Robert Mearns Yerkes (1876-1956), American psychologist, played a leading role in the development of psychology in America by laying the groundwork for important new areas of both research and practice.

Robert Yerkes was born in Bucks County, Pa., on May 26, 1876. He graduated from Ursinus College in 1892. Financial problems and the offer of a fellowship in zoology at Harvard deflected him from a long-held wish to study medicine. At Harvard he shifted gradually from zoology to animal psychology and received his doctorate in 1902. He remained at Harvard to teach and do research for the next 15 years. In 1916 he was elected president of the American Psychological Association.

As chief of the Psychology Division in the Surgeon General's Office during World War I, Yerkes organized the first large-scale utilization of psychologists in a professional capacity. He developed the Army Alpha Testing Program. This mental screening device, used on 1.7 million recruits, established the value of applying psychological methods to solving human problems and was a major factor in the development of psychology as an independent profession in America. Yerkes's books that resulted from this work, Army Mental Tests (1920) and Psychological Examining in the U.S. Army (1921), were models for the further expansion of intelligence testing as a field in psychology and are still in use today.

Yerkes also devised basic methodological tools for studying learning in animals and enunciated an important law relating the effect of fear on learning. Even more important was his pioneering effort to promote research on primates and the scientific study of sex. From 1921 until 1947 Yerkes served as chairman of the National Research Council Committee for Research on Problems of Sex, which sponsored projects that led to such studies as the Kinsey Report.

Yerkes's classic studies The Great Apes: A Study of Anthropoid Life (1919), coauthored with his wife, and Chimpanzees: A Laboratory Colony (1943) established the significance of studying the almost-human primate behavior. While a professor of psychology at Yale from 1924 to 1944, Yerkes established the first experimental primate breeding colony in America at Orange Park, Fla. It was renamed the Yerkes Laboratory of Comparative Psychobiology after his death.

Although sidetracked from pursuing a medical career directly, Yerkes realized his concern with medicine in his efforts toward making psychology one of the helping professions. He viewed his scientific studies of behavior as part of a basic science fundamental to the care of human problems. He died on Feb. 3, 1956.

Further Reading

• Yerkes's autobiography appears in A History of Psychology in Autobiography, edited by Carl Murchison (1961). The most extensive review of Yerkes is Earnest R. Hilgard's "Robert Mearns Yerkes" in National Academy of Sciences Biographical Memoirs, vol. 38 (1965), which includes a complete bibliography of Yerkes's writings. See also E. G. Boring's "Robert Mearns Yerkes (1876-1956)" in the 1936 Yearbook of the American Philosophical Society, published in 1956.