Robert Mearns Yerkes (; May 26, 1876 – February 3, 1956) was an American psychologist, ethologist, eugenicist and primatologist best known for his work in intelligence testing and in the field of comparative psychology.
Yerkes was a pioneer in the study both of human and primate intelligence and of the social behavior of gorillas and chimpanzees. Along with John D. Dodson, Yerkes developed the Yerkes–Dodson law relating arousal to performance.
As time went on, Yerkes began to propagate his support for eugenics in the 1910s and 1920s. His works are largely considered biased toward outmoded racialist theories by modern academics.
He also served on the board of trustees of Science Service, now known as Society for Science & the Public, from 1921 to 1925. He was elected to the American Academy of Arts and Sciences in 1915, the United States National Academy of Sciences in 1923, and the American Philosophical Society in 1936.
Education and early career
Robert Yerkes was born in Breadysville, Pennsylvania (near Ivyland, Pennsylvania). Growing up on a farm in rural Pennsylvania, Robert Yerkes wanted to leave the hard life of the rural farmer and become a physician. With the financial help of an uncle, Yerkes attended Ursinus College from 1892 to 1897. Upon graduating he received an offer from Harvard University to do graduate work in Biology. Faced with a choice of Harvard or medical training in Philadelphia, he chose to go to Harvard.
At Harvard, Yerkes became interested in animal behavior, so much so that he put off further medical training to study comparative psychology. He earned his Ph.D. in the Psychology Department in 1902.
His early career was strongly influenced by the debts Yerkes incurred paying for school. Upon his graduation from Harvard, he took up a position with the school as an instructor and assistant professor in comparative psychology. He had to supplement his income during the summer for several years by teaching general psychology at Radcliffe College. Another part-time job he took on was being the director of psychological research at the Boston Psychopathic Hospital, Boston, Massachusetts.
In 1907, Yerkes published his first book, The Dancing Mouse. Among his friends during this time was future behaviorist John Watson, with whom he exchanged ideas and collaborated. He was also a member of the Wicht Club (1903–1911).
Intelligence testing and eugenics
In 1917, Yerkes served as president of the American Psychological Association (APA). Under his influence, 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, the first nonverbal group tests, which were given to over 1 million United States soldiers during the war.
Although Yerkes claimed that the tests measured native intelligence, and not education or training, this claim is difficult to sustain in the face of the questions themselves. Question 18 of Alpha Test 8 reads: "Velvet Joe appears in advertisements of ... (tooth powder)(dry goods)(tobacco)(soap)."
Yerkes used the results of tests such as these to argue that recent immigrants (especially those from Southern and Eastern Europe) scored considerably lower than older waves of immigration (from Northern Europe.) 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. Nonetheless, the effects of Yerkes work would have a lasting effect on American xenophobia and anti-immigrant sentiment. His work was used as one of the eugenic motivations for harsh and racist immigration restrictions.
He was appointed as an "Expert Eugenic Agent" to The House Committee on Immigration and Naturalization, where his work would contribute to the creation of the discriminatory National Origins Formula. In his introduction to Carl C. Brigham's A Study of American Intelligence (which helped popularize eugenics in the U.S.), Yerkes stated that "no one of us as a citizen can afford to ignore the menace of race deterioration."
Along with Edward L. Thorndike, Yerkes was a member and Chairman of the Committee on Inheritance of Mental Traits, part of the Eugenics Record Office, which was founded by Charles Benedict Davenport, a former teacher of Yerkes at Harvard.