The child’s intelligence is to be judged by his success in the performance of certain tasks. These tasks may appear to the examiner to be very easy, indeed; but we must bear in mind that they are often anything but easy for the child. Real effort and attention are necessary for his success, and occasionally even his best efforts fall short of the desired result. If the tests are to display the child’s real intellectual ability it will be necessary, therefore, to avoid as nearly as possible every disturbing factor which would divide his attention or in any other way injure the quality of his responses. To insure this it will be necessary to consider somewhat in detail a number of factors which influence effort, such as degree of quiet, the nature of surroundings, presence or absence of others, means of gaining the child’s confidence, the avoidance of embarrassment, fatigue, etc.

One should not expect, however, to secure an absolutely equal degree of attention from all subjects. The power to give sustained attention to a difficult task is characteristically weak in dull and feeble-minded children. What we should labor to secure is the maximum attention of which the child is capable, and if this is unsatisfactory without external cause, we are to regard the fact as symptomatic of inferior mental ability, not as an extenuating factor or an excuse for lack of success in the tests.

Attention, of course, cannot be normal if any acute physical or mental disturbance is present. Toothache, headache, earache, nausea, fever, cold, etc., all render the test inadvisable. The same is true of mental anxiety or fear, as in the case of the child who has just been arrested and brought before the court.

Quiet and seclusion.

The tests should be conducted in a quiet room, located where the noises of the street and other outside distractions cannot enter. A reasonably small room is better than a very large one, because it is more homelike. The furnishings of the room should be simple. A table and two chairs are sufficient. If the room contains a number of unfamiliar objects, such as psychological apparatus, pictures on the walls, etc., the attention of the child is likely to be drawn away from the tasks which he is given to do. The halls and corridors which it is sometimes necessary to use in testing school children are usually noisy, cold, or otherwise objectionable.

Presence of others.

A still more disturbing influence is the presence of other persons. Generally speaking, if accurate results are to be secured it is not permissible to have any auditor, besides possibly an assistant to record the responses. Even the assistant, however quiet and unobtrusive, is sometimes a disturbing element. Though something of a convenience, the assistant is by no means necessary, after the examiner has thoroughly mastered the procedure of the tests and has acquired some skill in the use of abbreviations in recording the answers. If an assistant or any other person is present, he should be seated somewhat behind the child, not too close, and should take no notice of the child either when he enters the room or at any time during the examination.

At all events, the presence of parent, teacher, school principal, or governess is to be avoided. Contrary to what one might expect, these distract the child much more than a strange personality would do. Their critical attitude toward the child’s performance is very likely to cause embarrassment. If the child is alone with the examiner, he is more at ease from the mere fact that he does not feel that there is a reputation to sustain. The praise so lavishly bestowed upon him by the friendly and sympathetic examiner lends to the same effect.

As Binet emphasizes, if the presence of others cannot be avoided, it is at least necessary to require of them absolute silence. Parents, and sometimes teachers, have an almost irrepressible tendency to interrupt the examination with excuses for the child’s failures and with disturbing explanations which are likely to aid the child in comprehending the required task. Without the least intention of doing so, they sometimes practically tell the child how to respond. Parents, especially, cannot refrain from scolding the child or showing impatience when his answers do not come up to expectation. This, of course, endangers the child’s success still further.

The psychologist is not surprised at such conduct. It would be foolish to expect average parents, even apart from their bias in the particular case at hand, to adopt the scientific attitude of the trained examiner. Since we cannot in a few moments at our disposal make them over into psychologists, our only recourse is to deal with them by exclusion.

This is not to say that it is impossible to test a child satisfactorily in the presence of others. If the examiner is experienced, and if the child is not timid, it is sometimes possible to make a successful test in the presence of quite a number of auditors, provided they remain silent, refrain from staring, and otherwise conduct themselves with discretion. But not even the veteran examiner can always be sure of the outcome in demonstration testing.

Getting into “rapport.”

The examiner’s first task is to win the confidence of the child and overcome his timidity. Unless rapport has first been established, the results of the first tests given are likely to be misleading. The time and effort necessary for accomplishing this are variable factors, depending upon the personality of both the examiner and the subject. In a majority of cases from three to five minutes should be sufficient, but in a few cases somewhat more time is necessary.

The writer has found that when a strange child is brought to the clinic for examination, it is advantageous to go out of doors with him for a little walk around the university buildings. It is usually possible to return from such a stroll in a few minutes, with the child chattering away as though to an old friend. Another approach is to begin by showing the child some interesting object, such as a toy, or a form-board, or pictures not used in the test. The only danger in this method is that the child is likely to find the object so interesting that he may not be willing to abandon it for the tests, or that his mind will keep reverting to it during the examination.

Still another method is to give the child his seat as soon as he is ushered into the room, and, after a word of greeting, which must be spoken in a kindly tone but without gushiness, to open up a conversation about matters likely to be of interest. The weather, place of residence, pets, sports, games, toys, travels, current events, etc., are suitable topics if rightly employed. When the child has begun to express himself without timidity and it is clear that his confidence has been gained, one may proceed, as though in continuance of the conversation, to inquire the name, age, and school grade. The examiner notes these down in the appropriate blanks, rather unconcernedly, at the same time complimenting the child (unless it is clearly a case of serious retardation) on the fine progress he has made with his studies.

Keeping the child encouraged.

Nothing contributes more to a satisfactory rapport than praise of the child’s efforts. Under no circumstances should the examiner permit himself to show displeasure at a response, however absurd it may be. In general, the poorer the response, the better satisfied one should appear to be with it. An error is always to be passed by without comment, unless it is painfully evident to the child himself, in which case the examiner will do well to make some excuse for it; e.g., “You are not quite old enough to answer questions like that one; but, never mind, you are doing beautifully,” etc. Exclamations like “fine!” “splendid!” etc., should be used lavishly. Almost any innocent deception is permissible which keeps the child interested, confident, and at his best level of effort. The examination should begin with tests that are fairly easy, in order to give the child a little experience with success before the more difficult tests are reached.

The importance of tact.

It goes without saying that children’s personalities are not so uniform and simple that we can adhere always to a single stereotyped procedure in working our way into their good graces. Suggestions like the above have their value, but, like rules of etiquette, they must be supported by the tact which comes of intuition and cannot be taught. The address which flatters and pleases one child may excite disgust in another. The examiner must scent the situation and adapt his method to it. One child is timid and embarrassed; another may think his mental powers are under suspicion and so react with sullen obstinacy; a third may be in an angry mood as a result of a recent playground quarrel. Situations like these are, of course, exceptional, but in any case it is necessary to create in the child a certain mood, or indefinable attitude of mind, before the test begins.

Personality of the examiner.

Doubtless there are persons so lacking in personal adaptability that success in this kind of work would be for them impossible. The wooden, mechanical, matter-of-fact and unresponsive personality is as much out of place in the psychological clinic as the traditional bull in the china shop. It would make an interesting study for some one to investigate, by exact methods, the influence on test results of the personality of different examiners who have been equally trained in the methods to be employed and who are equally conscientious in applying them according to rules.

On the whole, differences of this kind are probably not very great among experienced and reasonably competent examiners. Adaptability grows with experience and with increase of self-confidence. After a few score tests there should be no serious failure from inability to get into rapport with the child. Even in those rare cases where the child breaks down and cries from timidity, or perhaps refuses to answer out of embarrassment, the difficulty can be overcome by sufficient tact so that the examination may proceed as though nothing had happened.

If the examiner has the proper psychological and personal equipment, the testing of twenty or thirty children forms a fairly satisfactory apprenticeship. Without psychological training, no amount of experience will guarantee absolute accuracy of the results.

The avoidance of fatigue.

Against the validity of intelligence tests it is often argued that the result of an examination depends a great deal on the time of day when it is made, whether in the morning hours when the mind is at its best, or in the afternoon when it is supposedly fatigued. Although no very extensive investigation has been made of this influence, there is no evidence that the ordinary fatigue incident to school work injures the child’s performance appreciably. Our tests of 1000children showed no inferiority of results secured from 1to4p.m., as compared with tests made from 9to12a.m.

An explanation for this is not hard to find. Although school work causes fatigue, in the sense that a part of the child’s available supply of mental energy is used up, there is always a reserve of energy sufficient to carry the child through a thirty-to fifty-minute test. The fact that the required tasks are novel and interesting to a high degree insures that the reserve energy will really be brought into play. This principle, of course, has its natural limits. The examiner would avoid testing a child who was exhausted either from work or play, or a child who was noticeably sleepy.

Duration of the examination.

About the only danger of fatigue lies in making the examination too long. Young children show symptoms of weariness much more quickly than older children, and it is therefore fortunate that not so much time is needed for testing them. The following allowances of time will usually be found sufficient:—

This allowance ordinarily includes the time necessary for getting into rapport with the child, in addition to that actually consumed in the tests. But the examiner need not expect to hold fast to any schedule. Some subjects respond in a lively manner, others are exasperatingly slow. It is more often the mentally retarded child who answers slowly, but exceptions to this rule are not uncommon. One 8-year-old boy examined by the writer answered so hesitatingly that it required two sittings of nearly an hour each to complete the test. The result, however, showed a mental age of 11½years, or an IQ of 143.

It is permissible to hurry the child by an occasional “that’s fine; now, quickly,” etc., but in doing this caution must be exercised, or the child’s mental process may be blocked. The appearance of nagging must be carefully avoided. If the test goes so slowly that it cannot be completed in the above limits of time, it is usually best to stop and complete the examination at another time. When this is not possible, it is advisable to take a ten-minute intermission and a little walk out of doors.

Time can be saved by having all the necessary materials close at hand and conveniently arranged. The coins should be kept in a separate purse, and the pictures, colors, stamps, and designs for drawing should be mounted on stiff cardboard which may be punched and kept in a notebook cover. The series of sentences, digits, comprehension questions, fables, etc., should either be mounted in similar fashion, or else printed in full on the record sheets used in the tests. The latter is more convenient.[43] All other materials should be kept where they will not have to be hunted for.

Besides saving valuable time, a little methodical foresight of this kind adds to the success of the test. If the child is kept waiting, the test loses its interest and attention strays. See to it, if possible, that no lull occurs in the performance.

Inexperienced examiners sometimes waste time foolishly by stopping to instruct the child on his failures. This is doubly bad, for besides losing time it makes the child conscious of the imperfection of his responses and creates embarrassment. Adhere to the purpose of the test, which is to ascertain the child’s intellectual level, not to instruct him.

Desirable range of testing.

There are two considerations here of equal importance. It is necessary to make the examination thorough, but in the pursuit of thoroughness we must be careful not to produce fatigue or ennui. Unless there is reason to suspect mental retardation, it is usually best to begin with the group of tests just below the child’s age. However, if there is a failure in the tests of that group, it is necessary to go back and try all the tests of the previous group. In like manner the examination should be carried up the scale, until a test group has been found in which all the tests are failed.

It must be admitted, however, that because of time limitations and fatigue, it is not always practicable to adhere to this ideal of thoroughness. In testing normal children, little error will result if we go back no farther than the year which yielded only one failure, and if we stop with the year in which there was only one success. This is the lowest permissible limit of thoroughness. Defectives are more uneven mentally than normal children, and therefore scatter their successes and failures over a wider range. With such subjects it is absolutely imperative that the test be thorough.

In the case of defectives it is sometimes necessary to begin with random testing, until a rough idea is gained of the mental level. But the skilled observer soon becomes able to utilize symptoms in the child’s conversation and conduct and to dispense with most of this preliminary exploration.

Order of giving the tests.

The child’s efforts in the tests are sometimes markedly influenced by the order in which they are given. If language tests or memory tests are given first, the child is likely to be embarrassed. More suitable to begin with are those which test knowledge or judgment about objective things, such as the pictures, weights, stamps, bow-knot, colors, coins, counting pennies, number of fingers, right and left, time orientation, ball and field, paper-folding, etc. Tests like naming sixty words, finding rhymes, giving differences or similarities, making sentences, repeating sentences, and drawing are especially unsuitable because they tend to provoke self-consciousness.

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 ½. 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 groupX, 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 100percent 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 yearX, 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 yearVIII, 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 2months toward mental age. There are eight tests in groupXII, which, because of the omission of the 11-year group, have a combined value of 24months, or 3months each. Similarly, each of the six tests in XIV has a value of 4months (24÷6=4). The tests of the “average adult” group are given a value of 5months each, and those of the “superior adult” group a value of 6months 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 2months for each test passed successfully up to and including yearX, 3months for each test passed in XII, 4months for each test passed in XIV, 5months for each success in “average adult,” and 6months 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:—

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:—

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

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:—

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 3years 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 IQ. 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 IQ 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 15or16years. It follows that in calculating the IQ 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 16years. Accordingly, any person over 16years of age, however old, is for purposes of calculating IQ considered to be just 16years old. If a youth of 18 and a man of 60years both have a mental age of 12years, the IQ in each case is 12÷16, or .75.

The significance of various values of the IQ is set forth elsewhere.[44] Here it need only be repeated that 100IQ means exactly average intelligence; that nearly all who are below 70or75IQ are feeble-minded; and that the child of 125IQ 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 95and105IQ may be considered as average in intelligence.

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]

[43] Examiners will find it a great convenience to use the record booklet which has been specially devised for testing with the Stanford revision. It contains all the necessary printed material, including digits, sentences, absurdities, fables, the vocabulary list, the reading selection, the square and diamond for copying, etc., and in addition gives with each test the standard for scoring. It is so arranged as to afford ample room for a verbatim record of all the child’s responses, and contains other features calculated to make testing easy and accurate. Regarding purchasing of supplies see p.141.