Another method of testing speed of thought is to pronounce a series of words and after each word have the subject speak the first word that comes to him. The answers are taken down and are timed with a stop-watch. About the quickest answers by an alert person will be made in one second, or one and one-fifth seconds, while most persons take from one and three-fifths to two and three-fifths seconds to answer, under the most favorable circumstances. Puzzling words or conflicting emotions will prolong this time to five and ten seconds in many cases. Much depends upon the kind of words propounded to the subject, starting with such simple words as "hat" and "coat," and changing to words that tend to arouse emotion. A list of words may be carefully selected to fit the requirements of different classes of subjects. [Sidenote: _Range of Mental Tests_] By appropriate tests, the quickness of response to sense-impressions, the character of the associations of ideas, the workings of the individual imagination, the nature of the emotional tendencies, the character and scope of the powers of attention and discrimination, the degree of persistence of the individual and his susceptibility to fatigue in certain forms of effort, the visual, auditory and manual skill, and even the moral character of the subject, can be more or less clearly and definitely determined. [Illustration: TESTING SHARPNESS OF HEARING WITH ACOUMETER. PRIVATE LABORATORY, SOCIETY OF APPLIED PSYCHOLOGY] It is possible by these tests to distinguish individual differences in thought processes as conditioned by age, sex, training, physical condition, and so on, to analyze the comparative mental efficiency of the worker at different periods in the day's work as affected by long hours of application, by monotony and variety of occupation and the like, and even to reveal obscure mental tendencies and to disclose motives or information that are being intentionally concealed. [Sidenote: _Tests for Army and Navy_] Among the simplest of such tests are those for vision, hearing and color discrimination. Tests of this kind are now given to all applicants for enlistment in the army, the navy and the marine corps, and more exacting tests of the same sort are given to candidates for licenses as pilots and for positions as officers of ships. [Sidenote: _Tests for Railroad Employees_] Employees of railroads, and in some cases those of street railroads, also, are subjected to tests for vision, hearing and color-discrimination. In the case of trainmen the color-discrimination tests result in the rejection of about four per cent of the applicants. The tests are repeated every two years for all the men and at intervals of six months for those suspected of defects in color discrimination. In all of these cases the tests have for their object the detection and rejection of unfit applicants. [Sidenote: _What One Factory Saved_]