At what Age does Intelligence cease to Develop? and Intelligence in Relation to Different Social Classes
- Author:
Dr Ovide Decroly. Translated from the French.
Methods of measuring- intelligence have produced results which have given rise abroad to many subjects of discussion, one of which is the age at which intelligence usually ceases to develop.
In the United States, Group Tests go to prove that intelligence does not develop beyond 13-14 years of age. Terman and other writers, have shown that the average soldier in the United States cannot go beyond the tests for children of 13 or 14. On the other hand, Dr Burt, who is Psychological Examiner of the children in the London Schools, points out that the tests which he has devised for children of 16 are the same as those which normal urban adults can, on the average, accomplish. He does not think it likely that intelligence grows by regular stages up to fourteen, and then ceases abruptly. He has carried on researches by means of tests, other than those of Binet, applied not only to the students at the University and at Training Colleges, who would of course be of higher mental capacity, but also to adults of various types who may be con- sidered as having been average pupils at the Elementary Schools. From these researches he is inclined to admit fifteen or sixteen as the point at which intel- ligence ceases to grow.
Having regard to the standard rate of progress, and taking the age of 9 as being the age at which the rate of pi ogress is commensurate with the actual age, it follows that, if the mental age were to increase after 9 at an equal rate, the limit of development would be 13. But as the fact is that the rate of develop- ment decreases from year to year, the age of 15 to 16 as the limit of development aPproaches more nearly to the truth.
According to the above, and we have only quoted evidence based on wide statistics, we must admit that development of the intelligence ceases somewhere between 13 and 16.
It seems, however, difficult to deny that a certain number of minds do con- tinue to develop; and the whole organisation of education is built up on this idea. For we have Secondary School Education for 5 to 10 per cent, of the total school population, and University Education for 1 to 2 per cent.. Now, by the provision of these educational opportunities, we surely presuppose that for a certain number of children there is an increase of capacity after the age of 16, But this is only a presumption, and positive proof is still needed to show that the mental aptitudes of all these pupils, who enjoy Higher Secondary and Uni- versity Education, really do increase beyond the age-limit indicated above.
The researches made even in Belgium, by means of group tests, do not provide this proof. It seems rather, from the results obtained,1 that the fact that groups of scholars, who pass in successive years through Higher Secondary and University Education, are capable of following more and more difficult courses of study, is due, less to the increase of their intellectual capacity, properly so called, than to other factors of quite a different order, such as health, home circum- stances, a good verbal memory, great perseverance, ambition, inclination, etc. The proof of this seems to be found in the fact that the average group improves mainly by the elimination of the inferior,2 and not by an increase in the number of the superior intelligences.
Besides, progress is most marked in the co-efficient of precision, that is to say, in the decrease in the number of errors in proportion to the actual number of questions, which seems to be due rather to an improvement in concentration and method of study than actually in the intelligence.
In short, what one can count as proved by modern investigations is that three-quarters at least of the adult population does not go beyond 15 years3 of age, from the point of view of ability to understand, to reflect, to profit by experience, to foresee, to analyse and generalise, and above all to work at abstract ideas. And this would agree in the main with the views of Moebius4 con- cerning the mental state of the female, and of Ch. iRichet5 concerning that of man in general. This also gives an explanation of Crowd Psychology, apart from the hypothesis of a special mentality characteristic of men in groups.
Another fact has been proved, to which we wish to call attention. This fact has not indeed greatly surprised those who happen to live in contact with chil- dren of various classes, but it should considerably modify the views of those theorists, who say that one man is just as good as another, that all children are equally endowed, equally disposed to goodness, according to the formula of Jean Jacques, that social conditions are alone responsible for the differences which one finds in human beings.
The fact to which we refer is this. The results of tests of the Binet-Simon type have shown that the children of the comfortable classes are more or less in advance of those of the proletariat.
We ourselves have since 1910? drawn attention to this fact, and we have actually proved it with a group of 45 children from 6-15 years from the comfortable classes, examined by tests which were only at the level of their age. Of this group, 13 were one year, 17 two years, and 9 as much as 3 years in advance of the Paris children.
(1) Decroly. Les divers types de tests (Bulletin de la Society Royale des Sciences medicales et naturelles, 1925). (2) Communication au Congrks Fran^ais pour l’avancement des Sciences. Li&ge, (3) This does not mean, of course, that three-quarters of the population all reach the mentality of 15 years. Intelligence, like other biological phenomena, is found in different individuals in differing degrees, which may be represented by the classical curves, of Galton, for quantity, and of Gauss, for frequency (see the statis- tics in regard to measuring education in my book in collaboration with M. Buyse to be published by Alcan). (4) Ueber den Physiologischen des Weibes. Halle, 1901. (5) Ch. Richet. L’homme stupide. Flammarian, 1919. (6) Decroly et De Gaud. La mesure de l’intelligence par la methode Binet- Simon (Arch, de Psychol), 1910.
By a further application of Binet’s tests (2nd series 1908) in collaboration with Messrs. Boulanger & Smelten on 80 children from a Public Elementary School in Brussels, we found on the other hand that the children were on an average one year behind those of Paris.7
Meurmann,8 dealing- with this question, points out that tests applied by Dr Schubert to poor children of Moscow, showed that these children are two years behind the Paris children, while the children of the middle class of Petrograd were two years in advance.
The children examined by Miss Johnston nt Sheffield (Public Elementary Schools) reached the level of those of Paris, while the children of an upper class school surpassed them.
The results of tests made by Goddard on 2,000 pupils in Vineland and district (U.S.A .) are also very similar to those obtained by the Binet Tests on the little Parisians. The same result is found among- the Italian children examined by Jeronutti : those of the comfortable classes of Rome go beyond the Binet average; the same applies to those examined by Treves and Saffiotti at Turin. Stern does not believe, however, that it is entirely due to heredity, and we have ourselves also admitted from the beginning that language has something to do with it : the tests being for the most part verbal, are easier for the children of the middle class, where language is more developed.
It is for this reason that we have emphasised on several occasions the need for the Binet Tests to be supplemented by tests of intelligence where language plays a less important part.
That is why we have advocated tests, such as arranging parts of a picture in the right order, grouping correctly the different activities of a picture, or opening Puzzle Boxes. It has become the practice to use such tests in the United States and here.
It is interesting to note what other writers have found from the point of view of social differences.
Investigations made in the same school among children of different social classes by Morle, Jaederholm, Max Schmitt, Treves and Saffiotti, have led generally to the conclusion that the difference is most marked in the early years of the Infant School, and disappears in the later years.
Karstadt explains this by the fact that in the later years of the Public Elemen- tary School, the children of the better class leave in order to go to Preparatory Secondary Schools. So that in the later years there only remain the more back- ward members of the better class, so much so that we may reverse the formula and say that the children of the better class who are left behind are inferior to those of the lower classes..
The comparison between schools belonging to different districts affords some convincing evidence. Thus Morle, at the suggestion of Binet, examined 30 pupils of the same age in two distinct schools, without taking into account their school records. The comparison revealed a difference of three quarters of a year in favour of the children of the better class.
Yerkes and Anderson compared in the same way two schools at Cambridge (Massachusetts), the one taking pupils from a good, the other from a bad environ- ment. Fifty-four pupils were chosen from among the children of both sexes in the Kindergarten and the first year Primary School (5-7 years). Hie average of the two groups was about six years. The Binet test, modified by Yerkes (7) Unpublished. (8) Meurmann. Preface to 2nd edition.
(point-scale) showed that the boys of the one school obtained on an average 37 points and of the other 29 points. In the case of the girls, the figures obtained were respectively 41 and 33. If one kept exclusively to the children of 6 years of age, the difference would be all the more marked.
According to this enquiry the children of the better class were 30 per cent, above those of the poorer class.
Certain writers, such as I. and R. Weintrob, of New York, and Schmitt, of Germany, state that they do not find such marked differences. But against this Stern objects that the first two are comparing children who are not only of different social classes, but also distinct in race, and as regards the second, he remarks that Schmitt was working in a Boarding School in the one instance and in Day Schools in the other, going on the assumption that the Boarders were in better circumstances than the day pupils?an assumption not justified.
Schmitt also assumes a priori, without examining the pupils, that the results of the day pupils must work out on a symmetrical curve, and as he states that those of the Boarders do not, but curve downwards more rapidly the greater the age, he concludes that the latter are inferior.
Schmitt, as Stern has rightly remarked, has not sufficiently taken into account the fact that his pupils were older, and that the Binet Tests are relatively more difficult for the more advanced ages than for the less.
The influence of environment becomes more marked, when one chooses schools of different types.
In 1912, at Breslau, Stern and his students compared pupils from 7-9 years attending Preparatory Schools (Vorschule) with pupils of 7-9 and 10 years from a Public Elementary School. In all there were 150 pupils. The results of the examination, made with special precautions, were as follows :?The chil- dren of both 7 and 9 years old from the Public Elementary School were about half a year below those of the other group of the same age?the 10 year olds from the former group were about on a level with the 9 year olds in the other group.
In comparing results in different parts of the tests, Stern comes to the conclusion that the superiority is most marked in the verbal (formal) tests. Investigations have been made with tests other than those of Binet. Eor example, G. and A. Schober submitted 60 children, of 4 to 8 years old, to Heilbrommer’s tests : half the children belonged to the better class; for each year there were 3 girls and 3 boys of each group. Although the numbers were too limited to be satisfactory, the differences are very marked, especially among the youngest children, and decrease as the ages advance, which the writers attribute to the influence of the school. The differences are more marked in the use of perception (Erkennens) and association (Erganzen) than in the vocabulary.
H. and P. Roloff, by means of a Definition test, made an enquiry among children of 9-13 years of the classical and modern sides of Secondary Schools and the Public Elementary Schools of Hamburg. The differences are more marked between the pupils of the classical and modern side of the Secondary School than between those of the Secondary School and the Public Elementary School.
The differences are as follows :? Between the 1st and 3rd group … 3 years. ,, ,, 1st and 2nd group 2J years. ,, ,, 2nd and 3rd group f of a year.
Stern believes that the differences between the first two groups is not due to educational conditions, but to stock. Thus if one classifies them according to the profession of their fathers, one can point out that in the first group, the fathers are mostly big commercial men, professors and higher officials; in the second, mostly manual and industrial workers, and officials of the lower rank; in the third, mostly labourers, sometimes illiterate..
The statistics of housing conditions also show a greater difference between the first two groups :?
1st group. 2nd group. 3rd group. Living in a House or Villa … 76% 25% Living in Workmen’s Dwellings… 24% 25% 100% At Breslau, Minkus experimented on children (12?16 years) belonging to the Public Elementary Schools and Vocational Schools (Fortbildungschule). For each sex the writer chose children of a different class..
The results only refer to one test, that of Masselon (to arrange words into a sentence). It is stated that in the upper class of the Public Elementary School there was hardly any difference, while the difference was very marked in the lower and middle class of the Vocational Schools. In these latter schools it seems that the difference can be attributed to the fact that the better type are attracted towards employment in shops while the rest tend towards manual occupations.
A School Inspector, of Bremen, Hartnacke, basing his inquiry on statistics and the opinion of the masters, compared the non-paying and paying children under the same school conditions, and states that the level of the latter was higher than that of the former..
The statistics of 1913?18 show in addition that 8 per cent, of the non- paying children and 3 per cent, of the paying fail, and double their years. Further, when the teachers were invited in 1916 to select the pupils whom they found capable of passing into the Secondary School, 96 were selected out of 836 paying pupils and 41 out of 1,413 non-paying pupils, which means 11.5 per cent, and 2 per cent.
In a third set of figures regarding 50 children, who were the most remark- able for their intelligence in two schools, the fathers belonged to the intellectual professions, for half of them were officials, business men, salaried people, con- tractors, and the other half were better-class artisans, the important category of labourers not being noticeably represented.
It is interesting to compare the results collected by Stern in his work on the intelligence of children and adolescents with those which were given by Burt of London, whom we have already quoted.
This writer gives in this connection a curious diagram in which he com- pares the differences which exist between the children of opposite sex and different social surroundings. In this diagram the sign + with the numbei following indicates the extent to which a test is easier for the children of the better class and for g’irls than for the children of the poorer class and for boys. The sign ? indicates the opposite. The numbers indicate the different place occupied by the tests in the order of difficulty in the four groups under considex- ation..
Thus, if a test occupies the 30th place among the boys and the 35th among the girls the difference is indicated by ? 5; if a test occupies the 33rd place among the children of the better class and the 40th among those of the poorer class, the difference is indicated by + 7.
14 MENTAL WELFARE* Test. Picture (Interpretation) 60 Words Reading (2 Facts) Dictation 16 Syllables Reading (6 Facts) Differences (Abstract) Sentence Building (1) Picture (Description) Transcription Age 4 Colours 26 Syllables Definition (Class) Re-statement 3 Rhymes Sentence Building (2) Mixed Sentences Definition (Use) Definition (Abstract) Days of Week Surname 10 Syllables 4 Pennies Fingers 6 Syllables Picture (Enumeration) Count 20 to 1 Right and Left Comparing Faces 6 Numbers Pointing 2 Lines Differences in Order Social Status. + 6 + 5 + 5 + 5 + 4 + 4 + 4 + 4 + 4 + 3 + 3 + 2 + 2 + 2 + 2 + 2 + 2 + 2 + 2 + 2 + 2 + 2 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + h o 0 0 Sex. - 1 - 5 + 5 + 5 + 9 + 6 + 2 + 2 + 1 + 4 + 1 + 6 + 3 + 3 + + 2 + 2 + 2 + 2 + 1 + 1 0 + 3 4- 2+ 2 + 1 - 1 - 3 - 4J 4- 2 + 3 - i - } Test. Differences (King, President) Months Morning and Afternoon 13 Pennies 3 Numbers … 4 Numbers 7 Numbers Sex 2 Numbers Differences (Concrete) Absurdities … Diamond Square 5 Numbers … Reversed Triangle … Naming Easy Questions Date … Missing Features Folded Paper 2 Weights Difficult Questions … 4 Coins Triple Order … Change Divided Card Memory Drawing … 5 Weights 9 Coins Pence and Halfpence Problems Suggestion Differences in Order. Social Status. 2 ? 2 ? 2 ? 2 ? 2 2 3 3 ? 4 ? 4 ? 4 ? 4 ? 5 ? 5 ? 6 ?10 Sex. - 1 - 1 - 1 _ n 4- 3 4- 2 4- 2 - li ? 2 - 2 _ 2 - 3 - 5 4- 3 4- 2 4- 1 - 1 - 1 - 14 - 3j - 4 - 1 - 3 - 5 - 2 - 4 - 4 - 5 - 4 - 5 - 3 - 7
From tins diagram, Burt concludes that the tests in which the children ot the better class excel are (1) those where language is more important, requiring a wide vocabulary; (2) those which have to do with scholastic attainment; (3) those which depend upon verbal memory; (4) those which relate to knowledge acquired early in life among the better and cultivated class. It sometimes iiappens that an only child, or the youngest in a family, has the best chance.
On the contrary, the poorest children excel in tests (1) which have to do with money (2) those which require perception rather than conception, especially when manual activity enters into play, such as drawing, weighing, games of patience, etc; (3) those which deal with practical affairs, errands, easy and diffi- cult questions, concrete problems; (4) those which require the critical faculty (absurdity, resistance to a suggestion).
As to the differences between the sexes, they are attributed by Burt for the most part to the influence of school; they are in fact more precise where the sexes are educated separately and less marked where they are together. He concludes therefore that the social differences as well as those between the sexes are for the most part the result of influences which have come since birth rather than the effect of heredity.
In Burt’s opinion these differences are relatively little marked and are not as important as those which exist between individuals of the same social standing- (1) and of the same sex.
The enquiries made in the United States, the evidence from which we have set out in an article on the ” Mieux-doues ” in the Bulletin International de la protection de 1’enfance, 1924, also prove in no uncertain manner the influence of social conditions.
As to the relative importance of environment and heredity in deter- mining- the differences found among- school children it is obvious that one cannot at the bidding of certain writers attribute to one too much importance to the exclusion of the other.
Evidently in some isolated instances one can see cases where one of the factors preponderates..
In our book, published with the collaboration of Inspector P. Renault on L’Enfance Malheureuse M1 we have shown particularly that in the case of GO to 80 children brought before the Magistrates the environment was the chief cause of the anti-social conduct of the child. On the other hand, there is no doubt that in order to produce the best a good heredity is the first essential. Only, in order that the natural disposition may develop completely in the right direction the environment must also play a part, and it cannot be doubted that on the one hand, among the descendants of gifted people, aptitudes arc often mis-directed, turned aside and wasted, while on the other hand, it is above all, thanks to the care, the sacrifices and the solicitude of the parents that an excep- tional nature can develop itself and reach its full height. But taking all things into consideration, it is not possible to admit one only of the two factors as being the sole contributory cause..
Evidently one can still argue that tests do not bring out actual capacity, and emphasise, as we and others after us have emphasised, that children who belong to circles where language is more developed, for reasons both of heredity and education, are given some advantage by tests like Binet’s. They also have the advantage of educational methods which are themselves based on the use of language. Besides there are children, and we ourselves have seen many, in whom the verbal side develops at the expense of the visual-manual, some- times to such an extent that all mental activities seem to depend on language, and there is a real inability to observe, and to realise actual facts and things. A serious want of balance is the result.
Sometimes these children give the impression at first of an astounding- precocity, but later they are outstripped by those less gifted in expression, who possess, however, greater powers of observation and initiative, even though they may develop more slowly.
Characteristic examples of this are the infant prodigies who give such brilliant promise, but whose want of balance makes it impossible for them in later life to turn to account their over-stimulated talents (see Claparcde). We will not here examine the peculiar difficulties created by the war among the peoples of Europe by the change in social conditions caused by the abnormal rise in the material and political position of certain persons. Nor will we examine how the facts which we have emphasised help to solve the problem of the single school, nor what relation there is between those facts and these social conditions. (l) Decroly et P. Renault. L’enfance malheureuse (office da la Protection de 1’enfance, Ministere de la Justice), 1922.
Our conclusions are :? (1) Mental tests, individual or group, confirm what has been already ob- served, namely, that the children of the comfortable classes are in advance of the others. (2) These tests can measure child) en according- to age or according- to the intelligence quotient. (3) The superiority, shown in 1, is due to hereditary and educational factors in varying proportions, often difficult to define. (4) In a certain number of cases where this superiority is due to facility of expression it is especially helpful in meeting school requirements at the beginning of the primary education, and in classical studies, but it does not necessarily mean that this advantage will be maintained in professions requiring other qualities. (5) A mental examination, to be complete, should not only be carried through by tests where language is predominant, but should also include tests which call upon other qualities, such as observation, concrete and abstract presentation of a visual and motor order, and the power to solve practical problems. (6) A mental examination should be completed by information or tests concerning the character, the social and moral tendencies of the child.
Bibliography: W. Stern. Die Intelligenz der Kinder und Jugendlichen. 1922. W. Stern. Differenzen der Pscychologie. 1911 nnd 1921. E. Claparede. Comment diagnostiquer les aptitude? chez les ecoliers. Flaummarian. 1924. XXIst Year Book. Society for the Study of Education, Bloomington, U.S.A. 1921. R. M. Yerkes, Physiological examining in the United States Army. Memoirs of the National Academy of Sciences. Vol. XV., Washington, 1921. C. Burt. Mental and scholastic tests. 1921.
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