The Measurement of Intelligence

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30. _Treasury._ Give half credit for definitions like "Valuables,"
"Lots of money," etc.; i.e., if the word is confused with
_treasure._

32. _Ramble._ "To go about fast." (Half credit.)

38. _Nerve._ Half credit if the slang use is defined, "You've got
nerve," etc.

41. _Majesty._ "What you say to a king." (Full credit.)

45. _Sportive._ "To like sports." (Half credit.) "Playful" or
"happy." (Full credit.)

46. _Hysterics._ "You laugh and cry at the same time." "A kind of
sickness." "A kind of fit." (All full credit.)

48. _Repose._ "You pose again." (Failure.)

52. _Coinage._ "A place where they make money." (Half credit.)

56. _Dilapidated._ "Something that's very old." (Half credit.)

58. _Conscientious._ "You're careful how you do your work." (Full
credit.)

60. _Artless._ "No art." (Failure unless correctly explained.)

61. _Priceless._ "It has no price." (Failure.)

66. _Promontory._ "Something prominent." (Failure unless child can
explain what it refers to.)

68. _Milksop._ "You sop up milk." (Failure.)

73. _Harpy._ "A kind of bird." (Full credit.)

80. _Exaltation._ "You feel good." (Full credit.)

85. _Retroactive._ "Acting backward." (Full credit.)

92. _Theosophy._ "A religion." (Full credit.)

It is seen from the above examples that a very liberal standard has been
used. Leniency in judging definitions is necessary because the child's
power of expression lags farther behind his understanding than is true
of adults, and also because for the young subject the word has a
relatively less unitary existence.

REMARKS. Our vocabulary test was derived by selecting the last word
of every sixth column in a dictionary containing approximately
18,000 words, presumably the 18,000 most common words in the language.
The test is based on the assumption that 100 words selected according to
some arbitrary rule will be a large enough sampling to afford a fairly
reliable index of a subject's entire vocabulary. Rather extensive
experimentation with this list and others chosen in a similar manner
has proved that the assumption is justified. Tests of the same
75 individuals with five different vocabulary tests of this type showed
that the average difference between two tests of the same person was
less than 5 per cent. This means that any one of the five tests used is
reliable enough for all practical purposes. It is of no special
importance that a given child's vocabulary is 8000 rather than 7600; the
significance lies in the fact that it is approximately 8000 and not
4000, 12,000, or some other widely different number.

It may seem to the reader almost incredible that so small a sampling of
words would give a reliable index of an individual's vocabulary. That it
does so is due to the operation of the ordinary laws of chance. It is
analogous to predicting the results of an election when only a small
proportion of the ballots have been counted. It is known that a ballot
box contains 600 votes, and if when only 30 have been counted it is
found that they are divided between two candidates in the proportion of
20 and 10, it is safe to predict that a complete count will give the two
candidates approximately 400 and 200 respectively.[61] In 1914 about
1,000,000 votes were cast for governor in California, and when only
10,000 votes had been counted, or a hundredth of all, it was announced
and conceded that Governor Johnson had been reelected by the 150,000
plurality. The completed count gave him 188,505 plurality. The error was
less than 4 per cent of the total vote.

[61] Supposing the ballots to have been shuffled.

The vocabulary test has a far higher value than any other single test of
the scale. Used with children of English-speaking parents (with children
whose home language is not English it is of course unreliable), it
probably has a higher value than any three other tests in the scale. Our
statistics show that in a large majority of cases the vocabulary test
alone will give us an intelligence quotient within 10 per cent of that
secured by the entire scale. Out of hundreds of English-speaking
children we have not found one testing significantly above age who had a
significantly low vocabulary; and correspondingly, those who test much
below age never have a high vocabulary.

Occasionally, however, a subject tests somewhat higher or lower in
vocabulary than the mental age would lead us to expect. This is often
the case with dull children in cultured homes and with very intelligent
children whose home environment has not stimulated language development.
But even in these cases we are not seriously misled, for the dull child
of fortunate home surroundings shows his dullness in the quality of his
definitions if not in their quantity; while the bright child of
illiterate parents shows his intelligence in the aptness and accuracy of
his definitions.

We have not worked out a satisfactory method of scoring the quality of
definitions in our vocabulary test, but these differences will be
readily observed by the trained examiner. Definitions in terms of use
and definitions which are slightly inaccurate or hazy are quite
characteristic of the lower mental ages. Children of the lower mental
age have also a tendency to venture wild guesses at words they do not
know. This is especially characteristic of retarded subjects and is
another example of their weakness of auto-criticism. One feeble-minded
boy of 12 years, with a mental age of 8 years, glibly and confidently
gave definitions for every one of the hundred words. About 70 of the
definitions were pure nonsense.

This vocabulary test was arranged and partially standardized by Mr.
H. G. Childs and the writer in 1911. Many experiments since then have
proved its value as a test of intelligence.

VIII, ALTERNATIVE TEST 1: NAMING SIX COINS

PROCEDURE is exactly as in VI, 5 (naming four coins). The dollar should
be shown before the half-dollar.

SCORING. _All six coins must be correctly named._ If a response is
changed the rule is to count the second answer and ignore the first.

REMARKS. Binet used nine pieces and required knowledge of all at year X
(1908), but at year IX in the 1911 revision. Most other workers have
used the same method, with the test located in either year IX or year X.

VIII, ALTERNATIVE TEST 2: WRITING FROM DICTATION

PROCEDURE. Give the child pen, ink, and paper, place him in a
comfortable position for writing, and say: "_I want you to write
something for me as nicely as you can. Write these words: 'See the
little boy.' Be sure to write it all: 'See the little boy.'_"

Do not dictate the words separately, but give the sentence as a whole.
Further repetition of the sentence is not permissible, as ability to
remember what has been dictated is a part of the test. Copy, of course,
must not be shown.

SCORING. Passed if the sentence is written legibly enough to be easily
recognized, and if no word has been omitted. Ordinary mistakes of
spelling are disregarded. The rule is that the mistake in spelling must
not mutilate the word beyond easy recognition. The performance may be
graded by the use of Thorndike's handwriting scale. The handwriting of
8-year-old children who have been in school not less than one year or
more than two usually falls between quality 7 and quality 9 on this
scale, but we shall, perhaps, not be too liberal if we consider a
performance satisfactory which does not grade below quality 6, provided
it is not seriously mutilated by errors, omissions, etc.[62]

[62] See scoring card for samples of satisfactory and unsatisfactory
performances.

REMARKS. This test found a place in year VIII of Binet's 1908 scale, but
has been omitted from all the other revisions, including Binet's own.
Bobertag did not even regard the test as worthy of a trial. The
universal criticism has been that it is a test of schooling rather than
of intelligence. That the performance depends, in a certain sense, upon
special instruction is self-evident. Without such instruction no child
of 8 years, however intelligent, would be able to pass the test. Nature
does not give us a conventionalized language, either written or spoken.
It must be acquired. It is also true that a high-grade feeble-minded
child, say 8 years of age and of 6-year intelligence, is sometimes
(though not always) able to pass the test after two years of
school instruction. It is exceedingly improbable, however, that a
feeble-minded subject with less than 6-year intelligence will ever be
able to pass this test, however long he remains in school.

The conclusions to be drawn from these facts are as follows: (1)
Inability to pass the test should not be counted against the child
unless it is known that he has had at least a full year of the usual
school instruction. (2) Ability to pass the test after only two years of
school instruction is almost certain proof that the child has reached a
mental level of at least 6 years. (3) Failure to pass the test must be
regarded as a grave symptom in the case of the child 9 or more years of
age who is known to have attended school as much as two years. (4) For
mental levels higher than 8 years the test has hardly any diagnostic
value, since feeble-minded persons of 8- or 9-year intelligence can
usually be taught to write quite legibly.

If the limitations above set forth are kept in mind, the test is by no
means without value, and is always worth giving as a supplementary test.
Learning to write simple sentences from dictation is no mean
accomplishment. It demands, in the first place, a fairly complete
mastery of rather difficult muscular cooerdinations. Moreover, these
cooerdinations must be firmly associated with the corresponding letters
and words, for if the writing cooerdinations are not fairly automatic, so
much attention will be required to carry them out that the child will
not be able to remember what he has been told to write. The necessity of
remembering the passage acts as a distraction, and writing from
dictation is therefore a more difficult task than writing from copy.

CHAPTER XV

INSTRUCTIONS FOR YEAR IX

IX, 1. GIVING THE DATE

PROCEDURE. Ask the following questions in order:--

(a) "_What day of the week is it to-day?_"
(b) "_What month is it?_"
(c) "_What day of the month is it?_"
(d) "_What year is it?_"

If the child misunderstands and gives the day of the month for the day
of the week, or _vice versa_, we merely repeat the question with
suitable emphasis, but give no other help.

SCORING. An error of three days in either direction is allowed for _c_,
but _a_, _b_, and _d_ must all be given correctly. If the child makes an
error and spontaneously corrects it, the change is allowed, but
corrections must not be called for or suggested.

REMARKS. Binet originally located this test in year IX, but
unfortunately moved it to year VIII in the 1911 revision. Kuhlmann,
Goddard, and Huey all retain it in year IX, where, according to our own
data, it unquestionably belongs. With the exception of Binet's 1911
results, the statistics for the test are in remarkably close agreement
for children in France, Germany, England, and Eastern and Western United
States. It seems that practically all children in civilized countries
have ample opportunity to learn the divisions of the year, month, and
week, and to become oriented with respect to these divisions. Special
instruction is doubtless capable of hastening time orientation to a
certain degree, but not greatly. Binet tells of a French _ecole
maternelle_ attended by children 4 to 6 years of age, where instruction
was given daily in regard to the date, and yet not a single one of the
children was able to pass this test. This is a beautiful illustration of
the futility of precocious teaching. In spite of well-meant instruction,
it is not until the age of 8 or 9 years that children have enough
comprehension of time periods, and sufficient interest in them, to keep
very close track of the date. Failure to pass the test at the age of
10 or 11 years is a decidedly unfavorable sign, unless the error is very
slight.

The fact that normal adults are occasionally unable to give the day of
the month is no argument against the validity of the test, since the
system of tests is so constructed as to allow for accidental failures on
any particular test. As a matter of fact, very nearly 100 per cent of
normal 12-year-old children pass this test.

The unavoidable fault of the test is its lack of uniformity in
difficulty at different dates. It is easier for school children to give
the day of the week on Monday or Friday than on Tuesday, Wednesday, or
Thursday. Mistakes in giving the day of the month are less likely to
occur at the beginning or end of the month than at any other time, while
mistakes in naming the month are most likely to occur then.

It is interesting to compare the four parts of this test in regard to
difficulty. Binet and Bobertag both state that ability to name the year
comes last, but they give no figures. Our own data show that the four
parts of the test are of almost exactly the same difficulty and that
this is true at all ages.

IX, 2. ARRANGING FIVE WEIGHTS

Use the five weights, 3, 6, 9, 12, and 15 grams. Be sure that the
weights are identical in appearance. The weights may be made as
described under V, 1, or they may be purchased of C. H. Stoelting & Co.,
Chicago, Illinois. If no weights are at hand one of the alternative
tests may be substituted.

PROCEDURE. Place the five boxes on the table in an irregular group
before the child and say: "_See the boxes. They all look alike, don't
they? But they are not alike. Some of them are heavy, some are not quite
so heavy, and some are still lighter. No two weigh the same. Now, I want
you to find the heaviest one and place it here. Then find the one that
is just a little lighter and put it here. Then put the next lighter one
here, and the next lighter one here, and the lightest of all at this
end_ (pointing each time at the appropriate spot). _Do you understand?_"
Whatever the child answers, in order to make sure that he does
understand, we repeat the instructions thus: "_Remember now, that no two
weights are the same. Find the heaviest one and put it here, the next
heaviest here, and lighter, lighter, until you have the very lightest
here. Ready; go ahead._"

It is best to follow very closely the formula here given, otherwise
there is danger of stating the directions so abstractly that the subject
could not comprehend them. A formula like "_I want you to arrange the
blocks in a gradually decreasing series according to weight_" would be
Greek to most children of 10 years.

If the subject still seems at a loss to know what to do, the
instructions may be again repeated. But no further help of any kind may
be given. Do not tell the subject to take the blocks one at a time in
the hand and try them, and do not illustrate by hefting the blocks
yourself. It is a part of the test to let the subject find his own
method.

Give three trials, shuffling the boxes after each. Do not repeat the
instructions before the second and third trials unless the subject has
used an absurd procedure in the previous trial.

SCORING. The test is passed if the blocks are arranged in the correct
order _twice out of three trials_. Always record the order of
arrangement and note the number and extent of displacement. Obviously an
arrangement like 12-6-15-3-9 is very much more serious than one like
15-12-6-9-3, but we require that two trials be absolutely without error.

Scoring is facilitated if the blocks are marked on the bottom so that
they may be easily identified. It is then necessary to exercise some
care to see that the subject does not examine the bottom of the blocks
for a clue as to the correct order.

REMARKS. Binet originally located this test in year IX, but in his 1911
revision changed it to year VIII. Other revisions have retained it in
year IX. The correct location depends upon the weights used and upon the
procedure and scoring. Kuhlmann uses weights of 3, 9, 18, 27, 36, and
45 grams, and this probably makes the test easier. Bobertag tried two
sets of boxes, one set being of larger dimensions than the other. The
larger gave decidedly the more errors. If we require only one success in
three trials the test could be located a year or two lower in the scale,
while three successes as a standard would require that it be moved
upward possibly as much as two years.

Much depends also on whether the child is left to find his own method,
and on this there has been much difference of procedure. Kuhlmann,
Bobertag, and Wallin illustrate the correct method of making the
comparison by first hefting and arranging the weights while the subject
looks on. We prefer to keep the test in its original form, and with the
procedure and scoring we have used it is well located in year IX.

Wallin carries his assistance still further by saying, after the first
block has been placed, "Now, find the heaviest of the four," and after
the second has been placed, "Now, find the heaviest of the three," etc.
Finally, when the arrangement has been made, he tells the subject to try
them again to make sure the order is correct, allowing the subject to
make whatever changes he thinks necessary. This procedure robs the test
of its most valuable features. The experiment was not devised primarily
as a test of sensory discrimination, for it has long been recognized
that individuals who have developed as far as the 9- or 10-year level of
intelligence are ordinarily but little below normal in sensory capacity.

Psychologically, the test resembles that of comparing weights in V, 1.
Success depends, in the first place, upon the correct comprehension of
the task and the setting of a goal to be attained; secondly, upon the
choice of a suitable method for realizing the goal; and finally, upon
the ability to keep the end clearly in consciousness until all the steps
necessary for its attainment have been gone through. Elementary as are
the processes involved, they represent the prototype of all purposeful
behavior. The statesman, the lawyer, the teacher, the physician, the
carpenter, all in their own way and with their own materials, are
continually engaged in setting goals, choosing means, and inhibiting the
multitudinous appeals of irrelevant and distracting ideas.

In this experiment the subject may fail in any one of the three
requirements of the test or in all of them. (1) He may not comprehend
the instructions and so be unable to set the goal. (2) Though
understanding what is expected of him, he may adopt an absurd method of
carrying out the task. Or (3) he may lose sight of the end and begin to
play with the blocks, stacking them on top of one another, building
trains, tossing them about, etc. Sometimes the guiding idea is not
completely lost, but is weakened or rendered only partially operative.
In such a case the subject may compare some of the blocks carefully,
place others without trying them at all, but continue in his
half-rational, half-irrational procedure until all the blocks have been
arranged.

It is essential, therefore, to supplement the mere record of success or
failure by jotting down a brief but accurate description of the
performance. Note any hesitation or inability to grasp the instructions.
Note especially any absurd procedure, such as placing all the blocks
without hefting any of them, comparing only some of them, holding them
up and shaking them, hefting two at once in the same hand, etc. The
ideal method, of course, is to try all the blocks carefully before
placing any of them, then to make a tentative arrangement, and finally,
to correct this tentative arrangement by means of individual
comparisons. A slight departure from this method does not always bring
failure, but it renders success less probable. As a rule it is only the
very intelligent children of 10 years who think to test out their first
arrangement by making a final and additional trial of each block in
turn. Contrary to what might be supposed, success is slightly favored by
hefting the blocks successively with one hand rather than by taking one
in each hand for simultaneous comparison, but as the child cannot be
expected to know this, we must regard the two methods as equally
logical.

The test of arranging weights has met universal praise. Its special
advantage is that it tests the subject's intelligence in the
manipulation of _things_ rather than his capacity for dealing with
_abstractions_. It tests his ability to do something rather than his
ability to express himself in language. It throws light upon certain
factors of motor adaptation and practical judgment which play a great
part in the everyday life of the average human being. It depends as
little upon school, perhaps, as any other test of the scale, and it is
readily usable with children of all nations without danger of being
materially altered in translation Moreover, it is always an interesting
test for the child. Bobertag goes so far as to say that any 8- or 9-year
child who passes this test cannot possibly be feeble-minded. This may be
true; but the converse is hardly the case; that is, the failure of older
children is by no means certain proof of mental retardation. The same
observation, however, applies equally well to many other of the Binet
tests, some of which correlate more closely with true mental age than
this one. A rather considerable fraction of normal 12-year-olds fail on
it, and it is in fact somewhat less dependable than certain other tests
if we wish to differentiate between 9-year and 11-year intelligence. But
it is a test we could ill afford to eliminate.[63]

[63] Compare with V, 1.

IX, 3. MAKING CHANGE

PROCEDURE. Ask the following questions in the order here given:--

(a) "_If I were to buy 4 cents worth of candy and should give
the storekeeper 10 cents, how much money would I get back?_"
(b) "_If I bought 13 cents worth and gave the storekeeper
15 cents, how much would I get back?_"
(c) "_If I bought 4 cents worth and gave the storekeeper
25 cents, how much would I get back?_"

Coins are not used, and the subject is not allowed the help of pencil
and paper. If the subject forgets the statement of the problem, it is
permissible to repeat it once, but only once. The response should be
made in ten or fifteen seconds for each problem.

SCORING, The test is passed if _two out of three_ problems are answered
correctly in the allotted time. In case two answers are given to a
problem, we follow the usual rule of counting the second and ignoring
the first.

REMARKS. Problems of this nature, when thoroughly standardized, are
extremely valuable as tests of intelligence. The difficulty of the test,
as we have used it, does not lie in the subtraction of 4 from 10, 12
from 15, etc. Such subtractions, when given as problems in subtraction,
are readily solved by practically all normal 8-year-olds who have
attended school as much as two years. The problems of the test have a
twofold difficulty: (1) The statement of the problem must be
comprehended and held in mind until the solution has been arrived at;
(2) the problem is so stated that the subject must himself select the
fundamental operation which applies. The latter difficulty is somewhat
the greater of the two, addition sometimes being employed instead of
subtraction.

It is just such difficulties as this that prove so perplexing to the
feeble-minded. High-grade defectives, although they require more than
the usual amount of drill and are likely to make occasional errors, are
nevertheless capable of learning to add, subtract, multiply, and divide
fairly well. Their main trouble comes in deciding which of these
operations a given problem calls for. They can master routine, but as
regards initiative, judgment, and power to reason they are little
educable. The psychology and pedagogy of mental deficiency is epitomized
in this statement.

There has been little disagreement as to the proper location of the test
of making change, but various procedures have been employed. Coins have
generally been employed, in which case the subject is actually allowed
to make the change. Most other revisions have also given only a single
problem, usually 4 cents out of 20 cents, or 4 out of 25, or 9 out of
25. It is evident that these are not all of equal difficulty. There is
general agreement, however, that normal children of 9 years should be
able to make simple change.

IX, 4. REPEATING FOUR DIGITS REVERSED

The series are 6-5-2-8; 4-9-3-7; 3-6-2-9.

PROCEDURE AND SCORING. Exactly as in VII, alternate test 2.[64]

[64] See discussion, p. 207 _ff._

IX, 5. USING THREE WORDS IN A SENTENCE

PROCEDURE The words used are:--

(a) _Boy_, _ball_, _river_.
(b) _Work_, _money_, _men_.
(c) _Desert_, _rivers_, _lakes_.

Say: "_You know what a sentence is, of course. A sentence is made up of
some words which say something. Now, I am going to give you three words,
and you must make up a sentence that has all three words in it. The
three words are 'boy,' 'ball,' 'river.' Go ahead and make up a sentence
that has all three words in it._" The others are given in the same way.

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