The Measurement of Intelligence

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

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[Illustration: FIG. 9. BALL AND FIELD TEST S. F., AGE 17; MENTAL
AGE 11-6]

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.

[Illustration: FIG. 10. WRITING FROM DICTATION. C. P., AGE 10-2;
MENTAL AGE 7-11]

_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.

[Illustration: FIG. 11. BALL AND FIELD TEST. M. P., AGE 14;
MENTAL AGE 10-8]

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.

[Illustration: FIG. 12. BALL AND FIELD. R. G., AGE 13-5, MENTAL
AGE 10-6]

_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.

AVERAGE INTELLIGENCE (I Q 90 TO 110). It is often said that the schools
are made for the average child, but that "the average child does not
exist." He does exist, and in very large numbers. About 60 per cent of
all school children test between 90 and 110 I Q, and about 40 per cent
between 95 and 105. That these children are average is attested by their
school records as well as by their I Q's. Our records show that, of more
than 200 children below 14 years of age and with I Q between 95 and 105,
not one was making much more nor much less than average school progress.
Four were two years retarded, but in each case this was due to late
start, illness, or irregular attendance. Children who test close to 90,
however, often fail to get along satisfactorily, while those testing
near 110 are occasionally able to win an extra promotion.

The children of this average group are seldom school problems, as far as
ability to learn is concerned. Nor are they as likely to cause trouble
in discipline as the dull and border-line cases. It is therefore hardly
necessary to give illustrative cases here.

The high school, however, does not fit their grade of intelligence as
well as the elementary and grammar schools. High schools probably enroll
a disproportionate number of pupils in the I Q range above 100. That is,
the average intelligence among high-school pupils is above the average
for the population in general. It is probably not far from 110. College
students are, of course, a still more selected group, perhaps coming
chiefly from the range above 115. The child whose school marks are
barely average in the elementary grades, when measured against children
in general, will ordinarily earn something less than average marks in
high school, and perhaps excessively poor marks in college.

SUPERIOR INTELLIGENCE (I Q 110 TO 120). Children of this group
ordinarily make higher marks and are capable of making somewhat more
rapid progress than the strictly average child. Perhaps most of them
could complete the eight grades in seven years as easily as the average
child does in eight years. They are not usually the best scholars, but
on a scale of excellent, good, fair, poor, and failure they will usually
rank as good, though of course the degree of application is a factor. It
is rare, however, to find a child of this level who is positively
indolent in his school work or who dislikes school. In high school they
are likely to win about the average mark.

Intelligence of 110 to 120 I Q is approximately five times as common
among children of superior social status as among children of inferior
social status; the proportion among the former being about 24 per cent
of all, and among the latter only 5 per cent of all. The group is
made up largely of children of the fairly successful mercantile or
professional classes.

The total number of children between 110 and 120 is almost exactly the
same as the number between 80 and 90; namely, about 15 per cent. The
distance between these two groups (say between 85 and 115) is as great
as the distance between average intelligence and border-line deficiency,
and it would be absurd to suppose that they could be taught to best
advantage in the same classes. As a matter of fact, pupils between
110 and 120 are usually held back to the rate of progress which the
average child can make. They are little encouraged to do their best.

VERY SUPERIOR INTELLIGENCE (I Q 120 TO 140). Children of this group are
better than somewhat above average. They are unusually superior. Not
more than 3 out of 100 go as high as 125 I Q, and only about 1 out of
100 as high as 130. In the schools of a city of average population only
about 1 child in 250 or 300 tests as high as 140 I Q.

In a series of 476 unselected children there was not a single one
reaching 120 whose social class was described as "below average."[29] Of
the children of superior social status, about 10 per cent reached 120 or
better. The 120-140 group is made up almost entirely of children whose
parents belong to the professional or very successful business classes.
The child of a skilled laborer belongs here occasionally, the child of a
common laborer very rarely indeed. At least this is true in the smaller
cities of California among populations made up of native-born Americans.
In all probability it would not have been true in the earlier history of
the country when ordinary labor was more often than now performed by men
of average intelligence, and it would probably not hold true now among
certain immigrant populations of good stock, but limited social and
educational advantages.

[29] In other investigations, however, we have found even brighter
children from very inferior homes. See p. 117 for an example.

What can children of this grade of ability do in school? The question
cannot be answered as satisfactorily as one could wish, for the simple
reason that such children are rarely permitted to do what they can. What
they do accomplish is as follows: Of 54 children (of the 1000 unselected
cases) falling in this group, 121/2 per cent were advanced in the
grades two years, approximately 54 per cent were advanced one year,
28 per cent were in the grade where they belonged by chronological age,
and three children, or 51/2 per cent, were actually retarded one year.
But wherever located, such children rarely get anything but the highest
marks, and the evidence goes to show that most of them could easily be
prepared for high school by the age of 12 years. Serious injury is done
them by schools which believe in "putting on the brakes."

The following are illustrations of children testing between 130 and 145.
Not all are taken from the 1000 unselected tests. The writer has
discovered several children of this grade as a result of lectures before
teachers' institutes. It is his custom, in such lectures, to ask the
teachers to bring in for a demonstration test the "brightest child in
the city" (or county, etc.). The I Q resulting from such a test is
usually between 130 and 140, occasionally a little higher.

_Examples of very superior intelligence_

_Margaret P. Age 8-10; mental age 11-1; I Q 130._ Father only a
skilled laborer (house painter), but a man of unusual
intelligence and character for his social class. Home care above
average. M. P. has attended school a little less than three
years and is completing fourth grade. Marks all "excellent."
Health perfect. Social and moral traits of the very best. Is
obedient, conscientious, and unusually reliable for her age.
Quiet and confident bearing, but no touch of vanity.

M. P. is known to be related on her father's side to John
Wesley, and her maternal grandfather was a highly skilled
mechanic and the inventor of an important train-coupling device
used on all railroads.

Although she is not yet 9 years old and is completing the fourth
grade, she is still about a grade below where she belongs by
mental age. She could no doubt easily be made ready for high
school by the age of 12.

_J. R. Girl, age 12-9; mental age 16 (average adult); I Q
approximately 130._ Daughter of a university professor. In first
year of high school. From first grade up her marks have been
nearly all of the A rank. For first semester of high school four
of six grades were A, the others B. A wonderfully charming,
delightful girl in every respect. Play life perfectly normal.

_J. R.'s_ parents have moved about a great deal and she has
attended eight different schools. She is two years above grade
in school, but of this gain only one-half grade was made in
school; _the other grade and a half she gained in a little over
a year by staying out of school and working a little each day
under the instruction of her mother_. But for this she would
doubtless now be in the seventh grade instead of in high school.
As it is she is at least a grade below where she belongs by
mental age. Something better than an average college record may
be safely predicted for J. R.

_E. B. Girl, age 7-9; mental age 10-2; I Q 130._ E. B. was
selected by the teachers of a small California city as the
brightest school child in that city (school population about
500). Her parents are said to be unusually intelligent. E. B. is
in the third grade, a year advanced, but her mental level shows
that she belongs in the fourth. The test was made as a
demonstration test in the presence of about 150 teachers, all
of whom were charmed by her delightful personality and keen
responses. No trace of vanity or queerness of any kind. Health
excellent. E. B. ought to be ready for high school at 12; she
will really have the intelligence to do high-school work by 11.

[Illustration: FIG. 13. BALL AND FIELD TEST. E. B., AGE 7-9;
I Q 130]

_L. B. Girl, age 8-6; mental age 11-6; I Q 135._ Tested nearly
three years earlier, age 5-11; mental age 7-6; I Q 127. Daughter
of a university professor. At age of 8-6 was doing very superior
work in the fifth grade. Later, at age of 10-6, is in the
seventh grade with all her marks excellent. Has two sisters who
test almost as high, both completing the eighth grade at barely
12 years of age. L. B. looks rather delicate, and though a
little nervous is ordinarily strong. We have known her since her
early childhood. Like both her sisters, she is a favorite with
young and old, as nearly perfection as the most charming little
girl could be.

_R. S. Boy, age 6-5; mental age 9-6; I Q 148._ When tested at
age 5-2 he had a mental age of 7-6, I Q 142. Father a university
professor. R. S. entered school at exactly 6 years of age, and
at the present writing is 71/2 years old and is entering the
third grade. Leads his class in school and takes delight in the
work. Is normal in play life and social traits and is dependable
and thoughtful beyond his years. Should enter high school not
later than 12; could probably be made ready a year earlier, but
as he is somewhat nervous this might not be wise.

_T. F. Boy, age 10-6; mental age 14; I Q 133._ At 13-6 tested at
"superior adult," and had vocabulary of 13,000 (also "superior
adult"). Son of a college professor. Did not go to school till
age of 9 years and was not taught to read till 81/2. At this
writing he is 151/2 years old and is a senior in high school.
He will complete the high-school course in three and one-half
years with A to B marks, mostly A. Gets his hardest mathematics
lessons in five to ten minutes. Science is his play. When he
discovered Hodge's _Nature Study and Life_ at age of 11 years he
literally slept with the book till he almost knew it by heart.
Since age 12 he has given much time to magazines on mechanics
and electricity. At 13 he installed a wireless apparatus
without other aid than his electrical magazines. He has, for a
boy of his age, a rather remarkable understanding of the
principles underlying electrical applications. He is known by
his playmates as "the boy with a hobby." Stamp collections,
butterfly and moth collections (over 70 different varieties),
seashore collections, and wireless apparatus all show that the
appellation is fully merited. He chooses his hobbies and "rides"
them entirely on his own initiative.

_J. S. Boy, age 8-2; mental age 11-4; I Q 138._ Father was a
lawyer, parents now dead. Is in high fourth grade. Leads his
class. Attractive, healthy, normal-appearing lad. Full of good
humor. Is loving and obedient, strongly attached to his foster
mother (an aunt). Composes verses and fables for pastime. Here
are a couple of verses composed before his eighth birthday. They
are reproduced without change of spelling or punctuation:--

_Christmas_

Hurrah for Christmas
And all it's joy's
That come that day
For girls and boy's.

_Flowers_

Flowers in the garden.
That is all you see
Who likes them best?
That's the honey bee.

J. S. ought to be in the fifth grade, instead of the fourth. He
will easily be able to enter college by the age of 15 if he is
allowed to make the progress which would be normal to a child of
his intelligence. But it is too much to expect that the school
will permit this.

_F. McA. Boy, age 10-3; mental age 14-6; I Q 142._ Father a
school principal. F. is leading his class of 24 pupils in the
high seventh grade. Has received so many extra promotions only
because his father insisted that the teachers allow him to try
the next grade. The dire consequences which they predicted have
never followed. F. is perfectly healthy and one of the most
attractive lads the writer has ever seen. He has the normal play
instincts, but when not at play he has the dignified bearing of
a young prince, although without vanity. His vocabulary is 9000
(14 years), and his ability is remarkably even in all
directions. F. should easily enter college by the age of 15.

[Illustration: FIG. 14. BALL AND FIELD F. McA., AGE 10-3, MENTAL
AGE 14-6]

_E. M. Boy, age 6-11; mental age 10; I Q 145._ Learned to read
at age of 5 without instruction and shortly afterward had
learned from geography maps the capitals of all the States of
the Union. Started to school at 71/2. Entered the first grade
at 9 A.M. and had been promoted to the fourth grade by 3 P.M. of
the same day! Has now attended school a half-year and is in the
fifth grade, age 7 years, 8 months. Father is on the faculty of
a university.

E. M. is as superior in personal and moral traits as in
intelligence. Responsible, sturdy, playful, full of humor,
loving, obedient. Health is excellent. Has had no home
instruction in school work. His progress has been perfectly
natural.

[Illustration: FIG. 15. DRAWING DESIGNS FROM MEMORY. E. M.,
AGE 6-11; MENTAL AGE 10, I Q 145

(This performance is satisfactory for year 10)]

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