In 1905-11 Binet and Simon devised a series of tests for determining the mental age of French school children. The purpose of the mental measurements was to gauge innate mental capacity. Therefore the tests excluded material which had to do with special social experience. With their introduction into the United States certain revisions and modifications, such as the Goddard Revision, the Terman Revision, the Yerkes-Bridges Point Scale, were made in the interests of standardization. The application of mental measurements to different races and social classes raised the question of the extent to which individual groups varied because of differences in social experience. While it is not possible absolutely to separate original tendencies from their expression in experience, it is practicable to devise tests which will take account of divergent social environments.
The study of volitional traits and of temperament is still in its infancy. Many recent attempts at classification of temperaments rest upon as impressionistic a basis as the popular fourfold division into sanguine, melancholic, choleric, and phlegmatic. Two of the efforts to define temperamental differences rest, however, upon first-hand study of cases. Dr. June E. Downey has devised a series of tests based upon handwriting material for measuring will traits. In her pamphlet The Will Profile she presents an analysis of twelve volitional traits: revision, perseverance, co-ordination of impulses, care for detail, motor inhibition, resistance, assurance, motor impulsion, speed of decision, flexibility, freedom from inertia, and speed of movement. From a study of several hundred cases she defined certain will patterns which apparently characterize types of individuals. In her experience she has found the rating of the subject by the will test to have a distinct value in supplementing the test for mentality.
Kraepelin, on the basis of his examination of abnormal mental states, offers a classification of types of psychopathic personalities. He distinguishes six groups: the excitable, the unstable, the psychopathic trend, the eccentric, the anti-social, and the contentious. In psychoanalysis a simpler twofold division is frequently made between the introverts, or the "introspective" and the extroverts, or the "objective" types of individual.
The study of social types is as yet an unworked field. Literature and life surround us with increasing specializations in personalities, but attempts at classification are still in the impressionistic stage. The division suggested by Thomas into the Philistine, Bohemian, and Creative types, while suggestive, is obviously too simple for an adequate description of the rich and complex variety of personalities.
This survey indicates the present status of attempts to define and measure differences in original and human nature. A knowledge of individual differences is important in every field of social control. It is significant that these tests have been devised to meet problems of policies and of administration in medicine, in industry, in education, and in penal and reformatory institutions. Job analysis, personnel administration, ungraded rooms, classes for exceptional children, vocational guidance, indicate fields made possible by the development of tests for measuring individual differences.
SELECTED BIBLIOGRAPHY
I. ORIGINAL NATURE
A. Racial Inheritance
(1) Thomson, J. Arthur. Heredity. London and New York, 1908.
(2) Washburn, Margaret F. The Animal Mind. New York, 1908.