Harry Harlow was a 20th century psychologist who worked with primates. He is best known for his studies on maternal separation and isolation with rhesus monkeys. 

Professional Life

Harry Harlow was born in Iowa on October 31, 1905. He received his BA and PhD in experimental psychology from Stanford University. Upon graduation, Harlow began teaching at the University of Wisconsin-Madison where he created and directed the Primate Laboratory. Harlow conducted many studies in the laboratory, and it became a top-notch research facility, helping dozens of students achieve their doctorates throughout the years.

Harlow was recognized for his work with a number of awards, including the Howard Crosby Warren Medal in 1956, the National Medal of Science in 1967, and the gold medal from the American Psychological Foundation in 1973. He served as Head of Human Resources Research Branch of Department of the Army from 1950–1952 and president of the American Psychological Association in 1958 and 1959.

Harlow married Clara Mears in 1932; they had two boys and divorced in 1946. Harlow later married child psychologist Margaret Kuenne, and the couple raised one girl and one boy. Kuenne died in 1971, and the following year, Harlow remarried Mears, to whom he remained married until his death in 1981. 

Contribution to Psychology

Harlow's experiments on primates remain controversial, and most are seen as inhumane by today's standards. He was interested in the effects of stress, isolation, and abandonment on humans, and because of their psychological similarity to human beings, primates made ideal subjects. However, this psychological similarity is also the reason that many of Harlow's experiments are viewed as inhumane.

Because Harlow wanted to observe rhesus monkeys across the life course and needed regular access to the primates, he created a breeding colony in 1932. The monkeys were raised in a nursery setting, away from their mothers, giving Harlow an opportunity to study the effects of maternal deprivation. Harlow found that primates reared without their mothers were psychologically maladapted.

Harlow also wanted to study the effects of a surrogate mother on monkeys. He created two surrogate mother options: one made of wood and wire mesh that dispensed milk and food, and another softer mother made of cloth that did not dispense food. The monkeys preferred the cloth version, even though it did not dispense food, indicating that maternal attachment is about comfort and safety rather than just food. As the monkeys grew and developed, they used the surrogate mothers as a “safe base” from which to explore the world, demonstrating the deep nature of early attachments—even if the attachment is to an inanimate object. This research continues to be used to validate theories of attachment popularized by John Bowlby.

Later in his career, Harlow studied the effects of partial and complete social isolation on monkeys. He separated monkeys from their peers and noticed immediate deleterious psychological effects. When he later reunited the monkeys with their peers, the monkeys did not display normal social behavior. Harlow also discovered that monkeys reared in isolation and by artificial surrogate mothers were socially incompetent and had fewer parental skills than those raised around peers or by real mothers, indicating a strong learning component to primate parenthood.

Harlow was often criticized for his inflammatory and anthropomorphic language. He referred, for example, to infant primates' relationships with their mothers as love, and called the isolation chamber in which isolated monkeys were kept a pit of despair. Some of Harlow's students criticized Harlow for continuing his experiments long after they had produced results.


  1. Harry Harlow, 1905-1981. (n.d.) A Science Odyssey: People and Discoveries. Retrieved from: http://www.pbs.org/wgbh/aso/databank/entries/bhharl.html.
  2. Harry F(rederick) Harlow. (2001). Contemporary Authors Online. Biography In Context. Retrieved from: http://www.gale.cengage.com/InContext/bio.htm.
  3. Baughman, Judith S. (Ed.), et al. (1998). Harry F. Harlow. American Decades. Biography In Context. Retrieved from: http://www.gale.cengage.com/InContext/bio.htm.