Part 3 (1/2)

Aside from the strictly motor and physical tests those devised were mainly of so-called intellectual character: measurements of speed and accuracy with which certain definite tasks could be accomplished. They were, moreover, very simple in character, not necessarily related to the work of daily life, with only a single or but a few trials made on each individual.

Tests of affective and volitional factors were slower in developing. Little account was taken of interests, instinctive and emotional characteristics, att.i.tudes, adaptation, methods of attack, limits of ability after practice, or many other aspects of individuality which later work has shown to be important.

The next step in the development of tests consisted in the cooperative effort to standardize the nature and methods, the conditions and mode of record. Many hands had part in this process, until in recent years, through publication, comparison and discussion of the subject, fairly uniform principles of technique, record, and treatment of measures have been agreed upon. This made possible the comparison of results secured by different investigators, and facilitated the statistical treatment of the data, so that later work might profit by what had already been tried or accomplished by earlier workers. After many years of this sort of cooperative work, another series of studies was inaugurated to attempt what has come to be known as ”testing the tests.” These studies proceeded by examining into the degree to which the various tests correlate with each other, with other indications of the individual's ability, with age, s.e.x, health, education, school standing, special training, etc. Such questions as the following will suggest the problems involved in ”testing the tests.”

1. Which of the various tests correlate with each other?

2. What correlation exists between mental and motor abilities?

3. Do the tests measure fundamental qualities or general powers of the individual, or specialized capacities, or perhaps mainly the effect of general or special training?

4. If they measure general qualities, which of the existing tests are the best for this purpose?

5. How many trials are needed to afford a reliable index of the individual's ability?

6. What are the princ.i.p.al incidental factors that influence the result of tests?

7. Which tests are most easily influenced or disturbed by extraneous factors?

8. Can tests of the simpler laboratory type be used to indicate the individual's ability as shown in his daily work and play?

9. How simple or complex should the various tests be in order to give the best results?

10. How many tests, and which, are required to give a fairly correct picture of the individual's psychological make-up?

11. To what degree do preliminary trials indicate the final capacity of an individual?

12. Does the intercorrelation of tests change in any way with practice, repet.i.tion, and familiarity with the material?

13. Just what mental functions may the particular tests be said to measure?

14. How important are these functions in practical, educational and vocational life?

15. By what amounts and in what various ways do individuals differ among themselves in such abilities as the tests measure?

16. Are there other important aspects of psychological const.i.tution and equipment for which there now exist no adequate tests?

The investigation of these numerous problems has resulted in the acc.u.mulation of a considerable literature of mental tests. Many of the earlier forms of tests were abandoned because of their unsatisfactory or meaningless character. Others have been retained and improved in form, and many new ones are constantly being devised and elaborated, described and standardized. The precautions to be observed, the instructions to be given, and the methods of record and interpretation have been presented in various books and manuals. The tests have been developed for more and more complex functions, and now relate not only to relatively simple capacities but to highly elaborate and subtle forms of achievement. As rapidly as is consistent with accuracy, norms and standards of performance for different ages, school grades, vocational requirements, etc., are being acc.u.mulated and reported. Typical charts of age norms in selected tests are given in the Appendix.

As the tests have thus developed they have been organized for a variety of special purposes, such as for school measurement, educational diagnosis, clinical examination, laboratory experiment, and more recently for the purposes of vocational guidance and selection. Among the first of these to develop systematically, and also the ones with the most immediate vocational application, are the graded intelligence scales, which shall be our next concern.

GRADED INTELLIGENCE SCALES AND NORMS

An important step in the history of general tests is represented by the acc.u.mulation of norms and standards of performance for the different selected tests, and the arrangement of scales of tests with increasing difficulty, as further aids in fixing the individual's status.

After a standardized and tested form of test has been selected, norms of performance are acc.u.mulated by applying the test to large numbers of persons of the same general type. The cla.s.sification may be on the basis of age, school grade, occupation, nationality, etc. In this way it becomes possible to determine for a given individual how he compares with other members of his group; whether he is above or below the average, and how far; whether he would belong among the best ten, or the poorest ten, or the third ten, etc., of one hundred selected at random. Such norms also reveal to what degree the tested ability varies with the other factors, on the basis of which the group was selected, as age, s.e.x, education, size, health, race, etc.

As rapidly as reliable norms are established, it becomes possible to select for each age, school grade, occupation, etc., a set of tests which the average person of that age, schooling or calling should be able to perform to a certain known degree of proficiency. Failure to accomplish this indicates performance lower than that expected and in so far as success is dependent solely on mental ability, indicates inferior capacity. Similarly, ability to do more than the average or normal record requires indicates a capacity that is precocious, rare, and superior.

In this way are derived standard graded scales which represent a decided advance in the science of psychological diagnosis. There are three rather different forms in which attempts have been made to secure such scales. In one form the scale consists of a series of steps, each step consisting of different sorts of performance; that is, different tests or tasks are used.