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Experimental Education Series

Edited by M. V. O’SHEA

SPECIAL TALENTS AND DEFECTS

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SPECIAL TALENTS AND DEFECTS
Their Significance for Education

BY

LETA S. HOLLINGWORTH, Ph.D.

Associate Professor of Education

Teachers College, Columbia University

New York

THE MACMILLAN COMPANY

1923

All rights reserved

PRINTED IN THE UNITED STATES OF AMERICA

Copyright, 1923

By THE MACMILLAN COMPANY

Set up and electrotyped. Published August, 1923.

Norwood Press

J. S. Cushing Co.—Berwick & Smith Co.

Norwood, Mass., U.S.A.

TO

THE MEMORY OF

RUTH ELINOR STETTER

A GOOD TEACHER

PREFACE

This book has proceeded haltingly, as must be evident in many places, for it attempts to explore and describe a field that is not well illuminated. The actual examination of those mental functions which are relatively dissociated from general intelligence has not been carried far by experimentalists. However, the problems have been sufficiently formulated, and enough evidence has been secured, to warrant attempts at gleaning implications for education, even now.

Mine is the comparatively humble task of bringing together in an ordered presentation the works of original investigators, in such a way that they will be available for application. The appeal of the data is above all to educators, but also, of course, to those who deal in any office with human beings.

The chief difficulty in organizing the subject has been to delimit it, as regards the psychology of the elementary school subjects on the one hand, and mental measurement on the other. It is not the purpose to cover either of these fields in the present volume. Yet so closely are they related to the study of special aptitudes in school children that it will be scarcely possible to obtain the very clearest view of what is here written without additional knowledge of these matters.

It will be observed, also, that there has been no attempt here to teach introductory psychology. It is assumed that readers of this volume will be acquainted with the vocabulary of elementary psychology. The time has definitely passed when it was either feasible or desirable to present all topics in a single volume. Those who would learn what modern educational psychology has to teach now expect, first of all, to equip themselves by study of a general introductory text.

The lists of references are selected, not complete. To present complete bibliographies of all works bearing immediately or remotely upon every topic treated would cumber the volume inexcusably. References have been selected for these lists because they are historically indispensable, because they contain information of fundamental importance, or because they summarize much previous work. I believe that the selection is such that from the books and articles listed it will be possible for the student who wishes to do so, to construct the complete bibliography and history of each topic, up to the present time.

The hundreds of teachers who have sat in the lecture room of Professor E. L. Thorndike will see how many guiding suggestions for this volume have come from that source. Professor W. A. McCall has given counsel on certain chapters. Many investigators and publishers have extended courtesies, which are acknowledged through the references, and to which attention is here gratefully directed. I am indebted to Dr. John S. Richards, Medical Superintendent of The Children’s Hospital, Randall’s Island, New York, and to Mr. L. L. Kolburne, student at Teachers College, for assistance in securing illustrative material for Chapter VII. Finally, I have enjoyed the advantage of editorial supervision by Professor M. V. O’Shea.

My chief hope for the volume is that it may contribute toward the welfare of school children compelled to attend upon prescribed education, without due regard for their idiosyncrasies of original endowment.

Leta S. Hollingworth

Teachers College

Columbia University

May, 1923

TABLE OF CONTENTS

TABLE OF FIGURES

EDITOR’S INTRODUCTION

When the writer of this introductory note began teaching, it was popularly believed that a pupil who showed special excellence in intellectual work or in some particular study owed his superiority to a faithful and energetic will which held him to his tasks until he had mastered them thoroughly. It was generally believed, also, that marked deficiency in school work as a whole or in a special subject was due principally to a lethargic or indifferent will which could not resist distractions and temptations to self-indulgence. In those days, pupils were upbraided and even physically chastised if they failed to prepare the lessons which were prescribed for them in any study. The writer has often seen pupils whipped because they failed in their spelling, arithmetic, reading, history, or grammar. When punishment was administered in the school it was frequently repeated in the home, since parents quite generally entertained the view that failure to perform intellectual tasks satisfactorily was due to negligence or laziness, and it was thought that the best way to correct such delinquency was to arouse the will, usually by means of dermal stimulation. In his early experience as a teacher, the writer never heard, either in training classes or in teachers’ institutes, that pupils possessed special talents or defects which were certain to be manifested in their school work because they were established by native endowment which could not be modified to any large extent by rewards or penalties.

But we are gradually abandoning the view that either brightness or dullness in general or in special directions is due primarily to volitional control or the absence of it. During the last few years, experimental studies have impressed the principle that individuals differ in their inheritance of special capacities. Dr. Hollingworth shows in this volume how far we have gone in the detection of special talents and defects, with particular regard to the work of the school. She shows in preliminary discussion what notions people have entertained regarding the nature of ability, and then she discusses methods of measuring ability, alike of a general and of a special sort. She discusses the bases for differences among individuals in ability in respect to various intellectual traits or functions. Then she presents in detail what is known to-day regarding special talents and defects as revealed in the more important subjects taught in the schools.

We believe in these times that the school should to the fullest extent provide opportunities for each pupil to develop his talents as completely and as rapidly as possible. It is still required in most public schools, though, that pupils in any group should be kept quite close together in their educational progress, even when they show marked differences in ability in particular subjects or in the entire work of the school. But the pressure is becoming constantly greater to arrange school programs so that pupils may go forward as rapidly as their abilities, either general or special, will enable them to do, while those who are deficient may receive help according to their needs. There are already a number of experimental schools and school systems in which the principle of individual differences in ability is recognized and applied to a greater or less extent. One may safely predict that we shall find a way in time so that the principle may be recognized and applied in all public schools.

Dr. Hollingworth’s book lays a sound foundation for the differentiation of pupils in a school or classroom according to special abilities or deficiencies. It can be read by teachers who have not had extensive study of educational psychology or statistical methods of investigating such problems as are treated in this volume. The book is written in a graceful style, and technical matters are discussed in an unusually clear, simple, and attractive way. It may be confidently asserted that any teacher who has charge of thirty or forty pupils—or a smaller or larger number—will be helped to understand individual traits of excellence or deficiency if she will read what Dr. Hollingworth has presented in this volume. It may be safely stated, also, that a teacher will be more sympathetic toward pupils who experience difficulty in mastering special subjects of study if she will become familiar with the facts and conclusions which this book contains.

M. V. O’Shea

The University of Wisconsin

May, 1923

SPECIAL TALENTS AND DEFECTS

CHAPTER I
Preliminary Discussion

I. SPECULATION CONCERNING THE NATURE OF ABILITY

Since reflective men began to record their speculations, theories have been expressed concerning the nature and relationships of mental functions. Plato in The Republic contemplated the importance of knowledge in this field. “Come now and we will ask you a question: when you spoke of a nature gifted or not gifted in any respect, did you mean to say that one man will acquire a thing easily, another with difficulty; a little learning will lead the one to discover a great deal; whereas the other, after much study and application, no sooner learns than he forgets; or, again, did you mean that the one has a body which is a good servant to his mind, while the body of the other is a hindrance to him? Would not these be the sort of differences which would distinguish the man gifted by nature from the one who is ungifted?”

In The Republic the use of mental tests to discover the caliber of the mind is foretold. “We must watch them from their youth upwards, and make them perform actions in which they are most likely to forget or to be deceived, and he who remembers and is not deceived is to be selected, and he who fails in the trial is to be rejected. That will be the way?”

Aside from the speculations of scholars, folk notions as expressed in proverbs are interesting, especially as showing what men wish were true concerning human talents and defects. Many of these proverbs embody the idea of a compensatory distribution of abilities: if I am weak in one respect, I am sure to be strong in another; if I am a failure now, I shall probably be a success later on. “Every dog has his day.” “Homely in the cradle, handsome at the table.” “Slow but sure.” “Easy come, easy go.” This doctrine of compensation satisfies certain cravings of human nature, and is therefore likely to be held wherever people have not given impartial attention to the results of experimental investigation.

Folk-wisdom has also seen men under mental types. According to the theory of types, the human species is divided into separate categories, with respect to mental constitution. There would thus be the musical and the unmusical, the quick and the slow, the imaginative and the unimaginative, the eye-minded and the ear-minded, and so forth. The observable complexities of behavior have further led to the description of a given person by a combination of type-terms, as, for example, “quick-musical-imaginative,” or “mathematical-accurate-unimaginative.” Persons thus classified by types, are thought to be of “different kinds,” “equal” but “unlike.” Two persons are thus compared as an apple is compared to an orange. Both fruits are “equal,” but of “different types.” People, according to this conception of human nature, are not thought of as differing from each other simply in amount, as an apple is compared with a larger, a smaller, or a sweeter apple. Comparison in terms of amount is disagreeable in some respects, so that uncontrolled speculation would surely tend to favor the theory of distinct types.

Type-terms have also been invented for temperament,—sanguine, choleric, melancholic, phlegmatic. The idea underlying this classification is that everyone belongs to one or another of these distinct temperamental types, and, furthermore, that there is a relationship among types which warrants fixed hyphenated categories.

The mental traits or “faculties” thus classified and hyphenated are conceived as entities, having each its distinct existence in the individual mind, and being susceptible to general training and strengthening, by prescribed exercises. Thus it has been believed that “the observation” may be developed by exercises with particular materials, so that all materials whatsoever will be observed equally or approximately as well.

Speculation has been much occupied, as the history of human thought shows, with the problem of the origin of individual endowment. Many different possible explanations were proposed, before the day of quantitative measurement in psychology. It has been surmised that mental endowment is the result of prenatal influences, the wishes and environment of the mother, during the period of gestation; or that it is the result of education; or that it arises from the physical accidents met with by the organism; or that it may be inherited from ancestors, as physical traits rather obviously are. On the whole, speculation has favored the notion that mental endowment originates in the environment. The idea that ability is hereditary, determined for each by the conditions of ancestry, is repugnant. Man prefers to consider that he can himself determine what he will do and be. This doctrine will not be tenable if it is admitted that talents and deficiencies are determined in the germ-plasm, from which the organism springs; that man can only use, not choose, his mental endowment.

II. RESULTS OF QUANTITATIVE INVESTIGATION

Many of the cherished hopes and desires of mankind concerning itself are in some part violated by the teachings of scientific psychology. Experimental psychology is not yet half a century old, dating its beginning as a technical science from the founding of Wundt’s laboratory at Leipzig, in 1879. Therefore, it is clear that the study of these problems by quantitative methods brings us very close to the present day.

When the problem of measuring mental capacity was first taken into the laboratory, the modern definition of a mental function began to be formulated. It became apparent that a mind must be judged by its product. The measurement of performance is the only approach there is, or probably ever will be, to the measurement of mind. On this basis it was found impossible to identify or measure any such function as “the reason,” “the memory,” “the observation,” “the imagination,” “the will,” and similar supposed entities. A mental function came to be defined as “an actually or possibly observable event in behavior.” Thus, memorizing digits, detecting absurdities, and reading English print are examples of mental functions, in the sense in which the term is used throughout the chapters of this discussion.

Other terms which are used to refer to performances or “events in behavior,” are abilities and capacities. A prolonged discussion might be conducted, in an attempt to assign different technical meanings to these words, and to bring out fine shades of distinction among them. For instance, it might be claimed that “ability” should be reserved to signify capacity plus the skill acquired by practice, if any; while “capacity” should mean the innate aptitude, apart from all training. However, since capacity in this sense can never be known, but can only be inferred from the degree of actual performance, under controlled conditions, it hardly seems necessary to maintain such distinctions for our purpose. Refinements of nomenclature will, therefore, be avoided, and the terms mental function, capacity, and ability will be used interchangeably, to denote performance which depends on the inborn integrity and sensitivity of the individual.

By way of clarifying the definition of a mental function as “an actually or possibly observable event in behavior,” we may quote from Spearman’s presentation of the distinction between “observation” as a mental function, and “observation of birds’ nests.” Spearman says: “Suppose, for instance, that a school boy has surpassed his fellows in the observation of birds’ nests. His victory has, no doubt, depended in part on his capacity for the general form of activity known as ‘observation.’ But it has also depended on his being able to apply this form of activity to the matter of birds’ nests; had the question been of tarts in the pastry cook’s window, the laurels might well have fallen to another boy. A further influence must have been exercised by the accompanying circumstances; to spy out nests as they lie concealed in the foliage is not the same thing as to make observations concerning them in the open light of a natural history museum. Again, to discover nests at leisure is different from doing so under the severe speed limits prescribed by the risk of an interrupting gamekeeper. The boy’s rank may even depend largely on the manner of estimating merit. Marks may be given either for the gross number or for the rarity of the nests observed; and he who most infallibly notes the obvious construction of the house-sparrow may not be the best at detecting the elusive hole of the kingfisher.” One cannot, therefore, identify and measure “observation.” One can only measure “observing birds’ nests, of all kinds, at leisure,” or “observing rare birds’ nests, under stress of pursuit,” and so forth, which are “actual or possible events in behavior.”

As one may glean further from Spearman’s discourse, it has been shown that most of the mental functions performed by men are not elementary, but consist of the coördination of complex factors, capable of analysis. Reading the English word “cat” from a printed page is, for instance, a very complex function.

The application of quantitative methods to the study of mental functions as thus defined, quickly revealed the fact that human beings, sampled at random, in large numbers, do not fall into distinct types. On the contrary, they yield one unbroken curve of distribution in the function measured, clustering around a single type (or mode). In all mental functions which have been measured, there has been found but one type—the average human type—from which the individual members of the species deviate in degree (though not in kind). The majority of individuals deviate but slightly from this biologically established type or mode. “The typical” in ability is, indeed, by definition, what the greatest number of people can do. From this performance of the average or typical person, a few individuals deviate widely in the direction of superiority, while a corresponding few deviate widely in the direction of inferiority. No doubt the conspicuousness, because of their infrequency, of extreme deviates in respect to any given function (or capacity) has led to the notion of separate types of mankind. Mental measurement shows clearly that men cluster closely around one type in mental traits, just as they do in such physical traits as height and weight. All men can be no more divided into the dull and the bright, than they can be divided into the tall and the short. The eye can see that most persons are best described as medium, in height.

This principle of one type, with deviations in both directions from it, in a measured trait, holds throughout organic nature. The study of it in all its bearings is called the study of individual differences. When the traits involved are mental, we speak of the psychology of individual differences. It is one of the marvelous facts about human beings that of all the millions born, no two are just equal in possession of a given trait, except by chance; and no two are identical in their combinations of traits, for the infinite possibilities of permutation practically exclude identity by chance. These combinations, which go to make up personality, are combinations of amounts of the same traits. This must be clearly understood. The mental classification of men under different “kinds” is a myth. All show the same kinds of functions; but they show all degrees of performance in these functions, within limits which are extremely wide, with multitudinous possibilities of combinations of functions, in different amounts of each.

There are, therefore, not types. There is one type—the typical or most frequently occurring amount of performance in a function—from which there is divergence among the individuals born, in various degrees. Is it possible to construct a picture of this fact, so that it may become concrete through visual representation? Psychologists have given us many such pictures, in the forms of curves platted from their measurements. We may cite as an example, Seashore’s curve of distribution for the ability to discriminate among intervals of time, which is one element in musical sensitivity. Seashore measured a large number of adults in this respect, with the result that is pictured in Figure 1.

Where the curve rises to its greatest height, at its peak, there the greatest number of those measured fall in respect to this function. That is, therefore, the human type, in sense of time. The typical individual has that amount of this trait. On each side of the type fall deviating persons, their frequency decreasing rapidly as the amount of deviation becomes greater. Very few persons in ten thousand have that amount of sensitivity to time represented by 95–100; and, on the other hand, very few are so inferior as to fall at the lowest point measurable on this scale. The typical person has that amount of the trait represented by 85–75, approximately. Distinct types, such as “sensitive” and “insensitive,” do not appear, as a result of mathematical distribution. But a few extreme deviates from the typical appear,—the superior in sensitivity and the inferior in sensitivity.

Fig. 1.—Distribution of ability to discriminate among intervals of time, the subjects being adults. (From Seashore’s The Psychology of Musical Talent. Reproduced by courtesy of Silver, Burdett and Company, and of The Columbia Graphophone Company.)

Occasionally it is possible to illustrate in nature, to the eye of the man untutored in the derivation of scientific laws, the form of this distribution. This happens, for example, when a very large flock of birds rises and passes overhead, during migration. Being tested in flight, the birds will be seen distributed somewhat as suggested in Figure 2. Not all are equally swift and enduring, but they deviate from a single type or mode—the great median mass of birds, which are typical of this species, in respect to the function of flight.

The same phenomena of distribution appear if a thousand wild horses run a race, or if a hundred unselected swimmers swim in competition. They appear whenever non-select organisms of a single species are submitted to an adequate test or measure of any function of endowment. The curve approximates that form which mathematicians tell us results when an infinite number of factors act together in an infinite number of ways.

We have spoken thus far of the distribution of individuals in a single kind of performance. What does quantitative psychology teach with respect to the combination of performances in a given personality? Is it true, as folk-wishes would have it, that abilities are distributed among us by a law of compensation? Is the slow man’s slowness offset by accuracy? Does the quick learner lose his learning more readily than the slow learner? Is he who excels in arithmetic likely to be surpassed at spelling? The general consideration of these questions, which form the topics of this volume, will be found in the chapter which follows. It will be seen that there is no law of compensation in human ability, however much we may long to find it there.

Fig. 2.—Flight of birds, illustrating distribution in ability to fly. (Schematic.)

As for the origin of talents and defects, psychology teaches that mental endowment in human beings is conditioned by ancestry, just as other traits of organisms are. Mental capacities are inherited through the germ-plasm. A child is gifted (if he is so) for the same reason that he is an Eskimo (if he is one)—because some or all of his ancestors carried those traits in their germ-plasm, and the combination of them in just that way was possible.

REFERENCES

Meumann, E.—Vorlesungen zur Einführung in die experimentelle Pädagogik; Engelmann, Leipzig, 1914.

Seashore, C.—Measures of Musical Talent; Columbia Graphophone Company, New York, 1919.

Stern, W.—Die differentielle Psychologie; Barth, Leipzig, 1911.

Thorndike, E. L.—Educational Psychology; 3 vols. Teachers College, Columbia University, 1913.

CHAPTER II
The Relationships among Capacities

I. THE COEFFICIENT OF CORRELATION

The question is: How are mental capacities mutually related, with regard to amounts of each found in given individuals?

Before verifiable facts can be established in a field of knowledge, it is necessary to introduce therein methods of enumeration and measurement. The question above propounded has waited long for answer, because of the great difficulty of applying mathematics to mental phenomena. The answer required first that single functions be accurately scored, and then that a measurement be obtained of the relationship between and among the single functions.

It seems well agreed that the quantitative determination of the relationship between and among mental characteristics began with Galton, about 1885. Various scholars have presented discussions of the subject since then, notably Baerwald in 1896, Spearman in 1904, Stern in 1911, Meumann in 1913, and Thorndike in 1913, each of whom summarized the findings up to the time of writing, with original interpretations.

The methods of quantitative measurement used to study the constitution of mental abilities, or functions, as related to each other, are chiefly those of correlation—simple correlation, multiple correlation, and partial correlation.

It is not within the scope of the present volume to give consideration to these methods as such. Highly technical instruction in the theory and practice of measurement is necessary for complete understanding of them. The results may be comprehended for our purposes, without complete knowledge of the methods. Much of the evidence we now have in the matter of relationships among mental functions has been obtained by the method of simple correlation. A brief exposition of how a relationship is established between two variable functions within a group, by simple correlation, will suffice to give a general understanding of the term coefficient of correlation, which is used here, and which frequently appears in modern texts of educational psychology. The interpretation of coefficients of correlation should not, however, be undertaken independently without full knowledge, as competent interpretation for practical purposes must take into account all the conditions under which they have been derived.

Below are listed fourteen school children, each of whom has been measured in each of two mental functions: (1) mental age, determined by a standard scale for measuring general intelligence (Stanford-Binet), and (2) spelling ability, as measured by a standard spelling scale (Ayres’ scale). These children were selected for study, because they appeared to be characterized by special discrepancy between the two functions.

We wish now to know whether and to what extent the child who falls high in the distribution of mental ages also falls high in the distribution of spelling ability. According to the formula which is most useful in this case,[^[1]] we arrange these pupils in their order of merit for one of the functions measured, e.g. for mental age. We then find the rank for each, within the group, in the second function, which is here spelling ability. The difference in rank between the paired functions is then found for each pupil, and the correlation formula is applied.[^[2]]

If there is in fact perfect correspondence, so that each pupil holds the same rank on the distribution in both functions, a perfect positive correlation is obtained, the coefficient of correlation being expressed as 1.00. If no relationship at all exists between the two functions measured, so that nothing whatever can be predicted of either from knowing about the other, the coefficient of correlation will be 0.00[^[3]] If there exists a perfect negative relationship, so that the person who stands highest in one stands lowest in the other, and so forth through the series, in a perfect inverse standing of all members, then a coefficient of correlation expressed by −1.00 is obtained.

In the sample given, the coefficient of correlation obtained is .081, which not being reliably greater than zero (because of possible error due to the smallness of the group and other conditions) tells us that the two functions are in this case related to each other only very slightly, if at all. The child who stands above the average of the group in mental age, may or may not stand above the group average in spelling. With a relationship so far from unity as is expressed by a coefficient of .081, we may expect to find in this group comparatively intelligent children who are very poor spellers, and good spellers who stand low in mental age. Among children taken at random, however, a different relationship exists between spelling ability and general intelligence, as represented by mental age. The positive correlation is much higher among children not selected, as these were, for an observed discrepancy.

At the present time the more elaborate methods of partial correlation and multiple correlation are being applied to the study of relationships, where more than two functions are involved. Into the intricacies of these we shall not enter, except as concerns their results.

II. GENERAL INTELLIGENCE vs. SPECIAL APTITUDES

The original attempts to apply mathematical formulæ to the study of relationship among mental traits eventuated in divergent hypotheses. In England, Spearman, with his students and collaborators, interpreted his researches to mean that there is in mental constitution a “general factor,” which shows itself in all the performances of a given individual. This would render relatively predictable the quality of performance in all functions, from knowledge of performance in one function. “All branches of intellectual activity have in common one fundamental function (or group of functions), whereas the remaining or specific elements of the activity seem in every case to be wholly different from that in all others.... The function almost entirely controls the relative position of children at school (after making due allowance for differences of age), and is nine parts out of ten responsible for success in such a simple act as Discrimination of Pitch.... Its relation to the intellectual activity does not appear to be of any loosely connected or auxiliary character (such as willingness to make an effort, readiness in adaption to unfamiliar tests, or dexterity in the fashion of executing them), but rather to be intimately bound up in the very essence of the process.”

Spearman noted that, though all functions seemed related to this “common factor,” they were not all equally related in his results; wherefore he formulated the concept of a hierarchy of relatedness. Discussion as to the essential nature of the fundamental factor was reserved, but it was predicted from the correlations made that “general intelligence” could and would be measured for practical purposes. This interpretation was based upon the fact that among abilities which yielded to his measurement, Spearman could find only positive coefficients of correlation, when the groups were large and the human beings non-select.

In the United States, Thorndike and his collaborators were most struck by the fact that the coefficients obtained fell short, in many cases far short, of unity. They laid stress upon the imperfection of the relations revealed, and were able to show that between some functions, such as discriminating among the lengths of lines, and others, such as naming the opposites of words, the correlation dropped in groups investigated to approximately zero.

As a result of interpretation from their point of view, they wrote as follows: “One is almost tempted to replace Spearman’s statement by the equally extravagant one that there is nothing whatever common to all mental functions, or to any half of them.” They maintained that mental functions are specialized, and that when excellence in one is correlated with excellence in another, “this is due chiefly to the fact that the two involve identical elements in their execution. It is not due to one and the same ‘faculty,’ which presides over their activities.”

These two divergent interpretations of the same array of data have been cited, because the controversy involved is of first rate importance for mental measurement, for the understanding of individuals, and for education. The controversy now appears to have been one of emphasis. To recapitulate, Spearman stressed the positive aspect of the coefficients found, and declared mental traits to be distributed so that status in one is predictable from status in another. Thorndike emphasized the reduction from unity of the coefficients, and formulated the hypothesis that there is no absolutely predictable coherence among mental functions, that each is special to itself within an individual. No laboratory scientist has ever found reason for adding a third side to the controversy, by advocating seriously that mental traits are compensatory in relation to each other. Negative coefficients of correlation have never been found, except occasionally by chance or selection.[^[4]] All know that the correlations among amounts of traits are positive. It is the reduction from unity which has caused the disagreements of interpretation.

During the twenty years which have elapsed since the first interpretations were set forth there have been modifications of each hypothesis, in the direction of mutual reconciliation. This has come about through extended researches by many inquirers, furnishing additional data.

III. CORRELATION OF ABILITIES IN VARIOUS GROUPS

Some of the significant studies of correlation made since Spearman and Thorndike proposed their conflicting interpretations, have been cited in the appended list of references. Two samples of the results of these studies are herewith presented. The first is from Simpson’s study of mental tests given to two groups of adults, chosen respectively from the opposite extremes of competency, as shown by social-economic success. One group was composed of successful professional educators. The other was composed of unskilled laborers and unemployed men. The table on page [18] shows how the traits measured cohere among these individuals. The coefficients are positive, in the majority of cases highly so.

The second sample is from Weglein’s study of standing in school subjects, among high school pupils.

Bearing in mind that, if no mutual relationship exists among the abilities considered, coefficients of correlation will approach zero, it is clear that there is decided positive, but not perfect, correspondence. The wider the range of competence tested, the greater the correspondence found. High school pupils (from among whom those having very little ability for the subject matter taught have already been eliminated) show smaller coefficients than do the persons measured by Simpson. If all adolescents in existence were obliged to study the subjects listed by Weglein, and if the resulting grades were then correlated, the coefficients would be notably higher than those recorded.

These are fair samples of the results of studies in correlation, among mental functions, in groups of individuals more or less select. Even physical traits, like height and longevity, have been found to give slight positive correlation with mental traits. Evidently there is a general organic quality, which shows itself to some extent wherever the individual is fairly tested or “sampled.”

IV. STUDIES OF DISORGANIZING MINDS

Another series of attempts at the solution of this problem has been made through observations upon deteriorating minds. The question is, Do mental functions deteriorate together or separately in dements? When a person is “losing his mind,” is the impairment general or selective in its progress?

The study of demented persons had been carried on by a few investigators in the hope that the decay of capacities might throw light upon their relationships. The chief obstacle to study from this approach has been that the investigators have never been able to know the original mentality of their subjects. They have always been obliged to make assumptions. It is difficult to see how this factor may be controlled, short of filing careful mental analyses of great sections of the population in youth. The chief conditions in which decay of ability is most probably present, as distinguished from decay of effort and attitude, are senile dementia, dementia paralytica, and alcoholic psychosis; and it cannot be known beforehand which persons are destined to represent these conditions. It cannot be predicted who will live long enough to become senile, who will contract syphilis, eventuating in general paresis, or who will be a chronic alcoholic. It is true that original mental status may be inferred with a moderate amount of accuracy from school status attained. If the dements studied had all been high school graduates, for instance, then we could be certain that the performances shown in the recorded studies really represent deterioration.

Unfortunately, the subjects of study have been, with rare exceptions, persons of elementary education and humble social status. They come from those sections of the education-occupation distributions, where very limited capacity is found. Therefore, we are rather uncertain as to how much deterioration from original status has really taken place. So far as actual figures go, it is not shown that there has been decay of intellect.

However, assuming that these segregated persons had actually deteriorated in their ability to perform tasks, let us inquire what the researches show. Binet and Simon worked with forty adults, classified as senile dements or as victims of dementia paralytica. They conclude that “Every dement has an intellectual level below normal,” as measured by tests of general intelligence. The limitations of dements are, nevertheless, qualitatively different from those of other incompetents (children and the feeble-minded); and the reactions of the senile differ from those with dementia paralytica. Of the victim of dementia paralytica they say, “He has not tumbled down the ladder of development, rung by rung. His is a difficulty of functioning.” “It is characteristic in these losses of functioning that the subject knows how to meet the problem submitted to him; he has the knowledge, but from time to time the power fails him.” This inertia of comprehension is general, and has the effect of lowering the total level of performance, though the particular items of failure and success may vary markedly from occasion to occasion. It is hardly the same thing as actual decay of a structure. Thus one cannot predict the responses of these dements, as one can those of other incompetents, like children and imbeciles, because their errors and failures have a remarkable degree of inconsistency. “In a general way, one can hardly foresee how such a one is going to conduct himself, for special failures and successes are at such variance with the general level.” “General paralytics are hardly able to perform the hundredth part of what they know.”

Senile dements are different, in that they actually no longer know. The structure itself has been demolished, not merely has it been paralyzed as to function. According to the observations of Binet and Simon the abilities of senile dements as a group are by no means equally impaired. They cannot remember events nor learn new things, yet they retain the power of auto-criticism, many complaining that they no longer “know anything.” They may be degraded to the level of early childhood in ability to repeat digits, yet retain use of the vocabulary of a superior adult.

These observations are extremely suggestive, but they lack statistical validity, being limited to narrative descriptions. It is true that one who has worked much among dements in a practical way, recognizes the pictures drawn by Binet, of persons decayed in some functions, yet “surprisingly preserved” in others. Proof of the extent to which this characteristically happens would necessarily be derived from tests of large numbers of cases, treated mathematically, and not by the method of narrative.

Hart and Spearman more recently presented a study of sixty-one insane persons,[^[5]] asking the question, “Does an insane person present, as a rule, much greater inequality of performance than a sane one?” Recognizing the error from not knowing the original status of the presumably deteriorated minds, in all the various functions to be tested, the attempt was made to allow for this by testing in the same way thirty-three sane persons, selected presumably to represent what the insane were like before they became alienated. Nineteen mental functions were thus tested, and the results were then treated by the method of correlation, the assumption being that if there were greater inequality among mental functions in the insane (that is to say, among deteriorated minds) than among the sane, this would show itself in diminished coefficients of correlation.

It is interesting to consult the original tables of data, which, however, will not be presented here. The conclusion reached is that “The inequality between the powers of the same person for different kinds of performances does not appear to be appreciably greater in insanity than in health, nor in one of the forms of insanity tested than in another. Thus, in the main, the mental injury appears to be of a perfectly diffuse character, or to constitute a lowering of the whole intellectual level.... Over and above this general impairment, elaborate methods can also detect certain damages characteristic of particular maladies. These are very narrow and specific in kind, but probably may be correspondingly grave in intensity.”

Spearman thus again maintains his “two factor” theory of endowment—the “general factor” conditioning performance as a whole, and “specific factors” conditioning certain mental functions to a much greater extent than others. To determine what these special mental functions are, Spearman leaves to further research.

This careful investigation is nevertheless imperfect for the purpose, which is to learn whether there is selective enfeeblement of abilities. It is really impossible to know that deterioration has occurred, unless there have been measurements made beforehand. Sane persons, selected from the same social stratum, are not entirely reliable as a control, because those who are of the psychic constitution destined for insanity undoubtedly differ originally from those who remain sane, and this difference may involve a difference in mental abilities, either of amount or of relationship. The degree of deterioration calculated by Hart and Spearman may be merely a matter of original differences in central tendency between the two groups.

Here, too, it should be noted that Hart and Spearman mixed a variety of psychoses (even including an imbecile not deteriorated so far as known), both those that do involve actual decay of ability, and those that involve only disturbances of general auxiliary functions, like attitude and effort. Just what would be the effect of this mixing upon the correlations could be told only if we knew how each form of disorder characteristically affects the relationship among mental functions, which is unknown. If mental functions are differently selected for impairment in the different forms of psychosis, then we should expect diminished coefficients of correlation among the insane, because mixing the psychoses would produce inconsistency of rank within the group. If, however, certain functions were deteriorated in all or nearly all of the insane, others remaining intact, or relatively so, this selective enfeeblement would not appear in correlation coefficients. Facts like those observed by Binet and Simon might be obscured by the methods of Hart and Spearman.

Moore, working subsequent to Hart and Spearman, limited his investigation to those cases believed by psychiatrists to be characterized by real loss of abilities, the dementias: dementia paralytica, senile dementia, and alcoholic dementia. He tested thirty dements, laborers and tradesmen, and, as controls, six young men from the same occupational group, in the following mental functions: (1) perceiving eight each (in a series) of real objects, pictures of objects, printed words, and spoken words, referring to real objects of ordinary everyday experience; (2) repeating after one exposure of the series as much of it as could be remembered without regard to sequence; (3) after a minute of mental work at calculation, repeating again what could then be remembered of the series. Moore then correlated performance within the group in each of these functions with that in each of the others. The coefficients thus resulting are interpreted as follows: “The average of all correlations of perception with the various memories is .538.... That the average correlation for memory and perception is as high as .538 shows that there must be a common factor present. But its presence does not exclude the existence of special forms of mental ability.” Moore also correlated perceiving with remembering in the functions separately, and remembering immediately with remembering after a minute of distraction. These coefficients are positive, and mostly high, but not perfect.

The work of Moore does not seem to go beyond knowledge already obtained from study of sane persons. The coefficients do not prove that the amounts of deterioration in the functions had been equal; or even that deterioration had taken place. Moore’s six sane subjects were too few to constitute a control, and are not referred to as such in treating results. Instead, Moore refers the reader to the records of subjects in preceding monographs to show that “the low values of these subjects (the insane) are distinctly pathological.” This comparison is seen to be invalid, for the subjects referred to as establishing the criterion of intactness are professors and university students, almost certainly much higher in ability by original nature than the insane group.

Assuming, nevertheless, here also that the subjects really had deteriorated, the method of correlation must again be brought under criticism as ill adapted to answer questions concerning selective enfeeblement. A group of senile dements, all high school graduates, might, for instance, be not at all deteriorated from their original status in the mechanics of reading, but greatly deteriorated in the ability to tell what has been read. Yet correlation might result in a positive coefficient as high as that found among typical high school graduates, if the decay in repeating matter took place in proportion to the degree of ability originally present in each individual. There might be marked selective impairment, which would be hidden in coefficients of correlation.

The problem of selective enfeeblement must be investigated by computing deviation in various functions from a known norm or standard in each; and the person’s original status in that function must be known. For such investigation senile dements would seem to be the best subjects, since in them there is natural decay of functions. It is, however, difficult to find very aged deteriorated persons, whose original status is known (known, at least, to have been generally high), and who have not some sensory or motor handicap to complicate performance, such as deafness, failing vision, or palsy.

The net result, for our purposes, of studies so far made of mental decay is not very helpful, because (1) the original status of the subjects is never known, (2) the psychoses have been mixed in experiment, without preliminary test-knowledge of the characteristics of each, if any, and (3) the method of correlation, which has been used, is not suited to show selective enfeeblement of mental functions. Every study made has suffered from one or more of these hindrances to interpretation. The information gleaned from them is much the same as that already gleaned from studies of the undeteriorated, namely, that among people (whether sane or insane) those who hold a certain rank within a group in one function tend also to hold a similar rank within that group in other functions. The question of selective enfeeblement of a function within a group of the insane remains unanswered. The investigators of the demented have, however, made a particular contribution in pointing the way to a new source of light. For the study of mental decay, when carried on by adequate methods, extremely difficult of attainment, is sure to throw light on the relationships among mental functions. From it we shall learn whether some functions remain intact, with impairment of other functions.

V. IS INTELLECT INHERITED AS A UNIT?

There are still other approaches to the study of the constitution of intellect. One is through the investigation of heredity. The question is whether intellect is inherited as a unit, or whether some different formula is indicated. If intellect is a unit character, subject to but one determiner in the germ-plasm, then it should act as an “all or none” capacity in its appearance among offspring of given matings. Children should be separable into distinct groups, each having a different median with respect to intellect, i.e. those who have intellect and those who lack it.

The methods of mental measurement teach us plainly that intellect is not inherited in this way. Instead of a broken curve, indicating a division of children into those who inherit and those who fail to inherit a unit character, we obtain the curve already demonstrated, which is continuous and symmetrical. There is but one diversified group of children, with respect to intellect—not distinct groups.

The inheritance of intellect does not, therefore, follow the simple formula of unit characters, as does the shape of peas, the color of rabbits’ coats, or eye-color in man. The trait we measure and name as general intelligence is a complex, resulting from the incidence of a great number of functions, acting together in a great number of ways, yet cohering in respect to amounts found in given individuals.

Possibly each of the indefinitely numerous functions, which thus appear to act together as man’s intellect, may be a unit character, inherited according to Mendel’s formula. Such a possibility is at present purely speculative.

The puzzle is that a given individual should “hit,” as it were, at approximately the same point in the distribution of nearly every function.

VI. CAN AN INTELLECT BE TRAINED AS A UNIT?

Studies of the learning process also give light upon the organization of capacities. The question here is as to whether training in one function spreads equally to all other functions. Is it possible to “train the mind” as a whole? Will it raise the proficiency of all performances fifty per cent, if a fifty per cent gain is achieved in Latin composition?

Numerous attempts have been made to determine the extent to which skill acquired in one performance increases skill in other performances. The conclusion which emerges from these studies is that intellect cannot be trained as a unit. Transfer of training from one function to other functions is far from complete. Apparently, there is spread of improvement from practice in a function only to such other functions as have elements in common with it. If two performances differ in any way, there is something in the second that remains untrained by the practice given to the first. If two performances differ in all respects, the second seems not to derive any benefit at all from training in the first.

To a very highly intelligent individual, nearly all situations and performances tend to have some identical elements, no doubt. To a very dull person, relatively few situations or demands present identical elements, for the dull perceive only gross similarities and differences. Thus, spread of improvement is without doubt greatest for the innately gifted, and least for the innately inferior minds. In connection with the present discussion, however, the chief point of interest is that no mind, of whatever degree of innate integrity and sensitivity, can be trained as a unit. Each function has elements special to itself, and some functions are very highly specialized, as regards the amount of transfer of training from them to others, or from others to them.

The evidence from learning, therefore, substantiates the evidence from heredity, indicating that intellect is not a unit, but a complex of many capacities, coinciding mysteriously in amount to a very marked extent in an individual.

VII. THE HIERARCHY OF ABILITIES

It has been stated that though all, or nearly all, mental functions so far measured and correlated, yield positive coefficients, all do not show an equal amount of positive correlation. Certain mental functions, for example, are shown to yield coefficients of as much as .80, for a total correlation with others of a series; while some yield coefficients as low as .10, approaching absence of relationship. To explain these facts, Spearman formulated the concept of a hierarchy of relatedness to a “general factor.” Those abilities showing slight correlation with others in series of tests, were thought of as but loosely related to “general intelligence,” and as constituting “special abilities.” They might be displayed by persons inferior in general, or might be lacking in persons otherwise superior.

Here again, the facts are not in question. It is admitted by all that functions show different amounts of positive correlation with one another, and of total correlation with members of a series. Not all experts agree, however, with Spearman’s theoretical explanation of the phenomena. Thomson has recently shown, by tossing dice of various colors, that in this game of chance (in which there is no “general factor,” but only many independent factors), hierarchical order of correlation coefficients is almost sure to be obtained, for combinations resulting from throws. Thomson, therefore, holds that the theory of a “general factor,” participating in all the separate performances of an individual, is not proved from the facts about correlation coefficients. He proposes the following, regarded by him as an alternative: “The mind, in carrying out any activity such as a mental test, has two levels at which it can operate. The elements of activity at the lower level are entirely specific, but those at the higher level are such that they may come into play in different activities. Any activity is a sample of these elements. The elements are assumed to be additive like dice, and each to act on the ‘all or none’ principle, not being in fact further divisible.”

It is not quite easy to see that this theory, finally proposed by Thomson, which might be termed the “two level” theory, is very different from Spearman’s “two factor” theory, nor why the terms “higher” and “lower” should be introduced. But demonstration of the probability of obtaining a hierarchy of correlations simply from the tossing together by chance of independent factors, as with dice, adds new data for consideration. It might be that non-biological principles of probability are sufficient to explain the hierarchical order of correlations, among many tests administered to a given group, just as they are apparently sufficient to account for the particular form in which ability in any single test is distributed through the human species.

But if this is so, how account for the consistency with which certain abilities, like ability to draw, are repeatedly shown to correlate but slightly, while others, like completing sentences, repeatedly yield high total correlation? How account for the fact that there is marked coherence among certain groups of tests, such as “tests dealing with words only,” and “tests dealing with numbers only,” as contrasted with the relative lack of coherence among “tests, some dealing with number, and some with words”? It would seem that these phenomena must be at bottom biological. It cannot, for instance, be demonstrated that yellow dice and red dice thrown, wherever and by whomever cast, tend always to correlate high, while green and maroon dice tend always to correlate low with each other, and with yellow and red dice. Nor can it be demonstrated that dice colored, let us say, from one end of the spectrum tend always to correlate high among themselves, but much lower with the dice colored from the other end of the spectrum, wherever and by whomever cast.

Furthermore, die-casting will not give a relationship in which throws resulting in low scores are paired with low scores, and so on, from low through high, high scores being also paired with high scores, as when organisms are tried. The correlation among throws of dice arises from a different form of relationship, in which the improbable throws, resulting in either very high or very low scores, are paired indifferently,[^[6]] this indifference not being able, however, to produce zero correlation, because of the infrequency of extreme scores. The frequently occurring, mediocre scores in both series are, however, very similar, the most frequently occurring score for both being, indeed, the same. Since the mediocre scores tend to occur both frequently and together, because of the laws of chance, they produce positive correlations, differing in amount from series to series (also because of the laws of chance). But when organisms are tested, as has been repeatedly demonstrated, the serial relationship between two functions holds through high and low, and this, also, must be biological, and not explainable by laws of chance.

The demonstrations from die-casting are extremely significant, as warning us not to depend wholly for our inferences upon the amount of positive coefficients of correlation, nor the possibility of arranging them in hierarchical order. Both of these features of apparent relationship may come of chance, within a single series. Other features of relationship must be examined in the attempt to infer biological law, especially the consistency with which given traits correlate to a given degree with others, when investigated by different examiners, in various groups; and the form of the relationship, whether all the way from highest to lowest, or only in central tendency.

VIII. PRESENT STATUS OF THE PROBLEM

Whatever may be the ultimate cause of the manifestations, educators are practically concerned with the facts. The practical implications for education of knowledge gleaned up to the present time, concerning the coherence among mental functions, have been well stated by Burt, in his recent discussion of Mental and Scholastic Tests: “The examiner should always discriminate between children who are backward in most subjects, and children who are backward in one subject, or limited group of subjects, alone. A child, for example, who suffers merely from a specialized disability in reading and spelling, such as so-called ‘word blindness,’ is to be carefully distinguished from one who is in every respect mentally defective.

“As I have shown in memoranda previously published, educational attainments depend largely upon capacities of two kinds: first, a common or general capacity, entering into every subject in different degrees, but best exhibited in those that need thought-processes of a higher order, such as the comprehension of reading matter among young children, and, among older children, problem arithmetic and literary (or rather logical) composition; secondly, specific capabilities—such as arithmetical ability, linguistic ability, manual ability, and musical ability—entering into a small group of subjects. A child who is deficient in the former will be backward in all subjects—most backward in those subjects most dependent on this central capacity (such as the subjects first named), least backward in those subjects least dependent on it (such as manual and musical subjects). A child who is deficient in one of the specific capacities alone will be backward in the limited group of implicated subjects, and in none but these.”

McCall writes as follows: “There is an objectively and practically measurable something, which constitutes the core of most aptitudes. It is overlaid with various incidental abilities, and furthered or retarded by emotional or physical characteristics of the individual. This something is general intelligence. If an individual’s intelligence is all that is known, some mistakes will be made in attempting vocational guidance, but if only one thing can be known, general intelligence is perhaps most important.... A pupil’s intelligence score is an approximate measure of the diameter of an approximate general ability circle, and is hence an approximate basis for vocational guidance.

“But any individual who assumes that all the spokes in an ability-wheel are of exactly equal length, or that instances of marked special aptitudes do not exist, or even that most individuals do not possess some tendency toward a special aptitude, would make as egregious an error as one who assumed that all individuals are markedly lopsided.”

These two summaries of the present status of this problem from the practical point of view, coming as they do, the one from a student of the British school, the other from a student of Thorndike, show how the two originally conflicting interpretations have been approaching middle ground. There is found to be a quality of the individual, which results in generally superior, mediocre, or inferior performances in his case—a positive coherence in the amounts of all traits possessed, extending even to appreciable coherence between mental and physical. General intelligence is now measured, for practical purposes, as Spearman long ago predicted. Nevertheless, there are, as Thorndike maintained and maintains, mental functions, standing in which is hardly predictable from knowledge of other capacities. In rare cases there may be complete discrepancy in rank between performance in one task and performance in other tasks, with equal training. These are the cases of special talents and defects, to which this volume is devoted.

IX. MEASUREMENT OF GENERAL INTELLIGENCE: THE IQ

We now see that the “general” factor in intelligence may be defined simply as the positive coherence which exists among the multitudinous abilities of an individual, as respects their amounts. The first to obtain a quantitative measure of general intelligence, for the practical purpose of classifying school children, was Binet. Binet concluded from reflection on the research done, that failure or success in one mental function may be of slight significance for the classification of an individual, because correlation is imperfect; but that failure or success in a score of different functions must be of very great significance, because correlation among mental functions tends strongly to be highly positive. Working on this basis, he devised a large number of mental tests, intended to sample the individual’s performance in many different functions.

A mental test may be defined as a standard stimulus, which provokes a response capable of quantitative interpretation. Binet devised numerous standard stimuli, and a method of interpreting the responses elicited, in terms of a context of scores made by children of various ages, throughout the period of immaturity. His measurements were thus in terms of “mental age,” a phrase now somewhat familiar in education.

The science of mental measurement is rapidly progressing to more exact usage. The concept of “mental age” when applied to persons who vary in birthday age is in some respects misleading, and in other respects quite inapplicable (as with superior adults). General intelligence is at present usually scored in terms of points achieved, percentile attained in total distribution, or of mental ratio. The most reliable scales now available for the measurement of general intelligence in school children, score in terms of mental age and intelligence quotient (IQ). This measure (IQ) signifies the ratio borne by the intellectual level attained by a given child in tests, to the level attained by the typical child of his birthday age. For instance, a child 9 years 6 months old has an IQ of 100, if his score in tests equals that made by the average child of 9 years 6 months. If he is inferior to the average child of his age, the amount of such inferiority will be expressed by a ratio less than 100. Thus, if his performance equals only that of the average child of 5 years 2 months, his IQ will be 62 months ÷ 114 months, or 54 (dropping fractions less than .5). On the other hand, if he is superior to the average, attaining, let us say, the performance of the average child of 14 years 0 months, his IQ will be 168 months ÷ 114 months, or 147. An IQ of 100 may thus be thought of as “par” in general intelligence for a school child, while anything less may be thought of as “below par” to the extent indicated; and anything greater than 100 may be thought of as “above par.” The IQ shows the point of focus, for amounts of performance in a variety of mental functions. It derives its value for educational procedure from the positive correlation, which has been demonstrated to exist among performances in mental operations.

Scales at present available will measure general intelligence, in terms of IQ, about as low as IQ 10, and about as high as IQ 190, at certain periods of development. No doubt human intelligence ranges somewhat below and above these limits, but adequate methods of establishing the two extremes have not yet been devised. It is by no means usually realized that the range of individual differences in general ability is so wide that it is extremely difficult to invent methods of discovering its full extent. However, for practical purposes, available scales are adequate to cover the range for young school children, because intelligences that fall below IQ 25 or above IQ 175 are so rare as to be dealt with very seldom.

Within the limitations named, the general intelligence of school children can now be determined by a competent examiner, with a very small margin of error. The average error made by such an examiner will not exceed ± 5 IQ.

Not all scales for the measurement of general intelligence are scorable in terms of IQ. Some have been standardized in terms of “raw” points achieved, and some in terms of percentile status. There is at present much variety of usage in scoring, the ideal being to find units of measurement. It does not lie within the scope of this volume to treat the problem of establishing units for the measurement of mental traits. The general intelligence of the children to be discussed here has usually been determined in terms of IQ, which will be comprehended from the brief description given.

An ideal of students of mental measurement is to devise a scale which will measure any intelligence, from the lowest to the highest existing, after maturity, in units every one of which is equal to every other; and to devise a scale fulfilling the same requirements for each 12-months interval of the period of immaturity. This ideal is far from being realized at the present time, but the future will see it achieved.

In the meantime scales for the measurement of special talents, which are not measured by the scales for measuring general ability, are being worked out. What these special talents are we shall now consider.

X. THE MEASUREMENT OF SPECIAL ABILITY

Although much further research is required before we can identify all the mental functions which are incoherent with general intelligence, we already have some knowledge of the matter, useful for the welfare of school children. Certain abilities are shown repeatedly by different investigators to be relatively independent. Success in music and in representative drawing is very slightly correlated with success in other school subjects. Spelling is far from perfectly predictable from grades in schooling generally. Mechanics is relatively independent. Whereas ability in reading and in arithmetic is highly, but not perfectly, correlated with general competence.

These facts mean that from knowledge of a pupil’s general intelligence we can make very reliable predictions as to his capacity for reading and for arithmetic, somewhat less reliable predictions as to his aptitude for spelling or mechanics, and that our predictions concerning his ability to draw, sing, or play musical instruments should be given without confidence in their reliability, if given at all.

Other kinds of performances, like the management of people, appreciation of a joke, dancing, the management of wild or domestic animals, have not been thoroughly studied in their relation to general intelligence, though these and scores of others which will occur to the reader, might be of great significance for practical psychology, if shown to be somewhat independent talents.

As we have already said, most of the functions performed by human beings are very complex, and capable of analysis. To read, understand, and execute a page of any musical composition is a very complicated performance. The attempt to measure special ability has been the attempt first to scale total performance in the function, and second to scale performance in the various coördinating functions contributing to total result. Thus in the case of musical talent, Seashore has found by analysis a large number of contributing factors, and has actually devised scales of measurement for five of these subsidiary functions.

Measurement more or less adequate can now be made of ability to read, spell, draw, write, put mechanical contrivances together, and calculate. This list does not by any means exhaust the possibilities of measurement in particular functions at present, but exemplifies them. Slowly we are approaching the point of being in position to tell not only how a child stands in general intelligence, but also to indicate his status in regard to special abilities. The “picture” of the total relationship among a person’s abilities is called a psychograph.

XI. THE PSYCHOGRAPHIC PICTURE OF INDIVIDUALITY

A psychograph may consist merely of numerical statements of the individual’s standing in various mental capacities respectively; or it may be presented in the form of a graph drawn from the figures. No standard graph has been agreed upon. Sometimes the method is to present points of deviation from a horizontal line representing the typical performance; sometimes to present the deviations from a vertical line, representing the typical; sometimes to present deviations along the spokes of a “wheel,” the typical being taken as a circumference drawn midway between the center and the perimeter of the circle.

Fig. 3.—The psychograph of a school boy, showing his standing in various mental functions; illustrating use of the horizontal line to denote typical performance. The scores are in terms of mental age. (From Hollingworth’s Judging Human Character. Reproduced by courtesy of D. Appleton and Company.)

Figure 3 is an illustration of the first mentioned mode of presentation. It shows the status of a school boy in various mental functions measured. This boy is 18 years old. In interpreting the psychograph, which is platted in terms of mental age, it must be borne in mind that many of the capacities here included are matured by the age of 16 years. The individual is not, therefore, subnormal with regard to them. This case illustrates some of the difficulties of treating adolescents and adults in terms of mental age.

Fig. 4.—The psychographs of three school girls, showing their standings in various mental functions, measured to determine mathematical ability; illustrating use of the vertical line to denote typical performance. The scores are in terms of weighted deviations. Scores to the right are above, and scores to the left are below, average. (From Tests of Mathematical Ability and Their Prognostic Value. Reproduced by courtesy of Agnes L. Rogers.)

Figure 4 shows the use of the vertical line as the “type” or “norm,” picturing the extent to which the individual measured departs from or corresponds to the typical, in the functions tested.

Figure 5 illustrates the use of the circle, with radii to show standing in the various mental functions. The adolescent presented is near the typical (the 50 percentile) in nearly all functions measured.

Which of these forms of graph is best adapted to its purpose has not been determined. All are simply different methods of picturing the same facts.

The chief obstacle to the platting of psychographs, for such capacities as are now measurable, is that scales for measurement have been standardized in different terms. To plat a lucid psychograph, some traits on which have been measured in P.E., some in IQ, some in percentiles, some in “raw” points, some in values of a T Scale, some in terms of school grade achieved[^[7]] is now impossible, because of the difficulties of equating all these “steps” of difference. The psychographs here presented will, therefore, be understood to be crude, merely approximating the lucidity of those which will be made in future, when the science of mental measurement has made greater progress. Each of the methods of standardization has some advantages and some disadvantages, as compared with the others. Only experience and discussion can finally determine which is best. It is desirable to achieve uniformity as soon as possible, in order that the psychographic study of individuals may be facilitated.

1. General Intelligence (Stanford-Binet)
2. Completion Test (Trabue)
3. Cancellation (Pinter)
4. Digit Symbol (Pinter)
5. Opposites (Pinter)
6. Mechanical Ability (Stenquist)
7. Tonal Memory (Seashore)
8. Pitch (Seashore)
9. Time (Seashore)
10. Intensity (Seashore)
11. Pictoral Completion (Healy)
12. Grip in Hand (Smedley)
Fig. 5.—The psychograph of a school boy, showing his standing in various mental functions; illustrating use of the circle as a diagram, the median circumference denoting the performance of typical persons of his age. The scores are in terms of percentiles.

XII. AT WHAT AGE IS MENTAL ENDOWMENT EVIDENT?

The question arises as to when special talents and deficiencies become evident in growing individuals. We know almost beyond any doubt that the degree of general intelligence is manifested from the beginning of life, and could be measured then if our instruments of precision were fine enough. With present methods we cannot undertake with confidence the measurement of general intelligence much before school age. Extreme deviations may be reliably identified as early as 3 years of age, or earlier, but slight amounts of deviation cannot be reliably determined by available methods before the age of 5 or 6. The inadequacy of method with very young children arises, partly because it is so difficult to obtain non-select children under school age for purposes of standardization, partly because of the coarseness of the “steps” at present used to measure. The most refined and reliable scales we have are cast in terms of “mental age,” and some do not allow for any difference of less than “2 months of mental age.” An error of only two misscorings in the same direction would therefore result in a considerable error in the IQ of a child 3 years old; since 4 months is a large percentage of 36 months.

As early as 6 years, however, even by present methods, we can determine objectively the individual’s status in general intelligence. The indications are that when the measurement of special talents has made similar progress, we shall find that these become evident just as early as general ability does. These special talents are gifts, innate in the organism, and manifested no doubt from the beginning of life, just as general intelligence is.

In the discussion of special gifts for music, drawing, and calculation we shall see that investigators have been particularly struck by the very early age at which these were manifested in the persons studied. It is common for those who later became historical prodigies in these performances to have shown symptoms of their ability as early as 3 or 4 years of age.

On the other hand, special deficiencies in these functions are not commonly noted until after school has been entered, usually long after. This is inevitable, because no one is likely to suspect a child of tone deafness, for instance, until his music teacher has worked with him for some time. But conspicuous aptitude for melody and rhythm is likely to be noticed.

The question arises: Can these special talents be acquired, or the special deficiencies be overcome, by any course of training? Scientific psychology tends more and more strongly to the conclusion that psychology and education can do nothing to alter the amounts or relationships of innate mental endowment. They can but measure endowment and give it training suited to its requirements. The history of Seguin’s form-board seems to illustrate the evolution of the point of view on this question. About sixty years ago this form-board was hopefully used as a supposed means of altering original endowment. Feeble-minded children were given exercises in placing and replacing the blocks in it, in order that they might become more intelligent. To-day this form-board is used as a means of gauging original endowment. Psychology cannot create endowment; it can merely measure and describe it. Education cannot bestow mental gifts; it can only utilize such as are innately present within the organism. Talent and genius can be created in children only by the procreation of parents, who are the biological carriers of extraordinary endowment.

XIII. THE FREQUENCY OF MARKED SPECIAL TALENTS AND DEFECTS

No census of special talents or defects of given degree has ever been taken. Surveys have been made showing the distribution of musical sensitivity, of ability in drawing, spelling, calculation, and so forth. These distributions tell us the frequency of extreme deviations in these functions, but they do not tell us to what extent the deviations are special. From them we cannot learn whether or not the extremely fortunate deviations are identified with great general superiority, and whether the unfortunate deviations represent the work of generally stupid children. What we require is a survey of children of uniform age, educational opportunity, and IQ, in respect to music, drawing, spelling, and so forth.

Although we cannot state with precision the frequency with which marked special gifts occur among the stupid, or marked special deficiencies occur among the highly intelligent, we know that such cases are quite rare. It is necessary to remind ourselves constantly of this fact, because it would gratify the demand for justice and fair play to find that special gifts are freely distributed among the generally inferior, and special defects frequently found among the superior. The truth which satisfies our desires need be stated but once, to be apprehended and remembered. The truth which offends kindliness, self-interest, or cherished beliefs, and is hence unsatisfying, requires emphasis. Therefore we must take particular care to bear in mind throughout the whole of our discussion of special talents and defects, that we are dealing with comparatively rare phenomena. The distribution of abilities, as determined by biological law, does not correspond to our concept of fair play. Nearly all stupid persons are inferior in all capacities. The great majority of gifted persons are superior in nearly all their abilities. The majority of human beings are neither markedly inferior nor markedly superior, but are “typical” (not far from the median or average) in all respects.

XIV. POSSIBLE ORIGIN OF THE DISSOCIATION OF CERTAIN CAPACITIES

Why should certain capacities, like musical sensitivity and ability in representative drawing, be so loosely correlated with general ability, throughout the species? Why should other capacities, like ability to name opposites and to complete sentences, give such high and positive total correlation? We do not know with assurance the answers to these questions. Perhaps the evolutionary explanation is adequate. Those variants lived to transmit their hereditary constitution, whose functions were so correlated that life was well sustained. Perhaps functions are, therefore, loosely correlated, where nothing would be added to the probability of survival by high correlation.

It makes little difference in a world like ours whether an intelligent man can or cannot sing. It is of small moment whether one who can easily detect absurdities of statement can also produce fine representative drawings. It is very important for survival, on the other hand, whether one who can detect similarities can also detect differences, in the objects which surround him, and whether he can at the same time anticipate incomplete meanings in the sentences and gestures of those whom he meets.

The suggestion also arises as to whether those performances which do not cohere closely with performances in general are such as involve the sensori-motor apparatus to a special degree, as distinguished from the central nervous system. Those functions which depend relatively little upon equipment of eye, ear, or hand, but essentially upon the sensitivity and integrity of the cortical neurones, might be expected to cohere closely, constituting what we should properly call intelligence. Where performance depends largely on sense organs and muscles, the correlation with functions largely independent of sensori-motor apparatus might be expected to be only as great as the tendency to general organic quality would bring about. Certainly drawing, music, and mechanical ability, for example, involve eye, ear, and muscle to a much greater extent than does the detection of absurdities in life situations, or the learning of symbolic significances. The mechanical technique of reading clearly involves the sensori-motor apparatus to a much greater extent than does the comprehension of what is read.

It would be valuable to determine to what extent a hierarchy of correlations would be consistently maintained in the use of tests, selected for graduated degrees of involvement of equipment accessory to the central nervous system.[^[8]]

REFERENCES

Baerwald, R.—Theorie der Begabung; Reisland, Leipzig, 1896.

Binet, A., and Simon, Th.—“Théorie nouvelle de la démence”; L’année psychologique, 1909.

Brown, Wm.—“Some Experimental Results in the Correlation of Mental Abilities”; British Journal of Psychology, 1909–10.

Burt, C.—“Experimental Tests of General Intelligence”; British Journal of Psychology, 1909–10.

Burt, C.—Mental and Scholastic Tests; London County Council, 1921.

Hart, B., and Spearman, C.—“General Ability, Its Existence and Nature”; British Journal of Psychology, 1912.

Hart, B., and Spearman, C.—“Mental Tests of Dementia”; Journal of Abnormal Psychology, 1915.

Hollingworth, H. L.—Judging Human Character; D. Appleton and Co., New York, 1922.

McCall, W. A.—Correlation of Some Psychological and Educational Measurements; Teachers College, Columbia University, 1916.

McCall, W. A.—How to Measure in Education; The Macmillan Company, New York, 1922.

Moore, T. V.—“The Correlation between Memory and Perception in the Presence of Diffuse Cortical Degeneration”; Psychological Monographs, 1919.

Révész, G.—“Ueber das frühzeitige Auftreten der Begabung”; Zeitschrift für angewandte Psychologie, 1919.

Rugg, H. O.—Statistical Methods Applied to Education; Houghton Mifflin Co., Boston, 1917.

Simpson, B. R.—Correlations of Mental Abilities; Columbia University, 1912.

Spearman, C.—“The Proof and Measurement of Association between Two Things”; American Journal of Psychology, 1904.

Spearman, C.—“General Intelligence Objectively Determined and Measured”; American Journal of Psychology, 1904.

Spearman, C., and Krueger, F.—“Die Korrelation zwischen verschiedenen geistigen Leistungsfähigkeiten”; Zeitschrift für Psychologie, 1906.

Terman, L. M.—The Measurement of Intelligence; Houghton Mifflin Co., Boston, 1916.

Thompson, J. R.—“The Rôle of Interference Factors in Producing Correlation”; British Journal of Psychology, 1919.

Thomson, G.—“The Proof or Disproof of the Existence of General Ability”; British Journal of Psychology, 1919.

Thomson, G.—“The Hierarchy of Abilities”; British Journal of Psychology, 1919.

Thorndike, E. L., and Aikens, H. A.—“Correlation among Perceptive and Associative Processes”; Psychological Review, 1902.

Thorndike, E. L.—Heredity, Correlation, and Sex Differences in School Abilities; Columbia University, 1903.

Thorndike, E. L.—“On the Organization of Intellect”; Psychological Review, 1921.

Weglein, D. E.—The Correlation of Abilities of High School Pupils; Johns Hopkins University, 1917.

CHAPTER III
Consideration of the Neural Basis

I. THE PHYSIOLOGICAL MECHANISM OF MENTAL LIFE

Psychologists no longer question that the product of mind, which we call behavior, by which mind is judged, is in some way intimately connected with the sensitivity and integrity of the nervous system. The proof of this has often been set forth, and will merely be taken for granted here. Any organ or substance which reacts upon this sensitivity or integrity may then indirectly influence mental life in certain respects. For instance, the glandular system of the body, especially that part of it which comprises the glands of internal secretion, may affect behavior by affecting the growth or function of the nervous system. Drugs may influence mental processes, because they act upon the neurones. However, all present knowledge points to the conclusion that if the nervous tissue could be isolated from such influences, mental life would be immune from their effects. Mental life is but indirectly subject to such influences, in so far as nervous tissue is affected in a particular manner by them.

II. ATTEMPTED LOCALIZATION OF MENTAL FUNCTIONS

When it was thought that such supposed entities as “the reason,” “the will,” “the memory,” and “the imagination” would be identified as mental functions, it was also supposed that a definite location for each might be found in the brain. As investigators were compelled to change their concept of a mental function, and to define mental functions in terms of observable performance, they still sought to discover whether or not each performance might be referred to a definite set of neurones. This question of brain localization constitutes a current topic of research. So little information can be given as yet upon the subject that it is, perhaps, unwarranted to consider it at all in this volume, where the chief interest does not center in the controverted theories of neurology.

Much of the proof for the statement first made in this chapter, that the nervous system is the physiological mechanism of mental life, has been adduced through study of neuropathology. Persons impaired in a given manner in their nervous tissue, show behavior characteristically altered. Moreover, given alterations in behavior can be produced experimentally in animals, by altering the connections in the nervous system, and by no other means. Through these observations it has been possible to assign certain functions to parts of the physiological mechanism.

In the case of man, both by observation and experiment, “the nervous structure below the hemispheres of the cerebrum has been excluded from the possibility of acting as the immediate physical basis of mental states.”[^[9]] The higher mental processes, which involve the possibility of speaking, calculating, and responding by learned reactions to complex situations, have their correlate in the cortex (the agglomeration of neurones in the cerebral hemispheres). Physiological psychologists therefore investigate the cortex, in their search for the particular neurone-patterns or areas involved in particular intellectual performances.

The problems of brain localization have, therefore, been approached through the study of the alterations in performance, which accompany alterations in given areas of the cortex. Alterations in restricted areas of brain tissue, in human beings, are brought about chiefly by obstruction of a blood vessel, hemorrhage, tumor, and laceration or depression through injury to the skull.

One of the early observations, bearing upon topics considered in the subsequent chapters of this volume, was that by Broca. Broca described two cases of pathological impairment in a limited convolutional region of the left cerebral hemisphere, in which the use of words was lost, without loss of intelligence as expressed in other ways. Broca therefore suggested “articulate language” to be a function connected with the part of the brain to which the impairment had been restricted.

A large number of similar observations have been reported since Broca’s publication, describing cases of selective loss of some linguistic function, especially in connection with paralysis of limbs. The localization of articulate language, as a special ability, in Broca’s area, is still, however, debated by those most competent to discuss the matter, and no positive statement is at present warranted. Head, one of the foremost among modern students of neurology, has recently advanced the theory that special disturbances of articulate language (aphasia, alexia, agraphia, aphemia) are due to disturbances of those psychic processes whereby symbolic association is accomplished,—whereby men learn to imbue symbols with meaning. Von Monakow interpreted the array of data existing in 1914 to show that all gnostic functions (intellectual performances) pertain to the cortex as a whole, and not to any center or centers in the brain. He held that no case of aphasia permanently remains, unless there is at the same time diffuse cortical degeneration. Ladd and Woodworth, writing in 1911, concluded that “there is good evidence that the Broca region is the most vulnerable part of the cortex, as regards the motor coördination of speech,” but that “the entire cerebrum would seem to be, of necessity, involved in man’s linguistic attainments and uses.”

III. THEORY OF CONGENITAL LESION OR ATROPHY CRITICIZED

Reasoning from analogy with cases where a function of language is lost selectively, through organic disease or impairment of brain structure, it was thought by those who first described innate special disabilities, as in reading or spelling, that such defects must be due to congenital brain lesions or atrophies. Neurological research has never verified this supposition. No cases showing innate disability to be correlated with any peculiarities of restricted areas in the cortex have ever been recorded. Tilney and Riley, summarizing critically the data of neurology in 1921, cite no cases considered to afford authentic evidence of localized lesions or defects, as the basis of congenital difficulty in reading, spelling, music, or other functions with which the present treatise is concerned.

The theory of innate lesion or atrophy of a cortical area, to account for disability in a special mental function, seems unscientific for other reasons, aside from the fact that it has never been objectively verified by actual observation of a structural defect. One of these reasons is that a theory, formulated to take care of the neural basis of specialized disabilities, must take care of specialized gifts, as well. Cases where a generally stupid child is innately gifted with special ability to master the mechanics of reading, for example, are no doubt as frequent as cases where a generally capable child learns them with difficulty. The theory of specialized lesions or other faults of structure might cover disabilities, but would it cover special talents as well?

Still another consideration prevents us from regarding the theory of localized brain defects as masterly. This is the fact referred to in our preliminary discussion, that every single mental function, which yields to measurement, is found to be distributed among human beings according to a probability curve. (See Figure 1, page [8].) The functions which we herein consider are not exceptions to this principle. Performance in reading, spelling, arithmetic, drawing, music, and so forth, shows children or adults, chosen at random, to be distributed in the given form. Those who have exceptional talents or defects in the function fall within the symmetrical surface of this curve, at its opposite extremes. Nowhere is there a point of demarkation, denoting absolute lack of the trait in a group falling below that point, as there would be if a number of individuals suffering from lesions were introduced into the distribution. We may fairly demand of a theory which undertakes the explanation of the most extreme deviations, the explanation of the deviations of lesser magnitude, as well. The curve obtained by test approximates that form which mathematicians tell us appears when an infinite number of factors act together in an infinite number of ways, the extreme deviations occurring inevitably, by chance. A theory introducing the adventitious circumstance of lesion or atrophy is thus superfluous to the explanation of the extreme unfortunate deviations. To admit it would violate the rule of scientific method known as the law of parsimony, for we do not need it in order to explain the facts.

IV. RESTITUTION OF FUNCTION WITHOUT REGENERATION OF STRUCTURE IN INJURED BRAINS

Fully as important as any of the facts mentioned above, for criticism of the theory that special deficiencies are due to localized defects in brain structure, are the experiments with reëducation of those who have suffered loss of an ability. Persons who have lost the power to read, or write, or speak after destruction of brain tissue, may learn to perform these functions again, without regeneration of the area impaired.

If the neurones destroyed, and no others, were the special mechanisms rendering possible the functions lost, how would restitution of function be possible, without repair of the destroyed tissues?

V. ATTEMPTS TO ESTABLISH A NEURAL BASIS FOR THE “TWO FACTOR THEORY” AND “THE TWO LEVEL THEORY”

In prosecuting their researches from the psychological point of view, by the method of testing performance, Spearman, Moore, Thomson, and other investigators referred to in the preceding chapter, did not neglect the attempt to reconcile their findings with a possible neural basis.

Spearman wrote: “The theory of ‘two factors’ just delineated, though primarily of psychological origin, has shown itself capable of translation into terms of cerebral physiology.” The “specific factors” Spearman would identify with some “particular cortical region, or other neural characteristic, coördinated to the particular performance in question.” The “general factor” is derived from the fact that all neurones of the cortex arise from the same heredity, and must resemble each other, as “the hair in one region of a person’s scalp normally resembles that on the other regions” (a somewhat precarious analogy); also, from the fact that all parts of the brain are nourished by the same blood supply; and from the supposition that “each momentary focus of cortical activity receives continual support from energy liberated by the entire cortex (or some still wider neural area).”

Thomson said: “Let us suppose that the mind, in carrying out any activity such as a mental test, has two levels at which it can operate. The elements of activity at the lower level are entirely specific; but those at the higher level are such that they may come into play in more than one kind of activity, in more than one mental test.... The difference between the levels may be physiological, as between cortex and spinal cord, or it may be the difference between conscious and non-conscious, or what not. The theory may later be reduced to a less harsh dichotomy and there may be gradations from the one level to the other.”

These attempts to find a neural basis for the “Two Factor Theory” and the “Two Level Theory” are obviously not very complete.

VI. PRESENT STATUS OF THE PROBLEM

The conclusion is that at present experimental neurology has nothing secure to offer by way of establishing the neural basis of the special talents and defects, which we wish to consider. We must suppose that in some way unknown they are connected with neural activity, but localization of each function in a restricted area of the brain structure has never been established.

The deviations in performance are almost certainly biological, and not pathological. Each mental function is by original nature possible in some degree to every person, the degrees of potentiality being of enormous range, and distributed among members of the species according to a frequency curve. The form of this curve indicates that the determinants of aptitude are approximately infinite in possibility of combination. The extremes of deviation from the typical result of these determinants acting together, are, as stated, very widely separated, as in any game of chance combining many factors, but they nevertheless have limits, which are knowable. The determinants exist chiefly (perhaps exclusively) in the germ-plasm, from which human organisms spring, and which carries inheritance from countless combinations of ancestry for persons now alive. It is neither necessary nor plausible to introduce a theory of brain lesion or atrophy to explain the extreme minus deviations, leaving the equally extreme plus deviations thus unexplained.

The sum total of a child’s standings on these curves, in the multitude of mental functions which are possible to human beings, constitutes his psychograph or mentality. The physiological aspects of this inheritance may ultimately be found in brain chemistry, or in the discovery of some principle of physics at present unknown. It may be an inheritance of function, rather than of structure. We do not know.

The present status of the problems indicated in this chapter may be recapitulated in the words of Ladd and Woodworth: “The analysis of mental functions into their elements, in a manner suitable for physiological use, has scarcely been begun.”

REFERENCES

Broca, P. P.—Sur le siège de la faculté du langage articulé, avec deux observations d’aphémie; V. Masson et Fils, Paris, 1861.

Franz, S. I.—“Cerebral-Mental Relations”; Psychological Review, 1921.

Head, H.—“Aphasia and Kindred Disorders of Speech”; Brain, 1920.

Head, H.—“Release of Function in the Nervous System”; Proceedings of the Royal Society, Series B, 1921.

Head, H.—“Disorders of Symbolic Thinking Due to Local Lesions of the Brain”; British Journal of Psychology, 1921.

Ladd, G., and Woodworth, R. S.—Physiological Psychology; Charles Scribner’s Sons, New York, 1911.

Lashley, K. S.—“Studies of Cerebral Functions in Learning”; Psycho-Biology, 1920.

Monakow, C. von—Die Lokalisation im Grosshirn; Bergmann, Wiesbaden, 1914.

Tilney, F., and Riley, H. A.—The Form and Functions of the Central Nervous System; Hoeber, New York, 1921.

CHAPTER IV
Reading

I. RELATION BETWEEN IQ AND CAPACITY FOR READING

It has been stated that most of the mental functions, which human beings perform, are not elementary, but are capable of analysis into many contributing factors. Reading has been shown by such analysis to be a very complex function, interference in any part of which may result in disability. The causes of failure to learn to read under instruction, therefore, differ from child to child. Huey, who spent years studying the psychology of reading, finally became so imbued with the wonder of the process, that he felt that to know it in all its aspects and ramifications would be to know all psychology.

Correlations between IQ and reading ability, among children of the same age, in both silent and oral reading, are positive and very high. This is especially true of reading for the understanding of sentences. Correlation between general intelligence, as measured by a scale like Stanford-Binet, and reading ability, as measured by a scale like Trabue’s Language Completion, or Thorndike-McCall’s scale for understanding of sentences, reaches as high as .90, and hardly ever in any group falls below .60.

These correlations indicate that general mental maturity is very closely related to learning to read. The very intelligent children are the best readers in by far the majority of cases, while school children who do not learn to read under ordinary instruction, are usually feeble-minded. On the basis of experimentation in this field, Ranschburg suggests that even so mechanical an aspect of reading as ability to call correctly words exposed in a tachistoscope, may serve as a rough means of separating feeble-minded school children from the others. Nevertheless, even with correlation coefficients reaching as high as .90, there may occur occasional cases of very marked discrepancy between general intelligence and ability to read.

Very early reading, with little or no formal instruction, is often found among children of very high IQ. Of four children measuring over 180 IQ (Stanford-Binet), found by the present writer in New York City, every one learned to read simple matter fluently during or before the third year of life. Their early mastery of reading was but a symptom of their great general capacity.

Just what degree of intellectual development is typically reached before children can be taught to read is not known, but it is probably not far from a 6-year level. That is, children of ordinary intelligence can learn to read after they have passed their sixth birthday. A child who can read fluently at a mental age much below this must be considered to show a special ability; while one who cannot begin to learn at or above this general level[^[10]] is afflicted with a special defect, in some of the functions which enter into the reading process. These functions may be classified as those which enter into mechanics, and those which enter into comprehension, of reading.

II. THE MECHANICS OF READING

Under the mechanics of the process fall the sensory, motor, and to a great extent the perceptual, elements in reading.

The sensory elements include the participation of eye, ear, and muscles as sense organs, furnishing respectively the visual, auditory, and kinæsthetic contributions to the total function. In the case of the blind, tactual sensations replace the visual, and in the deaf, the visual replace the auditory. Sensory impairment, that is, impairment of eye, ear, or muscle as an organ, may prevent an intelligent child from learning to read. Examination of the special senses is the first step dictated by common sense and scientific procedure, when an intelligent child does not learn to read. In this way it has happened historically that the first cases of special disability in reading and spelling among school children have been reported by ophthalmologists, to whom they were taken for examination of the eyes. Parents naturally sought the expert who knows eyes in such cases, for to one who has not studied the psychology of reading, it appears that a person “reads with his eyes” only.

The visual defects which may most commonly interfere with the mastery of the mechanics of reading are myopia, hyperopia, astigmatism, cataract, muscle-weakness, diplopia, and anomalies of the retina. Surveys of school children by competent oculists have shown that considerable numbers suffer from eye-defects sufficient to cause difficulty.

Deafness obviously may constitute an interference, since the correct sound of the word is essential to reading. Not so obvious is the rôle of the kinæsthetic sensations, but we are led to believe that their part is important through the studies of Fernald, later to be reported here.

Under the motor elements involved, we have to consider articulation, pronunciation, eye-movements, and the coördination of arm, hand, and fingers in writing words. It is hard for an expert reader, like an educated adult, to realize without first-hand study of the facts, to what extent these elements originally entered into his learning. The inexpert reader tends to retain lip-movements, and, indeed, movements of the whole apparatus of articulation, in silent reading.

Perception of a stimulus may be defined for our purposes as seeing, hearing, or otherwise interpreting it in a certain way. Perception is habit, learned just as other habits are learned. We perceive the spoken words “home again” as such, because we learned to do so. One who has not learned, will not perceive two words, but only a jumble of articulate sound. In reading, the perceptual elements include the formulation of habits of responding to parts, and to groups of words, as such. Many investigations have been made of the perceptual elements in the mechanics of reading within the past twenty years.

It has been discovered that the word may be learned without first learning the separate letters which compose it. Spelling and reading are thus psychologically far from identical. In perceiving a word, all parts are not equally stressed. The first half and the upper half of the word have a great advantage over the last and lower halves. In fluent reading, the eye moves by jerks across the line, making three to five pauses in crossing an ordinary page of printed matter. Oral reading requires about 1.6 more pauses per line than silent reading, and the average duration of these pauses is longer. Thus oral reading requires 44 to 64 per cent more perception time than does silent reading. The unit of perception in reading may be the letter, the word, the phrase, the sentence, or even the paragraph, according to the training of the pupil, the degree of skill attained, and the extent to which he “skims.” The letter or the word as the unit of perception results in halting and expressionless oral reading, and in retarded silent reading.

These are some of the results of fundamental studies in the psychology of reading, which help us to understand cases of individual difficulty. Recently Gates has made intensive study of reading and spelling by the methods of correlation, with special reference to disability. He finds that partial and multiple correlations reveal an ability or abilities common to all perceptual tests involving words as materials, sufficient to cause fairly high correlations between them, as compared with the correlations between these tests and tests not involving words. By hypothesis, this common factor is defined as an ability to perceive clearly the significant details of words. The multiple correlations of these tests with spelling are higher than with reading, and it is suggested that those who have a very favorable form of word-perception are to some extent learning (or relearning) to spell during the course of ordinary reading. Gates also points out that poor reading is not caused by bad habits of eye-movement, but on the contrary, faulty eye-movements are merely symptomatic of the fact that the child cannot read well. Not having mastered the mechanics of reading, his eyes move hither and yon at random, seeking, by trial and error methods, to get at the matter before him. Wrong eye-movements can be cured by teaching the child how to read. The child cannot be taught to read by correcting his eye-movements.

It should be added, finally, that all the functions referred to above, and possibly others that analysis has not yet made evident, must be synthesized in an automatic set of habits before the child becomes proficient in the mechanics of reading.

III. COMPREHENSION IN READING

The elements of reading thus far considered are those that contribute to mechanics. Reading to recognize forms and to pronounce words is to be distinguished psychologically and pedagogically from reading for the understanding of sentences. Every teacher of much experience in the elementary school will be able to recall children who could read fluently from the printed page, but could not tell what they had read, nor answer questions about the context. In reading to grasp meaning, additional processes, more difficult to perform, are involved, beyond those required to “see and say” the words.

As would be expected, the ability to master the mechanics of reading is more loosely correlated with general intelligence than is ability to comprehend the matter read. The comprehension of meaning is a very large factor in intelligence. It might almost be maintained that intelligence is grasp of meaning. A child who has perfected the mechanics of reading, understands what is read in accordance with his general intelligence, as correlations prove.

Gates has shown that even in the case of children who are quite deficient in oral reading, the correspondence between general intelligence and comprehension of the context in silent reading, as revealed in answers to questions about the material read, is very much higher than would be believed probable. Such a child, using his lame mechanics, draws meaning from fragments, in accordance with his general intelligence.

On the other hand, young children are sometimes found, who have become very fluent in mechanical reading, who can thus read very abstruse matter, without getting any meaning from what they read, because of the limitations of general intellectual development.

As a result of his studies of “Reading as Reasoning,” Thorndike observes: “Reading may be wrong or inadequate (1) because of wrong connection with words singly, (2) because of over-potency or under-potency of elements, (3) because of failure to treat the ideas produced by the reading as provisional and to inspect, and welcome or reject them.”

This third cause of inferior reading is found invariably in children of low IQ, for to read in this way, understandingly, involves the weighing of many elements in a sentence, their organization in the proper relations to one another, and the selection and rejection of connotations—all functions of general intelligence. It is by tests of such functions that IQ is determined. Therefore, it is not surprising that comprehension in reading is so highly correlated with IQ, among school children of the same age. It is between IQ and mechanical ability to read words, that marked discrepancies may occasionally exist, as illustrative cases show.

IV. WORD BLINDNESS

As has been stated, the first cases of inferiority in reading were reported by ophthalmologists, who, upon discovering nothing wrong with the visual apparatus of the child brought for examination, pronounced the difficulty to be word blindness or “congenital alexia.” In using these terms, they reasoned from analogy with pathological cases of selective loss of function in adults, referred to by us in Chapter III.

The first cases reported from this point of view were, so far as the present writer can determine, those of Kerr and those of Morgan, both reporting in 1896. After these, a number of individual cases were reported in France, England, Germany, and the United States. In 1915, Schröck and Clemesha respectively summarized all literature to that date, the former presenting a bibliography of thirty-two titles. The great drawback to clear interpretation of these cases is that general intelligence was not measured. Some, at least, of the children were feeble-minded, for we find cited as evidence of good general endowment, performances which we now know to be typical of children much younger than those being described.

Hinshelwood, an ophthalmologist, published in 1917 a general discussion of non-readers, from the medical standpoint. According to his treatment of the subject, non-readers constitute a group apart, defined by some congenital, pathological defect in brain structure, but for which they would have read normally. This concept is directly derived from analogy with cases of lost function in diseased persons.

“By the term congenital word blindness, we mean a congenital defect occurring in children with otherwise normal and undamaged brains characterized by a difficulty in learning to read so great that it is manifestly due to a pathological condition, and where the attempts to teach the child by the ordinary methods have completely failed.... The recognition of this condition was the direct outcome and result of the previously acquired knowledge of those symptoms of cerebral disease, which we have been studying.... No doubt it is a comparatively common thing to find some who lag considerably behind their fellows, because of their slowness and difficulty in acquiring their visual word memories, but I regard these slight defects as only physiological variations, and not to be regarded as pathological conditions. It becomes a source of confusion to apply to such cases, as has been done of late, the term congenital word blindness, which should be reserved for the really grave degrees of this defect, which manifestly are the result of a pathological condition of the visual memory center, and which have proved refractory to all the ordinary methods of school instruction.”

This is the supposition which was critically considered in Chapter III, and shown to be irreconcilable with facts known to psychology. Hinshelwood did not make mental examinations of the cases which he describes, by standard psychological methods. He did, however, work out by experience a method of teaching, whereby all the non-reading children described learned to read. This consists simply in returning to the primitive method of instruction, beginning with the letters of the alphabet as units of perception, and proceeding by teaching the spelling of words. The necessity of individual teaching is insisted upon.

Aside from the improbabilities of neurological theory, this work is a valuable contribution to the study of children who have special difficulty in reading. It calls attention to the needs of such children, and shows that they can be taught.

V. PSYCHOLOGICAL STUDIES OF SPECIAL DEFECT IN READING

In 1917 Bronner published several interesting cases of special backwardness in reading, studied by the methods of psychological analysis. Bronner states that deficiency in reading, in children of normal sensory capacity and intelligence, sometimes is related to special deficiencies in making visual associations or auditory associations. In the former case the visual details of the word would be elusive. In the latter case, the phonetic elements would be inadequately heeded. Since ordinary success in reading arises through both these avenues of approach, deficiency in either might result in poor reading. Bronner suggests that the avenue which is most approachable in these cases be specially utilized. All children cannot easily learn to read by the method which serves the majority. Bronner does not give results of experimental teaching in the cases analyzed.

In 1918 Schmitt reported thirteen cases from the Chicago Schools, with many details of mental and physical examination. Unfortunately, systematic standard tests of general intelligence were not given, which must be considered a defect in the study, since exact comparisons of reading deficiency and mental age, or IQ, cannot be made. We have the investigator’s assurance that “sufficient tests were given to establish normal intelligence.”

The conclusion that special deficiency in reading ability was present, was made upon the following criteria: (1) regular school attendance; (2) reasonably good health and physical condition; (3) no sign of visual defect; (4) persisting slowness in learning to read, or total inability manifested over one or more years of school life; (5) general mental ability good or average; (6) no other interfering factor, such as foreign language in the home, dislike of school, abnormal unresponsiveness to school, or other social situations. Where all these conditions were satisfactorily met, central deficiency in capacity for learning to read was assumed to characterize the child.