Cattell did more than any psychologist of his time to advance the cause of experimental psychology in this country. He learned his basic techniques at the University of Leipzig, where he worked for years, first as a student and later as assistant in the celebrated laboratory of Wilhelm Wundt. He also worked with Francis Galton in England and was deeply influenced by his studies of individual differences. At the age of twenty-eight he was appointed professor of psychology at the University of Pennsylvania, this country’s first chair in psychology as a distinct discipline. He held this post from 1888 to 1891, then transferred to Columbia University until 1917, when he was dismissed by President Nicholas Murray Butler for taking a pacifist stand during the war.Cattell was extremely active and influential not only in psychology but in science as a whole. He founded and became the first president of the Psychological Corporation, an organization which provides psychological services to education and industry. He served as editor of a number of scientific publications, including Science, Scientific Monthly, Psychological Review, Popular Science Monthly, American Men of Science, and American Naturalists. He occupied a position of leadership in many professional organizations, serving as president of the American Psychological Association, the International Congress of Psychology at Yale in 1929, and the American Association for the Advancement of Science.Cattell did much to shape the early character of American psychology, not only through his many articles and papers, but through his pupils as well. It is said that more students came into contact with him than with any psychologist of the time, and an impressive number of them became distinguished contributors to the field—among them Thorndike, Woodworth, Franz, Hollingsworth, Strong, Dashiell, and Gates.Practically all of Cattell’s major contributions stem from laboratory experiments involving measurement and control. Since most of them have been incorporated in the main body of modern psychology and are therefore represented in many of the topics of this book, they will be mentioned only briefly at this point. His studies of reaction time, begun at Leipzig, covered practically every phase of this subject including the effects of concentrating on the stimulus and on the response, and its use in investigating discrimination and the average speed of reaction to different stimuli, such as sound, light, touch, and electric shock. He made tachistoscopic measurements of the perception of colors, forms, letters, sentences, and objects, and showed that groups of words could be recognized in a fraction of a second if they formed a meaningful unit. These experiments, plus his work on the legibility of different letters and different type faces, contributed greatly to our knowledge of the dynamics of reading.Cattell advanced the understanding of association by showing that free associations are generally slower than controlled associations (for instance, naming the state in which a given city is found), and he constructed the first tables showing frequency of response to various stimulus words. In the field of psychophysics he devised a formula for errors in observation that proved more accurate than Weber’s Law. He invented the “order of merit” rating system and applied it to the study of eminent men of science, showing that personal attitudes that appear to be hard to measure in the laboratory can actually be handled quantitatively.Finally, Cattell devised the first battery of psychological tests ever given to a large population. It included such items as rate of tapping, strength of grip, memory span for letters, reaction time to sound, free and controlled association. He began administering these tests to Columbia University students and others as early as 1894. Even though Cattell described the series as “mental tests,” they could not be said to measure intelligence since, as Binet pointed out, complex intellectual processes can only be measured by complex tasks. However, they were the first valid tests made of specific abilities, and added considerably to our knowledge of the range and variability of human capacity. Through these tests and his experimental measurements of behavior, Cattell probably did more than any other psychologist with the exception of Galton to make individual differences an important field of scientific inquiry. See GALTON, INTELLIGENCE TESTS.