It is necessary also for the reader to bear in mind that there is as yet much controversy among those best equipped to understand the problems of variation, as to the proper methods of measuring comparative variability.

The mathematical considerations involved need not be rehea.r.s.ed here. But until it has been definitely determined just how comparative variability can be scientifically measured, it would seem premature to make any final statement as to s.e.x differences in this respect.

We can therefore answer our second question thus: There is little or no agreement among those best qualified to speak, as to what const.i.tutes the scientific method of measuring comparative variability. But according to the methods now deemed the most reliable, and according to those studies wherein presumably correct methods of measurement have been employed, there is no reason to suppose that there is any s.e.x difference in variability, so far as the numerous traits tested are concerned. There has never been an experimental study made in which the sampling from both s.e.xes was large, random, equal, and from groups of equal h.o.m.ogeneity socially and racially, that showed any reliable s.e.x difference in variability. If we adhere to the literature of fact, we must conclude that, so far as we know, human females differ from each other as much as do human males in abilities and apt.i.tudes.

We now come to the inquiry as to whether there are any special causes of intellectual inefficiency which affect one s.e.x but not the other. Under this topic we may consider the periodic function, which characterizes girls and women, but which does not characterize boys and men. This periodic function has always been the object of superst.i.tion and taboo, and is such even among the civilized peoples of today. The literature of opinion is replete with references to it as a source of intellectual weakness and irresponsibility. We may let Frederick Harrison speak for a large group of writers on this point:

"Supposing all other forces equal, it is just the percentage of periodical unfitness which makes the whole difference between the working capacity of the s.e.xes. It is owing to a very natural shrinking from hard facts, and a somewhat misplaced conventionality that this fundamental point has been kept out of sight."

The literature of opinion abounds in different notions, inconsistencies, and contradictory instances in the matter of the periodic function, and its alleged enormous influence on the intellectual and vocational life of women. Much of the opposition to the education of women was based on it, and it has even been exploited as a good reason why political freedom should be denied to women. It is positively stated that women are on this account unfitted to pursue professional and commercial life; yet it is not proposed that cooks, scrub women, mothers, nursemaids, housekeepers or dancers should be periodically relieved from their labors and responsibilities.

There is almost no literature of fact concerning the periodic function as related to the mental abilities of women. No effort had ever been made to subject this matter to study by instruments and methods of precision until very recently. Psychologists, while often stating the influence of periodicity on mental life to be fundamental and characteristic, entirely neglected to consider it when performing experiments on women subjects. In 1909 Voitsecovsky, at Petrograd, performed an experiment on six women by means of instruments of precision. He thought he found a positive result and that there was shown to be an actual influence of periodicity on certain mental functions. His conclusions are, however, largely invalidated by the fact that all his subjects knew the purpose of the experiment, and by the fact that he neglected to use, as a control, human beings not subject to the phenomenon in question. He also neglected to present his data in full, so that the reliability of his conclusions might be calculated.

Two studies of this phenomenon appeared in 1914. The first was a study by Dr. A. E. Arnold, as to the effect of school work on the periodic function, and this is reported in the January number of the _American Physical Education Review_. This investigator suspected, from his experience as a physician and teacher, "that much of the incapacity claimed was fict.i.tious," and he determined, as an experiment, to inst.i.tute a regime whereby no student under his supervision would be excused periodically from mental or physical duties, except in cases where some pathological condition existed. In summing up the data he says: "So far our results show all improvement [in the health of students]."

The second study, which appeared in 1914, was by the present writer. She made a prolonged and careful experimental study of twenty-three women (using as a control the records of men subjects), and failed to demonstrate any influence of periodicity on those mental abilities which she tested.

These included speed and accuracy of perception, controlled a.s.sociation, steadiness, speed of voluntary movement, fatigability, and rate of learning.

A great amount of scientific work remains to be done before any final answer of any kind can be given to the question, Does functional periodicity exercise a fundamental and characteristic influence on the intellectual abilities of women? We must answer our third question in this way: There is very little experimental evidence on which to base a reply, but the few data which we do possess show no influence, either detrimental or beneficial.

Our fourth inquiry is this: Are there any innate s.e.x differences in affective or instinctive equipment that would naturally lead to a vocational differentiation of the s.e.xes? Here we must acknowledge ourselves to be entirely without a literature of fact. The literature of opinion is very extensive on the subject, and it would be an interesting and no doubt an instructive task to collect and summarize the various and conflicting opinions of men as to the affective and instinctive differences between the s.e.xes. Men and women as we see them in the world do differ in affective behavior, but no one can say whether these differences in behavior are original or acquired. There are different conventional standards of emotional behavior for men and for women, but no one would be justified in saying that such standards arose from inherent affective differences between the s.e.xes. The very variety that characterizes the statements on this subject const.i.tutes proof of the ignorance of mankind in regard to it.

Since exact data are entirely lacking, the discussion of this last question need not detain us. We may, however, glance at one instinct which has repeatedly been stated to characterize women, and to const.i.tute in itself a natural justification for differentiating the s.e.xes vocationally. This is the "maternal instinct." Since the period of helpless infancy is very prolonged in the human animal, and since the care of infants is an exacting and onerous labor, it would be natural for those who are not biologically attached to infants, to use all means at their disposal to fasten the whole burden of infant-tending upon those who are originally so attached. We should expect this to happen, and it does happen. There has been a continuous social effort to establish as a norm the woman whose vocational proclivities are completely and "naturally" satisfied by child-bearing and child-rearing.

In the absence of all data, it would seem most reasonable to suppose that if it were possible to obtain a quant.i.tative measurement of "maternal instinct," we should find this trait distributed among women just as we have found all other traits distributed, which have yielded to quant.i.tative measurement. It is most reasonable to a.s.sume that we should obtain a curve of distribution, varying from an extreme where individuals have a zero or negative interest in the care of infants, through a mode where there is a moderate amount of impulse to tend infants, to a second extreme where the only vocational interest lies in such activity. The bearing and rearing of children is in many respects a.n.a.logous to the work of soldiers. It is necessary to national existence, it means great sacrifice of personal advantage, and it involves suffering and danger, and, in a certain percentage of cases, the actual loss of life. Thus, as in the case of soldiers, every effort is and must be made to establish as a norm the extreme end of the distribution curve, where there is an all-consuming interest in patriotism, in the one case, and in motherhood in the other. In the absence of all scientific data, we should, therefore, guard against accepting as an established fact about human nature a doctrine that we might expect to find in use as a means of social control. It is also fitting to raise the question as to just what is meant by the term, "maternal instinct." Does it mean desire for offspring which are as yet non-existent? Does it mean only the tendency to care for helpless offspring after they are actually in existence? Does it mean an interest in children as such, regardless of their origin? Or does it consist in a mingling of all these elements? Above all, does it involve, as an essential element, an interest in waiting personally upon infants? One certainly gains the impression from a perusal of the extensive literature of opinion that to most persons the term is quite una.n.a.lyzed, and that it calls for a.n.a.lysis.

We have now considered four of our inquiries in the light of experimental evidence. We have discovered that a great amount of work remains to be done before we can answer most of them conclusively, and that to one question, at least, no answer at all can be given from the literature of fact. We can only say that, so far, scientific experiment has revealed no s.e.x differences in the original nature of intellect that would imply a necessary differentiation of vocations on the ground of s.e.x. There exist no scientific data to show (1) differences in average intellect; (2) differences in mental variability; (3) special causes of intellectual inefficiency affecting one s.e.x but not the other; (4) differences in affective or instinctive equipment, implying a "natural" division of labor.

The division of labor between the s.e.xes, which has existed through historic times and still persists, originated, so far as we know, in physiological, not in psychological differences. The momentous physiological fact that women bear and nourish infants and men do not, is the great primary s.e.x difference on which our economic and vocational organization has been built up. It might be supposed that natural selection would have evolved an intellectual (or unintellectual) type in women, which could find its complete natural satisfaction in the vocation of child-bearing and child-rearing. But such a selection could take place only if mental traits were s.e.x-limited in inheritance, or existed as secondary s.e.x characteristics. No mental trait has ever been proved to be s.e.x-limited in inheritance, or to exist as a secondary s.e.x character. So far as we know, daughters inherit mental traits from fathers as well as from mothers, and sons inherit them from mothers as well as from fathers. Under such circ.u.mstances the law of natural selection can never become operative to solve the vocational problems of women.

The fact that women have not in the past equaled men in "philosophy, science, art, invention and management" is frequently adduced as evidence of their innate unfitness for pursuits other than the domestic. From such evidence, however, we glean in reality no information whatever about the vocational apt.i.tudes of women. We should not expect any notable achievement by women in the fields mentioned above, for the following reasons. Women must bear and nourish infants, and men cannot. The period of gestation and the period of infancy are very protracted in the human species, together covering, for each infant reared, about six years. Until very recently no scientific methods of controlling procreation have been generally known or utilized. Thus women have borne great numbers of infants, all their youth and maturity being consumed by bearing and rearing young. The small minority of women whose lives happened not to be so consumed would be very unlikely to make any contributions in extra-domestic vocational achievement for two reasons. In the first place, all women were expected to mate and thus to procreate and rear offspring, and no provision was made by society for their training in lines other than those they would be expected to use. In the second place, those women who did not meet the common fate failed to do so for some special reason, such as ill health, mental disease, or the necessity of caring for decrepit relatives. The very causes of their celibacy would operate also against any vocational achievement on their part.

In the irrational trial and error method by which our human inst.i.tutions have been developed, the logical expectation would be that the great physiological s.e.x difference in reproductive function would probably influence vocational activities just as it has done. We find in the traditional division of labor between the s.e.xes exactly what we should expect to find, even though there were an ident.i.ty of intellectual abilities and interests. It seems both psychologically and socially desirable that the one incontestable conditioning factor in the vocational differentiation of men and women be raised clearly to consciousness, rather than submerged, as in the past, by an elaborate system of defense mechanisms and traditional devices of social control. It would be going afield from the immediate purpose of this chapter to offer constructive suggestions for such changes in economic and domestic management as might be necessary to overcome this conditioning factor, and thus to give free vocational opportunity to both s.e.xes alike. To effect these changes in such a way that the maximum social betterment may be achieved thereby will be a task not simple but complex. It will call for the best thought and the most enlightened effort of which we are capable, and will be accomplished only with the pa.s.sing of years and decades.

The essential thing at present is to know whether any basis for future action may now be found in the established facts of human nature. In the present state of scientific knowledge it would be as dogmatic (and therefore as undesirable) to state that significant s.e.x differences in intellect do not exist, as to state that such differences do exist. All we can say is that up to the present time experimental psychology has disclosed no s.e.x differences in mental traits which would imply a division of labor on psychological grounds. The social gain would be very great if the public could be brought to recognize intelligently that to many of the questions regarding the vocational apt.i.tudes of women no definite answers can at present be given, because the necessary data for the formulation of answers have never been collected. So far as is at present known, women are as competent intellectually as men are, to undertake any and all human vocations.

FOOTNOTES:

[15] There was published in the October (1914) issue of the _Psychological Bulletin_ a summary of all important experimental work done on s.e.x differences in recent years. Any reader wishing to take up the evidence greatly in detail will do well to consult all of the references there given.

CHAPTER XI

THEORY AND PRINCIPLE OF PSYCHOLOGICAL TESTS AS APPLIED TO VOCATIONAL a.n.a.lYSIS

The more general questions of the theory of tests, their selection, evaluation, and technique of application and record, need not be considered here. The reader unfamiliar with these matters will find them fully treated in the various standard manuals of tests, and in numerous special articles and monographs referred to in the bibliography.

There are, however, certain particular aspects of the theory and use of mental tests which have special importance for vocational psychology. These are:

1. The question of the degree to which proficiency in one respect or ability or test implies proficiency in others.

2. The degree to which these intercorrelations are revealed by preliminary trials and modified by continued practice.

3. The question of the significance of preliminary trials in revealing the relative abilities of individuals as these would be shown after all the individuals had acquired their maximum skill or practice level of proficiency; that is, the relation between momentary capacity and ultimate achievement.

Attempts to intercorrelate mental or motor abilities as measured by laboratory tests have usually produced more or less irregular results. Some of the coefficients have been positive, some negative, but in only a few cases have many of them been large when the individuals tested have been chosen at random or with no deliberate intention of measuring only the extremes of the curve of distribution. Thus in a recent report of the correlations of abilities among several hundred adult individuals it is remarked that a certain test for logical memory is "one of the very best tests," partly because of "its high correlation with other tests" (an average correlation of .29).

Two reasons are largely responsible for these low coefficients. The first is the fact that the measures correlated have usually been initial trials, or at most averages of a very few trials. This means great individual variability and considerable consequent unreliability of the data. A more important factor, perhaps, is the fact that these preliminary trials do not necessarily represent the final capacities of the individuals. They are determined by a host of incidental or accidental influences and reveal only momentary ability, not ultimate capacity. There is every reason for expecting to find positive correlation of "desirable" traits, and we may well expect to find this increasingly true the more our measures test the final limits of capacity in the various tests. In other words, the only real correction for unreliable measures is to be made by continuing the test until the individual has reached the limit of practice in it.

Only occasional attempts have been made to determine the influence of practice on the correlation of abilities, and those that have been reported have been based on so few practice trials that no review of them need be given. In the present chapter I shall present the results of an experiment in which a group of observers were repeatedly tested until in each test a practice limit was approximated, a limit which, in most cases, one hundred further trials failed to improve. The results have a real interest for vocational psychology.

The experiment consisted in putting each of thirteen individuals through 205 repet.i.tions of seven different mental tests. The trials were controlled as thoroughly as possible with respect to such factors as _interim_ occupation, exercise, food, rotation of tests, temperature, illumination, and incentive and interest. The subjects, four women and nine men, ranging from eighteen to thirty-nine years in age, were mature, zealous, and faithful. Compet.i.tion was stimulated by the award of desirable prizes, and each worker received a daily wage. Records were announced to the subjects only after each thirty-five trials. So far as previous practice in these particular tests is concerned, all the subjects were nave. Five trials were made daily, these trials being distributed through the day at about two-hour intervals. The tests themselves occupied about forty minutes at each sitting.

The tests used were the following familiar laboratory forms:

1. Adding. Adding seventeen mentally to each of fifty two-place numbers and reciting aloud the correct answer. Order of numbers random at each trial.

Record with stop watch, time required for perfect score.

2. Naming Opposites. Correctly naming opposites of each of fifty adjectives which occurred each time in random order. Record, time required for a perfect score.

3. Color Naming. The Columbia laboratory form of this test, with ten repet.i.tions of each of twelve colors. Position of card changed at each trial. Record, time required for perfect score.

4. Discrimination Reaction. Discriminating between red and blue, and reacting correctly with appropriate hand. Record, average time, in _sigma_, and number of false reactions.

5. Cancellation. Crossing out digits from the Woodworth-Wells form of this test. Record, time required for 75 correct cancellations of equally difficult digits.

6. Coordination. The familiar three-hole test, for accuracy of aim. Record, time required for one hundred correct strokes.

7. Tapping. Executing four hundred taps at maximal speed, with hand stylus, right hand, elbow support. Record, time required.

Each test has been correlated[16] with all the remaining tests at various points in the curve of practice. Correlations were made at each of the following points:

1. Preliminary trial designated 1st trial 2. Median of first 5 trials designated 5th trial 3. Median of trials 20 to 25 designated 25th trial 4. Median of trials 75 to 80 designated 80th trial 5. Median of trials 200 to 205 designated 205th trial

At each of these points the thirteen individuals were arranged in an order of relative ability for each of the tests, and these orders were correlated with each other. Table 23 gives, for each test, at each point, the average correlation with all the other tests, and also the grand average correlations of all tests.

TABLE 23

SHOWING THE AVERAGE CORRELATION OF EACH TEST WITH ALL OTHERS, AT VARIOUS POINTS IN THE CURVE OF PRACTICE

-------------------------------------------------------------- Trial

Adding

Opposites

Color

Discrim-

Coordi-

Tapping

Final

Naming

ination

nation

Average -----+------+---------+------+--------+-------+-------+------- 1

.19

.10

.15

-.07

-.15

.17

.065 5

.41

.26

.15

.35

.21

.32

.280 25

.50

.35

.43

.27

.03

.35

.320 80

.55

.43

.53

.31

.18

.34

.390 205

.48

.62

.61

.35

.34

.52

.490 --------------------------------------------------------------

Except in the case of discrimination the effect of practice is to increase to a marked degree the intercorrelations of the various tests. Adding increases steadily up to the eightieth trial. Opposites and color naming gain even more steadily to the very end of the experiment, the increase in the coefficients being four to six fold. Tapping increases more slowly but no less certainly. In coordination the increase is very irregular, but the coefficients show, on the whole, a change from -.15 at the first trial to .34 at the finish. Only in the case of discrimination is there failure to increase after the fifth trial. In no case, after the preliminary trial, is there a negative coefficient among the average correlations, and indeed in only one case is there a coefficient smaller than .15. The final averages show steady increase from .065 at the preliminary to .28 at the fifth, .32 at the twenty-fifth, .39 at the eightieth, and .49 at the two-hundred-and-fifth trials. _With practice, then, the average correlations of all tests become positive, and the coefficients become greater the longer the practice is continued._

In producing this increase in the intercorrelation of specific abilities through the medium of practice, at least three different factors probably cooperate. These factors have not an equal significance for vocational psychology and its interests in tests.