Individual differences are, therefore, seen to be not simply differences with respect to given mental traits, but differences with respect to general mental capacity. Experimental investigation points to a graded difference in mental capacity, ranging from idiocy to genius, the largest group being normal or average, the size of the group diminishing with further deviation from the average in either direction.

Certain important correlations, furthermore, have been found between the level of intelligence and the level of character.

The great in mind, it may be said briefly, are also great in spirit. "General moral defect commonly involves intellectual inferiority. Woods and Pearson find the correlation between intellect and character to be about .5.... General moral defect is due in part to a generally inferior nervous organization."[1]

[Footnote 1: Thorndike: _Educational Psychology_ (1910), p. 224.]

One other important correlation must be noted. While gifts and capacities are specific, superiority in a given trait commonly involves superiority in most others. Exceptional talent in one direction in most cases involves exceptionality in many other respects. While talents are not indiscriminately transferable from one field to another, the same complex of traits which makes a person stand out preeminently in a given field, say law, would make him stand out in any one of half a dozen different fields into which he might have gone.

There seems to be no evidence that extraordinary capacity in one direction is balanced by extraordinary incapacity and stupidity in others. The fact that individuals differ not only in specific traits but in general mental capacity has, also, certain obvious practical consequences. It means that there are present in society, in the light of recent tests in the army, an unexpectedly large number of individuals below the level of normal intelligence. One in five hundred, Thorndike estimates, is the "frequency of intellectual ability so defective as to disturb the home, resist school influence, and excite popular derision." These are clearly liabilities in the social order.

On the other hand, there is a large number above the level of average intelligence. The importance of this group for human progress can hardly be overestimated. As we have seen in other connections, progress is contingent upon variation from the "normal" or the accustomed, and such variation from the normal is initiated in the majority of cases by members of this comparatively small super-normal group. If civilization is to advance it must capitalize its intelligence; that is, educate up to the highest point of native ability. But in any case, its chief guarantee of progress lies in the comparatively small group in whom native ability is exceptionally high. For it is among this group that original thinking, invention, and discovery almost exclusively occur.

CAUSES OF INDIVIDUAL DIFFERENCES. Among the chief causes of individual differences may, in general, be set down the following: (1) s.e.x, (2) Race, (3) Near Ancestry or Family, (4) Environment. The particular fund of human nature which an individual displays, that is, his specific native endowments, as they appear in practice, will be a resultant of these various causes. In the study of each of these characteristics, we should be able ideally to eliminate all the others and to consider them each in isolation.

THE INFLUENCE OF s.e.x. In the case of s.e.x, for example, we should not confuse individual differences due to the fact of s.e.x with individual differences due to divergent training given to each of the s.e.xes. In scientific experiments to determine s.e.x differences in mental traits, there have been careful attempts to eliminate everything but the factor of s.e.x itself. Thus in Karl Pearson's studies of fifty twin brothers and sisters, the factors of ancestry and difference of training and age were practically eliminated.

In so far as allowance can be made for other contributing factors, studies of individual differences due to s.e.x have revealed, roughly speaking, the following results. There have been, in the field of sensory discrimination and accuracy of motor response, slight--and negligible--differences of responses made by male and female. The subjects stated were, in most cases, selected so far as possible from the same social strata, social and intellectual interest, and background.[1]

[Footnote 1: As, for example, the members of the graduating and junior cla.s.ses of the co-educational college at the University of Chicago, studied by Dr. Thompson.]

Thorndike reports the general results of such tests as follows:

The percentages of males reaching or exceeding the median ability of females in such traits as have been subjected to exact investigation are roughly as follows:

In speed of naming colors and sorting cards by color and discriminating colors as in a test for color blindness 24 In finding and checking small visual details such as letters 33 In spelling 33 In school "marks" in English 35 In school "marks" in foreign languages 40 In memorizing for immediate recall 42 In lowness of sensory thresholds 43 In retentiveness 47 In tests of speed and accuracy of a.s.sociation 48 In tests of general information 50 In school "marks" in mathematics 50 In school "marks" (total average) 50 In tests of discrimination (other than for color) 51 In range of sensitivity 52 In school "marks" in history 55 In tests of ingenuity 63 In accuracy of arm movements 66 In school "marks" in physics and chemistry 68 In reaction time 70 In speed of finger and arm movement 71

The most important characteristic of these differences is their small amount. The individual differences within one s.e.x so enormously outweigh the differences between the s.e.xes in these intellectual and semi-intellectual traits that for practical purposes the s.e.x difference may be disregarded. So far as ability goes, there could hardly be a stupider way to get two groups alike within each group but differing between the groups than to take the two s.e.xes. As is well known, the experiments of the past generation in educating women have shown their equal competence in school work of elementary, secondary, and collegiate grade. The present generation's experience is showing the same fact for professional education and business service. The psychologists' measurements lead to the conclusion that this equality of achievement comes from an equality of natural gifts, not from an overstraining of the lesser talents of women.[1]

[Footnote 1: Thorndike: _Educational Psychology_, briefer course, pp. 345-46.]

That is, so far as experiments upon objectively measurable traits have been conducted, the specific differences that individuals display have comparatively nothing to do with the fact that an individual happens to be a man or a woman.

These experiments have been conducted with boys and girls as young as seven, and with men and women ranging up to the age of twenty-five.[2]

[Footnote 2: There seems, as might be expected to be, a slightly higher differentiation between the two s.e.xes after adolescence than before.]

These experiments have been conducted to test sensory discrimination, precision of motor response and some of the simpler types of judgment, such as those involved in the solution of simple puzzles with blocks, matches, etc. The fact of the negligibility of s.e.x difference with regard to certain minor measurable traits has been adequately demonstrated by a wide variety of experiments. The fact of s.e.x equality or mental capacity has been less accurately but fairly universally noted by popular consensus of observation and opinion of the work of women in the various trades and professions. There are differences between men and women in physical strength and in consequent susceptibility to fatigue. These are important considerations in qualifying the amount of work a woman can do as compared with that of a man, and have justly resulted in the regulation of hours for women, as a special cla.s.s. But there do not seem to be, on the average, significant original differences in mental capacity.[3]

[Footnote 3: On this subject there has been collected a large amount of accurate experimental data. See Goldmark: _Fatigue and Efficiency_, part II, pp. 1-22. These refer to physiological differences.]

There do exist, as a matter of practical fact, some of the special attributes commonly ascribed to the masculine and feminine mental life, but it is generally agreed by investigators that these are to be accounted for by the different environment and standards socially established for men and for women. There are radical and subtle differences in training to which boys and girls are subjected from early childhood.

There are deeply fixed traditions as to the standards of action, feeling, and demeanor to which boys and girls are respectively trained and to which they are expected to conform. If a boy should not live up to this training and expectation, he may be marked out as "effeminate." If a girl does not conform, she is defined as a "hoyden" or a "tomboy."

These social distinctions, which are emphasized even in the behavior of young boys and young girls, grow more p.r.o.nounced as individuals grow older. One need hardly call attention to actions regarded as perfectly legitimate for men which provoke disapproval if practiced by women. Rigid training in these different codes of behavior may cause acquired characteristics to seem inborn. But whether these general features commonly held to distinguish the mental life of man or woman are or are not intrinsic and original, they have been marked out by certain investigators as socially fundamental. Thus Heymans and Wiersma, two German investigators, set down as the differentia of feminine mental life (1) greater activity, (2) greater emotionality, (3) greater unselfishness of the female.[1]

[Footnote 1: See Thorndike's _Educational Psychology_ (1910), p. 136.]

There are some general differences noted by both layman and psychologist, which, though not subject to quant.i.tative determination, yet seem to differentiate somewhat definitely between feminine and masculine mental activity. These may be set down in general as occurring in the field of emotional susceptibility. Thorndike traces them back to the varying intensity of two human traits earlier discussed: the fighting instinct, relatively much stronger in the male, and the nursing or mothering instinct, much stronger in the female. With this fact are a.s.sociated important differences in the conduct of men and women in social relations. The maternal instinct is held by some writers, for instance, to be in large measure the basis of altruism, and is closely a.s.sociated with sensitivity to the needs and desires of others. Thorndike writes:

It has been common to talk of women's dependence. This is, I am sure, only an awkward name for less resentment at mastery. The actual nursing of the young seems likewise to involve equally unreasoning tendencies to pet, coddle, and "do for" others. The existence of these two instincts has been long recognized by literature and common knowledge, but their importance in causing differences in the general activities of the two s.e.xes has not.

The fighting instinct is in fact the cause of a very large amount of the world's intellectual endeavor. The financier does not think merely for money, nor the scientist for truth, nor the theologian to save souls. Their intellectual efforts are aimed in great measure to outdo the other man, to subdue nature, to conquer a.s.sent. The maternal instinct in its turn is the chief source of woman's superiorities in the moral life. The virtues in which she excels are not so much due to either any general moral superiority or any set of special moral talents as to her original impulses to relieve, comfort, and console.[1]

[Footnote 1: Thorndike: _loc. cit._, pp. 48-49.]

Ordinary observation reveals, as literature has in general recorded, what Havelock Ellis has called the "greater affectability of the female mind." There is evidenced in many women a singular and immediate responsiveness to other people's emotions, a quick intuition, a precise though non-logical discrimination, which, though shared to some extent by all individuals gifted with sympathy and affection, is a peculiarly feminine quality. Indeed when a man possesses it, it is common to speak of him as possessing "almost a woman's intuition." Such emotional susceptibility is manifested in the higher frequency of emotional instability and emotional outbreaks among women than among men, and the decreased power of inhibition which women have over instinctive and emotional reactions. Further than this, women more than men may be said to qualify their judgments of persons and situations by their emotional reactions to them.

The common suspicion that in general women's abilities are less than those of men has seemed to gain strength from the greater number of geniuses and eminent persons there have been among men than among women. Professor Cattell writes in this connection:

I have spoken throughout of eminent men as we lack in English words including both men and women, but as a matter of fact women do not have an important place on the list. They have in all thirty-two representatives in the thousand. Of these eleven are hereditary sovereigns, and eight are eminent through misfortunes, beauty, or other circ.u.mstances. Belles-lettres and fiction--the only department in which woman has accomplished much--give ten names as compared with seventy-two men. Sappho and Joan d'Arc are the only other women on the list. It is noticeable that with the exception of Sappho--a name a.s.sociated with certain fine fragments--women have not excelled in poetry or art. Yet these are the departments least dependent on environment, and at the same time those in which the environment has been perhaps as favorable to women as to men. Women depart less from the normal than men--a fact that usually holds for the female throughout the animal series; in many closely related species only the male can be readily distinguished.[1]

[Footnote 1: Cattell: "A Statistical Study of Eminent Men,"

_Popular Science Monthly_, vol. LXII. pp. 375-77.]

In the facts of higher variability among males, and the hitherto restricted social opportunities provided for women are to be found the chief reasons for the comparatively high achievement of the male s.e.x as compared with the female.

But on the average the difference between the two s.e.xes with respect to mental capacity is slight.

THE INFLUENCE OF RACE. A second factor in determining individual differences in mental traits is race. There are certain popular presuppositions as to the inherent differences in the mental activity of different races. The Irishman's wit, the negro's joyousness, the emotionality of the Latin races, the stolidity of the Chinese, are all supposed to be fundamental.

And in a sense they are. That is, in the life and culture of these groups, such traits may stand out distinctively.

But most psychologists and anthropologists question seriously whether these traits are to be traced to radical differences in racial inheritance. For the most part they seem rather to be the result of radical differences in environment.

"Many of the mental similarities of an Indian to Indians and of his differences from Anglo-Saxons disappear, if he happens to be adopted and brought up as an Anglo-Saxon."[1]

[Footnote 1: Thorndike _loc. cit._, p. 52.]

There have been various experimental studies made to determine how much divergences in the mental activity of different races are determined by differences in racial inheritance. Such experiments have been conducted chiefly upon very simple traits and capacities. The accuracy of sensory response among different races has, for example, been examined. There have proved to be, in regard to these, slight differences in the effectiveness and accuracy of response.

There are racial differences in hearing, as tested by the ticking of a watch or clock artificially made. In this test, Papuans, to take an instance, were inferior to Europeans. The sense of touch has been similarly tested, and comparatively negligible differences have been found. In regard to the five senses, their efficiency seems to be about equal in all the races of mankind. The proverbial keenness of vision of the Indian, for example, is found to be due to a superior training in its use, a training made imperative by the conditions of Indian life. In reaction time tests--that is, tests in the speed of simple mental and motor performances--the time consumed in response has been found to be about the same for all races tested. The results have been similar with regard to certain simple processes of judgment or inference:

There are a number of illusions and constant errors of judgment which are well known in the psychological laboratory, and which seem to depend, not on peculiarities of the sense organs, but on quirks and twists in the process of judgment. A few of these have been made the matter of comparative tests, with the result that peoples of widely different cultures are subject to the same errors, and in about the same degree. There is an illusion which occurs when an object, which looks heavier than it is, is lifted by the hand; it then feels, not only lighter than it looks, but even lighter than it really is. The contrast between the look and the feel of the thing plays havoc with the judgment. Women are, on the average, more subject to this illusion than men. The amount of this illusion has been measured in several peoples, and found to be, with one or two exceptions, about the same in all. Certain visual illusions, in which the apparent length or direction of a line is greatly altered by the neighborhood of other lines, have similarly been found present in all races tested, and to about the same degree. As far as they go, these results tend to show that simple sorts of judgment, being subject to the same disturbances, proceed in the same manner among various peoples; so that the similarity of the races in mental processes extends at least one step beyond sensation.[1]

[Footnote 1: Woodworth: "Racial Differences in Mental Traits,"

_Science_, New Series, vol. 31, pp. 179-81.]

Professor Woodworth also points out that these simple tests are not adequate to measure general intelligence.

A good test for intelligence would be much appreciated by the comparative psychologist, since, in spite of equal standing in such rudimentary matters as the senses and bodily movement, attention and the simpler sorts of judgment, it might still be that great differences in mental efficiency existed between different groups of men.

Probably no single test could do justice to so complex a trait as intelligence. Two important features of intelligent action are quickness in seizing the key to a novel situation, and firmness in limiting activity to the right direction, and suppressing acts which are obviously useless for the purpose in hand. A simple test which calls for these qualities is the so-called "form test." There are a number of blocks of different shapes, and a board with holes to match the blocks. The blocks and board are placed before a person, and he is told to put the blocks in the holes in the shortest possible time. The key to the situation is here the matching of blocks and holes by their shape; and the part of intelligence is to hold firmly to this obvious necessity, wasting no time in trying to force a round block into a square hole. The demand on intelligence certainly seems slight enough; and the test would probably not differentiate between a Newton and you or me; but it does suffice to catch the feeble-minded, the young child, or the chimpanzee, as any of these is likely to fail altogether, or at least to waste much time in random moves and vain efforts. This test was tried on representatives of several races and considerable differences appeared. As between whites, Indians, Eskimos, Ainus, Filipinos, and Singhalese, the average differences were small, and much overlapping occurred. As between these groups, however, and the Igorot and Negrito from the Philippines and a few reputed Pygmies from the Congo, the average differences were great, and the overlapping small.[1]

[Footnote 1: Woodworth: _loc. cit._, pp. 171-86.]

Equality among races in the various traits that have been measured by psychologists does not imply that common observation is wrong in counting one race as intellectually superior to another. There have, as yet, been no measurements of such general features of social life as energy, self-reliance, inventiveness, and the like. But from indications of experiments already made, these so-called (and for practical purposes genuine) intellectual differences between the individuals of different races must be attributed to differences in environment. Races _as_ races seem to be equally gifted.

Professor Boas points out that civilized investigators traveling among savage tribes commit one serious fallacy in insisting on the inferiority of these primitive peoples. They are said to be irrational, for example, when they are quite logical in their way of dealing with the material which is at their disposal. Without any scientific information available, for example, anthropomorphism, or the tendency to interpret cosmic phenomena in human terms is quite natural and reasonable.

Again:

The difference in the mode of thought of primitive man and that of civilized man seems to consist largely in the difference of character of the traditional material with which the new perception a.s.sociates itself. The instruction given to the child of primitive man is not based on centuries of experimentation, but consists of the crude experience of generations. When a new experience enters the mind of primitive man, the same process which we observe among civilized man brings about an entirely different series of a.s.sociations, and therefore results in a different type of explanation. A sudden explosion will a.s.sociate itself in his mind, perhaps, with the tales he has heard in regard to the mythical history of the world, and consequently will be accompanied by superst.i.tious fear. When we recognize that neither among civilized men nor among primitive men the average individual carries to completion the attempt at causal explanation of phenomena, but carries it only so far as to amalgamate it with other previously known facts, we recognize that the result of the whole process depends entirely upon the character of the traditional material.[1]

[Footnote 1: Boas: _Mind of Primitive Man_, pp. 203-04.]

This may be ill.u.s.trated by our immediate reactions of pleasure or disgust at customs or ideas that provoke directly opposite reactions among races reared in another tradition.

Again primitive races have been accused of lacking self-control.

The fact is that they exhibit self-control about matters which they regard as important, and lack of it in respect to matters which they regard as trivial. "When an Eskimo community is on the point of starvation, and their religious proscriptions forbid them to make use of the seals that are basking on the ice, the amount of self-control of the whole community which restrains them from killing those seals is certainly very great."[2] The case is similar with regard to nearly all the alleged inferiorities of primitive man, his improvidence, unreliability, and the like. In nearly every instance, it has been found that we are holding him to account for not being able to persist in courses of action which do not seem to him, with his training and education, worth persisting in, and for not conforming to standards which, given his background, are meaningless.