The Measurement of Intelligence

L >> Lewis Madison Terman >> The Measurement of Intelligence

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Every child who fails in his school work or is in danger of failing
should be given a mental examination. The examination takes less than
one hour, and the result will contribute more to a real understanding of
the case than anything else that could be done. It is necessary to
determine whether a given child is unsuccessful in school because of
poor native ability, or because of poor instruction, lack of interest,
or some other removable cause.

It is not sufficient to establish any number of special classes, if they
are to be made the dumping-ground for all kinds of troublesome
cases--the feeble-minded, the physically defective, the merely backward,
the truants, the incorrigibles, etc. Without scientific diagnosis and
classification of these children the educational work of the special
class must blunder along in the dark. In such diagnosis and
classification our main reliance must always be in mental tests,
properly used and properly interpreted.

INTELLIGENCE TESTS OF THE FEEBLE-MINDED. Thus far intelligence tests
have found their chief application in the identification and grading of
the feeble-minded. Their value for this purpose is twofold. In the first
place, it is necessary to ascertain the degree of defect before it is
possible to decide intelligently upon either the content or the method
of instruction suited to the training of the backward child. In the
second place, intelligence tests are rapidly extending our conception of
"feeble-mindedness" to include milder degrees of defect than have
generally been associated with this term. The earlier methods of
diagnosis caused a majority of the higher grade defectives to be
overlooked. Previous to the development of psychological methods the
low-grade moron was about as high a type of defective as most physicians
or even psychologists were able to identify as feeble-minded.

Wherever intelligence tests have been made in any considerable number in
the schools, they have shown that not far from 2 per cent of the
children enrolled have a grade of intelligence which, however long they
live, will never develop beyond the level which is normal to the average
child of 11 or 12 years. The large majority of these belong to the moron
grade; that is, their mental development will stop somewhere between the
7-year and 12-year level of intelligence, more often between 9 and 12.

The more we learn about such children, the clearer it becomes that they
must be looked upon as real defectives. They may be able to drag
along to the fourth, fifth, or sixth grades, but even by the age of
16 or 18 years they are never able to cope successfully with the more
abstract and difficult parts of the common-school course of study. They
may master a certain amount of rote learning, such as that involved in
reading and in the manipulation of number combinations but they cannot
be taught to meet new conditions effectively or to think, reason, and
judge as normal persons do.

It is safe to predict that in the near future intelligence tests will
bring tens of thousands of these high-grade defectives under the
surveillance and protection of society. This will ultimately result in
curtailing the reproduction of feeble-mindedness and in the elimination
of an enormous amount of crime, pauperism, and industrial inefficiency.
It is hardly necessary to emphasize that the high-grade cases, of the
type now so frequently overlooked, are precisely the ones whose
guardianship it is most important for the State to assume.

INTELLIGENCE TESTS OF DELINQUENTS. One of the most important facts
brought to light by the use of intelligence tests is the frequent
association of delinquency and mental deficiency. Although it has long
been recognized that the proportion of feeble-mindedness among
offenders is rather large, the real amount has, until recently, been
underestimated even by the most competent students of criminology.

The criminologists have been accustomed to give more attention to the
physical than to the mental correlates of crime. Thus, Lombroso and
his followers subjected thousands of criminals to observation and
measurement with regard to such physical traits as size and shape of the
skull, bilateral asymmetries, anomalies of the ear, eye, nose, palate,
teeth, hands, fingers, hair, dermal sensitivity, etc. The search was for
physical "stigmata" characteristic of the "criminal type."

Although such studies performed an important service in creating a
scientific interest in criminology, the theories of Lombroso have been
wholly discredited by the results of intelligence tests. Such tests have
demonstrated, beyond any possibility of doubt, that the most important
trait of at least 25 per cent of our criminals is mental weakness. The
physical abnormalities which have been found so common among prisoners
are not the stigmata of criminality, but the physical accompaniments of
feeble-mindedness. They have no diagnostic significance except in so far
as they are indications of mental deficiency. Without exception, every
study which has been made of the intelligence level of delinquents has
furnished convincing testimony as to the close relation existing between
mental weakness and moral abnormality. Some of these findings are as
follows:--

Miss Renz tested 100 girls of the Ohio State Reformatory and
reported 36 per cent as certainly feeble-minded. In every one of
these cases the commitment papers had given the pronouncement
"intellect sound."

Under the direction of Dr. Goddard the Binet tests were given to
100 juvenile court cases, chosen at random, in Newark, New
Jersey. Nearly half were classified as feeble-minded. One boy
17 years old had 9-year intelligence; another of 151/2 had
8-year intelligence.

Of 56 delinquent girls 14 to 20 years of age tested by Hill and
Goddard, almost half belonged either to the 9- or the 10-year
level of intelligence.

Dr. G. G. Fernald's tests of 100 prisoners at the Massachusetts
State Reformatory showed that at least 25 per cent were
feeble-minded.

Of 1186 girls tested by Miss Dewson at the State Industrial
School for Girls at Lancaster, Pennsylvania, 28 per cent were
found to have subnormal intelligence.

Dr. Katherine Bement Davis's report on 1000 cases entered in the
Bedford Home for Women, New York, stated that there was no doubt
but that at least 157 were feeble-minded. Recently there has
been established at this institution one of the most important
research laboratories of the kind in the United States, with a
trained psychologist, Dr. Mabel Fernald, in charge.

Of 564 prostitutes investigated by Dr. Anna Dwyer in connection
with the Municipal Court of Chicago, only 3 per cent had gone
beyond the fifth grade in school. Mental tests were not made,
but from the data given it is reasonably certain that half or
more were feeble-minded.

Tests, by Dr. George Ordahl and Dr. Louise Ellison Ordahl, of
cases in the Geneva School for Girls, Geneva, Illinois, showed
that, on a conservative basis of classification, at least
18 per cent were feeble-minded. At the Joliet Prison, Illinois,
the same authors found 50 per cent of the female prisoners
feeble-minded, and 26 per cent of the male prisoners. At the St.
Charles School for Boys 26 per cent were feeble-minded.

Tests, by Dr. J. Harold Williams, of 150 delinquents in the
Whittier State School for Boys, Whittier, California, gave
28 per cent feeble-minded and 25 per cent at or near the
border-line. About 300 other juvenile delinquents tested by
Mr. Williams gave approximately the same figures. As a result of
these findings a research laboratory has been established at the
Whittier School, with Dr. Williams in charge. In the girls'
division of the Whittier School, Dr. Grace Fernald collected a
large amount of psychological data on more than 100 delinquent
girls. The findings of this investigation agree closely with
those of Dr. Williams for the boys.

At the State Reformatory, Jeffersonville, Indiana, Dr. von
Klein-Schmid, in an unusually thorough psychological study of
1000 young adult prisoners, finds the proportion of
feeble-mindedness not far from 50 per cent.

But it is needless to multiply statistics. Those given are but samples.
Tests are at present being made in most of the progressive prisons,
reform schools, and juvenile courts throughout the country, and while
there are minor discrepancies in regard to the actual percentage who are
feeble-minded, there is no investigator who denies the fearful role
played by mental deficiency in the production of vice, crime, and
delinquency.[1]

[1] See References at end of volume.

Heredity studies of "degenerate" families have confirmed, in a striking
way, the testimony secured by intelligence tests. Among the best known
of such families are the "Kallikaks," the "Jukes," the "Hill Folk," the
"Nams," the "Zeros," and the "Ishmaelites."

_The Kallikak family._ Martin Kallikak was a youthful soldier in
the Revolutionary War. At a tavern frequented by the militia he
met a feeble-minded girl, by whom he became the father of a
feeble-minded son. In 1912 there were 480 known direct
descendants of this temporary union. It is known that 36 of
these were illegitimates, that 33 were sexually immoral, that 24
were confirmed alcoholics, and that 8 kept houses of ill-fame.
The explanation of so much immorality will be obvious when it is
stated that of the 480 descendants, 143 were known to be
feeble-minded, and that many of the others were of questionable
mentality.

A few years after returning from the war this same Martin
Kallikak married a respectable girl of good family. From this
union 496 individuals have been traced in direct descent, and in
this branch of the family there were no illegitimate children,
no immoral women, and only one man who was sexually loose. There
were no criminals, no keepers of houses of ill-fame, and only
two confirmed alcoholics. Again the explanation is clear when it
is stated that this branch of the family did not contain a
single feeble-minded individual. It was made up of doctors,
lawyers, judges, educators, traders, and landholders.[2]

[2] H. H. Goddard: _The Kallikak Family_. (1914.) 141 pp.

_The Hill Folk._ The Hill Folk are a New England family of which
709 persons have been traced. Of the married women, 24 per cent
had given birth to illegitimate offspring, and 10 per cent were
prostitutes. Criminal tendencies were clearly shown in
24 members of the family, while alcoholism was still more
common. The proportion of feeble-minded was 48 per cent. It was
estimated that the Hill Folk have in the last sixty years cost
the State of Massachusetts, in charitable relief, care of
feeble-minded, epileptic, and insane, conviction and punishment
for crime, prostitution pauperism, etc., at least $500,000.[3]

[3] Danielson and Davenport: _The Hill Folk_. Eugenics Record Office,
Memoir No. 1. 1912. 56 pp.

The Nam family and the Jukes give equally dark pictures as
regards criminality, licentiousness, and alcoholism, and
although feeble-mindedness was not as fully investigated in
these families as in the Kallikaks and the Hill Folk, the
evidence is strong that it was a leading trait. The 784 Nams who
were traced included 187 alcoholics, 232 women and 199 men known
to be licentious, and 40 who became prisoners. It is estimated
that the Nams have already cost the State nearly $1,500,000.[4]

[4] Estabrook and Davenport: _The Nam Family_. Eugenics Record Office
Memoir No. 2. (1912). 85 pp.

Of 540 Jukes, practically one fifth were born out of wedlock, 37
were known to be syphilitic, 53 had been in the poorhouse, 76
had been sentenced to prison, and of 229 women of marriageable
age 128 were prostitutes. The economic damage inflicted upon the
State of New York by the Jukes in seventy-five years was
estimated at more than $1,300,000, to say nothing of diseases
and other evil influences which they helped to spread.[5]

[5] R. L. Dugdale: _The Jukes_. (Fourth edition, 1910.) 120 pp. G. P.
Putnam's Sons.

But why do the feeble-minded tend so strongly to become delinquent? The
answer may be stated in simple terms. Morality depends upon two things:
(a) the ability to foresee and to weigh the possible consequences for
self and others of different kinds of behavior; and (b) upon the
willingness and capacity to exercise self-restraint. That there are many
intelligent criminals is due to the fact that (a) may exist without
(b). On the other hand, (b) presupposes (a). In other words, not
all criminals are feeble-minded, but all feeble-minded are at least
potential criminals. That every feeble-minded woman is a potential
prostitute would hardly be disputed by any one. Moral judgment, like
business judgment, social judgment, or any other kind of higher thought
process, is a function of intelligence. Morality cannot flower and fruit
if intelligence remains infantile.

All of us in early childhood lacked moral responsibility. We were as
rank egoists as any criminal. Respect for the feelings, the property
rights, or any other kind of rights, of others had to be laboriously
acquired under the whip of discipline. But by degrees we learned that
only when instincts are curbed, and conduct is made to conform to
principles established formally or accepted tacitly by our neighbors,
does this become a livable world for any of us. Without the intelligence
to generalize the particular, to foresee distant consequences of present
acts, to weigh these foreseen consequences in the nice balance of
imagination, morality cannot be learned. When the adult body, with its
adult instincts, is coupled with the undeveloped intelligence and weak
inhibitory powers of a 10-year-old child, the only possible outcome,
except in those cases where constant guardianship is exercised by
relatives or friends, is some form of delinquency.

Considering the tremendous cost of vice and crime, which in all
probability amounts to not less than $500,000,000 per year in the United
States alone, it is evident that psychological testing has found here
one of its richest applications. Before offenders can be subjected
to rational treatment a mental diagnosis is necessary, and while
intelligence tests do not constitute a complete psychological diagnosis,
they are, nevertheless, its most indispensable part.

INTELLIGENCE TESTS OF SUPERIOR CHILDREN. The number of children with
very superior ability is approximately as great as the number of
feeble-minded. The future welfare of the country hinges, in no small
degree, upon the right education of these superior children. Whether
civilization moves on and up depends most on the advances made by
creative thinkers and leaders in science, politics, art, morality, and
religion. Moderate ability can follow, or imitate, but genius must show
the way.

Through the leveling influences of the educational lockstep such
children at present are often lost in the masses. It is a rare child who
is able to break this lockstep by extra promotions. Taking the country
over, the ratio of "accelerates" to "retardates" in the school is
approximately 1 to 10. Through the handicapping influences of poverty,
social neglect, physical defects, or educational maladjustments, many
potential leaders in science, art, government, and industry are denied
the opportunity of a normal development. The use we have made of
exceptional ability reminds one of the primitive methods of surface
mining. It is necessary to explore the nation's hidden resources of
intelligence. The common saying that "genius will out" is one of those
dangerous half-truths with which too many people rest content.

Psychological tests show that children of superior ability are very
likely to be misunderstood in school. The writer has tested more than a
hundred children who were as much above average intelligence as moron
defectives are below. The large majority of these were found located
below the school grade warranted by their intellectual level. One third
had failed to reap any advantage whatever, in terms of promotion, from
their very superior intelligence. Even genius languishes when kept
over-long at tasks that are too easy.

Our data show that teachers sometimes fail entirely to recognize
exceptional superiority in a pupil, and that the degree of such
superiority is rarely estimated with anything like the accuracy which is
possible to the psychologist after a one-hour examination. _B. F._, for
example, was a little over 71/2 years old when tested. He was in the
third grade, and was therefore thought by his teacher to be accelerated
in school. This boy's intelligence, however, was found to be above the
12-year level. There is no doubt that his mental ability would have
enabled him, with a few months of individual instruction, to carry fifth
or even sixth-grade work as easily as third, and without injury to body
or mind. Nevertheless, the teacher and both the parents of this child
had found nothing remarkable about him. In reality he belongs to a grade
of genius not found oftener than once in several thousand cases.

Another illustration is that of a boy of 101/2 years who tested at the
"average adult" level. He was doing superior work in the sixth grade,
but according to the testimony of the teacher had "no unusual ability."
It was ascertained from the parents that this boy, at an age when most
children are reading fairy stories, had a passion for standard medical
literature and textbooks in physical science. Yet, after more than a
year of daily contact with this young genius (who is a relative of
Meyerbeer, the composer), the teacher had discovered no symptoms of
unusual ability.[6]

[6] See p. 26 _ff._ for further illustrations of this kind.

Teachers should be better trained in detecting the signs of superior
ability. Every child who consistently gets high marks in his school work
with apparent ease should be given a mental examination, and if his
intelligence level warrants it he should either be given extra
promotions, or placed in a special class for superior children where
faster progress can be made. The latter is the better plan, because it
obviates the necessity of skipping grades; it permits rapid but
continuous progress.

The usual reluctance of teachers to give extra promotions probably rests
upon three factors: (1) mere inertia; (2) a natural unwillingness to
part with exceptionally satisfactory pupils; and (3) the traditional
belief that precocious children should be held back for fear of dire
physical or mental consequences.

In order to throw light on the question whether exceptionally bright
children are specially likely to be one-sided, nervous, delicate,
morally abnormal, socially unadaptable, or otherwise peculiar, the
writer has secured rather extensive information regarding 31 children
whose mental age was found by intelligence tests to be 25 per cent above
the actual age. This degree of intelligence is possessed by about
2 children out of 100, and is nearly as far above average intelligence
as high-grade feeble-mindedness is below. The supplementary information,
which was furnished in most cases by the teachers, may be summarized as
follows:--

1. _Ability special or general._ In the case of 20 out of 31 the
ability is decidedly general, and with 2 it is mainly general.
The talents of 5 are described as more or less special, but
only in one case is it remarkably so. Doubtful 4.

2. _Health._ 15 are said to be perfectly healthy; 13 have one or
more physical defects; 4 of the 13 are described as delicate;
4 have adenoids; 4 have eye-defects; 1 lisps; and 1 stutters.
These figures are about the same as one finds in any group of
ordinary children.

3. _Studiousness._ "Extremely studious," 15; "usually studious" or
"fairly studious," 11; "not particularly studious," 5; "lazy,"
0.

4. _Moral traits._ Favorable traits only, 19; one or more
unfavorable traits, 8; no answer, 4. The eight with
unfavorable moral traits are described as follows: 2 are "very
self-willed"; 1 "needs close watching"; 1 is "cruel to
animals"; 1 is "untruthful"; 1 is "unreliable"; 1 is "a
bluffer"; 1 is "sexually abnormal," "perverted," and
"vicious."

It will be noted that with the exception of the last child,
the moral irregularities mentioned can hardly be regarded,
from the psychological point of view, as essentially abnormal.
It is perhaps a good rather than a bad sign for a child to be
self-willed; most children "need close watching"; and a
certain amount of untruthfulness in children is the rule and
not the exception.

5. _Social adaptability._ Socially adaptable, 25; not adaptable,
2; doubtful, 4.

6. _Attitude of other children._ "Favorable," "friendly," "liked
by everybody," "much admired," "popular," etc., 26; "not
liked," 1; "inspires repugnance," 1; no answer, 1.

7. _Is child a leader?_ "Yes," 14; "no," or "not particularly,"
12; doubtful, 5.

8. _Is play life normal?_ "Yes," 26; "no," 1; "hardly," 1;
doubtful, 3.

9. _Is child spoiled or vain?_ "No," 22; "yes," 5; "somewhat," 2;
no answer, 2.

According to the above data, exceptionally intelligent children are
fully as likely to be healthy as ordinary children; their ability is far
more often general than special, they are studious above the average,
really serious faults are not common among them, they are nearly always
socially adaptable, are sought after as playmates and companions, their
play life is usually normal, they are leaders far oftener than other
children, and notwithstanding their many really superior qualities they
are seldom vain or spoiled.

It would be greatly to the advantage of such children if their superior
ability were more promptly and fully recognized, and if (under proper
medical supervision, of course) they were promoted as rapidly as their
mental development would warrant. Unless they are given the grade of
work which calls forth their best efforts, they run the risk of falling
into lifelong habits of submaximum efficiency. The danger in the case of
such children is not over-pressure, but under-pressure.

INTELLIGENCE TESTS AS A BASIS FOR GRADING. Not only in the case of
retarded or exceptionally bright children, but with many others also,
intelligence tests can aid in correctly placing the child in school.

The pupil who enters one school system from another is a case in point.
Such a pupil nearly always suffers a loss of time. The indefensible
custom is to grade the newcomer down a little, because, forsooth, the
textbooks he has studied may have differed somewhat from those he is
about to take up, or because the school system from which he comes may
be looked upon as inferior. Teachers are too often suspicious of all
other educational methods besides their own. The present treatment
accorded such children, which so often does them injustice and injury,
should be replaced by an intelligence test. The hour of time required
for the test is a small matter in comparison with the loss of a school
term by the pupils.

Indeed, it would be desirable to make all promotions on the basis
chiefly of intellectual ability. Hitherto the school has had to rely on
tests of information because reliable tests of intelligence have not
until recently been available. As trained Binet examiners become more
plentiful, the information standard will have to give way to the
criterion which asks merely that the child shall be able to do the work
of the next higher grade. The brief intelligence test is not only more
enlightening than the examination; it is also more hygienic. The school
examination is often for the child a source of worry and anxiety; the
mental test is an interesting and pleasant experience.

INTELLIGENCE TESTS FOR VOCATIONAL FITNESS. The time is probably not far
distant when intelligence tests will become a recognized and widely used
instrument for determining vocational fitness. Of course, it is not
claimed that tests are available which will tell us unerringly exactly
what one of a thousand or more occupations a given individual is best
fitted to pursue. But when thousands of children who have been tested by
the Binet scale have been followed out into the industrial world, and
their success in various occupations noted, we shall know fairly
definitely the vocational significance of any given degree of mental
inferiority or superiority. Researches of this kind will ultimately
determine the minimum "intelligence quotient" necessary for success in
each leading occupation.

Industrial concerns doubtless suffer enormous losses from the employment
of persons whose mental ability is not equal to the tasks they are
expected to perform. The present methods of trying out new employees,
transferring them to simpler and simpler jobs as their inefficiency
becomes apparent, is wasteful and to a great extent unnecessary. A
cheaper and more satisfactory method would be to employ a psychologist
to examine applicants for positions and to weed out the unfit. Any
business employing as many as five hundred or a thousand workers, as,
for example, a large department store, could save in this way several
times the salary of a well-trained psychologist.

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