Robert Yerkes

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Robert Mearns Yerkes (born May 26, 1876 , Breadysville , Bucks County , Pennsylvania , USA ; † February 3, 1956 , New Haven , Connecticut ) was an American psychologist and zoologist and worked primarily in the field of ethology (comparative or animal psychology ).


Yerkes grew up as the first child of a farming family near Philadelphia. After studying at Ursinus College in Pennsylvania, he went to study zoology and psychology at Harvard University in 1897 , where he made his bachelor's degree in 1898. Here, through Hugo Münsterberg , he found comparative psychology, which compares animals with humans. After receiving his doctorate in 1902, he was given a teaching position in comparative psychology, and later a position as professor of psychology. From 1912 to 1917 he also worked at the Boston Psychopathic Hospital. He turned increasingly to intelligence research in humans. In 1915 he was elected to the American Academy of Arts and Sciences . After developing a multiple choice intelligence test, he was entrusted by the US Army in 1917 with developing a recruitment test. In the same year he was president of the American Psychological Association . After the war, he went to the National Research Council in Washington, DC , where he chaired the information committee. In 1923 Yerkes was elected to the National Academy of Sciences and in 1936 to the American Philosophical Society . In 1924 he was called to Yale University , where he taught until 1944. Together with John D. Dodson , Yerkes formulated the Yerkes-Dodson law in 1908 .

Intelligence research

The examination of the intelligence of animals led him to measure human intelligence . Together with GV Hamilton he developed the multiple choice method, which they introduced in 1915 in the widespread 'point scale' for measuring mental skills. When the United States entered the First World War , he convened a panel of leading psychologists in 1917, with whom he developed two group intelligence tests at the rank of colonel for the classification examinations of the US Army: the Army Alpha Test and the Army Beta Test, the latter for illiterate people and immigrants who did not speak English. Around 1.7 million recruits were examined with these tests. The tests classified the intelligence performance of the recruits according to the American school grades A to E in order to divide them with their help for the correct area of ​​work. This mass testing has been widely evaluated and has formed the basis for the widespread use of psychological tests in many areas of the United States. Despite many deficiencies in the data, which Yerkes himself saw, they also served him as eugenic arguments against certain immigrant groups. Starting in 1924, these were the basis of United States' immigration restrictions. Stephen Jay Gould deals with the eugenic and racist implications of these studies in The Mismeasure of Man .

Animal psychology

Yerkes was one of the founders of animal psychology (see also Conwy Lloyd Morgan ). He made early studies on the behavior of invertebrates. At the beginning of the 20th century he established the work with mice and rats in psychological laboratories with his experimental set-ups. When Yerkes was called to Yale as a psychology professor in 1924, he and his wife Ada Watterson Yerkes resumed research on primates. His book Almost human, published in 1925, was based on behavioral observations of two chimpanzees he had kept privately since 1923 and on a visit to the primate husbandry of Rosalía Abreu in Havana , where the world's first chimpanzee baby was born and successfully raised in 1915. He founded in 1929 the Yale University Laboratories for Primate Biology in Orange Park ( Florida ), which he headed from 1930 to 1941. In his animal research, Yerkes assumed a comprehensive approach in which the anatomical and physiological foundations were included in the investigation of their social behavior. His research soon set international standards. After his death, the laboratories were at the Emory University in Atlanta ( Georgia moved) and hot today Yerkes National Primate Research Center . His successor in laboratory management and research was the biologist and psychologist Karl Lashley (1890-1958), who worked closely with Roger Sperry (1913-1994).

With Yerkish, a language was developed that enables monkeys and humans to communicate.


  • 1907: The Dancing Mouse, A Study in Animal Behavior
  • 1908: The relation of strength of stimulus to rapidity of habit formation . Journal of Comparative Neurology and Psychology, 18, 459–482 (with JD Dodson) [1]
  • 1911a: Introduction to Psychology
  • 1911b: Methods of Studying Vision in Animals (with John B. Watson )
  • 1914: Outline of a Study of the Self
  • 1915: A Point Scale for Measuring Mental Ability (with co-authors)
  • 1916: The mental life of monkeys and apes
  • 1917a: The Binet version versus the point scale method of measuring intelligence. Journal of Applied Psychology 1, 111-122
  • 1917b: How may we discover the children who need special care. Mental Hygiene 1, 252-259
  • 1920: Army mental test (with C. Yoakum)
  • 1921: Psychological examining in the United States Army Memoirs of the National Academy of Sciences, Vol. 15 (editor)
  • 1925: Almost human. The Century Co., New York
  • 1925: Chimpanzee intelligence and its vocal expressions (with B. Learned)
  • 1927: The mind of a gorilla
  • 1929: The great apes (with Ada Watterson Yerkes) digitized
  • 1932: Yale Laboratories of Comparative Psychobiology . Baltimore: Johns Hopkins Press
  • 1941: Man power and military effectiveness: the case for human engineering. Journal of Consulting Psychology 5, 205-209
  • 1943: Chimpanzees: A laboratory colony

He was the editor of the Journal of Animal Behavior

Web links

Individual evidence

  1. ^ Member History: Robert M. Yerkes. American Philosophical Society, accessed December 12, 2018 .
  2. Donald A Dewsbury: Comparative Psychology. In: Irving B. Weiner (Ed.): Handbook of Psychology, Vol. 1 , John Wiley & Sons, Hoboken 2001, p. 71
  3. Louis Montané: A Cuban chimpanzee. In: Journal of Animal Behavior, Vol. 6, No. 4, 1916, pp. 330-333