PREFACE THE publishers offer this book primarily as a popular treatise on the measurement of intelligence by scientific methods. Every effort has been made to conform to the soundest scienti fic principles, both in the preparation of the Mentimeter tests, around which the volume is largely written, and in the intro ductory and explanatory chapters, in which the principles of applied psychology, as they bear upon mental tests, are stated in popular language. The Mentimeters are based upon Doctor Trabues experience 1 as Assistant in Educational Psychology at Teachers College, Columbia University, as psychological investigator of the intellectual status of inmates of charitable institutions and of pupils in the public schools, 3 as author of various intellectual and educational scales, widely used by psychologists and educators, 4 as Chief Psychological Examiner in two of the largest Army camps, directing the intellectual examination of more than a hundred thousand soldiers, 5 as Captain in the Adjutant Generals Department, U. S. Army, measuring the intellectual abilities of men in the Aviation Service, and 6 as Assistant Professor in Columbia University, giving instruc tion in the theory and practice of intellectual measurements nd directing the application of such measurements to tens of thousands of school pupils. Frank Parker Stockbridge, Doctor Trabues collaborator, is an author and journalist of a high order. As managing editor of Popular Mechanics and contributor to the Worlds Work, Harper s y Popular Science Monthly, etc., he has been thrown into contact with important affairs in the world of science so that he is especially equipped to work with Doctor Trabue in presenting this interesting subject. As director of the publicity campaign of the American Library Association War Fund his contact with the Army and the results of the biggest experiment in the way of psychological tests that the world has ever seen was invaluable to him in this work. The publishers feel that the collaboration is a particularly happy one. The success of the scientific method of testing intelligence among both officers and men in the Army has directed wide spread attention to the general subject. The Mentimeter is the first comprehensive system of tests, applicable to the whole range of educational and industrial requirements, to be offered for general use. To employers and those in charge of the selection, grading, and promotion of workers of every class, in factories, offices, and stores to teachers of all grades, from kindergarten to university to parents who are interested in ascertaining, and watching the growth of their childrens mental development and to young men and young women striving for self - improvement and ad vancement and desirous of learning something of their own mental capacities and limitations as a guide to the intelligent choice of vocations or professions, the publishers offer this book in the confident belief that it will be found of real service. CONTENTS CHAPTER PAGE I SCIENCE VERSUS GUESSWORK S II THE APPLICATIONS OF PSYCHOLOGICAL, TESTS . . 16 III WHAT THESE TESTS MEASURE 23 IV STANDARDS FOR MENTAL TESTS 33 V DIFFERENT TYPES OF MENTAL TESTS .... 44 VI MENTAL TESTS IN THE ARMY 53 VII PSYCHOLOGICAL TESTS IN EDUCATION .... 63 VIII MENTAL TESTS IN INDUSTRY 76 IX How TO USE THE MENTIMETER TESTS 88 X THE MENTIMETER TESTS 109 XI TRADE TESTS OR TESTS OF SKILL ..... 274 APPENDICES MEASURE YOUR MIND CHAPTER I SCIENCE VERSUS GUESSWORK THERE are two ways, and only two, in which we can find out what a machine is capable of doing... --This text refers to the Paperback edition.