MENTAL TESTS. In the early eighties the experimental method was developed in the study of mental life through the establishment of various psychological laboratories. Certain aspects of this work, though not originally aimed at any practical application, did attract the attention of those interested in abnormal minds, the psychiatrists, and to a lesser extent the attention of those interested in controlling the development of minds, the educators. Gradu ally there came to be developed in this way methods of investigation somewhat more direct and somewhat simpler than the typical labora tory experiment — methods aimed at probing or measuring mental capacities for diagnostic purposes — and these methods became known as "mental tests." The things tested were at first mainly sensory vacuity and sensory discrimination, like keenness of vision and ability to notice small differences of pitch; motor ability, like speed of tapping, accuracy of aiming and steadiness; memory in its varied aspects, like memory for nonsense syllables, recognition of forms and colors and capacity to commit to memory; imagination, both passive and active; and especially quickness of association, that is, the speed with which a person, on being given a word, can respond to it with another word related to the first in some prescribed manner. There were also many attempts at measuring capacity to attend, as by the various "cancellation" tests in which the examinee had to cross out, or cancel, designated materials, e.g., every a in a page of print ; and again by tests in which words, pic tures, diagrams, etc., were exposed to view for a very brief time by specially devised in struments. Much was expected, too, from the development in the laboratory of very elaborate apparatus and technique for measuring reaction time, i.e., the speed with which a person could respond by a designated movement to a given signal, e.g., by pressing a telegraph key on seeing a flash of red light — a type of work evidently closely connected with that just mentioned in the measurement of speed of asso ciation.
Now, with a few exceptions, these attempts to develop a series of mental tests from the experimental methods of the laboratory psychol ogist have been worth while, but the progress thus made in measuring special aspects of mental life has been entirely overshadowed in the mind of the lay public by developments in another direction — namely, in the determina tion by mental tests of levels of general in telligence.
About 1905 the French psythologist, Alfred Binet, reported the result of an attempt made by him in conjunction with a physician, Dr. Simon, to devise a system of tests that would serve to select children of subnormal mentality for segregation for special instruction in special classes. In 1908 and again in 1911 the same authors published improved editions of what is now generally referred to as the "Binet-Simon Scale for Intelligence Testing,* or, more briefly, as the "Binet Tests." The root idea of the Binet scale is to as semble a considerable number of relatively simple short tasks of varied character and to classify these into groups which correspond with the average or "normal' performance of children of a given age. Each "age" is repre sented by five or six tests. Thus, in the recent "Stanford Revision" of the Binet tests, pre pared by Dr. L. M. Terman of Stanford versity, an eight-year-old child is given thd5 tasks: counting backwards from 20 to 1; dray in a simple plan for finding a ball lost it field; answering certain simple inquiries III °What should you do if a playmate should you accidentally?" ; stating the similarities bf ' tween things like wood and coal ; defining vor.'_ like balloon, tiger; knowing the meaning of a least 20 of a set of prepared terms.
Others of these mental tasks, to name a few at random, are the counting of pennies, ti naming of colors, memory for digits, the inter pretation of fables, the detection of absurditie in statements, etc.