The Measurement of Intelligence Part 2

That the industrially inefficient are often of subnormal intelligence has already been demonstrated in a number of psychological investigations. Of 150 "hoboes" tested under the direction of the writer by Mr. Knollin, at least 15 per cent belonged to the moron grade of mental deficiency, and almost as many more were border-line cases. To be sure, a large proportion were found perfectly normal, and a few even decidedly superior in mental ability, but the ratio of mental deficiency was ten or fifteen times as high as that holding for the general population. Several had as low as 9- or 10-year intelligence, and one had a mental level of 7 years. The industrial history of such subjects, as given by themselves, was always about what the mental level would lead us to expect--unskilled work, lack of interest in accomplishment, frequent discharge from jobs, discouragement, and finally the "road."

The above findings have been fully paralleled by Mr. Glenn Johnson and Professor Eleanor Rowland, of Reed College, who tested 108 unemployed charity cases in Portland, Oregon. Both of these investigators made use of the Stanford revision of the Binet scale, which is especially serviceable in distinguis.h.i.+ng the upper-grade defectives from normals.

It hardly needs to be emphasized that when charity organizations help the feeble-minded to float along in the social and industrial world, and to produce and rear children after their kind, a doubtful service is rendered. A little psychological research would aid the united charities of any city to direct their expenditures into more profitable channels than would otherwise be possible.

OTHER USES OF INTELLIGENCE TESTS. Another important use of intelligence tests is in the study of the factors which influence mental development.

It is desirable that we should be able to guard the child against influences which affect mental development unfavorably; but as long as these influences have not been sifted, weighed, and measured, we have nothing but conjecture on which to base our efforts in this direction.

When we search the literature of child hygiene for reliable evidence as to the injurious effects upon mental ability of malnutrition, decayed teeth, obstructed breathing, reduced sleep, bad ventilation, insufficient exercise, etc., we are met by endless a.s.sertion painfully unsupported by demonstrated fact. We have, indeed, very little exact knowledge regarding the mental effects of any of the factors just mentioned. When standardized mental tests have come into more general use, such influences will be easy to detect wherever they are really present.

Again, the most important question of heredity is that regarding the inheritance of intelligence; but this is a problem which cannot be attacked at all without some accurate means of identifying the thing which is the object of study. Without the use of scales for measuring intelligence we can give no better answer as to the essential difference between a genius and a fool than is to be found in legend and fiction.

Applying this to school children, it means that without such tests we cannot know to what extent a child's mental performances are determined by environment and to what extent by heredity. Is the place of the so-called lower cla.s.ses in the social and industrial scale the result of their inferior native endowment, or is their apparent inferiority merely a result of their inferior home and school training? Is genius more common among children of the educated cla.s.ses than among the children of the ignorant and poor? Are the inferior races really inferior, or are they merely unfortunate in their lack of opportunity to learn?

Only intelligence tests can answer these questions and grade the raw material with which education works. Without them we can never distinguish the results of our educational efforts with a given child from the influence of the child's original endowment. Such tests would have told us, for example, whether the much-discussed "wonder children,"

such as the Sidis and Wiener boys and the Stoner girl, owe their precocious intellectual prowess to superior training (as their parents believe) or to superior native ability. The supposed effects upon mental development of new methods of mind training, which are exploited so confidently from time to time (e.g., the Montessori method and the various systems of sensory and motor training for the feeble-minded), will have to be checked up by the same kind of scientific measurement.

In all these fields intelligence tests are certain to play an ever-increasing role. With the exception of moral character there is nothing as significant for a child's future as his grade of intelligence. Even health itself is likely to have less influence in determining success in life. Although strength and swiftness have always had great survival value among the lower animals, these characteristics have long since lost their supremacy in man's struggle for existence.

For us the rule of brawn has been broken, and intelligence has become the decisive factor in success. Schools, railroads, factories, and the largest commercial concerns may be successfully managed by persons who are physically weak or even sickly. One who has intelligence constantly measures opportunities against his own strength or weakness and adjusts himself to conditions by following those leads which promise most toward the realization of his individual possibilities.

All cla.s.ses of intellects, the weakest as well as the strongest, will profit by the application of their talents to tasks which are consonant with their ability. When we have learned the lessons which intelligence tests have to teach, we shall no longer blame mentally defective workmen for their industrial inefficiency, punish weak-minded children because of their inability to learn, or imprison and hang mentally defective criminals because they lacked the intelligence to appreciate the ordinary codes of social conduct.

CHAPTER II

SOURCES OF ERROR IN JUDGING INTELLIGENCE

ARE INTELLIGENCE TESTS SUPERFLUOUS? Binet tells us that he often encountered the criticism that intelligence tests are superfluous, and that in going to so much trouble to devise his measuring scale he was forcing an open door. Those who made this criticism believed that the observant teacher or parent is able to make an offhand estimate of a child's intelligence which is accurate enough. "It is a stupid teacher,"

said one, "who needs a psychologist to tell her which pupils are not intelligent." Every one who uses intelligence tests meets this att.i.tude from time to time.

This should not be surprising or discouraging. It is only natural that those who are unfamiliar with the methods of psychology should occasionally question their validity or worth, just as there are many excellent people who do not "believe in" vaccination against typhoid and small pox, operations for appendicitis, etc.

There is an additional reason why the applications of psychology have to overcome a good deal of conservatism and skepticism; namely, the fact that every one, whether psychologically trained or not, acquires in the ordinary experiences of life a certain degree of expertness in the observation and interpretation of mental traits. The possession of this little fund of practical working knowledge makes most people slow to admit any one's claim to greater expertness. When the astronomer tells us the distance to Jupiter, we accept his statement, because we recognize that our ordinary experience affords no basis for judgment about such matters. But every one acquires more or less facility in distinguis.h.i.+ng the coa.r.s.er differences among people in intelligence, and this half-knowledge naturally generates a certain amount of resistance to the more refined method of tests.

It should be evident, however, that we need more than the ability merely to distinguish a genius from a simpleton, just as a physician needs something more than the ability to distinguish an athlete from a man dying of consumption. It is necessary to have a definite and accurate diagnosis, one which will differentiate more finely the many degrees and qualities of intelligence. Just as in the case of physical illness, we need to know not merely that the patient is sick, but also why he is sick, what organs are involved, what course the illness will run, and what physical work the patient can safely undertake, so in the case of a r.e.t.a.r.ded child, we need to know the exact degree of intellectual deficiency, what mental functions are chiefly concerned in the defect, whether the deficiency is due to innate endowment, to physical illness, or to faults of education, and what lines of mental activity the child will be able to pursue with reasonable hope of success. In the diagnosis of a case of malnutrition, the up-to-date physician does not depend upon general symptoms, but instead makes a blood test to determine the exact number of red corpuscles per cubic millimeter of blood and the exact percentage of haemoglobin. He has learned that external appearances are often misleading. Similarly, every psychologist who is experienced in the mental examination of school children knows that his own or the teacher's estimate of a child's intelligence is subject to grave and frequent error.

THE NECESSITY OF STANDARDS. In the first place, in order to judge an individual's intelligence it is necessary to have in mind some standard as to what const.i.tutes normal intelligence. This the ordinary parent or teacher does not have. In the case of school children, for example, each pupil is judged with reference to the average intelligence of the cla.s.s. But the teacher has no means of knowing whether the average for her cla.s.s is above, equal to, or below that for children in general. Her standard may be too high, too low, vague, mechanical, or fragmentary.

The same, of course, holds in the case of parents or any one else attempting to estimate intelligence on the basis of common observation.

THE INTELLIGENCE OF r.e.t.a.r.dED CHILDREN USUALLY OVERESTIMATED. One of the most common errors made by the teacher is to overestimate the intelligence of the over-age pupil. This is because she fails to take account of age differences and estimates intelligence on the basis of the child's school performance in the grade where he happens to be located. She tends to overlook the fact that quality of school work is no index of intelligence unless age is taken into account. The question should be, not, "Is this child doing his school work well?" but rather, "In what school grade should a child of this age be able to do satisfactory work?" A high-grade imbecile may do average work in the first grade, and a high-grade moron average work in the third or fourth grade, provided only they are sufficiently over-age for the grade in question.

Our experience in testing children for segregation in special cla.s.ses has time and again brought this fallacy of teachers to our attention. We have often found one or more feeble-minded children in a cla.s.s after the teacher had confidently a.s.serted that there was not a single exceptionally dull child present. In every case where there has been opportunity to follow the later school progress of such a child the validity of the intelligence test has been fully confirmed.

The following are typical examples of the neglect of teachers to take the age factor into account when estimating the intelligence of the over-age child:--

_A. R. Girl, age 11; in low second grade._ She was able to do the work of this grade, not well, but pa.s.sably. The teacher's judgment as to this child's intelligence was "dull but not defective." What the teacher overlooked was the fact that she had judged the child by a 7-year standard, and that, instead of only being able to do the work of the second grade indifferently, a child of this age should have been equal to the work of the fifth grade. In reality, A. R. is definitely feeble-minded. Although she is from a home of average culture, is 11 years old, and has attended school five years, she has barely the intelligence of the average child of six years.

_D. C. Boy, age 17; in fifth grade._ His teacher knew that he was dull, but had not thought of him as belonging to the cla.s.s of feeble-minded. She had judged this boy by the 11-year standard and had perhaps been further misled by his normal appearance and exceptionally satisfactory behavior. The Binet test quickly showed that he had a mental level of approximately 9 years. There is little probability that his comprehension will ever surpa.s.s that of the average 10-year-old.

_R. A. Boy, age 17; mental age 11; sixth grade; school work "nearly average"; teacher's estimate of intelligence "average."_ Test plainly shows this child to be a high-grade moron, or border-liner at best. Had attended school regularly 11 years and had made 6 grades. Teacher had compared child with his 12-year-old cla.s.smates.

_H. A. Boy, age 14; mental age 9-6; low fourth grade; school work "inferior"; teacher's estimate of intelligence "average."_ The teacher blamed the inferior quality of school work to "bad home environment." As a matter of fact, the boy's father is feeble-minded and the normality of the mother is questionable.

An older brother is in a reform school. We are perfectly safe in predicting that this boy will not complete the eighth grade even if he attends school till he is 21 years of age.

_F. I. Boy, age 12-11; mental age 9-4; third grade; school work "average"; teacher's estimate of intelligence "average"; social environment "average"; health good and attendance regular._ Intelligence and school success are what we should expect of an average 9-year-old.

_D. A. Boy, age 12; mental age 9-2; third grade; school work "inferior"; teacher's estimate of intelligence "average."_ Teacher imputes inferior school work to "absence from school and lack of interest in books"; we have yet to find a child with a mental age 25 per cent below chronological age who _was_ particularly interested in books or enthusiastic about school.

_C. U. Girl, age 10; mental age 7-8; second grade; school work "average"; teacher's estimate of intelligence "average."_ Teacher blames adenoids and bad teeth for r.e.t.a.r.dation. No doubt of child's mental deficiency.

_P. I. Girl, age 8-10; mental age 6-7; has been in first grade 2 years; school work "average"; teacher's estimate of intelligence "average."_ The mother and one brother of this girl are both feeble-minded.

_H. O. Girl, age 7-10; mental age 5-2; first grade for 2 years; school work "inferior"; teacher's estimate of intelligence "average."_ The teacher nevertheless adds, "This child is not normal, but her ability to respond to drill shows that she has intelligence." It is of course true that even feeble-minded children of 5-year intelligence are able to profit a little from drill. Their weakness comes to light in their inability to perform higher types of mental activity.

THE INTELLIGENCE OF SUPERIOR CHILDREN USUALLY UNDERESTIMATED. We have already mentioned the frequent failure of teachers and parents to recognize superior ability.[7] The fallacy here is again largely due to the neglect of the age factor, but the resulting error is in the opposite direction from that set forth above. The superior child is likely to be a year or two younger than the average child of his grade, and is accordingly judged by a standard which is too high. The following are ill.u.s.trations:--

[7] See p. 13 _ff._

_M. L. Girl, age 11-2; mental age "average adult" (16); sixth grade; school work "superior"; teacher's estimate of intelligence "average."_ Teacher credits superior school work to "unusual home advantages." Father a college professor. The teacher considers the child accelerated in school. In reality she ought to be in the second year of high school instead of in the sixth grade.

_H. A. Boy, age 11; mental age 14; sixth grade; school work "average"; teacher's estimate of intelligence "average."_ According to the supplementary information the boy is "wonderfully attentive," "studious," and possessed of "all-round ability." The estimate of "average intelligence" was probably the result of comparing him with cla.s.smates who averaged about a year older.

_K. R. Girl, age 6-1; mental age 8-5; second grade; school work "average"; teacher's estimate of intelligence "superior"; social environment "average."_ Is it not evident that a child from ordinary social environment, who does work of average quality in the second grade when barely 6 years of age, should be judged "very superior" rather than merely "superior" in intelligence?

The intelligence quotient of this girl is 140, which is not reached by more than one child in two hundred.

_S. A. Boy, age 8-10; mental age 10-9; fourth grade; school work "average"; teacher's estimate of intelligence "average."_ Teacher attributed school acceleration to "studiousness" and "delight in school work." It would be more reasonable to infer that these traits are indications of unusually superior intelligence.

OTHER FALLACIES IN THE ESTIMATION OF INTELLIGENCE. Another source of error in the teacher's judgment comes from the difficulty in distinguis.h.i.+ng genuine dullness from the mental condition which results sometimes from unfavorable social environment or lack of training.

_V. P. Boy, age 7._ Had attended school one year and had profited very little from the instruction. He had learned to read very little, spoke chiefly in monosyllables, and seemed "queer." The teacher suspected his intelligence and asked for a mental examination. The Binet test showed that except for vocabulary, which was unusually low, there was practically no mental r.e.t.a.r.dation. Inquiry disclosed the fact that the boy's parents were uneducated deaf-mutes, and that the boy had a.s.sociated little with other children. Four years later this boy was doing fairly well in school, though a year r.e.t.a.r.ded because of his unfavorable home environment.

_X. Y. Boy, age 10._ Son of a successful business man, he was barely able to read in the second reader. The Binet test revealed an intelligence level which was absolutely normal. The boy was removed to a special cla.s.s where he could receive individual attention, and two years later was found doing good work in a regular cla.s.s of the fifth grade. His bad beginning seemed to have been due to an unfavorable att.i.tude toward school work, due in turn to lack of discipline in the home, and to the fact that because of the father's frequent change of business headquarters the boy had never attended one school longer than three months.

Another source of error in judging intelligence from common observation is the tendency to overestimate the intelligence of the sprightly, talkative, sanguine child, and to underestimate the intelligence of the child who is less emotional, reacts slowly, and talks little. One occasionally finds a feeble-minded adult, perhaps of only 9- or 10-year intelligence, whose verbal fluency, mental liveliness, and self-confidence would mislead the offhand judgment of even the psychologist. One individual of this type, a border-line case at best, was accustomed to harangue street audiences and had served as "major" in "Kelly's Army," a horde of several hundred unemployed men who a few years ago organized and started to march from San Francisco to Was.h.i.+ngton.

BINET'S QUESTIONNAIRE ON TEACHERS' METHODS OF JUDGING INTELLIGENCE.[8]

Aroused by the skepticism so often shown toward his test method, Binet decided to make a little study of the methods by which teachers are accustomed to arrive at a judgment as to a child's intelligence.

Accordingly, through the cooperation of the director of elementary education in Paris, he secured answers from a number of teachers to the following questions:--

[8] See p. 169 _ff._ of reference 2, at end of this book

1. _By what means do you judge the intelligence of your pupils?_ 2. _How often have you been deceived in your judgments?_

About 40 replies were received. Most of the answers to the first question were vague, one-sided, "verbal," or bookish. Only a few showed much psychological discrimination as to what intelligence is and what its symptoms are. There was a very general tendency to judge intelligence by success in one or more of the school studies. Some thought that ability to master arithmetic was a sure criterion. Others were influenced almost entirely by the pupil's ability to read. One teacher said that the child who can "read so expressively as to make you feel the punctuation" is certainly intelligent, an observation which is rather good, as far as it goes. A few judged intelligence by the pupil's knowledge of such subjects as history and geography, which, as Binet points out, is to confound intelligence with the ability to memorize.

"Memory," says Binet, is a "great simulator of intelligence." It is a wise teacher who is not deceived by it. Only a small minority mentioned resourcefulness in play, capacity to adjust to practical situations, or any other out-of-school criteria.