The Measurement of Intelligence

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The above list of "very superior" children includes only a few of those
we have tested who belong to this grade of intelligence. Every child in
the list is so interesting that it is hard to omit any. We have found
all such children (with one or two exceptions not included here) so
superior to average children in all sorts of mental and moral traits
that one is at a loss to understand how the popular superstitions about
the "queerness" of bright children could have originated or survived.
Nearly every child we have found with I Q above 140 is the kind one
feels, before the test is over, one would like to adopt. If the crime of
kidnaping could ever be forgiven it would be in the case of a child like
one of these.

GENIUS AND "NEAR" GENIUS. Intelligence tests have not been in use long
enough to enable us to define genius definitely in terms of I Q. The
following two cases are offered as among the highest test records of
which the writer has personal knowledge. It is doubtful whether more
than one child in 10,000 goes as high as either. One case has been
reported, however, in which the I Q was not far from 200. Such a
record, if reliable, is certainly phenomenal.

_E. F. Russian boy, age 8-5; mental age 13; I Q approximately
155._ Mother is a university student apparently of very superior
intelligence. E. F. has a sister almost as remarkable as
himself. E. F. is in the sixth grade and at the head of his
class. Although about four grades advanced beyond his
chronological age he is still one grade retarded! He could
easily carry seventh-grade work. In all probability E. F. could
be made ready for college by the age of 12 years without injury
to body or mind. His mother has taken the only sensible course;
she has encouraged him without subjecting him to
overstimulation.

E. F. was selected for the test as probably one of the brightest
children in a city of a third of a million population. He may
not be the brightest in that city, but he is one of the three or
four most intelligent the writer has found after a good deal of
searching. He is probably equaled by not more than one in
several thousand unselected children. How impatiently one waits
to see the fruit of such a budding genius!

_B. F. Son of a minister, age 7-8; mental age 12-4; I Q 160._
Vocabulary 7000 (12 years). This test was not made by the
writer, but by one of his graduate students. The record included
the _verbatim_ responses, so that it was easy to verify the
scoring. There can be no doubt as to the substantial accuracy
of the test. This I Q of 160 is the highest one in the Stanford
University records. B. F. has excellent health, normal play
interests, and is a favorite among his playfellows. Parents had
not thought of him as especially remarkable. He is only in the
third grade, and is therefore about three grades below his
mental age.

[Illustration: FIG. 16. BALL AND FIELD. B. F., AGE 7-8; MENTAL
AGE 12-4; I Q 160

(This is a 12-year performance)]

It is especially noteworthy that not one of the children we have
described with I Q above 130 has ever had any unusual amount or kind of
home instruction. In most cases the parents were not aware of their very
great superiority. Nor can we give the credit to the school or its
methods. The school has in most cases been a deterrent to their
progress, rather than a help. These children have been taught in classes
with average and inferior children, like those described in the first
part of this chapter. Their high I Q is only an index of their
extraordinary cerebral endowment. This endowment is for life. There is
not the remotest probability that any of these children will deteriorate
to the average level of intelligence with the onset of maturity. Such an
event would be no less a miracle (barring insanity) than the development
of an imbecile into a successful lawyer or physician.

IS THE I Q OFTEN MISLEADING? Do the cases described in this chapter give
a reliable picture as to what one may expect of the various I Q levels?
Does the I Q furnish anything like a reliable index of an individual's
general educational possibilities and of his social worth? Are there not
"feeble-minded geniuses," and are there not children of exceptionally
high I Q who are nevertheless fools?

We have no hesitation in saying that there is not one case in fifty in
which there is any serious contradiction between the I Q and the child's
performances in and out of school. We cannot deny the existence of
"feeble-minded geniuses," but after a good deal of search we have not
found one. Occasionally, of course, one finds a feeble-minded person
who is an expert penman, who draws skillfully, who plays a musical
instrument tolerably well, or who handles number combinations with
unusual rapidity; but these are not geniuses; they are not authors,
artists, musicians, or mathematicians.

As for exceptionally intelligent children who appear feeble-minded, we
have found but one case, a boy of 10 years with an I Q of about 125.
This boy, whom we have tested several times and whose development we
have followed for five years, was once diagnosed by a physician as
feeble-minded. His behavior among other persons than his familiar
associates is such as to give this impression. Nothing less than an
entire chapter would be adequate for a description of this case, which
is in reality one of disturbed emotional and social development with
superior intelligence.

It should be emphasized, however, that what we have said about the
significance of various I Q's holds only for the I Q's secured by the
use of the Stanford revision. As we have shown elsewhere (p. 62 _ff._)
the I Q yielded by other versions of the Binet tests are often so
inaccurate as to be misleading.

We have not found a single child who tested between 70 and 80 I Q by the
Stanford revision who was able to do satisfactory school work in the
grade where he belonged by chronological age. Such children are usually
from two to three grades retarded by the age of 12 years. 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 school work is so superior as to
suggest strongly the desirability of extra promotions. Those who test
between 96 and 105 are almost never more than one grade above or below
where they belong by chronological age, and even the small displacement
of one year is usually determined by illness, age of beginning school,
etc.

CHAPTER VII

RELIABILITY OF THE BINET-SIMON METHOD

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

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

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

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

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

[31] Dr. Otto Bobertag: "L'echelle metrique de l'intelligence," in
_L'Annee Psychologique_ (1912), p. 272.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Cautions regarding embarrassment, fatigue, fright, illness, etc. are
given in Chapter IX. Most of the errors which have been reported along
this line are such as can nearly always be avoided by ordinary prudence,
coupled with a little power of observation.[38] We must not charge the
mistakes of untrained and indiscreet examiners against the validity of
the method itself.

[38] See, for example, the rather ludicrous "errors" of the Binet method
reported in _The Psychological Clinic_ for 1915, pp. 140 _ff._ and
167 _ff._

It is possibly true that even if the examiner is tactful and prudent an
unfavorable attitude on the part of the subject may occasionally affect
the results of a test to some extent, but it ought not seriously to
invalidate one examination out of five hundred. The greatest danger is
in the case of a young subject who has been recently arrested and
brought before a court. Even here a little common sense and scientific
insight should enable one to guard against a mistaken diagnosis.

THE INFLUENCE OF COACHING. It might be supposed that after the
intelligence scale had been used with a few pupils in a given school all
of their fellows would soon be apprised of the nature of the tests, and
so learn the correct responses. Experience shows, however, that there is
little likelihood of such influence except in the case of a small
minority of the tests. Experiments in the psychology of testimony have
demonstrated that children's ability to report upon a complex set of
experiences is astonishingly weak. In testing with the Stanford revision
a child is ordinarily given from twenty-four to thirty different tests,
many of which are made up of three or more items. Of the total forty to
fifty items the child is ordinarily able to report but few, and these
not always correctly.

Such tests as memory for sentences and digits, drawing the square and
diamond, reproducing the designs from memory, comparing weights and
lines, describing and interpreting pictures, aesthetic comparison,
vocabulary, dissected sentences, fables, reading for memories, finding
differences and similarities, arithmetical reasoning, and the form-board
test, are hardly subject to report at all. While almost any of the other
tests might, theoretically, be communicated, there is little danger that
many of them will be. It is assumed, of course, that the examiner will
take proper precautions to prevent any of his blanks or other materials
from falling into the hands of those who are to be examined.

The following tests are the ones most subject to the influence of
coaching: Ball and field, giving date, naming sixty words, finding
rhymes, changing hands of clock, comprehension of physical relations,
"induction test," and "ingenuity test."

In several instances we have interviewed children an hour or two after
they had taken the examination, in order to find out how many of the
tests they could recall. A boy of 4 years, after repeated questioning,
could only say: "He showed me some pictures. He had a knife and a penny.
He told me to shut the door." A girl of 3 years could recall nothing
whatever that was intelligible.

An 8-year-old boy said: "He made me tie a knot. He asked me about a ship
and an auto. He wanted me to count backwards. He made me say over some
things, numbers and things."

A boy of 12 years said: "He told me to say all the words I could think
of. He said some foolish things and asked what was foolish [he could not
repeat a single absurdity]. I had to put some blocks together. I had to
do some problems in arithmetic [he could not repeat a single problem].
He read some fables to me. [Asked about the fables he was able to recall
only part of one, that of the fox and the crow.] He showed me the
picture of a field and wanted to know how to find a ball."

It is evident from the above samples of report that the danger of
coaching increases considerably with the age of the children concerned.
With young subjects the danger is hardly present at all; with children
of the upper-grammar grades, in the high school, and most of all in
prisons and reformatories, it must be taken into account. Alternative
tests may sometimes be used to advantage when there is evidence of
coaching on any of the regular tests. It would be desirable to have two
or three additional scales which could be used interchangeably with the
Binet-Simon.

RELIABILITY OF REPEATED TESTS. Will the same tests give consistent
results when used repeatedly with the same subject? In general we
may say that they do. Something depends, however, on the age and
intelligence of the subject and on the time interval between the
examinations.

Goddard proves that feeble-minded individuals whose intelligence has
reached its full development continue to test at exactly the same mental
age by the Binet scale, year after year. In their case, familiarity with
the tests does not in the least improve the responses. At each retesting
the responses given at previous examinations are repeated with only the
most trivial variations. Of 352 feeble-minded children tested at
Vineland, three years in succession, 109 gave absolutely no variation,
232 showed a variation of not more than two fifths of a year, while 22
gained as much as one year in the three tests. The latter, presumably,
were younger children whose intelligence was still developing.

Goddard has also tested 464 public-school children for three successive
years. Approximately half of these showed normal progress or more in
mental age, while most of the remainder showed somewhat less than normal
progress.

Bobertag's retesting of 83 normal children after an interval of
a year gave results entirely in harmony with those of Goddard.
The reapplication of the tests showed absolutely no influence of
familiarity, the correlation of the two tests being almost perfect
(.95). Those who tested "at age" in the first test had advanced, on
the average, exactly one year. Those who tested _plus_ in the first
test advanced in the twelve months about a year and a quarter, as we
should expect those to do whose mental development is accelerated.
Correspondingly, those who tested _minus_ at the first test advanced
only about three fourths of a year in mental age during the
interval.[39]

[39] Otto Bobertag: "Ueber Intelligenz Pruefungen," in _Zeitsch. f.
Angew. Psychol._ (1912), p. 521 _ff._

Our own results with a mixed group of normal, superior, dull and
feeble-minded children agree fully with the above findings. In this case
the two tests were separated by an interval of two to four years, and
the correlation between their results was practically perfect. The
average difference between the I Q obtained in the second test and that
obtained in the first was only 4 per cent, and the greatest difference
found was only 8 per cent.[40]

[40] See _The Stanford Revision and Extension of the Binet-Simon Scale
for Measuring Intelligence_. (Warwick and York, 1916.)

The repetition of the test at shorter intervals will perhaps affect the
result somewhat more, but the influence is much less than one might
expect. The writer has tested, at intervals of only a few days to a few
weeks, 14 backward children of 12 to 18 years, and 8 normal children of
5 to 13 years. The backward children showed an average improvement in
the second test of about two months in mental age, the normal children
an average improvement of little more than three months. No child varied
in the second test more than half a year from the mental age first
secured. On the whole, normal children profit more from the experience
of a previous test than do the backward and feeble-minded.

Berry tested 45 normal children and 50 defectives with the Binet 1908
and 1911 scales at brief intervals. The author does not state which
scale was applied first, but the mental ages secured by the two scales
were practically the same when allowance was made for the slightly
greater difficulty of the 1911 series of tests.[41]

[41] Charles Scott Berry: "A Comparison of the Binet Tests of 1908 and
1911," in _Journal of Educational Psychology_ (1912), pp. 444-51.

We may conclude, therefore, that while it would probably be desirable
to have one or more additional scales for alternative use in testing the
same children at very brief intervals, the same scale may be used for
repeated tests at intervals of a year or more with little danger of
serious inaccuracy. Moreover, results like those set forth above are
important evidence as to the validity of the test method.

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