Robert Mearns Yerkes, PhD, (b. May 26, 1876, d. February 3, 1956) was a psychologist, ethologist and primatologist best known for his work in intelligence testing and in the field of comparative psychology. Yerkes was a pioneer in the study of both human and primate intelligence, and of the social behavior of gorillas and chimpanzees. Joining with John D. Dodson, Yerkes developed the Yerkes-Dodson law relating arousal to performance.

Education and early careerEdit

Yerkes received his bachelor's degree from Harvard University in 1898, and his PhD in psychology from Harvard in 1902. He then became an instructor and later a professor at Harvard.

Prior to World War I, Yerkes worked closely with John B. Watson to develop the theory of behaviorism. Although Yerkes never subscribed to the strict behaviorism that Watson advocated, the correspondence between the two psychologists reveals evidence of a close collaboration and sharing of ideas.

Intelligence testingEdit

In 1917, Yerkes served as president of the American Psychological Association (APA). Under his urging, the APA began several programs devoted to the war effort in World War I. As chairman of the Committee on the Psychological Examination of Recruits, he developed the Army's Alpha and Beta Intelligence Tests, given to over 1 million United States soldiers during the war. The test ultimately concluded that recent immigrants (especially those from Southern and Eastern Europe) scored considerably lower than older waves of immigration (from Northern Europe), and was used as one of the eugenic motivations for harsh immigration restriction. The results would later be criticized as very clearly only measuring acculturation, as the test scores correlated nearly exactly with the number of years spent living in the US

National Research CouncilEdit

Immediately after Word War I, Yerkes worked as a paid officer for the National Research Council (NRC) and took the helm of the NRC Committee for Research in Problems of Sex. The Committee for Research in Problems of Sex helped Yerkes establish close relationships with officers from Rockefeller philanthropic foundations, relationships that later helped him to solicit substantial funds for his chimpanzee projects.

Primatology pioneerEdit

Yerkes had a long and storied fascination with the study of chimpanzees. He had spent time observing chimpanzees in Cuba at Madame Abreu's colony in the early 1920s, and had returned from the trip determined to raise and observe chimps on his own. He began by purchasing two chimpanzees, Chim and Panzee, from a zoo. He brought the two chimps home, where they lived in a bedroom and ate with a fork at a miniature table. Chim was a particular delight for Yerkes, and the summer that chimp and psychologist spent together is memorialized in Almost Human (1924).

In 1924, Yerkes was hired as a professor of psychobiology, a field that he pioneered, at Yale University. He founded the Yale University Laboratories of Primate Biology in New Haven, followed by his Anthropoid Breeding and Experiment Station in Orange Park, Florida with funds from the Rockefeller Foundation. After Yerkes death, the lab was moved to Emory University in Atlanta, Georgia and is now called the Yerkes National Primate Research Center. The primate language Yerkish was developed there.

Preceded by:
Raymond Dodge
APA President
Succeeded by:
J.W. Baird

See alsoEdit

References & BibliographyEdit

Key textsEdit


  • Yerkes, R. M.(1907), The Dancing Mouse, A Study in Animal Behavior
  • Yerkes, R. M.(1911), Introduction to Psychology
  • Yerkes, R. M. & Watson, J.B. (1911), Methods of Studying Vision in Animals
  • Yerkes, R. M.(1914), Outline of a Study of the Self
  • Yerkes, R. M. et al (1915), A Point Scale for Measuring Mental Ability


  • Yerkes, Robert M. & Dodson, John D. (1908). The relation of strength of stimulus to rapidity of habit-formation. Journal of Comparative Neurology and Psychology, 18, 459-482. (The origin of the Yerkes-Dodson Law.)Full text
  • Yerkes, Robert M. & Morgulis, Sergius. (1909). The method of Pawlow in animal psychology. Psychological Bulletin, 6, 257-273. (The paper introducing Pavlov's work to the west.) Full text
  • Yerkes, R.M. (ed-) (1921) Psychological examining in the United States army, Memoirs of the National Academy of Science 15.
  • Yerkes, R.M. (1939) Social dominance and sexual status in the chimpanzee, Quarterly Review of biology 14: 115-36.

Additional materialEdit



External linksEdit

Further ReadingEdit

Yerkes, Robert M. (1930). Autobiography of Robert M. Yerkes. In C. Murchison (Ed.), History of psychology in autobiography (Vol. 2, pp. 381-407). Worcester, MA: Clark University Press. Fulltext

Gutenberg projectEdit

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