It should be emphasized that merely to name the tests in this way gives little idea of their nature and meaning, and tells nothing about Binet's method of conducting the 54 experiments. In order to use the tests intelligently it is necessary to acquaint one's self thoroughly with the purpose of each test, its correct procedure, and the psychological interpretation of different types of response.[10]

[10] See Part II of this volume, and References 1 and 29, for discussion and interpretation of the individual tests.

In fairness to Binet, it should also be borne in mind that the scale of tests was only a rough approximation to the ideal which the author had set himself to realize. Had his life been spared a few years longer, he would doubtless have carried the method much nearer perfection.

HOW THE SCALE IS USED. By means of the Binet tests we can judge the intelligence of a given individual by comparison with standards of intellectual performance for normal children of different ages. In order to make the comparison it is only necessary to begin the examination of the subject at a point in the scale where all the tests are passed successfully, and to continue up the scale until no more successes are possible. Then we compare our subject's performances with the standard for normal children of the same age, and note the amount of acceleration or retardation.

Let us suppose the subject being tested is 9 years of age. If he goes as far in the tests as normal 9-year-old children ordinarily go, we can say that the child has a "mental age" of 9 years, which in this case is normal (our child being 9 years of age). If he goes only as far as normal 8-year-old children ordinarily go, we say that his "mental age" is 8 years. In like manner, a mentally defective child of 9 years may have a "mental age" of only 4 years, or a young genius of 9 years may have a mental age of 12 or 13 years.

SPECIAL CHARACTERISTICS OF THE BINET-SIMON METHOD. Psychologists had experimented with intelligence tests for at least twenty years before the Binet scale made its appearance. The question naturally suggests itself why Binet should have been successful in a field where previous efforts had been for the most part futile. The answer to this question is found in three essential differences between Binet's method and those formerly employed.

1. The use of age standards. Binet was the first to utilize the idea of age standards, or norms, in the measurement of intelligence. It will be understood, of course, that Binet did not set out to invent tests of 10-year intelligence, 6-year intelligence, etc. Instead, as already explained, he began with a series of tests ranging from very easy to very difficult, and by trying these tests on children of different ages and noting the percentages of successes in the various years, he was able to locate them (approximately) in the years where they belonged.

This plan has the great advantage of giving us standards which are easily grasped. To say, for illustration, that a given subject has a grade of intelligence equal to that of the average child of 8 years is a statement whose general import does not need to be explained. Previous investigators had worked with subjects the degree of whose intelligence was unknown, and with tests the difficulty of which was equally unknown. An immense amount of ingenuity was spent in devising tests which were used in such a way as to preclude any very meaningful interpretation of the responses.

The Binet method enables us to characterize the intelligence of a child in a far more definite way than had hitherto been possible. Current descriptive terms like "bright," "moderately bright," "dull," "very dull," "feeble-minded," etc., have had no universally accepted meaning. A child who is designated by one person as "moderately bright" may be called "very bright" by another person. The degree of intelligence which one calls "moderate dullness," another may call "extreme dullness," etc. But every one knows what is meant by the term 8-year mentality, 4-year mentality, etc., even if he is not able to define these grades of intelligence in psychological terms; and by ascertaining experimentally what intellectual tasks children of different ages can perform, we are, of course, able to make our age standards as definite as we please.

Why should a device so simple have waited so long for a discoverer? We do not know. It is of a class with many other unaccountable mysteries in the development of scientific method. Apparently the idea of an age-grade method, as this is called, did not come to Binet himself until he had experimented with intelligence tests for some fifteen years. At least his first provisional scale, published in 1905, was not made up according to the age-grade plan. It consisted merely of 30 tests, arranged roughly in order of difficulty. Although Binet nowhere gives any account of the steps by which this crude and ungraded scale was transformed into the relatively complete age-grade scale of 1908, we can infer that the original and ingenious idea of utilizing age norms was suggested by the data collected with the 1905 scale. However the discovery was made, it ranks, perhaps, from the practical point of view, as the most important in all the history of psychology.

2. The kind of mental functions brought into play. In the second place, the Binet tests differ from most of the earlier attempts in that they are designed to test the higher and more complex mental processes, instead of the simpler and more elementary ones. Hence they set problems for the reasoning powers and ingenuity, provoke judgments about abstract matters, etc., instead of attempting to measure sensory discrimination, mere retentiveness, rapidity of reaction, and the like. Psychologists had generally considered the higher processes too complex to be measured directly, and accordingly sought to get at them indirectly by correlating supposed intelligence with simpler processes which could readily be measured, such as reaction time, rapidity of tapping, discrimination of tones and colors, etc. While they were disputing over their contradictory findings in this line of exploration, Binet went directly to the point and succeeded where they had failed.

It is now generally admitted by psychologists that higher intelligence is little concerned in such elementary processes as those mentioned above. Many of the animals have keen sensory discrimination. Feeble-minded children, unless of very low grade, do not differ very markedly from normal children in sensitivity of the skin, visual acuity, simple reaction time, type of imagery, etc. But in power of comprehension, abstraction, and ability to direct thought, in the nature of the associative processes, in amount of information possessed, and in spontaneity of attention, they differ enormously.

3. Binet would test "general intelligence." Finally, Binet's success was largely due to his abandonment of the older "faculty psychology" which, far from being defunct, had really given direction to most of the earlier work with mental tests. Where others had attempted to measure memory attention, sense discrimination, etc., as separate faculties or functions, Binet undertook to ascertain the general level of intelligence. Others had thought the task easier of accomplishment by measuring each division or aspect of intelligence separately, and summating the results. Binet, too, began in this way, and it was only after years of experimentation by the usual methods that he finally broke away from them and undertook, so to speak, to triangulate the height of his tower without first getting the dimensions of the individual stones which made it up.

The assumption that it is easier to measure a part, or one aspect, of intelligence than all of it, is fallacious in that the parts are not separate parts and cannot be separated by any refinement of experiment. They are interwoven and intertwined. Each ramifies everywhere and appears in all other functions. The analogy of the stones of the tower does not really apply. Memory, for example, cannot be tested separately from attention, or sense-discrimination separately from the associative processes. After many vain attempts to disentangle the various intellective functions, Binet decided to test their combined functional capacity without any pretense of measuring the exact contribution of each to the total product. It is hardly too much to say that intelligence tests have been successful just to the extent to which they have been guided by this aim.

Memory, attention, imagination, etc., are terms of "structural psychology." Binet's psychology is dynamic. He conceives intelligence as the sum total of those thought processes which consist in mental adaptation. This adaptation is not explicable in terms of the old mental "faculties." No one of these can explain a single thought process, for such process always involves the participation of many functions whose separate roles are impossible to distinguish accurately. Instead of measuring the intensity of various mental states (psycho-physics), it is more enlightening to measure their combined effect on adaptation. Using a biological comparison, Binet says the old "faculties" correspond to the separate tissues of an animal or plant, while his own "scheme of thought" corresponds to the functioning organ itself. For Binet, psychology is the science of behavior.

BINET'S CONCEPTION OF GENERAL INTELLIGENCE. In devising tests of intelligence it is, of course, necessary to be guided by some assumption, or assumptions, regarding the nature of intelligence. To adopt any other course is to depend for success upon happy chance.

However, it is impossible to arrive at a final definition of intelligence on the basis of a-priori considerations alone. To demand, as critics of the Binet method have sometimes done, that one who would measure intelligence should first present a complete definition of it, is quite unreasonable. As Stern points out, electrical currents were measured long before their nature was well understood. Similar illustrations could be drawn from the processes involved in chemistry physiology, and other sciences. In the case of intelligence it may be truthfully said that no adequate definition can possibly be framed which is not based primarily on the symptoms empirically brought to light by the test method. The best that can be done in advance of such data is to make tentative assumptions as to the probable nature of intelligence, and then to subject these assumptions to tests which will show their correctness or incorrectness. New hypotheses can then be framed for further trial, and thus gradually we shall be led to a conception of intelligence which will be meaningful and in harmony with all the ascertainable facts.

Such was the method of Binet. Only those unacquainted with Binet's more than fifteen years of labor preceding the publication of his intelligence scale would think of accusing him of making no effort to analyze the mental processes which his tests bring into play. It is true that many of Binet's earlier assumptions proved untenable, and in this event he was always ready, with exceptional candor and intellectual plasticity, to acknowledge his error and to plan a new line of attack.

Binet's conception of intelligence emphasizes three characteristics of the thought process: (1) Its tendency to take and maintain a definite direction; (2) the capacity to make adaptations for the purpose of attaining a desired end; and (3) the power of auto-criticism.[11]

[11] See Binet and Simon: "L'intelligence des imbeciles," in L'Annee Psychologique (1909), pp. 1-147. The last division of this article is devoted to a discussion of the essential nature of the higher thought processes, and is a wonderful example of that keen psychological analysis in which Binet was so gifted.

How these three aspects of intelligence enter into the performances with various tests of the scale is set forth from time to time in our directions for giving and interpreting the individual tests.[12] An illustration which may be given here is that of the "patience test," or uniting the disarranged parts of a divided rectangle. As described by Binet, this operation has the following elements: "(1) to keep in mind the end to be attained, that is to say, the figure to be formed; (2) to try different combinations under the influence of this directing idea, which guides the efforts of the subject even though he may not be conscious of the fact; and (3) to judge the combination which has been made, to compare it with the model, and to decide whether it is the correct one."

[12] See especially pages 162 and 238.

Much the same processes are called for in many other of the Binet tests, particularly those of arranging weights, rearranging dissected sentences, drawing a diamond or square from copy, finding a sentence containing three given words, counting backwards, etc.

However, an examination of the scale will show that the choice of tests was not guided entirely by any single formula as to the nature of intelligence. Binet's approach was a many-sided one. The scale includes tests of time orientation, of three or four kinds of memory, of apperception, of language comprehension, of knowledge about common objects, of free association, of number mastery, of constructive imagination, and of ability to compare concepts, to see contradictions, to combine fragments into a unitary whole, to comprehend abstract terms, and to meet novel situations.

OTHER CONCEPTIONS OF INTELLIGENCE. It is interesting to compare Binet's conception of intelligence with the definitions which have been offered by other psychologists. According to Ebbinghaus, for example, the essence of intelligence lies in comprehending together in a unitary, meaningful whole, impressions and associations which are more or less independent, heterogeneous, or even partly contradictory. "Intellectual ability consists in the elaboration of a whole into its worth and meaning by means of many-sided combination, correction, and completion of numerous kindred associations.... It is a combination activity."

Meumann offers a twofold definition. From the psychological point of view, intelligence is the power of independent and creative elaboration of new products out of the material given by memory and the senses. From the practical point of view, it involves the ability to avoid errors, to surmount difficulties, and to adjust to environment.

Stern defines intelligence as "the general capacity of an individual consciously to adjust his thinking to new requirements: it is general adaptability to new problems and conditions of life."

Spearman, Hart, and others of the English school define intelligence as a "common central factor" which participates in all sorts of special mental activities. This factor is explained in terms of a psycho-physiological hypothesis of "cortex energy," "cerebral plasticity," etc.

The above definitions are only to a slight extent contradictory or inharmonious. They differ mainly in point of view or in the location of the emphasis. Each expresses a part of the truth, and none all of it. It will be evident that the conception of Binet is broad enough to include the most important elements in each of the other definitions quoted.

GUIDING PRINCIPLES IN CHOICE AND ARRANGEMENT OF TESTS. In choosing his tests Binet was guided by the conception of intelligence which we have set forth above. Tests were devised which would presumably bring into play the various mental processes thought to be concerned in intelligence, and then these tests were tried out on normal children of different ages. If the percentage of passes for a given test increased but little or not at all in going from younger to older children this test was discarded. On the other hand, if the proportion of passes increased rapidly with age, and if children of a given age, who on other grounds were known to be bright, passed more frequently than children of the same age who were known to be dull, then the test was judged a satisfactory test of intelligence. As we have shown elsewhere,[13] practically all of Binet's tests fulfill these requirements reasonably well, a fact which bears eloquent testimony to the keen psychological insight of their author.

[13] See p. 55.

In arranging the tests into a system Binet's guiding principle was to find an arrangement of the tests which would cause an average child of any given age to test "at age"; that is, the average 5-year-old must show a mental age of 5 years, the average 8-year-old a mental age of 8 years, etc. In order to secure this result Binet found that his data seemed to require the location of an individual test in that year where it was passed by about two thirds to three fourths of unselected children.

It was in the assembling of the tests that the most serious faults of the scale had their origin. Further investigation has shown that a great many of the tests were misplaced as much as one year, and several of them two years. On the whole, the scale as Binet left it was decidedly too easy in the lower ranges, and too difficult in the upper. As a result, the average child of 5 years was caused to test at not far from 6 years, the average child of 12 years not far from 11. In the Stanford revision an effort has been made to correct this fault, along with certain other generally recognized imperfections.

SOME AVOWED LIMITATIONS OF THE BINET TESTS. The Binet tests have often been criticized for their unfitness to perform certain services which in reality they were never meant to render. This is unfair. We cannot make a just evaluation of the scale without bearing in mind its avowed limitations.

For example, the scale does not pretend to measure the entire mentality of the subject, but only general intelligence. There is no pretense of testing the emotions or the will beyond the extent to which these naturally display themselves in the tests of intelligence. The scale was not designed as a tool for the analysis of those emotional or volitional aberrations which are concerned in such mental disorders as hysteria, insanity, etc. These conditions do not present a progressive reduction of intelligence to the infantile level, and in most of them other factors besides intelligence play an important role. Moreover, even in the normal individual the fruitfulness of intelligence, the direction in which it shall be applied, and its methods of work are to a certain extent determined by the extraneous factors of emotion and volition.

It should, nevertheless, be pointed out that defects of intelligence, in a large majority of cases, also involve disturbances of the emotional and volitional functions. We do not expect to find perfectly normal emotions or will power of average strength coupled with marked intellectual deficiency, and as a matter of fact such a combination is rare indeed. In the course of an examination with the Binet tests, the experienced clinical psychologist is able to gain considerable insight into the subject's emotional and volitional equipment, even though the method was designed primarily for another purpose.

A second misunderstanding can be avoided by remembering that the Binet scale does not pretend to bring to light the idiosyncrasies of special talent, but only to measure the general level of intelligence. It cannot be used for the discovery of exceptional ability in drawing, painting, music, mathematics, oratory, salesmanship, etc., because no effort is made to explore the processes underlying these abilities. It can, therefore, never serve as a detailed chart for the vocational guidance of children, telling us which will succeed in business, which in art, which in medicine, etc. It is not a new kind of phrenology. At the same time, as we have already pointed out, it is capable of bounding roughly the vocational territory in which an individual's intelligence will probably permit success, nothing else preventing.[14]

[14] See p. 17.

In the third place, it must not be supposed that the scale can be used as a complete pedagogical guide. Although intelligence tests furnish data of the greatest significance for pedagogical procedure, they do not suggest the appropriate educational methods in detail. These will have to be worked out in a practical way for the various grades of intelligence, and at great cost of labor and patience.

Finally, in arriving at an estimate of a subject's grade of intelligence and his susceptibility to training, it would be a mistake to ignore the data obtainable from other sources. No competent psychologist, however ardent a supporter of the Binet method he might be, would recommend such a policy. Those who accept the method as all-sufficient are as much in error as those who consider it as no more important than any one of a dozen other approaches. Standardized tests have already become and will remain by far the most reliable single method for grading intelligence, but the results they furnish will always need to be interpreted in the light of supplementary information regarding the subject's personal history, including medical record, accidents, play habits, industrial efficiency, social and moral traits, school success, home environment, etc. Without question, however, the improved Binet tests will contribute more than all other data combined to the end of enabling us to forecast a child's possibilities of future improvement, and this is the information which will aid most in the proper direction of his education.



CHAPTER IV

NATURE OF THE STANFORD REVISION AND EXTENSION

Although the Binet scale quickly demonstrated its value as an instrument for the classification of mentally-retarded and otherwise exceptional children, it had, nevertheless, several imperfections which greatly limited its usefulness. There was a dearth of tests at the higher mental levels, the procedure was so inadequately defined that needless disagreement came about in the interpretation of data, and so many of the tests were misplaced as to make the results of an examination more or less misleading, particularly in the case of very young subjects and those near the adult level. It was for the purpose of correcting these and certain other faults that the Stanford investigation was planned.[15]

[15] The writer wishes to acknowledge his very great indebtedness to Miss Grace Lyman, Dr. George Ordahl, Dr. Louise Ellison Ordahl, Miss Neva Galbreath, Mr. Wilford Talbert, Dr. J. Harold Williams, Mr. Herbert E. Knollin, and Miss Irene Cuneo for their cooeperation in making the tests on which the Stanford revision is chiefly based. Without their loyal assistance the investigation could not have been carried through.

Grateful acknowledgment is also made to the many public school teachers and principals for their generous and invaluable cooeperation in furnishing subjects for the tests, and in supplying, sometimes at considerable cost of labor, the supplementary information which was called for regarding the pupils tested. Their contribution was made in the interest of educational science, and without expectation of personal benefits of any kind. Their professional spirit cannot be too highly commended.

SOURCES OF DATA. Our revision is the result of several years of work, and involved the examination of approximately 2300 subjects, including 1700 normal children, 200 defective and superior children, and more than 400 adults.

Tests of 400 of the 1700 normal children had been made by Childs and Terman in 1910-11, and of 300 children by Trost, Waddle, and Terman in 1911-12. For various reasons, however, the results of these tests did not furnish satisfactory data for a thoroughgoing revision of the scale. Accordingly a new investigation was undertaken, somewhat more extensive than the others, and more carefully planned. Its main features may be described as follows:—

1. The first step was to assemble as nearly as possible all the results which had been secured for each test of the scale by all the workers of all countries. The result was a large sheet of tabulated data for each individual test, including percentages passing the test at various ages, conditions under which the results were secured, method of procedure, etc. After a comparative study of these data, and in the light of results we had ourselves secured, a provisional arrangement of the tests was prepared for try-out.

2. In addition to the tests of the original Binet scale, 40 additional tests were included for try-out. This, it was expected, would make possible the elimination of some of the least satisfactory tests, and at the same time permit the addition of enough new ones to give at least six tests, instead of five, for each age group.

3. A plan was then devised for securing subjects who should be as nearly as possible representative of the several ages. The method was to select a school in a community of average social status, a school attended by all or practically all the children in the district where it was located. In order to get clear pictures of age differences the tests were confined to children who were within two months of a birthday. To avoid accidental selection, all the children within two months of a birthday were tested, in whatever grade enrolled. Tests of foreign-born children, however, were eliminated in the treatment of results. There remained tests of approximately 1000 children, of whom 905 were between 5 and 14 years of age.

4. The children's responses were, for the most part, recorded verbatim. This made it possible to re-score the records according to any desired standard, and thus to fit a test more perfectly to the age level assigned it.

5. Much attention was given to securing uniformity of procedure. A half-year was devoted to training the examiners and another half-year to the supervision of the testing. In the further interests of uniformity all the records were scored by one person (the writer).

METHOD OF ARRIVING AT A REVISION. The revision of the scale below the 14-year level was based almost entirely on the tests of the above-mentioned 1,000 unselected children. The guiding principle was to secure an arrangement of the tests and a standard of scoring which would cause the median mental age of the unselected children of each age group to coincide with the median chronological age. That is, a correct scale must cause the average child of 5 years to test exactly at 5, the average child at 6 to test exactly at 6, etc. Or, to express the same fact in terms of intelligence quotient,[16] a correct scale must give a median intelligence quotient of unity, or 100 per cent, for unselected children of each age.

[16] The intelligence quotient (often designated as I Q) is the ratio of mental age to chronological age. (See pp. 65 ff. and 78 ff.)

If the median mental age resulting at any point from the provisional arrangement of tests was too high or too low, it was only necessary to change the location of certain of the tests, or to change the standard of scoring, until an order of arrangement and a standard of passing were found which would throw the median mental age where it belonged. We had already become convinced, for reasons too involved for presentation here, that no satisfactory revision of the Binet scale was possible on any theoretical considerations as to the percentage of passes which an individual test ought to show in a given year in order to be considered standard for that year.

As was to be expected, the first draft of the revision did not prove satisfactory. The scale was still too hard at some points, and too easy at others. In fact, three successive revisions were necessary, involving three separate scorings of the data and as many tabulations of the mental ages, before the desired degree of accuracy was secured. As finally revised, the scale gives a median intelligence quotient closely approximating 100 for the unselected children of each age from 4 to 14.

Since our school children who were above 14 years and still in the grades were retarded left-overs, it was necessary to base the revision above this level on the tests of adults. These included 30 business men and 150 "migrating" unemployed men tested by Mr. H. E. Knollin, 150 adolescent delinquents tested by Mr. J. Harold Williams, and 50 high-school students tested by the writer.

The extension of the scale in the upper range is such that ordinarily intelligent adults, little educated, test up to what is called the "average adult" level. Adults whose intelligence is known from other sources to be superior are found to test well up toward the "superior adult" level, and this holds whether the subjects in question are well educated or practically unschooled. The almost entirely unschooled business men, in fact, tested fully as well as high-school juniors and seniors.

Figure 1 shows the distribution of mental ages for 62 adults, including the 30 business men and the 32 high-school pupils who were over 16 years of age. It will be noted that the middle section of the graph represents the "mental ages" falling between 15 and 17. This is the range which we have designated as the "average adult" level. Those above 17 are called "superior adults," those between 13 and 15, "inferior adults." Subjects much over 15 years of age who test in the neighborhood of 12 years may ordinarily be considered border-line cases.



The following method was employed for determining the validity of a test. The children of each age level were divided into three groups according to intelligence quotient, those testing below 90, those between 90 and 109, and those with an intelligence quotient of 110 or above. The percentages of passes on each individual test at or near that age level were then ascertained separately for these three groups. If a test fails to show a decidedly higher proportion of passes in the superior I Q group than in the inferior I Q group, it cannot be regarded as a satisfactory test of intelligence. On the other hand, a test which satisfies this criterion must be accepted as valid or the entire scale must be rejected. Henceforth it stands or falls with the scale as a whole.

When tried out by this method, some of the tests which have been most criticized showed a high degree of reliability; certain others which have been considered excellent proved to be so little correlated with intelligence that they had to be discarded.

After making a few necessary eliminations, 90 tests remained, or 36 more than the number included in the Binet 1911 scale. There are 6 at each age level from 3 to 10, 8 at 12, 6 at 14, 6 at "average adult," 6 at "superior adult," and 16 alternative tests. The alternative tests, which are distributed among the different groups, are intended to be used only as substitutes when one or more of the regular tests have been rendered, by coaching or otherwise, undesirable.[17]

[17] See p. 137 ff. for explanations regarding the calculation of mental age and the use of alternative tests.

Of the 36 new tests, 27 were added and standardized in the various Stanford investigations. Two tests were borrowed from the Healy-Fernald series, one from Kuhlmann, one was adapted from Bonser, and the remaining five were amplifications or adaptations of some of the earlier Binet tests.

Following is a complete list of the tests of the Stanford revision. Those designated al. are alternative tests. The guide for giving and scoring the tests is presented at length in Part II of this volume.

The Stanford revision and extension

Year III. (6 tests, 2 months each.) 1. Points to parts of body. (3 to 4.) Nose; eyes; mouth; hair. 2. Names familiar objects. (3 to 5.) Key, penny, closed knife, watch, pencil. 3. Pictures, enumeration or better. (At least 3 objects enumerated in one picture.) (a) Dutch Home; (b) River Scene; (c) Post-Office. 4. Gives sex. 5. Gives last name. 6. Repeats 6 to 7 syllables. (1 to 3.) Al. Repeats 3 digits. (1 success in 3 trials. Order correct.)

Year IV. (6 tests, 2 months each.) 1. Compares lines. (3 trials, no error.) 2. Discrimination of forms. (Kuhlmann.) (Not over 3 errors.) 3. Counts 4 pennies. (No error.) 4. Copies square. (Pencil. 1 to 3.) 5. Comprehension, 1st degree. (2 to 3.) (Stanford addition.) "What must you do": "When you are sleepy?" "Cold?" "Hungry?" 6. Repeats 4 digits. (1 to 3. Order correct.) (Stanford addition.) Al. Repeats 12 to 13 syllables. (1 to 3 absolutely correct, or 2 with 1 error each.)

Year V. (6 tests, 2 months each.) 1. Comparison of weights. (2 to 3.) 3-15; 15-3; 3-15. 2. Colors. (No error.) Red; yellow; blue; green. 3. AEsthetic comparison. (No error.) 4. Definitions, use or better. (4 to 6.) Chair; horse; fork; doll; pencil; table. 5. Patience, or divided rectangle. (2 to 3 trials. 1 minute each.) 6. Three commissions. (No error. Order correct.) Al. Age.

Year VI. (6 tests, 2 months each.) 1. Right and left. (No error.) Right hand; left ear; right eye. 2. Mutilated pictures. (3 to 4 correct.) 3. Counts 13 pennies. (1 to 2 trials, without error.) 4. Comprehension, 2d degree. (2 to 3.) "What's the thing for you to do": (a) "If it is raining when you start to school?" (b) "If you find that your house is on fire?" (c) "If you are going some place and miss your car?" 5. Coins. (3 to 4.) Nickel; penny; quarter; dime. 6. Repeats 16 to 18 syllables. (1 to 3 absolutely correct, or 2 with 1 error each.) Al. Morning or afternoon.

Year VII. (6 tests, 2 months each.) 1. Fingers. (No error.) Right; left; both. 2. Pictures, description or better. (Over half of performance description:) Dutch Home; River Scene; Post-Office. 3. Repeats 5 digits. (1 to 3. Order correct.) 4. Ties bow-knot. (Model shown. 1 minute.) (Stanford addition.) 5. Gives differences. (2 to 3.) Fly and butterfly; stone and egg; wood and glass. 6. Copies diamond. (Pen. 2 to 3.) Al. 1. Names days of week. (Order correct. 2 to 3 checks correct.) Al. 2. Repeats 3 digits backwards. (1 to 3.)

Year VIII. (6 tests, 2 months each.) 1. Ball and field. (Inferior plan or better.) (Stanford addition.) 2. Counts 20 to 1. (40 seconds. 1 error allowed.) 3. Comprehension, 3d degree. (2 to 3.) "What's the thing for you to do": (a) "When you have broken something which belongs to some one else?" (b) "When you are on your way to school and notice that you are in danger of being tardy?" (c) "If a playmate hits you without meaning to do it?" 4. Gives similarities, two things. (2 to 4.) (Stanford addition.) Wood and coal; apple and peach; iron and silver; ship and automobile. 5. Definitions superior to use. (2 to 4.) Balloon; tiger; football; soldier. 6. Vocabulary, 20 words. (Stanford addition. For list of words used, see record booklet.) Al. 1. First six coins. (No error.) Al. 2. Dictation. ("See the little boy." Easily legible. Pen. 1 minute.)

Year IX. (6 tests, 2 months each.) 1. Date. (Allow error of 3 days in c, no error in a, b, or d.) (a) day of week; (b) month; (c) day of month; (d) year. 2. Weights. (3, 6, 9, 12, 15. Procedure not illustrated. 2 to 3.) 3. Makes change. (2 to 3. No coins, paper, or pencil.) 10—4; 15—12; 25—4. 4. Repeats 4 digits backwards. (1 to 3.) (Stanford addition.) 5. Three words. (2 to 3. Oral. 1 sentence or not over 2 cooerdinate clauses.) Boy, river, ball; work, money, men; desert, rivers, lakes. 6. Rhymes. (3 rhymes for two of three words. 1 minute for each part.) Day; mill; spring. Al. 1. Months. (15 seconds and 1 error in naming. 2 checks of 3 correct.) Al. 2. Stamps, gives total value. (Second trial if individual values are known.)

Year X. (6 tests, 2 months each.) 1. Vocabulary, 30 words. (Stanford addition.) 2. Absurdities. (4 to 5. Warn. Spontaneous correction allowed.) (Four of Binet's, one Stanford.) 3. Designs. (1 correct, 1 half correct. Expose 10 seconds.) 4. Reading and report. (8 memories. 35 seconds and 2 mistakes in reading.) (Binet's selection.) 5. Comprehension, 4th degree. (2 to 3. Question may be repeated.) (a) "What ought you to say when some one asks your opinion about a person you don't know very well?" (b) "What ought you to do before undertaking (beginning) something very important?" (c) "Why should we judge a person more by his actions than by his words?" 6. Names 60 words. (Illustrate with clouds, dog, chair, happy.) Al. 1. Repeats 6 digits. (1 to 2. Order correct.) (Stanford addition.) Al. 2. Repeats 20 to 22 syllables. (1 to 3 correct, or 2 with 1 error each.) Al. 3. Form board. (Healy-Fernald Puzzle A. 3 times in 5 minutes.)

Year XII. (8 tests, 3 months each.) 1. Vocabulary, 40 words. (Stanford addition.) 2. Abstract words. (3 to 5.) Pity; revenge; charity; envy; justice. 3. Ball and field. (Superior plan.) (Stanford addition.) 4. Dissected sentences. (2 to 3. 1 minute each.) 5. Fables. (Score 4; i.e., two correct or the equivalent in half credits.) (Stanford addition.) Hercules and Wagoner; Maid and Eggs; Fox and Crow; Farmer and Stork; Miller, Son, and Donkey. 6. Repeats 5 digits backwards. (1 to 3.) (Stanford addition.) 7. Pictures, interpretation. (3 to 4. "Explain this picture.") Dutch Home; River Scene; Post-Office; Colonial Home. 8. Gives similarities, three things. (3 to 5.) (Stanford addition.) Snake, cow, sparrow; book, teacher, newspaper; wool, cotton, leather; knife-blade, penny, piece of wire; rose, potato, tree.

Year XIV. (6 tests, 4 months each.) 1. Vocabulary, 50 words. (Stanford addition.) 2. Induction test. (Gets rule by 6th folding.) (Stanford addition.) 3. President and king. (Power; accession; tenure. 2 to 3.) 4. Problems of fact. (2 to 3.) (Binet's two and one Stanford addition.) 5. Arithmetical reasoning. (1 minute each. 2 to 3.) (Adapted from Bonser.) 6. Clock. (2 to 3. Error must not exceed 3 or 4 minutes.) 6.22. 8.10. 2.46. Al. Repeats 7 digits. (1 to 2. Order correct.)

"AVERAGE ADULT." (6 tests, 5 months each.) 1. Vocabulary, 65 words. (Stanford addition.) 2. Interpretation of fables. (Score 8.) (Stanford addition.) 3. Difference between abstract words. (3 real contrasts out of 4.) Laziness and idleness; evolution and revolution; poverty and misery; character and reputation. 4. Problem of the enclosed boxes. (3 to 4.) (Stanford addition.) 5. Repeats 6 digits backwards. (1 to 3.) (Stanford addition.) 6. Code, writes "Come quickly." (2 errors. Omission of dot counts half error. Illustrate with "war" and "spy.") (From Healy and Fernald.) Al. 1. Repeats 28 syllables. (1 to 2 absolutely correct.) Al. 2. Comprehension of physical relations. (2 to 3.) (Stanford addition.) Path of cannon ball; weight of fish in water; hitting distant mark.

"SUPERIOR ADULT." (6 tests, 6 months each.) 1. Vocabulary, 75 words. (Stanford addition.) 2. Binet's paper-cutting test. (Draws, folds, and locates holes.) 3. Repeats 8 digits. (1 to 3. Order correct.) (Stanford addition.) 4. Repeats thought of passage heard. (1 to 2.) (Binet's and Wissler's selections adapted.) 5. Repeats 7 digits backwards. (1 to 3.) (Stanford addition.) 6. Ingenuity test. (2 to 3. 5 minutes each.) (Stanford addition.)

SUMMARY OF CHANGES. A comparison of the above list with either the Binet 1908 or 1911 series will reveal many changes. On the whole, it differs somewhat more from the Binet 1911 scale than from that of 1908. Thus, of the 49 tests below the "adult" group in the 1911 scale, 2 are eliminated and 29 are relocated. Of these, 25 are moved downward and 4 upward. The shifts are as follows:—

Down 1 year, 18 Down 2 years, 4 Down 3 years, 2 Down 6 years, 1 Up 1 year, 3 Up 2 years, 1

Of the adult group in Binet's 1911 series 1 is eliminated, 2 are moved up to "superior adult," and 1 is moved up to 14. Accordingly, of Binet's entire 54 tests, we have eliminated 3 and relocated 32, leaving only 19 in the positions assigned them by Binet. The 3 eliminated are: repeating 2 digits, resisting suggestion, and "reversed triangle."

The revision is really more extensive than the above figures would suggest, since minor changes have been made in the scoring of a great many tests in order to make them fit better the locations assigned them. Throughout the scale the procedure and scoring have been worked over and made more definite with the idea of promoting uniformity. This phase of the revision is perhaps more important than the mere relocation of tests. Also, the addition of numerous tests in the upper ranges of the scale affects very considerably the mental ages above the level of 10 or 11 years.

EFFECTS OF THE REVISION ON THE MENTAL AGES SECURED. The most important effect of the revision is to reduce the mental ages secured in the lower ranges of the scale, and to raise considerably the mental ages above 10 or 11 years. This difference also obtains, though to a somewhat smaller extent, between the Stanford revision and those of Goddard and Kuhlmann.

For example, of 104 adult individuals testing by the Stanford revision between 12 and 14 years, and who were therefore somewhat above the level of feeble-mindedness as that term is usually defined, 50 per cent tested below 12 years by the Goddard revision. That the dull and border-line adults are so much more readily distinguished from the feeble-minded by the Stanford revision than by other Binet series is due as much to the addition of tests in the upper groups as to the relocation of existing tests.

On the other hand, the Stanford revision causes young subjects to test lower than any other version of the Binet scale. At 5 or 6 years the mental ages secured by the Stanford revision average from 6 to 10 months lower than other revisions yield.

The above differences are more significant than would at first appear. An error of 10 months in the mental age of a 5-year-old is as serious as an error of 20 months in the case of a 10-year-old. Stating the error in terms of the intelligence quotient makes it more evident. Thus, an error of 10 months in the mental age of a 5-year-old means an error of almost 15 per cent in the intelligence quotient. A scale which tests this much too low would cause the child with a true intelligence quotient of 75 (which ordinarily means feeble-mindedness or border-line intelligence) to test at 90, or only slightly below normal.

Three serious consequences came from the too great ease of the original Binet scale at the lower end, and its too great difficulty at the upper end:—

1. In young subjects the higher grades of mental deficiency were overlooked, because the scale caused such subjects to test only a little below normal.

2. The proportion of feeble-mindedness among adult subjects was greatly overestimated, because subjects who were really of the 12- or 13-year mental level could only earn a mental age of about 11 years.

3. Confusion resulted in efforts to trace the mental growth of either feeble-minded or normal children. For example, by other versions of the Binet scale an average 5-year-old will show an intelligence quotient probably not far from 110 or 115; at 9, an intelligence quotient of about 100; and at 14, an intelligence quotient of about 85 or 90.

By such a scale the true border-line case would test approximately as follows:—

At age 5, 90 I Q (apparently not far below normal). At age 9, 75 I Q (border-line). At age 14, 65 I Q (moron deficiency).

On the other hand, re-tests of children by the Stanford revision have been found to yield intelligence quotients almost identical with those secured from two to four years earlier by the same tests. Those who graded feeble-minded in the first test graded feeble-minded in the second test: the dull remained dull, the average remained average, the superior remained superior, and always in approximately the same degree.[18]

[18] See "Some Problems relating to the Detection of Border-line Cases of Mental Deficiency," by Lewis M. Terman and H. E. Knollin, in Journal of Psycho-Asthemes, June, 1916.

It is unnecessary to emphasize further the importance of having an intelligence scale which is equally accurate at all points. Absolute perfection in this respect is not claimed for the Stanford revision, but it is believed to be at least free from the more serious errors of other Binet arrangements.



CHAPTER V

ANALYSIS OF 1000 INTELLIGENCE QUOTIENTS

An extended account of the 1000 tests on which the Stanford revision is chiefly based has been presented in a separate monograph. This chapter will include only the briefest summary of some of those results of the investigation which contribute to the intelligent use of the revision.

THE DISTRIBUTION OF INTELLIGENCE. The question as to the manner in which intelligence is distributed is one of great practical as well as theoretical importance. One of the most vital questions which can be asked by any nation of any age is the following: "How high is the average level of intelligence among our people, and how frequent are the various grades of ability above and below the average?" With the development of standardized tests we are approaching, for the first time in history, a possible answer to this question.

Most of the earlier Binet studies, however, have thrown little light on the distribution of intelligence because of their failure to avoid the influence of accidental selection in choosing subjects for testing. The method of securing subjects for the Stanford revision makes our results on this point especially interesting.[19] It is believed that the subjects used for this investigation were as nearly representative of average American-born children as it is possible to secure.

[19] See p. 52 ff. for method used to avoid accidental selection of subjects for the Stanford investigation.

The intelligence quotients for these 1000 unselected children were calculated, and their distribution was plotted for the ages separately. The distribution was found fairly symmetrical at each age from 5 to 14. At 15 the range is on either side of 90 as a median, and at 16 on either side of 80 as a median. That the 15- and 16-year-olds test low is due to the fact that these children are left-over retardates and are below average in intelligence.



The I Q's were then grouped in ranges of ten. In the middle group were thrown those from 96 to 105; the ascending groups including in order the I Q's from 106 to 115, 116 to 125, etc.; correspondingly with the descending groups. Figure 2 shows the distribution found by this grouping for the 905 children of ages 5 to 14 combined. The subjects above 14 are not included in this curve because they are left-overs and not representative of their ages.

The distribution for the ages combined is seen to be remarkably symmetrical. The symmetry for the separate ages was hardly less marked, considering that only 80 to 120 children were tested at each age. In fact, the range, including the middle 50 per cent of I Q's, was found practically constant from 5 to 14 years. The tendency is for the middle 50 per cent to fall (approximately) between 93 and 108.

Three important conclusions are justified by the above facts:—

1. Since the frequency of the various grades of intelligence decreases gradually and at no point abruptly on each side of the median, it is evident that there is no definite dividing line between normality and feeble-mindedness, or between normality and genius. Psychologically, the mentally defective child does not belong to a distinct type, nor does the genius. There is no line of demarcation between either of these extremes and the so-called "normal" child. The number of mentally defective individuals in a population will depend upon the standard arbitrarily set up as to what constitutes mental deficiency. Similarly for genius. It is exactly as we should undertake to classify all people into the three groups: abnormally tall, normally tall, and abnormally short.[20]

[20] See Chapter VI for discussion of the significance of various I Q's.

2. The common opinion that extreme deviations below the median are more frequent than extreme deviations above the median seems to have no foundation in fact. Among unselected school children, at least, for every child of any given degree of deficiency there is another child as far above the average I Q as the former is below. We have shown elsewhere the serious consequences of neglect of this fact.[21]

[21] See p. 12 ff.

3. The traditional view that variability in mental traits becomes more marked during adolescence is here contradicted, as far as intelligence is concerned, for the distribution of I Q's is practically the same at each age from 5 to 14. For example, 6-year-olds differ from one another fully as much as do 14-year-olds.

THE VALIDITY OF THE INTELLIGENCE QUOTIENT. The facts presented above argue strongly for the validity of the I Q as an expression of a child's intelligence status. This follows necessarily from the similar nature of the distributions at the various ages. The inference is that a child's I Q, as measured by this scale, remains relatively constant. Re-tests of the same children at intervals of two to five years support the inference. Children of superior intelligence do not seem to deteriorate as they get older, nor dull children to develop average intelligence. Knowing a child's I Q, we can predict with a fair degree of accuracy the course of his later development.

The mental age of a subject is meaningless if considered apart from chronological age. It is only the ratio of retardation or acceleration to chronological age (that is, the I Q) which has significance.

It follows also that if the I Q is a valid expression of intelligence, as it seems to be, then the Binet-Simon "age-grade method" becomes transformed automatically into a "point-scale method," if one wants to use it that way. As such it is superior to any other point scale that has been proposed, because it includes a larger number of tests and its points have definite meaning.[22]

[22] For discussion of the supposed advantages of the "point-scale method," see Yerkes and Bridges: A New Point Scale for Measuring Mental Ability. (Warwick and York, 1915.)

SEX DIFFERENCES. The question as to the relative intelligence of the sexes is one of perennial interest and great social importance. The ancient hypothesis, the one which dates from the time when only men concerned themselves with scientific hypotheses, took for granted the superiority of the male. With the development of individual psychology, however, it was soon found that as far as the evidence of mental tests can be trusted the average intelligence of women and girls is as high as that of men and boys.

If we accept this result we are then confronted with the difficult problem of finding an explanation for the fact that so few of those who have acquired eminence in the various intellectual fields have been women. Two explanations have been proposed: (1) That women become eminent less often than men simply for lack of opportunity and stimulus; and (2) that while the average intelligence of the sexes is the same, extreme variations may be more common in males. It is pointed out that not only are there more eminent men than eminent women, but that statistics also show a preponderance of males in institutions for the mentally defective. Accordingly it is often said that women are grouped closely about the average, while men show a wider range of distribution.



Many hundreds of articles and books of popular or quasi-scientific nature have been written on one aspect or another of this question of sex difference in intelligence; but all such theoretical discussions taken together are worth less than the results of one good experiment. Let us see what our 1000 I Q's have to offer toward a solution of the problem.

1. When the I Q's of the boys and girls were treated separately there was found a small but fairly constant superiority of the girls up to the age of 13 years. At 14, however, the curve for the girls dropped below that for boys. This is shown in Figure 3.

The supplementary data, including the teachers' estimates of intelligence on a scale of five, the teachers' judgments in regard to the quality of the school work, and records showing the age-grade distribution of the sexes, were all sifted for evidence as to the genuineness of the apparent superiority of the girls age for age. The results of all these lines of inquiry support the tests in suggesting that the superiority of the girls is probably real even up to and including age 14, the apparent superiority of the boys at this age being fully accounted for by the more frequent elimination of 14-year-old girls from the grades by promotion to the high school.[23]

[23] It will be remembered that this series of tests did not follow up and test those who had been promoted to high school.

2. However, the superiority of girls over boys is so slight (amounting at most ages to only 2 to 3 points in terms of I Q) that for practical purposes it would seem negligible. This offers no support to the opinion expressed by Yerkes and Bridges that "at certain ages serious injustice will be done individuals by evaluating their scores in the light of norms which do not take account of sex differences."

3. Apart from the small superiority of girls, the distribution of intelligence in the two sexes is not different. The supposed wider variation of boys is not found. Girls do not group themselves about the median more closely than do boys. The range of I Q including the middle fifty per cent is approximately the same for the two sexes.[24]

[24] For an extensive summary of other data on the variability of the sexes see the article by Leta S. Hollingworth, in The American Journal of Sociology (January, 1914), pp. 510-30. It is shown that the findings of others support the conclusions set forth above.

4. When the results for the individual tests were examined, it was found that not many showed very extreme differences as to the per cent of boys and girls passing. In a few cases, however, the difference was rather marked.

The boys were decidedly better in arithmetical reasoning, giving differences between a president and a king, solving the form board, making change, reversing hands of clock, finding similarities, and solving the "induction test." The girls were superior in drawing designs from memory, aesthetic comparison, comparing objects from memory, answering the "comprehension questions," repeating digits and sentences, tying a bow-knot, and finding rhymes.

Accordingly, our data, which for the most part agree with the results of others, justify the conclusion that the intelligence of girls, at least up to 14 years, does not differ materially from that of boys either as regards the average level or the range of distribution. It may still be argued that the mental development of boys beyond the age of 14 years lasts longer and extends farther than in the case of girls, but as a matter of fact this opinion receives little support from such tests as have been made on men and women college students.

The fact that so few women have attained eminence may be due to wholly extraneous factors, the most important of which are the following: (1) The occupations in which it is possible to achieve eminence are for the most part only now beginning to open their doors to women. Women's career has been largely that of home-making, an occupation in which eminence, in the strict sense of the word, is impossible. (2) Even of the small number of women who embark upon a professional career, a majority marry and thereafter devote a fairly large proportion of their energy to bearing and rearing children. (3) Both the training given to girls and the general atmosphere in which they grow up are unfavorable to the inculcation of the professional point of view, and as a result women are not spurred on by deep-seated motives to constant and strenuous intellectual endeavor as men are. (4) It is also possible that the emotional traits of women are such as to favor the development of the sentiments at the expense of innate intellectual endowment.

INTELLIGENCE OF THE DIFFERENT SOCIAL CLASSES. Of the 1000 children, 492 were classified by their teachers according to social class into the following five groups: very inferior, inferior, average, superior, and very superior. A comparative study was then made of the distribution of I Q's for these different groups.[25]

[25] The results of this comparison have been set forth in detail in the monograph of source material and some of the conclusions have been set forth on p. 115 ff. of the present volume.

The data may be summarized as follows:—

1. The median I Q for children of the superior social class is about 7 points above, and that of the inferior social class about 7 points below, the median I Q of the average social group. This means that by the age of 14 inferior class children are about one year below, and superior class children one year above, the median mental age for all classes taken together.

2. That the children of the superior social classes make a better showing in the tests is probably due, for the most part, to a superiority in original endowment. This conclusion is supported by five supplementary lines of evidence: (a) the teachers' rankings of the children according to intelligence; (b) the age-grade progress of the children; (c) the quality of the school work; (d) the comparison of older and younger children as regards the influence of social environment; and (e) the study of individual cases of bright and dull children in the same family.

3. In order to facilitate comparison, it is advisable to express the intelligence of children of all social classes in terms of the same objective scale of intelligence. This scale should be based on the median for all classes taken together.

4. As regards their responses to individual tests, our children of a given social class were not distinguishable from children of the same intelligence in any other social class.

THE RELATION OF THE I Q TO THE QUALITY OF THE CHILD'S SCHOOL WORK. The school work of 504 children was graded by the teachers on a scale of five grades: very inferior, inferior, average, superior, and very superior. When this grouping was compared with that made on the basis of I Q, fairly close agreement was found. However, in about one case out of ten there was rather serious disagreement; a child, for example, would be rated as doing average school work when his I Q would place him in the very inferior intelligence group.

When the data were searched for explanations of such disagreements it was found that most of them were plainly due to the failure of teachers to take into account the age of the child when grading the quality of his school work.[26] When allowance was made for this tendency there were no disagreements which justified any serious suspicion as to the accuracy of the intelligence scale. Minor disagreements may, of course, be disregarded, since the quality of school work depends in part on other factors than intelligence, such as industry, health, regularity of attendance, quality of instruction, etc.

[26] See p. 24 ff.

THE RELATION BETWEEN I Q AND GRADE PROGRESS. This comparison, which was made for the entire 1000 children, showed a fairly high correlation, but also some astonishing disagreements. Nine-year intelligence was found all the way from grade 1 to grade 7, inclusive; 10-year intelligence all the way from grade 2 to grade 7; and 12-year intelligence all the way from grade 3 to grade 8. Plainly the school's efforts at grading fail to give homogeneous groups of children as regards mental ability. On the whole, the grade location of the children did not fit their mental ages much better than it did their chronological ages.

When the data were examined, it was found that practically every child whose grade failed to correspond fairly closely with his mental age was either exceptionally bright or exceptionally dull. Those who tested between 96 and 105 I Q were never seriously misplaced in school. The very dull children, however, were usually located from one to three grades above where they belonged by mental age, and the duller the child the more serious, as a rule, was the misplacement. On the other hand, the very bright children were nearly always located from one to three grades below where they belonged by mental age, and the brighter the child the more serious the school's mistake. The child of 10-year mental age in the second grade, for example, is almost certain to be about 7 or 8 years old; the child of 10-year intelligence in the sixth grade is almost certain to be 13 to 15 years of age.

All this is due to one fact, and one alone: the school tends to promote children by age rather than ability. The bright children are held back, while the dull children are promoted beyond their mental ability. The retardation problem is exactly the reverse of what we have thought it to be. It is the bright children who are retarded, and the dull children who are accelerated.

The remedy is to be sought in differentiated courses (special classes) for both kinds of mentally exceptional children. Just as many special classes are needed for superior children as for the inferior. The social consequences of suitable educational advantages for children of superior ability would no doubt greatly exceed anything that could possibly result from the special instruction of dullards and border-line cases.[27]

[27] See Chapter VI for further discussion of the school progress possible to children of various I Q's.

Special study of the I Q's between 70 and 79 revealed the fact that a child of this grade of intelligence never does satisfactory work in the grade where he belongs by chronological age. By the time he has attended school four or five years, such a child is usually found doing "very inferior" to "average" work in a grade from two to four years below his age.

On the other hand, the child with an I Q of 120 or above is almost never found below the grade for his chronological age, and occasionally he is one or two grades above. Wherever located, his work is always "superior" or "very superior," and the evidence suggests strongly that it would probably remain so even if extra promotions were granted.

CORRELATION BETWEEN I Q AND THE TEACHERS' ESTIMATES OF THE CHILDREN'S INTELLIGENCE. By the Pearson formula the correlation found between the I Q's and the teachers' rankings on a scale of five was .48. This is about what others have found, and is both high enough and low enough to be significant. That it is moderately high in so far corroborates the tests. That it is not higher means that either the teachers or the tests have made a good many mistakes.

When the data were searched for evidence on this point, it was found, as we have shown in Chapter II, that the fault was plainly on the part of the teachers. The serious mistakes were nearly all made with children who were either over age or under age for their grade, mostly the former. In estimating children's intelligence, just as in grading their school success, the teachers often failed to take account of the age factor. For example, the child whose mental age was, say, two years below normal, and who was enrolled in a class with children about two years younger than himself, was often graded "average" in intelligence.

The tendency of teachers is to estimate a child's intelligence according to the quality of his school work in the grade where he happens to be located. This results in overestimating the intelligence of older, retarded children, and underestimating the intelligence of the younger, advanced children. The disagreements between the tests and the teachers' estimates are thus found, when analyzed, to confirm the validity of the test method rather than to bring it under suspicion.

THE VALIDITY OF THE INDIVIDUAL TESTS. The validity of each test was checked up by measuring it against the scale as a whole in the manner described on p. 55. For example, if 10-year-old children having 11-year intelligence succeed with a given test decidedly better than 10-year-old children who have 9-year intelligence, then either this test must be accepted as valid or the scale as a whole must be rejected. Since we know, however, that the scale as a whole has at least a reasonably high degree of reliability, this method becomes a sure and ready means of judging the worth of a test.

When the tests were tried out in this way it was found that some of those which have been most criticized have in reality a high correlation with intelligence. Among these are naming the days of the week, giving the value of stamps, counting thirteen pennies, giving differences between president and king, finding rhymes, giving age, distinguishing right and left, and interpretation of pictures. Others having a high reliability are the vocabulary tests, arithmetical reasoning, giving differences, copying a diamond, giving date, repeating digits in reverse order, interpretation of fables, the dissected sentence test, naming sixty words, finding omissions in pictures, and recognizing absurdities.

Among the somewhat less satisfactory tests are the following: repeating digits (direct order), naming coins, distinguishing forenoon and afternoon, defining in terms of use, drawing designs from memory, and aesthetic comparison. Binet's "line suggestion" test correlated so little with intelligence that it had to be thrown out. The same was also true of two of the new tests which we had added to the series for try-out.

Tests showing a medium correlation with the scale as a whole include arranging weights, executing three commissions, naming colors, giving number of fingers, describing pictures, naming the months, making change, giving superior definitions, finding similarities, reading for memories, reversing hands of clock, defining abstract words, problems of fact, bow-knot, induction test, and comprehension questions.

A test which makes a good showing on this criterion of agreement with the scale as a whole becomes immune to theoretical criticisms. Whatever it appears to be from mere inspection, it is a real measure of intelligence. Henceforth it stands or falls with the scale as a whole.

The reader will understand, of course, that no single test used alone will determine accurately the general level of intelligence. A great many tests are required; and for two reasons: (1) because intelligence has many aspects; and (2) in order to overcome the accidental influences of training or environment. If many tests are used no one of them need show more than a moderately high correlation with the scale as a whole. As stated by Binet, "Let the tests be rough, if there are only enough of them."



CHAPTER VI

THE SIGNIFICANCE OF VARIOUS INTELLIGENCE QUOTIENTS

FREQUENCY OF DIFFERENT DEGREES OF INTELLIGENCE. Before we can interpret the results of an examination it is necessary to know how frequently an I Q of the size found occurs among unselected children. Our tests of 1000 unselected children enable us to answer this question with some degree of definiteness. A study of these 1000 I Q's shows the following significant facts:—

The lowest 1 % go to 70 or below, the highest 1 % reach 130 or above " " 2 % " " 73 " " " " 2 % " 128 " " " " 3 % " " 76 " " " " 3 % " 125 " " " " 5 % " " 78 " " " " 5 % " 122 " " " " 10 % " " 85 " " " " 10 % " 116 " " " " 15 % " " 88 " " " " 15 % " 113 " " " " 20 % " " 91 " " " " 20 % " 110 " " " " 25 % " " 92 " " " " 25 % " 108 " " " " 33+1/3% " " 95 " " " " 33+1/3% " 106 " "

Or, to put some of the above facts in another form:—

The child reaching 110 is equaled or excelled by 20 out of 100 " " " (about) 115 " " " " " 10 " " " " " " " 125 " " " " " 3 " " " " " " " 130 " " " " " 1 " " "

Conversely, we may say regarding the subnormals that:—

The child testing at (about) 90 is equaled or excelled by 80 out of 100 " " " " " 85 " " " " " 90 " " " " " " " " 75 " " " " " 97 " " " " " " " " 70 " " " " " 99 " " "

CLASSIFICATION OF INTELLIGENCE QUOTIENTS. What do the above I Q's imply in such terms as feeble-mindedness, border-line intelligence, dullness, normality, superior intelligence genius, etc.? When we use these terms two facts must be borne in mind: (1) That the boundary lines between such groups are absolutely arbitrary, a matter of definition only; and (2) that the individuals comprising one of the groups do not make up a homogeneous type.

Nevertheless, since terms like the above are convenient and will probably continue to be used, it is desirable to give them as much definiteness as possible. On the basis of the tests we have made, including many cases of all grades of intelligence, the following suggestions are offered for the classification of intelligence quotients:—

I Q Classification

Above 140 "Near" genius or genius. 120-140 Very superior intelligence. 110-120 Superior intelligence. 90-110 Normal, or average, intelligence. 80- 90 Dullness, rarely classifiable as feeble-mindedness. 70- 80 Border-line deficiency, sometimes classifiable as dullness, often as feeble-mindedness. Below 70 Definite feeble-mindedness.

Of the feeble-minded, those between 50 and 70 I Q include most of the morons (high, middle, and low), those between 20 or 25 and 50 are ordinarily to be classed as imbeciles, and those below 20 or 25 as idiots. According to this classification the adult idiot would range up to about 3-year intelligence as the limit, the adult imbecile would have a mental level between 3 and 7 years, and the adult moron would range from about 7-year to 11-year intelligence.

It should be added, however, that the classification of I Q's for the various sub-grades of feeble-mindedness is not very secure, for the reason that the exact curves of mental growth have not been worked out for such grades. As far as the public schools are concerned this does not greatly matter, as they never enroll idiots and very rarely even the high-grade imbecile. School defectives are practically all of the moron and border-line grades, and these it is important teachers should be able to recognize. The following discussions and illustrative cases will perhaps give a fairly definite idea of the significance of various grades of intelligence.[28]

[28] The clinical descriptions to be given are not complete and are designed merely to aid the examiner in understanding the significance of intelligence quotients found.

FEEBLE-MINDEDNESS (RARELY ABOVE 75 I Q.) There are innumerable grades of mental deficiency ranging from somewhat below average intelligence to profound idiocy. In the literal sense every individual below the average is more or less mentally weak or feeble. Only a relatively small proportion of these, however, are technically known as feeble-minded. It is therefore necessary to set forth the criterion as to what constitutes feeble-mindedness in the commonly accepted sense of that word.

The definition in most general use is the one framed by the Royal College of Physicians and Surgeons of London, and adopted by the English Royal Commission on Mental Deficiency. It is substantially as follows:—

A feeble-minded person is one who is incapable, because of mental defect existing from birth or from an early age, (a) of competing on equal terms with his normal fellows; or (b) of managing himself or his affairs with ordinary prudence.

Two things are to be noted in regard to this definition: In the first place, it is stated in terms of social and industrial efficiency. Such efficiency, however, depends not merely on the degree of intelligence, but also on emotional, moral, physical, and social traits as well. This explains why some individuals with I Q somewhat below 75 can hardly be classed as feeble-minded in the ordinary sense of the term, while others with I Q a little above 75 could hardly be classified in any other group.

In the second place, the criterion set up by the definition is not very definite because of the vague meaning of the expression "ordinary prudence." Even the expression "competing on equal terms" cannot be taken literally, else it would include also those who are merely dull. It is the second part of the definition that more nearly expresses the popular criterion, for as long as an individual manages his affairs in such a way as to be self-supporting, and in such a way as to avoid becoming a nuisance or burden to his fellowmen, he escapes the institutions for defectives and may pass for normal.

The most serious defect of the definition comes from the lax interpretation of the term "ordinary prudence," etc. The popular standard is so low that hundreds of thousands of high grade defectives escape identification as such. Moreover, there are many grades of severity in social and industrial competition. For example, most of the members of such families as the Jukes, the Nams, the Hill Folk, and the Kallikaks are able to pass as normal in their own crude environment, but when compelled to compete with average American stock their deficiency becomes evident. It is therefore necessary to supplement the social criterion with a more strictly psychological one.

For this purpose there is nothing else as significant as the I Q. All who test below 70 I Q by the Stanford revision of the Binet-Simon scale should be considered feeble-minded, and it is an open question whether it would not be justifiable to consider 75 I Q as the lower limit of "normal" intelligence. Certainly a large proportion falling between 70 and 75 can hardly be classed as other than feeble-minded, even according to the social criterion.

Examples of feeble-minded school children

F. C. Boy, age 8-6; mental age 4-2; I Q approximately 50. From a very superior home. Has had the best medical care and other attention. Attended a private kindergarten until rejected because he required so much of the teacher's time and appeared uneducable. Will probably develop to about the 6- or 7-year mental level. High grade imbecile. Has since been committed to a state institution. Cases as low as F. C. very rarely get into the public schools.

R. W. Boy, age 13-10; mental age 7-6; I Q approximately 55. Home excellent. Is pubescent. Because of age and maturity has been promoted to the third grade, though he can hardly do the work of the second. Has attended school more than six years. Will probably never develop much if any beyond 8 years, and will never be self-supporting. Low-grade moron.



M. S. Girl, age 7-6; mental age 4-6; I Q 60. Father a gardener, home conditions and medical attention fair. Has twice attempted first grade, but without learning to read more than a few words. In each case teacher requested parents to withdraw her. "Takes" things. Is considered "foolish" by the other children. Will probably never develop beyond a mental level of 8 years.

R. M. Boy, age 15; mental age 9; I Q 60. Decidedly superior home environment and care. After attending school eight years is in fifth grade, though he cannot do the work of the fourth grade. Parents unable to teach him to respect property. Boys torment him and make his life miserable. At middle-moron level and has probably about reached the limit of his development. Has since been committed to a state institution.



S. M. Girl, age 19-2; mental age 10; I Q approximately 65 (not counting age beyond 16). From very superior family. Has attended public and private schools twelve years and has been promoted to seventh grade, where she cannot do the work. Appears docile and childlike, but is subject to spells of disobedience and stubbornness. Did not walk until 4 years old. Plays with young children. Susceptible to attention from men and has to be constantly guarded. Writing excellent, knows the number combinations, but missed all the absurdities and has the vocabulary of an average 10-year-old. The type from which prostitutes often come.

R. H. Boy, age 14; mental age 8-4; I Q 65. Father Irish, mother Spanish. Family comfortable and home care average. Has attended school eight years and is unable to do fourth-grade work satisfactorily. Health excellent and attendance regular. Reads in fourth reader without expression and with little comprehension of what is read. Fair skill in number combinations. Writing and drawing very poor. Cannot use a ruler. Has no conception of an inch.

R. H. is described as high-tempered, irritable, lacking in physical activity, clumsy, and unsteady. Plays little. Just "stands around." Indifferent to praise or blame, has little sense of duty, plays underhand tricks. Is slow, absent-minded, easily confused, in thought, never shows appreciation or interest. So apathetic that he does not hear commands. Voice droning. Speech poor in colloquial expressions.

Three years later, at age of 17, was in a special class attempting sixth-grade work. Reported as doing "absolutely nothing" in that grade. Still sullen, indifferent, and slow in grasping directions, and lacking in play interests. "No apperception of anything, but has mastered such mechanical things as reading (calling the words) and the fundamentals in arithmetic."

In school work, moral traits, and out-of-school behavior R. H. shows himself to be a typical case of moron deficiency.

I. M. Girl, age 14-2; mental age 9; I Q approximately 65. Father a laborer. Does unsatisfactory work in fourth grade. Plays with little girls. A menace to the morals of the school because of her sex interests and lack of self-restraint. Rather good-looking if one does not hunt for appearances of intelligence. Mental reactions intolerably slow. Will develop but little further and will always pass as feeble-minded in any but the very lowest social environment.



G. V. Boy, age 10; mental age 6-4; I Q 65. Father Spanish, mother English. Family poor but fairly respectable. Brothers and sisters all retarded. In high first grade. Work all very poor except writing, drawing, and hand work, in all of which he excels. Is quiet and inactive, lacks self-confidence, and plays little. Mentally slow, inert, "thick," and inattentive. Health fair.

Three years later G. V. was in the low third grade and still doing extremely poor work in everything except manual training, drawing, and writing. Is not likely ever to go beyond the fourth or fifth grade however long he remains in school.

V. J. Girl, age 11-6; mental age 8; I Q 70. Has been tested three times in the last five years, always with approximately the same result in terms of I Q. Home fair to inferior. Has been in a special class two years and in school altogether nearly six years. Is barely able to do third-grade work. Her feeble-mindedness is recognized by teachers and by other pupils. Belongs at about middle-moron to high-moron level.

A. W. Boy, age 9-4; mental age 7; I Q 75. A year and a half ago he tested at 6-2. From superior family, brothers of very superior intelligence. In school three years and has made about a grade and a half. Has higher I Q than V. J. described above, but his deficiency is fully as evident. Is generally recognized as mentally defective. Slyly abstracted one of the pennies used in the test and slipped it into his pocket. Has caused much trouble at school by puncturing bicycle tires. High-grade moron.



A. C. Boy, age 12; mental age 8-5; I Q 70. From Portuguese family of ten children. Has a feeble-minded brother. Parents in comfortable circumstances and respectable. A. C. has attended school regularly since he was 6 years old. Trying unsuccessfully to do the work of the fourth grade. Reads poorly in the third reader. Hesitates, repeats, miscalls words, and never gets the thought. Writes about like a first-grade pupil. Cannot solve such simple problems as "How many marbles can you buy for ten cents if one marble costs five cents?" even when he has marbles and money in his hands. Described by teacher as "mentally slow and inert, inattentive, easily distracted, memory poor, ideas vague and often absurd, does not appreciate stories, slow at comprehending commands." Is also described as "unruly, boisterous, disobedient, stubborn, and lacking sense of propriety. Tattles."

Three years later, at age of 15, was in a special class and was little if any improved. He had, however, learned the mechanics of reading and had mastered the number combinations. Deficiencies described as "of wide range." Conduct, however, had improved. Was "working hard to get on."

A. C. must be considered definitely feeble-minded.

H. S. Boy, age 11; mental age 8-3; I Q approximately 75. At 8 years tested at 6. Parents highly educated, father a scholar. Brother and sister of very superior intelligence. Started to school at 7, but was withdrawn because of lack of progress. Started again at 8 and is now doing poor work in the second grade. Weakly and nervous. Painfully aware of his inability to learn. During the test keeps saying, "I tried anyway," "It's all I can do if I try my best, ain't it?" etc. Regarded defective by other children. Will probably never be able to do work beyond the fourth or fifth grade and is not likely to develop above the 11-year level, if as high.



I. S. Boy, age 9-6; mental age 7; I Q 75. German parentage. Started to school at 6. Now in low second grade and unable to do the work. Health good. Inattentive, mentally slow and inert, easily distracted, speech is monotone. Equally poor in reading, writing, and numbers. I. S. is described as quiet, sullen, indifferent, lazy, and stubborn. Plays little.

Three years later had advanced from low second to low fourth grade, but was as poor as ever in his school work. "Miscalls the simplest words." Moral traits unsatisfactory. May reach sixth or seventh grade if he remains in school long enough.

I. S. learned to walk at 2 years and to talk at 3.

The above are cases of such marked deficiency that there could be no disagreement among competent judges in classifying them in the group of "feeble-minded." All are definitely institutional cases. It is a matter of record, however, that one of the cases, H. S., was diagnosed by a physician (without test) as "backward but not a defective." and with the added encouragement that "the backwardness will be outgrown." Of course the reverse is the case; the deficiency is becoming more and more apparent as the boy approaches the age where more is expected of him.

In at least three of the above cases (S. M., I. S., and I. M.) the teachers had not identified the backwardness as feeble-mindedness. Not far from 2 children out of 100, or 2 out of 1000, in the average public school are as defective as some of those just described. Teachers get so accustomed to seeing a few of them in every group of 200 or 300 pupils that they are likely to regard them as merely dull,—"dreadfully dull," of course,—but not defective.

Children like these, for their own good and that of other pupils, should be kept out of the regular classes. They will rarely be equal to the work of the fifth grade, however long they attend school. They will make a little progress in a well-managed special class, but with the approach of adolescence, at latest, the State should take them into custodial care for its own protection.

BORDER-LINE CASES (USUALLY BETWEEN 70 AND 80 I Q). The border-line cases are those which fall near the boundary generally recognized as such and the higher group usually classed as normal but dull. They are the doubtful cases, the ones we are always trying (rarely with success) to restore to normality.

It must be emphasized, however, that this doubtful group is not marked off by definite I Q limits. Some children with I Q as high as 75 or even 80 will have to be classified as feeble-minded; some as low as 70 I Q may be so well endowed in other mental traits that they may manage as adults to get along fairly well in a simple environment. The ability to compete with one's fellows in the social and industrial world does not depend upon intelligence alone. Such factors as moral traits, industry, environment to be encountered, personal appearance, and influential relatives are also involved. Two children classified above as feeble-minded had an I Q as high as 75. In these cases the emotional, moral, or physical qualities were so defective as to render a normal social life out of the question. This is occasionally true even with an I Q as high as 80. Some of the border-line cases, with even less intelligence, may be so well endowed in other mental traits that they are capable of becoming dependable unskilled laborers, and of supporting a family after a fashion.

Examples of border-line deficiency

S. F. Girl, age 17; mental age 11-6; I Q approximately 72 (disregarding age above 16 years). Father intelligent; mother probably high-grade defective. Lives in a good home with aunt, who is a woman of good sense and skillful in her management of the girl. S. F. has attended excellent schools for eleven years and has recently been promoted to the seventh grade. The teacher admits, however, that she cannot do the work of that grade, but says, "I haven't the heart to let her fail in the sixth grade for the third time." She studies very hard and says she wants to become a teacher! At the time the test was made she was actually studying her books from two to three hours daily at home. The aunt, who is very intelligent, had never thought of this girl as feeble-minded, and had suffered much concern and humiliation because of her inability to teach her to conduct herself properly toward men and not to appropriate other people's property.



S. F. is ordinarily docile, but is subject to fits of anger and obstinacy. She finally determined to leave her home, threatening to take up with a man unless allowed to work elsewhere. Since then she has been tried out in several families, but after a little while in a place she flies into a rage and leaves. She is a fairly capable houseworker when she tries.

This young woman is feeble-minded and should be classed as such. She is listed here with the border-line cases simply for the reason that she belongs to a group whose mental deficiency is almost never recognized without the aid of a psychological test. Probably no physician could be found who would diagnose the case, on the basis of a medical examination alone, as one of feeble-mindedness.

F. H. Boy, age 16-6; mental age 11-5; I Q approximately 72 (disregarding age above 16 years). Tested for three successive years without change of more than four points in I Q. Father a laborer, dull, subject to fits of rage, and beats the boy. Mother not far from border-line. F. H. has always had the best of school advantages and has been promoted to the seventh grade. Is really about equal to fifth-grade work. Fairly rapid and accurate in number combinations, but cannot solve arithmetical problems which require any reasoning. Reads with reasonable fluency, but with little understanding. Appears exceedingly good-natured, but was once suspended from school for hurling bricks at a fellow pupil. Played a "joke" on another pupil by fastening a dangerous, sharp-pointed, steel paper-file in the pupil's seat for him to sit down on. He is cruel, stubborn, and plays truant, but is fairly industrious when he gets a job as errand or delivery boy. Discharged once for taking money.

F. H. is generally called "queer," but is not ordinarily thought of as feeble-minded. His deficiency is real, however, and it is altogether doubtful whether he will be able to make a living and to keep out of trouble, though he is now (at age 20) employed as messenger boy for the Western Union at $30 per month. This is considerably less than pick-and-shovel men get in the community where he lives. Delinquents and criminals often belong to this level of intelligence.

W. C. Boy, age 16-8; mental age 12; I Q 75 (disregarding age above 16 years). Father a college professor. All the other children in the family of unusually superior intelligence. When tested (four years ago) was trying to do seventh-grade work, but with little success. Wanted to leave school and learn farming, but father insisted on his getting the usual grammar-school and high-school education. Made $25 one summer by raising vegetables on a vacant lot. In the four years since the test was made he has managed to get into high school. Teachers say that in spite of his best efforts he learns next to nothing, and they regard him as hopelessly dull. Is docile, lacks all aggressiveness, looks stupid, and has head circumference an inch below normal.

Here is a most pitiful case of the overstimulated backward child in a superior family. Instead of nagging at the boy and urging him on to attempt things which are impossible to his inferior intelligence, his parents should take him out of school and put him at some kind of work which he could do. If the boy had been the son of a common laborer he would probably have left school early and have become a dependable and contented laborer. In a very simple environment he would probably not be considered defective.

C. P. Boy, age 10-2; mental age 7-11; I Q 78. Portuguese boy, son of a skilled laborer. One of eleven children, most of whom have about this same grade of intelligence. Has attended school regularly for four years. Is in the third grade, but cannot do the work. Except for extreme stubbornness his social development is fairly normal. Capable in plays and games, but is regarded as impossible in his school work. Like his brother, M. P., the next case to be described, he will doubtless become a fairly reliable laborer at unskilled work and will not be regarded, in his rather simple environment, as a defective. From the psychological point of view, however, his deficiency is real. He will probably never develop beyond the 11- or 12-year level or be able to do satisfactory school work beyond the fifth or sixth grade.



M. P. Boy, age 14; mental age 10-8; I Q 77. Has been tested four successive years, I Q being always between 75 and 80. Brother to C. P. above. In school nearly eight years and has been promoted to the fifth grade. At 16 was doing poor work in the sixth grade. Good school advantages, as the father has tried conscientiously to give his children "a good education." Perfectly normal in appearance and in play activities and is liked by other children. Seems to be thoroughly dependable both in school and in his outside work. Will probably become an excellent laborer and will pass as perfectly normal, notwithstanding a grade of intelligence which will not develop above 11 or 12 years.



What shall we say of cases like the last two which test at high-grade moronity or at border-line, but are well enough endowed in moral and personal traits to pass as normal in an uncomplicated social environment? According to the classical definition of feeble-mindedness such individuals cannot be considered defectives. Hardly any one would think of them as institutional cases. Among laboring men and servant girls there are thousands like them. They are the world's "hewers of wood and drawers of water." And yet, as far as intelligence is concerned, the tests have told the truth. These boys are uneducable beyond the merest rudiments of training. No amount of school instruction will ever make them intelligent voters or capable citizens in the true sense of the word. Judged psychologically they cannot be considered normal.

It is interesting to note that M. P. and C. P. represent the level of intelligence which is very, very common among Spanish-Indian and Mexican families of the Southwest and also among negroes. Their dullness seems to be racial, or at least inherent in the family stocks from which they come. The fact that one meets this type with such extraordinary frequency among Indians, Mexicans, and negroes suggests quite forcibly that the whole question of racial differences in mental traits will have to be taken up anew and by experimental methods. The writer predicts that when this is done there will be discovered enormously significant racial differences in general intelligence, differences which cannot be wiped out by any scheme of mental culture.

Children of this group should be segregated in special classes and be given instruction which is concrete and practical. They cannot master abstractions, but they can often be made efficient workers, able to look out for themselves. There is no possibility at present of convincing society that they should not be allowed to reproduce, although from a eugenic point of view they constitute a grave problem because of their unusually prolific breeding.

DULL NORMALS (I Q USUALLY 80 TO 90). In this group are included those children who would not, according to any of the commonly accepted social standards, be considered feeble-minded, but who are nevertheless far enough below the actual average of intelligence among races of western European descent that they cannot make ordinary school progress or master other intellectual difficulties which average children are equal to. A few of this class test as low as 75 to 80 I Q, but the majority are not far from 85. The unmistakably normal children who go much below this (in California, at least) are usually Mexicans, Indians, or negroes.

R. G. Negro boy, age 13-5; mental age 10-6; I Q approximately 80. Normal in appearance and conduct, but very dull. Is attempting fifth-grade work in a special class, but is failing. From a fairly good home and has had ordinary school advantages. In the examination his intelligence is very even as far as it goes, but stops rather abruptly after the 10-year tests. Will unquestionably pass as normal among unskilled laborers, but his intelligence will never exceed the 12-year level and he is not likely to advance beyond the seventh grade, if as far.



F. D. Boy, tested at age 10-2; I Q 83, and again at 14-1; I Q 79. Mental age in the first test was 8-6 and in the second test 11. Son of a barber. Father dead; mother capable; makes a good home, and cares for her children well. At 10 was doing unsatisfactory work in the fourth grade, and at 12 unsatisfactory work in low sixth. Good-looking, normal in appearance and social development, and though occasionally obstinate is usually steady. Any one unacquainted with his poor school work and low I Q would consider him perfectly normal. No physical or moral handicaps of any kind that could possibly account for his retardation. Is simply dull. Needs purely a vocational training, but may be able to complete the eighth grade with low marks by the age of 16 or 17.

G. G. Girl, age 12-4; mental age 10-10; I Q 82. From average home. Excellent educational advantages and no physical handicaps. At 12 years was doing very poor work in fifth grade. Appearance, play life, and attitude toward other children normal. Simply dull. Will probably never go beyond the 12- or 13-year level and is not likely to get as far as the high school.

Those testing 80 and 90 will usually be able to reach the eighth grade, but ordinarily only after from one to three or four failures. They are so very numerous (about 15 per cent of the school enrollment) that it is doubtful whether we can expect soon to have special classes enough to accommodate all. The most feasible solution is a differentiated course of study with parallel classes in which every child will be allowed to make the best progress of which he is capable, without incurring the risk of failure and non-promotion. The so-called Mannheim system, or something similar to it, is what we need.