1876-1956

American psychologist who is regarded as one of the founders of comparative animal psychology. Yerkes was interested in the great apes as well as psychological testing and the measurement of human mental ability. During World War I, Yerkes directed the first mass-scale testing program, which administered psychological tests to almost two million men. The Yale Laboratories of Primate Biology (later, the Yerkes Laboratories of Primate Biology) became a major center for the study of primate behavior.