another; and provisionally should depend upon the amount of accommodation available. Too often high-grade cases, examined at an early date or by a certifying officer with a high standard of normality, are accepted, and transferred to a special school; then cases of a lower grade, presented for examination later on, are forced to remain in the ordinary school, or even at home, because the milder cases have usurped their room. Such a lack of co-ordination is manifestly unjust. There should be one weight and1 one measure. The merit of any criterion lies not so much in its absolute character, which is arbitrary, but in its uniform observance, which is essential.
CRUCIAL TESTS FOR CHILDREN. ————————–With the line of demarcation here suggested, the following tests in the Binet-Simon scale l>ecome borderline or crucial tests for the several ages: age 5, distinguishing pretty and ugly faces in a picture; age 6, performing a triple order and naming the four primary colours (a test assigned’ by Binet to normals aged 7, but far easier for London children) ; copying a diamond or transcribing three words of 3 to 6 letters; age 8, recognising 3 pennies and 3 halfpennies as 4^d. and the missing features in unfinished portraits; age 9, giving simple differences between concrete objects (wood and glass, etc.) ; age 10, naming the months, the date, and perhaps giving actual change for a twopenny article out of a shilling (the coins necessitating the use of a sixpenny piece as well as the odd coppers) ; age 11, counting backwards from 20 to 1, or repeating six numbers (one trial correct out of three) ; age 12, arranging 5 weights in order; age 13, building two sentences toi contain 3 words; age 14, drawing Binet’s two designs from memory, and perhaps explaining the absurd sentences. In terming these tests crucial I do not, of course, imply that failure or success in the one test specified! for a given age can decide the question of deficiency; all I suggest is this: with the complete series of tests, arranged in the order of their difficulty for defective children, a child who fails with tests easier than those mentioned is presumably ” deficient,” and a child who answers harder tests is presumably ” normal,” that is, not necessarily of average ability, quite possibly distinctly backward, but as regards intelligence not mentally deficient.
For measuring the intelligence of older cases above the borderline?for example, dull or backward unstables?the Binet tests are unsatisfactory. 1 prefer some form of reasoning test. A graded age-scale of reasoning tests, together with a revised version of the Binet scale, will be found in Dr Ballard’s recent book on Mental Tests.
For mental deficiency among adults the legal definition differs wholly from that given for mental deficiency among children. The former hinges on economic competence; the latter on school progress. More than half of the children relegated to special schools as unable to benefit by the instruction in the ordinary school have yet sufficient ability to float in society when they leave, and, with tolerable success, to earn their livings and manage their homes.
If for adults we retained the criterion above suggested for school cases, then, assuming, as has commonly been done, that intelligence advances little, if at all, beyond the age of 16, we should have, as the upper limit of mental deficiency for those above school age, the mental age of n. This is a high level. But the borderline suggested by the American Psychological Association is higher still, namely, a mental age of 12. An upper limit so comprehensive would include among the mentally defective an excessive proportion of the population; and seems plainly inadmissible. Psychological tests have been recently applied upon an enormous scale to recruits for the American Army; and the results show that in the United States the general average of the population lies about a mental age of 13. In this country many are below this level. Rural labourers in Warwickshire, dock labourers in Liverpool, and domestic servants of the poorest type can, in a benign environment, manage themselves and their affairs, unsupervised and uncontrolled, with a mental age, as given by my tests, of only 8 or 9. Provisionally, therefore, while accommodation for adult defectives is so small, and while ignorance of the psychology of borderline cases is so great, I should hesitate to consider a person defective on the ground of intelligence alone, unless his mental age were only 8 or less, that is to say, unless his mental ratio were below 50 per cent., and his attainments only half those of an average adult.
This means that many, who will not be deemed’ defective in maturity, are during childhood certified, stigmatised, and segregated. Our special schools, in fact, appear to contain cases of three grades: (1) Children with mental ratios between 40 and 50 per cent. ; these will fall amongst the lowest ^ per cent, of the: population, and are likely to become institution cases; (2) Children with mental ratios between 50 and 60 per cent.; these fall among the next i per cent, of the population, and perhaps may best be treated’, when they leave, as supervision cases; (3) Children with mental ratios between 60 and’ 70 per cent.; these fall among the remaining ^ per cent, of the defective population; and, in an average environment, and apart from temperamental defects, will manage quite satisfactorily to provide for themselves. One ‘ mentally defective ‘ boy in the provinces is now, at the age of 19, earning ,<?300 a year?a far higher income than that of the teacher who taught him. Whether this third group should not be termed, even during school years, 4 educationally defective ‘ rather than ‘ mentally defective,’ and whether they should not be taught in backward classes in an ordinary or ‘ intermediate ‘ school (when such classes or such schools are provided) rather than be associated with those whose life must lie forever in an institution, is an obvious question; but, it is an issue which we need! not here discuss.
CRUCIAL TESTS FOR ADULTS. ———————–With the lower line of demarcation, thus recommended for adults, the crucial tests in the Binet-Simon scale are those allotted to the ages of 8 and 9. If a person over 16 can repeat the months of the year, and1 give the date with approximate exactness, name correctly all the commoner coins of the realm (including a half-crown and a two-shilling piece) and give correct change for a twopenny article out of a shilling, repeat six numbers and count backwards from 20 to 1, read Binet’s newspaper extract and recall six items from what he has read, then he is, in my view, hardly to be judged an institution case, unless special circumstances in his home environment, in his physical condition, or in his temperament and character are present in addition to disabilities in intelligence.*
SUPPLEMENTARY SOURCES OF EVIDENCE. ———————————-These reservations, however, are all-important. No adult should be classed as mentally defective solely on the results of mental tests. If the patient’s condition were so gross that the findings of the Binet scale were alone conclusive, then probably the application of the Binet scale would in this instance be superfluous: the diagnosis could be reached at a glance. If, 011 the other hand, * It is but just to add that the six tests, selected by Binet as crucial, are somewhat harder : namely, arranging weights, answering his ‘ difficult ‘ questions, building a sentence to contain 3 words, interpreting his pictures, and finding rhymes. No patients from institutions tested by him and Dr Simon, could pass more than three of these six. In one of the bestknown English institutions for the mental defective, however, I have found a girl ot only sixteen who could pass all these tests. She gave as rhymes to ‘ obey,’ such words as ‘ decay,’ ‘ delay,’ hurray and her sentence ran as follows : ” The Houses of Parliament in London stand by the River Thames, and cost a lot of money to build.” There were no complaints against her conduct or character. Certainly, she was happier and more helpful in the colony than she would have been outside. But, considering the number of low-grade cases awaiting admission to institutions of this kind, such an instance points urgently to the need of some uniform standard, generally accepted, and, for the present, not too lofty.
The patient were so near the borderline that a methodical examination of intelligence seemed indispensable, then other fields of enquiry should be explored and other sources of information searched. These sources of evidence fall under half-dozen separate and familiar heads; and should be kept distinct. Among them, the psychological examination?conducted chiefly by means of standardised tests for intelligence, for special abilities, for school knowledge, and for practical knowledge and general information?is undoubtedly the most helpful source, but it is by no means the only source. And with adults psychological tests are even less conclusive than with children. In addition to:
the psychological tests,
the physical examination (which may include, beside the usual medical examination, anthropometric measurements, inspection for stigmata, laboratory tests of the sense-organs and of the nervous system),
the family history (including particularly, of course, such details as may shed light on the child’s Physical and mental heredity),
the personal history, pre-natal and post-natal (including the conditions of gestation and’ birth, the date of sitting up, of walking, of talking, of dentition and of pubescence, the general course of the child’s development, and the incidence and after-effects of his childish illnesses),
the report of school attendance, progress and conduct,
of moral and social behaviour,
of economic and vocational efficiency, and, finally,
of the material and moral environment to be faced in and out of the home,
These all contribute data which should be weighed and collated! before the diagnosis is made, before the patient’s ability to manage himself and his affairs, or his need! for permanent care and control, can be satisfactorily determined. The various sources of information possess a very different value. The physical examination usually has a negative value, since ill-health or sensory defects are sometimes sufficient to explain an appearance of deficiency. The family history is often too uncertain to be helpful. The developmental history, where reliable, may be suggestive or confirmatory in a positive diagnosis, or explanatory in negative diagnosis. Moral and vocational failure is too frequently influenced by environmental conditions to have more than a suggestive worth. Hence, positive evidence from two or three of these vaguer sources may, even when unanimous, yet be inconclusive; but, combined with positive evidence from the psychological tests, additional evidence from one other source alone may be final. Seldom is it possible, or even necessary, to obtain satisfactory evidence from every source; but evidence from all the sources that may be available, will, in the majority of typical cases of general deficiency, be found affirmative.
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