CHAPTER VII

RELIABILITY OF THE BINET-SIMON METHOD

GENERAL VALUE OF THE METHOD. In a former chapter we have noted certain imperfections of the scale devised by Binet and Simon; namely, that many of the tests were not correctly located, that the choice of tests was in a few cases unsatisfactory, that the directions for giving and scoring the tests were sometimes too indefinite, and that the upper and lower ranges of the scale especially stood in need of extensions and corrections. All of these faults have been quite generally admitted. The method itself, however, after being put to the test by psychologists of all countries and of all faiths, by the skeptical as well as the friendly, has amply demonstrated its value. The agreement on this point is as complete as it is regarding the scale's imperfections.

The following quotations from prominent psychologists who have studied the method will serve to show how it is regarded by those most entitled to an opinion:--

There can be no question about the fact that the Binet-Simon tests do not make half as frequent or half as great errors in the mental ages (of feeble-minded children) as are included in gradings based on careful, prolonged general observation by experienced observers.[30]

[30] Dr. F. Kuhlmann: "The Binet-Simon Tests of Intelligence in Grading Feeble-Minded Children," in _Journal of Psycho-Asthenics_ (1912), p. 189.

All of the different authors who have made these researches (with Binet's method) are in a general way unanimous in recognizing that the principle of the scale is extremely fortunate, and all believe that it offers the basis of a most useful method for the examination of intelligence.[31]

[31] Dr. Otto Bobertag: "L'échelle métrique de l'intelligence," in _L'Année Psychologique_ (1912), p. 272.

It serves as a relatively simple and speedy method of securing, by means accessible to every one, a true insight into the average level of ability of a child between 3 and 15 years of age.[32]

[32] Dr. Ernest Meumann: _Experimentelle Pädagogik_ (1913), vol. II, p. 277.

That, despite the differences in race and language, despite the divergences in school organization and in methods of instruction, there should be so decided agreement in the reactions of the children--is, in my opinion, the best vindication of the _principle_ of the tests that one could imagine, because this agreement demonstrates that _the tests do actually reach and discover the general developmental conditions of intelligence_ (so far as these are operative in public-school children of the present cultural epoch), and not mere fragments of knowledge and attainments acquired by chance.[33]

[33] Dr. W. Stern: _The Psychological Methods of Testing Intelligence._ Translated by Whipple (1913), p. 49.

It is without doubt the most satisfactory and accurate method of determining a child's intelligence that we have, and so far superior to everything else which has been proposed that as yet there is nothing else to be considered.[34]

[34] Dr. H. H. Goddard: "The Binet Measuring Scale of Intelligence; What it is and How it is to be Used," in _The Training School Bulletin_ (1912).

The value of the method lies both in the swiftness and the accuracy with which it works. One who knows how to apply the tests correctly and who is experienced in the psychological interpretation of responses can in forty minutes arrive at a more accurate judgment as to a subject's intelligence than would be possible without the tests after months or even years of close observation. The reasons for this have already been set forth.[35] The difference is something like that between measuring a person's height with a yardstick and estimating it by guess. That this is not an unfair statement of the case is well shown by the following candid confession by a psychologist who tested 200 juvenile delinquents brought before Judge Lindsey's court:--

[35] See this volume, p. 24 _ff._

As a matter of interest I estimated the mental ages of 150 of my subjects before testing them. In 54 of the estimates the error was not more than one year in either direction; 70 of the subjects were estimated too high, the average error being 2 years and 7 months; 26 of the subjects were estimated too low, the average error being 2 years and 2 months. _These figures would seem to imply that an estimate with nothing to support it is wholly unreliable, more especially as many of the estimates were four or five years wide of the mark._[36]

[36] C. S. Bluemel: "Binet Tests on 200 Delinquents," in _The Training School Bulletin_ (1915), p. 192. (Italics inserted.)

Criticisms of the Binet method have also been frequently voiced, but chiefly by persons who have had little experience with it or by those whose scientific training hardly justifies an opinion. It cannot be too strongly emphasized that eminence in law, medicine, education, or any other profession does not of itself enable any one to pass judgment on the validity of a psychological method.

DEPENDENCE OF THE SCALE'S RELIABILITY ON THE TRAINING OF THE EXAMINER. On this point two radically different opinions have been urged. On the one hand, some have insisted that the results of a test made by other than a thoroughly trained psychologist are absolutely worthless. At the opposite extreme are a few who seem to think that any teacher or physician can secure perfectly valid results after a few hours' acquaintance with the tests.

The dispute is one which cannot be settled by the assertion of opinion, and, unfortunately, thoroughgoing investigations have not yet been made as to the frequency and extent of errors made by untrained or partially trained examiners. The only study of this kind which has so far been reported is the following:--[37]

[37] Samuel C. Kohs: "The Binet Test and the Training of Teachers," in _The Training School Bulletin_ (1914), pp. 113-17.

Dr. Kohs gives the results of tests made by 58 inexperienced teachers who were taking a summer course in the Training School at Vineland. The class met three times a week for instruction in the use of the Binet scale. During the first week the students listened to three lectures by Dr. Goddard. The second week was given over to demonstration testing. Each student saw four children tested, and attended two discussion periods of an hour each. During the third, fourth, and fifth weeks each student tested one child per week, and observed the testing of two others. The student was allowed to carry the test through in his own way, but received criticism after it was finished. Twice a week Dr. Goddard spent an hour with the class, discussing experimental procedure. The subjects tested were feeble-minded children whose exact mental ages were already known, and for this reason it was possible to check up the accuracy of each student's work.

Kohs's table of results for the trial testing of the 174 children showed:--

(1) That 50 per cent of the work was as exact as any one in the laboratory could make it;

(2) That in an additional 38 per cent the results were within three fifths of a year of being exact;

(3) That nearly 90 per cent of the work of the summer students was sufficiently accurate for all practical purposes;

(4) That the records improved during the brief training so that during the third week only one test missed the real mental age by as much as a year.

Since hardly any of these students had had any previous experience with the Binet tests, Dr. Kohs seems to be entirely justified in his conclusion that it is possible, in the brief period of six weeks, to teach people to use the tests with a reasonable degree of accuracy.

What shall we say of the teacher or of the physician who has not even had this amount of instruction? The writer's experience forces him to agree with Binet and with Dr. Goddard, that any one with intelligence enough to be a teacher, and who is willing to devote conscientious study to the mastery of the technique, can use the scale accurately enough to get a better idea of a child's mental endowment than he could possibly get in any other way. It is necessary, however, for the untrained person to recognize his own lack of experience, and in no case would it be justifiable to base important action or scientific conclusions upon the results of the inexpert examiner. As Binet himself repeatedly insisted, the method is not absolutely mechanical, and cannot be made so by elaboration of instructions.

It is sometimes held that the examination and classification of backward children for special instruction should be carried out by the school physicians. The fact is, however, that there is nothing in the physician's training to give him any advantage over the ordinary teacher in the use of the Binet tests. Because of her more intimate knowledge of children and because of her superior tact and adaptability, the average teacher is perhaps better equipped than the average physician to give intelligence tests.

Finally, it should be emphasized that whatever the previous training or experience of the examiner may have been, his ability to adjust to the child's personality and his willingness to follow conscientiously the directions for giving the tests are important factors in his equipment.

INFLUENCE OF THE SUBJECT'S ATTITUDE. One continually meets such queries as, "How do you know the subject did his best?" "Possibly the child was nervous or frightened," or, "Perhaps incorrect answers were purposely given." All such objections may be disposed of by saying that the competent examiner can easily control the experiment in such a way that embarrassment is soon replaced by self-confidence, and in such a way that effort is kept at its maximum. As for mischievous deception, it would be a poor clinicist who could not recognize and deal with the little that is likely to arise.

Cautions regarding embarrassment, fatigue, fright, illness, etc. are given in