The Measurement of Intelligence

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The tests as arranged in this revision are in the order which it is
usually best to follow, but one should not hesitate to depart from the
order given when it seems best in a given case to do so. It is necessary
to be constantly alert so that when the child shows a tendency to balk
at a given type of test, such as those of memory, language, numbers,
drawing, "comprehension," etc., the work can be shifted to more
agreeable tasks. When the child is at his ease again, it is usually
possible to return to the troublesome tests with better success. In the
case of 8-year-old D. C., who is a speech defective but otherwise above
normal, it was quite impossible at the first sitting to give such tests
as sentence-making, naming sixty words, reading, repeating sentences,
giving definitions, etc.; at each test of this type the child's voice
broke and he was ready to cry, due, no doubt, to sensitiveness regarding
his speech defect. Others do everything willingly except the drawing and
copying. The younger children sometimes refuse to repeat the sentences
or digits. In all such cases it is best to pass on to something else.
After a few minutes the rejected task may be done willingly.

COAXING TO BE AVOIDED. Although we should always encourage the child to
believe that he can answer correctly, if he will only try, we must avoid
the common practice of dragging out responses by too much urging and
coaxing. The sympathies of the examiner tend to lead him into the habit
of repeating and explaining the question if the child does not answer
promptly. This is nearly always a mistake, for the question is one which
should be understood. Besides, explanations and coaxing are too often
equivalent to answering the question for the child. It is almost
impossible to impress this danger sufficiently upon the untrained
examiner. One who is not familiar with the psychology of suggestion may
put the answer in the child's mouth without suspecting what he is doing.

ADHERING TO FORMULA. It cannot be too strongly emphasized that unless we
follow a standardized procedure the tests lose their significance. The
danger is chiefly that of unintentionally and unconsciously introducing
variations which will affect the meaning of the test. One who has not
had a thorough training in the methods of mental testing cannot
appreciate how numerous are the opportunities for the unconscious
transformation of a test. Many of these are pointed out in the
description of the individual tests, but it would be folly to undertake
to warn the experimenter against every possible error of this kind.
Sometimes the omission or the addition of a single phrase in giving
the test will alter materially the significance of the response.
Only the trained psychologist can vary the formula without risk of
invalidating the result, and even he must be on his guard. All sorts of
misunderstandings regarding the correct placing of tests and regarding
their accuracy or inaccuracy have come about through the failure of
different investigators to follow the same procedure.

One who would use the tests for any serious purpose, therefore,
must study the procedure for each and every test until he knows it
thoroughly. After that a considerable amount of practice is necessary
before one learns to avoid slips. During the early stages of practice it
is necessary to refer to the printed instructions frequently in order to
check up errors before they have become habitual.

The instructions hitherto available are at fault in not defining the
procedure with sufficient definiteness, and it is the purpose of this
volume to make good this deficiency as far as possible.

It is too much, however, to suppose that the instructions can be made
"fool-proof." With whatever definiteness they may be set forth,
situations are sure to arise which the examiner cannot be formally
prepared for. There is no limit to the multitude of misunderstandings
possible. After testing hundreds of children one still finds new
examples of misapprehension. In a few such cases the instruction may be
repeated, if there is reason to think the child's hearing was at fault
or if some extraordinary distraction has occurred. But unless otherwise
stated in the directions, the repetition of a question is ordinarily to
be avoided. Supplementary explanations are hardly ever permissible.

In short, numberless situations may arise in the use of a test which may
injure the validity of the response, events which cannot always be
dealt with by preconceived rule. Accordingly, although we must urge
unceasingly the importance of following the standard procedure, it is
not to be supposed that formulas are an adequate substitute either for
scientific judgment or for common sense.

SCORING. The exact method of scoring the individual tests is set forth
in the following chapters. Reference to the record booklet for use in
testing will show that the records are to be kept in detail. Each
subdivision of a test should be scored separately, in order that the
clinical picture may be as complete as possible. This helps in the final
evaluation of the results. It makes much difference, for example,
whether success in repeating six digits is earned by repeating all three
correctly or only one; or whether the child's lack of success with the
absurdities is due to failure on two, three, four, or all of them. Time
should be recorded whenever called for in the record blanks.

RECORDING RESPONSES. Plus and minus signs alone are not usually
sufficient. Whenever possible the entire response should be recorded. If
the test results are to be used by any other person than the examiner,
this is absolutely essential. Any other standard of completeness opens
the door to carelessness and inaccuracy. In nearly all the tests, except
that of naming sixty words, the examiner will find it possible by the
liberal use of abbreviations to record practically the entire response
_verbatim_. In doing so, however, one must be careful to avoid keeping
the child waiting. Occasionally it is necessary to leave off recording
altogether because of the embarrassment sometimes aroused in the child
by seeing his answer written down. The writer has met the latter
difficulty several times. When for any reason it is not feasible to
record anything more than score marks, success may be indicated by the
sign +, failure by -, and half credit by 1/2. An exceptionally good
response may be indicated by ++ and an exceptionally poor response by --.
If there is a slight doubt about a success or failure the sign? may
be added to the + or -. In general, however, score the response either +
or -, avoiding half credit as far as it is possible to do so.

If the entire response is not recorded it is necessary to record at
least the score mark for each test _when the test is given_. It must be
borne in mind that the scoring is not a purely mechanical affair.
Instead, the judgment of the examiner must come into play with every
record made. If the scoring is delayed, there is not only the danger of
forgetting a response, but the judgment is likely to be influenced by
the subject's responses to succeeding questions. Our special record
booklet contains wide margins, so that extended notes and observations
regarding the child's responses and behavior can be recorded as the test
proceeds.

SCATTERING OF SUCCESSES. It is sometimes a source of concern to the
untrained examiner that the successes and failures should be scattered
over quite an extensive range of years. Why, it may be asked, should not
a child who has 10-year intelligence answer correctly all the tests up
to and including group X, and fail on all the tests beyond? There are
two reasons why such is almost never the case. In the first place, the
intelligence of an individual is ordinarily not even. There are many
different kinds of intelligence, and in some of these the subject is
better endowed than in others. A second reason lies in the fact that no
test can be purely and simply a test of native intelligence. Given a
certain degree of intelligence, accidents of experience and training
bring it about that this intelligence will work more successfully with
some kinds of material than with others. For both of these reasons there
results a scattering of successes and failures over three or four years.
The subject fails first in one or two tests of a group, then in two or
three tests of the following group, the number of failures increasing
until there are no successes at all. Success "tapers off" from
100 per cent to 0. Once in a great while a child fails on several of the
tests of a given year and succeeds with a majority of those in the next
higher year. This is only an extreme instance of uneven intelligence or
of specialized experience, and does not necessarily reflect upon the
reliability of the tests for children in general. The method of
calculation given above strikes a kind of average and gives the general
level of intelligence, which is essentially the thing we want to know.

SUPPLEMENTARY CONSIDERATIONS. It would be a mistake to suppose that any
set of mental tests could be devised which would give us complete
information about a child's native intelligence. There are no tests
which are absolutely pure tests of intelligence. All are influenced to a
greater or less degree also by training and by social environment. For
this reason, all the ascertainable facts bearing on such influences
should be added to the record of the mental examination, and should be
given due weight in reaching a final conclusion as to the level of
intelligence.

The following supplementary information should be gathered, when
possible:--

1. Social status (very superior, superior, average, inferior, or
very inferior).

2. The teacher's estimate of the child's intelligence (very
superior, superior, average, inferior, or very inferior).

3. School opportunities, including years of attendance,
regularity, retardation or acceleration, etc.

4. Quality of school work (very superior, superior, average,
inferior, or very inferior).

5. Physical handicaps, if any (adenoids, diseased tonsils, partial
deafness, imperfect vision, malnutrition, etc.).

In addition, the examiner will need to take account of the general
attitude of the child during the examination. This is provided for in
the record blanks under the heading "comments." The comments should
describe as fully as possible the conduct and attitude of the child
during the examination, with emphasis upon such disturbing factors as
fear, timidity, unwillingness to answer, overconfidence, carelessness,
lack of attention, etc. Sometimes, also, it is desirable to verify the
child's age and to make record of the verification.

Once more let it be urged that no degree of mechanical perfection of the
tests can ever take the place of good judgment and psychological
insight. Intelligence is too complicated to be weighed, like a bag of
grain, by any one who can read figures.

ALTERNATIVE TESTS. The tests designated as "alternative tests" are not
intended for regular use. Inasmuch as they have been standardized and
belong in the year group where they are placed, they may be used as
substitute tests on certain occasions. Sometimes one of the regular
tests is spoiled in giving it, or the requisite material for it may not
be at hand. Sometimes there may be reason to suspect that the subject
has become acquainted with some of the tests. In such cases it is a
great convenience to have a few substitutes available.

It is necessary, however, to warn against a possible misuse of
alternative tests. _It is not permissible to count success in an
alternative test as offsetting failure in a regular test._ This would
give the subject too much leeway of failure. There are very exceptional
cases, however, when it is legitimate to break this rule; namely, when
one of the regular tests would be obviously unfair to the subject being
tested. In year X, for example, one of the three alternative tests
should be substituted for the reading test (X, 4) in case we are testing
a subject who has not had the equivalent of at least two years of
school work. In year VIII, it would be permissible to substitute the
alternative test of naming six coins, instead of the vocabulary test, in
the case of a subject who came from a home where English was not spoken.
In VII, it would perhaps not be unfair to substitute the alternative
test, in place of the test of copying a diamond, in the case of a
subject who, because of timidity or embarrassment, refused to attempt
the diamond. But it would be going entirely too far to substitute an
alternative test in the place of every regular test which the subject
responded to by silence. In the large majority of cases persistent
silence deserves to be scored failure.

Certain tests have been made alternatives because of their inferior
value, some because the presence of other tests of similar nature in the
same year rendered them less necessary.

FINDING MENTAL AGE. As there are six tests in each age group from III to
X, each test in this part of the scale counts 2 months toward mental
age. There are eight tests in group XII, which, because of the omission
of the 11-year group, have a combined value of 24 months, or 3 months
each. Similarly, each of the six tests in XIV has a value of 4 months
(24 / 6 = 4). The tests of the "average adult" group are given a value
of 5 months each, and those of the "superior adult" group a value of
6 months each. These values are in a sense arbitrary, but they are
justified in the fact that they are such as to cause ordinary adults to
test at the "average adult" level.

The calculation of mental age is therefore simplicity itself. The rule
is: (1) Credit the subject with all the tests below the point where the
examination begins (remembering that the examination goes back until a
year group has been found in which all the tests are passed); and (2)
add to this basal credit 2 months for each test passed successfully up
to and including year X, 3 months for each test passed in XII, 4 months
for each test passed in XIV, 5 months for each success in "average
adult," and 6 months for each success in "superior adult."

For example, let us suppose that a child passes all the tests in VI,
five of the six tests in VII, three in VIII, two in IX, and one in X.
The total credit earned is as follows:--

_Years__Months_
Credit presupposed, years I to V 5
Credit earned in VI, 6 tests passed, 2 months each 1
Credit earned in VII, 5 tests passed, 2 months each 10
Credit earned in VIII, 3 tests passed, 2 months each 6
Credit earned in IX, 2 tests passed, 2 months each 4
Credit earned in X, 1 test passed, 2 months 2
---- ----
Total credit 7 10

Taking a subject who tests higher, let us suppose the following tests
are passed: All in X, six of the eight in XII, two of the six in XIV,
and one of the six in "average adult." The total credit is as follows:--

_Years__Months_
Credit presupposed, years I to IX 9
Credit earned in X, 6 tests passed, 2 months each 1
Credit earned in XII, 6 tests passed, 3 months each 1 6
Credit earned in XIV, 2 tests passed, 4 months each 0 8
Credit earned in "average adult," 1 success, 5 months 5
---- ----
Total credit 12 7

One other point: If one or more tests of a year group have been omitted,
as sometimes happens either from oversight or lack of time, the question
arises how the tests which were given in such a year group should be
evaluated. Suppose, for example, a subject has been given only four of
the six tests in a given year, and that he passes two, or half of those
given. In such a case the probability would be that had all six tests
been given, three would have been passed; that is, one half of all.
It is evident, therefore, that when a test has been omitted, a
proportionately larger value should be assigned to each of those given.

If all six tests are given in any year group below XII, each has a value
of 2 months. If only four are given, each has a value of 3 months
(12 / 4 = 3). If five tests only are given, each has a value of
2.4 months (12 / 5 = 2.4). If in year group XII only six of the eight
tests are given, each has a value of 4 months (24 / 6 = 4). If in the
"average adult" group only five of the six tests are given, each has a
value of 6 months instead of the usual 5 months. In this connection it
will need to be remembered that the six "average adult" tests have a
combined value of 30 months (6 tests, 5 months each); also that the
combined value of the six "superior adult" tests is 36 months
(6 x 6 = 36). Accordingly, if only five of the six "superior adult"
tests are given, the value of each is 36 / 5 = 7.2 months.

For example, let us suppose that a subject has been tested as follows:
All the six tests in X were given and all were passed; only six of the
eight in XII were given and five were passed; five of the six in XIV
were given and three were passed; five of the six in "average adult"
were given and one was passed; five were given in "superior adult" and
no credit earned. The result would be as follows:--

_Years__Months_
Credit presupposed, years I to IX 9
Credit earned in X, 6 given, 6 successes 1
Credit earned in XII, 6 given, 5 passed. Unit value
of each test given is 24 / 6 = 4. Total value
of the 5 tests passed is 5 x 4 or 1 8
Credit earned in XIV, 5 tests given, 3 passed. Unit
value of each of the 5 given is 24 / 5 = 4.8.
Value of the 3 passed is 3 x 4.8, or 0 14+
Credit earned in "average adult," 5 tests given,
1 passed. Unit value of the 5 tests given is
30 / 5 = 6. Value of the 1 success 0 6
Credit earned in "superior adult" 0 0
---- ----
Total credit 13 4+

The calculation of mental age is really simpler than our verbal
illustrations make it appear. After the operation has been performed
twenty or thirty times, it can be done in less than a half-minute
without danger of error.

THE USE OF THE INTELLIGENCE QUOTIENT. As elsewhere explained, the mental
age alone does not tell us what we want to know about a child's
intelligence status. The significance of a given number of years of
retardation or acceleration depends upon the age of the child. A
3-year-old child who is retarded one year is ordinarily feeble-minded; a
10-year-old retarded one year is only a little below normal. The child
who at 3 years of age is retarded one year will probably be retarded two
years at the age of 6, three years at the age of 9, and four years at
the age of 12.

What we want to know, therefore, is the ratio existing between mental
age and real age. This is the intelligence quotient, or I Q. To find it
we simply divide mental age (expressed in years and months) by real age
(also expressed in years and months). The process is easier if we
express each age in terms of months alone before dividing. The division
can, of course, be performed almost instantaneously and with much less
danger of error by the use of a slide rule or a division table. One who
has to calculate many intelligence quotients should by all means use
some kind of mechanical help.

HOW TO FIND THE I Q OF ADULT SUBJECTS. Native intelligence, in so far as
it can be measured by tests now available, appears to improve but little
after the age of 15 or 16 years. It follows that in calculating the I Q
of an adult subject, it will be necessary to disregard the years he has
lived beyond the point where intelligence attains its final development.

Although the location of this point is not exactly known, it will be
sufficiently accurate for our purpose to assume its location at
16 years. Accordingly, any person over 16 years of age, however old, is
for purposes of calculating I Q considered to be just 16 years old. If a
youth of 18 and a man of 60 years both have a mental age of 12 years,
the I Q in each case is 12 / 16, or .75.

The significance of various values of the I Q is set forth
elsewhere.[44] Here it need only be repeated that 100 I Q means exactly
average intelligence; that nearly all who are below 70 or 75 I Q are
feeble-minded; and that the child of 125 I Q is about as much above the
average as the high-grade feeble-minded individual is below the average.
For ordinary purposes all who fall between 95 and 105 I Q may be
considered as average in intelligence.

[44] See Chapter VI.

MATERIAL FOR USE IN TESTING. It is strongly recommended that in testing
by the Stanford revision the regular Stanford record booklets be
used. These are so arranged as to make testing accurate, rapid, and
convenient. They contain square, diamond, round field, vocabulary list,
fables, sentences, digits, and selections for memory tests, the reading
selection barred for scoring, the dissected sentences, arithmetical
problems, etc. One is required for each child tested.[45]

[45] Houghton Mifflin Company will supply all the printed material
needed in the tests, including the lines for the forms for VI, 2, the
four pictures for "enumeration," "description," and "interpretation,"
the pictures for V, 3 and VI, 2, the colors, designs for X, 3, the code
for Average Adult 6, and score cards for square, diamond, designs, and
ball-and-field.

This is all the material required for the use of the Stanford revision,
except the five weights for IX, 2, and V, 1, and the Healy-Fernald
Construction Puzzle for X. These may be purchased of C. H. Stoelting &
Co., 3037 Carroll Avenue, Chicago. It is not necessary, however, to have
the weights and the Construction Puzzle, as the presence of one or
more alternative tests in each year makes it possible to substitute
other tests instead of those requiring these materials. This saves
considerable expense. Apart from these, which may either be made at home
(see pages 278, 279) or dispensed with, the only necessary equipment for
using the Stanford revision is a copy of this book with the accompanying
set of printed matter, and the record booklets. The record booklets are
supplied only in packages of 25.

CHAPTER IX

Instructions For Year III

III, 1. POINTING TO PARTS OF THE BODY

PROCEDURE. After getting the child's attention, say: "_Show me your
nose._" "_Put your finger on your nose._" Same with eyes, mouth, and
hair.

Tact is often necessary to overcome timidity. If two or three
repetitions of the instruction fail to bring a response, point to the
child's chin or ear and say: "_Is this your nose?_" "_No?_" "_Then where
is your nose?_" Sometimes, after one has tried two or three parts of the
test without eliciting any response, the child may suddenly release his
inhibitions and answer all the questions promptly. In case of persistent
refusal to respond it is best not to harass the child for an answer, but
to leave the test for a while and return to it later. This is a rule
which applies generally throughout the scale. In the case of one
exceptionally timid little girl, it was impossible to get any response
by the usual procedure, but immediately when a doll was shown the child
pointed willingly to its nose, eyes, mouth, and hair. The device was
successful because it withdrew the child's attention from herself and
centered it upon something objective.

SCORING. _Three responses out of four_ must be correct. Instead of
pointing, the child sometimes responds by winking the eyes, opening the
mouth, etc., which is counted as satisfactory.

REMARKS. Binet's purpose in this test is to ascertain whether the
subject is capable of comprehending simple language. The ability to
comprehend and use language is indeed one of the most reliable
indications of the grade of mental development. The appreciation of
gestures comes first, then the comprehension of language heard, next the
ability to repeat words and sentences mechanically, and finally the
ability to use language as a means of communication. The present test,
however, is not more strictly a test of language comprehension than the
others of the 3-year group, and in any case it could not be said to mark
the _beginning_ of the power to comprehend spoken language. That is
fairly well advanced by the age of 2 years. The test closely resembles
III, 2 (naming familiar objects), and III, 3 (enumeration of objects in
a picture), except that it brings in a personal element and gives some
clue to the development of the sense of self. All the data agree in
locating the test at year III.

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