Measure Your Mind: The Mentimeter and How to Use It

by Marion Rex Trabue; Frank Parker Stockbridge

Now we have a record of performance that compares at all times with universal standards. If we add another automobile to the group we do not need again to run all the cars, including the new one, along the speedway to determine where the added member of the group ranks with reference to the others; we can apply to it alone a test based upon the universal standards of time and distance with which we have already compared the others, and the new one falls instantly into its proper rank among its fellows. So, too, we are enabled by this means to compare any member of the group with any automobile anywhere in the world, the performance of which has been gauged by these same universal standards of time and space, and we are thus able to tell, not only how each particular car ranks with reference to the limited group of cars, but how it ranks with reference to all cars of all kinds or of a particular type so far as these have been tested by the universal standard.

So in testing groups of individuals as to their intelligence or mental capacity, the use of universal standards of comparison makes the relative grading of the members of the group with reference to each other just as easy and simple as though the only standard were that of the group’s collective performance, and at the same time furnishes a record of the performance of each individual member of the group by which he or she may be readily compared with the members of any new group to which he or she may be at some subsequent time attached, and at all times with the general run of men or women of the same or differing social, economic, vocational, or educational status.

It is in the determination of these universal standards and the preparation of tests, the results of which indicate the individual’s relative approximation to these standards, that the scientific training of the psychologist comes principally into play. Rough standards for testing the more obvious mental capacities might be set up by any intelligent person who would take the pains to collect the essential data. These standards would not, however, be universal unless they were based upon research and experimentation covering as broad a field as that in which the psychologists have been working for many years. Nor would they, except by accident, be as simple and as accurate as the universal standards compiled by scientifically trained persons. For just as the average untrained individual cannot form an accurate or even an approximately accurate estimate of another person’s character and abilities by observation alone, so persons untrained in the study of the human mind are prone to be misled by the obvious and to lay undue emphasis upon external indications which do not, as a matter of scientific fact, actually signify what they are popularly believed to indicate. The scientific psychologist’s training enables him to eliminate to a large extent the non-essentials and to include, in the establishment of standards of mental measurement and the preparation of tests or methods of applying these standards, many facts which, to the untrained mind, do not at once present themselves as important elements.

Even in the simplest of mechanical operations every workman knows that it is not safe to trust to the accuracy of homemade measuring implements. In the absence of a try-square made by a responsible manufacturer in conformity with the universal standard right angle, even the most expert carpenter will refuse to run the risk of error until he has either obtained a new standard from the hardware store or by the application of geometrical science and the exercise of careful and painstaking technical skill constructed for himself a new try-square that conforms, without the variation of a hair’s-breadth, to the universal standard to which he must work. Still less would a good machinist undertake to gauge the close tolerances of an automobile bearing with a homemade micrometer. He knows it is not sufficient merely to have a perfect fit of this particular bearing, which might be worked out by rule of thumb, but that it is essential that the dimensions of the bearing, down to within a thousandth of an inch, must conform to the universal standards for automobile bearings, and that the best implement with which to test the degree of conformity to the universal standard is the standardized micrometer, prepared by specialized methods and produced only by the exercise of highly trained technical skill. Once given such implements of precision, any good workman can readily apply all the scientific intelligence that went into the devising of the standards and the preparation of the methods of applying them.

So, once there are at hand scientifically devised standards with which the mental qualities of any individual may be gauged and compared, and tests have been prepared for the scientific measurement of these qualities with reference to the established standards, the application of these tests to individuals may be made by anybody sufficiently intelligent to grasp their purport and follow directions exactly. It is not necessary, in other words, even for the testing of the most complex and highly developed mental powers, that the actual application of the test be made by the scientific psychologist. It is possible, and it has been the purpose in the preparation of the tests which are presented in this book, to devise mental tests which, if applied precisely as indicated in the instructions accompanying them, will yield the same results in the hands of the wholly untrained examiner as though the actual administration of the tests had been made by the scientist who devised them.

It must not be thought that the result of any test is always 100 per cent. accurate. Even good workmen sometimes make errors in the use of the most precise scientific instruments. Even though constructed with the most painstaking care, according to the truest scientific formulas and by men of the highest technical training and skill, the mechanical instruments of precision are occasionally found to be inaccurate. If this is the case with material implements and dimensions which are finite, concrete, and tangible, how much greater is the liability to error in dealing with the intangible, infinite, and more or less abstract qualities of the human mind. The scientific psychologist is, after all, merely another human being, and as such equally liable with all other human beings to human error. Of no man or woman can it be said that he or she is infallible, and as every one who applies a psychological test is human, and so liable to error either in its application or the reading of its result, conclusions drawn from the results of any particular test should be accepted as accurate only when they have been checked by the results of other tests applied to the same subject, and substantial conformity of the results of one to those of the others has been obtained. For this reason, among others, no single test can be expected to yield definite and complete information as to any particular individual’s mental capacity or ability, whether gauged by the universal standard or by group comparison. It has, therefore, been necessary to establish, as preliminary to the preparation of the Mentimeter tests, a variety of standards, and to prepare a considerable number of tests under each of these standards, all or most of which must be used in each instance if anything approaching scientific accuracy is to be reflected in the resulting scores.

As has previously been pointed out, however, the scientific method is incomparably freer from the liability to error than any method of determining human ability and capacity that depends upon unaided personal observation. How completely this has been demonstrated in practice in a wide range of fields is set forth in subsequent chapters. To yield results of maximum accuracy, however, scientific mental tests must be used only with reference to the standards on which they are based.

Lest it has not been made clear already to the reader how the method of establishing mental standards of comparison operates, let us again briefly try to point out just what is meant by a universal standard of mental capacity.

It is a comparatively simple matter, involving merely a considerable amount of painstaking search and the expenditure of a good deal of time to find, let us say, a thousand engineers, each of whom has demonstrated in the course of his professional practice that he possesses unusual ability to project and design bridges and viaducts. Let us suppose that we wish to take the average capacity of these thousand engineers as the standard by which to measure every budding engineer in the technical schools with reference to the capacity of each to become a planner and designer of bridges and viaducts.

The scientific psychologist must first familiarize himself with the essentials of that combination of artistic, technical, and mathematical skill which makes a great engineer. This is not a simple or easy task to begin with, and to accomplish it calls for the exercise of highly trained mental powers on the part of the investigator as well as a thorough understanding of the operation of the various processes of the human mind. Then there must be devised methods by which, as simply and yet as precisely as possible, each of these thousand engineers of known capacity may be tested as to the degree in which he possesses the various abilities, the sum total of which is the measure of his capacity as an engineer. It may be necessary to make these tests over a period of years, and the tests themselves may and probably will require frequent revision and amendment as it is found in the course of their application that some of them are unnecessary and others inadequate. If it is found that any of the tests so applied is readily fulfilled by every subject examined, the effort is made to increase the difficulty of the test, until it has reached a stage where the perfect performance of all its requirements is barely within the reach of the ablest and most competent of all the engineers under examination. Indeed, some of the tests may be so difficult that none of those examined may conform precisely to the set requirements. In respect of some classes of tests this is, in fact, desirable, as what is being sought is an average of group capacity, and if any considerable percentage exhibit a capacity greater than can be measured by the tests set there arises an element of doubt as to the accuracy of the average combined score, since some of those contributing to it have obviously greater mental ability than can be measured by the particular scale used.