Robert Mearns Yerkes (/ˈjɜːrkiːz/; 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. He also served on the board of trustees of Science Service, now known as Society for Science & the Public, from 1921-1925.