The Columbia tests may be thought of as representative of several similar projects developed in this country and in Germany, France and England by many workers. The names of Galton, Cattell, Kraepelin, Binet, Henri, and Jastrow stand out conspicuously in the early history of mental tests. The first step was thus the invention, description and trial of a great number of miscellaneous tests, with little analysis of the tests themselves, the nature of the functions tested by them, or their relation to each other. 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, attitudes, 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 coöperative 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 coöperative 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, sex, health, education, school standing, special training, etc. Such questions as the following will suggest the problems involved in "testing the tests."