Another application of mental tests has a very direct interest for vocational psychology. This is the method of the "psychograph," as it is commonly called. The French and German psychologists especially have been active in advocating the practice of submitting to careful and detailed experimental examination the physical and mental characteristics of men who have achieved marked success in their chosen vocations. By the application of this clinical method to men of superior attainment it is hoped that light may be thrown on the psychological foundations of their genius and, in general, on the relation between mental traits, as shown in the results of psychological tests, and actual success in life's work. This psychographic method represents the earliest methodical attempt to differentiate the various vocations from one another on the basis of special aptitudes and characteristics, as distinguished from the factor of general intelligence. Dr. E. Toulouse has already published reports of such examinations or psychographs in the cases of Zola, Dalou, and Henri Poincaré. It is the intention of this investigator to continue this line of work, utilizing from time to time such refinements of technique as may be available. As an illustration of the psychographic method, an account of the study of the eminent mathematician, Poincaré, may be given in some detail.
The investigation of Poincaré took account of such special topics as heredity, development, physical condition, sensory acuity, various kinds of memory, attention, imagery, reaction time, association of ideas, language and handwriting, character, habits and opinions. Although the tests followed a technique which the investigator recognized to have been quite imperfect and fragmentary, they are said to have yielded results quite sufficient to characterize the intellectual type of the man. The account of the tests is followed by a synthesis in which is attempted a general picture of Poincaré's type and an interpretation of the conditions of invention and speculative genius.
From the point of view of heredity, development and general vital characteristics Poincaré was found to resemble most his mother and grandmother, who, with collateral relatives, are said to have shown special aptitude in mathematical calculation. Several male members of the family have had successful careers in neurology, law, meteorology, politics and mathematics. Poincaré's development was not precocious, although he was bright and showed, when quite young, mathematical ability of an unusual order. His history, up the age of thirty years, at which time he was elected to the Academy of Sciences, was not unlike that of many other mathematicians whose freedom from the necessity of experiment allows them to make rapid progress. He was at one time troubled with rheumatism, and in his childhood suffered from an attack of diphtheria, followed by paralysis. This attack is said to have profoundly modified his nervous system, perhaps providing the neuropathic basis for traits shown later in life, such as awkwardness, restlessness, flighty attention, distractibility and general sensori-motor deficiency.