Harry Harlow

Harry Harlow (October 31, 1905 – December 6, 1981) was an American psychologist whose work with rhesus monkeys revealed how crucial caregiving and companionship are for social and cognitive growth. His most famous experiments involved separating infant monkeys from their mothers and offering them surrogate "mothers" made of wire or cloth. Even when the wire mother held a bottle of food, the infants overwhelmingly preferred the cloth-covered mother, only visiting the wire one to eat. Later, he raised monkeys in isolation for up to a year, and they emerged deeply disturbed. These studies sparked ethical controversy and are sometimes credited with fueling the animal liberation movement in the United States. A 2002 survey ranked Harlow as the 26th most cited psychologist of the 20th century. He did most of his research at the University of Wisconsin–Madison, where Abraham Maslow briefly worked alongside him.

Harlow was born in Fairfield, Iowa, to Mabel Rock and Alonzo Harlow Israel, the third of four boys. In an unfinished autobiography, he recalled his mother as cold and noted he struggled with depression throughout his life. After a year at Reed College, he took a special aptitude test and gained admission to Stanford University. He started as an English major with poor grades but switched to psychology. At Stanford in 1924, he became a graduate student under Calvin Perry Stone and Walter Richard Miles, both supervised by Lewis Terman, the creator of the Stanford-Binet IQ test. Terman strongly influenced him. After earning his PhD in 1930, Harlow changed his surname from Israel at Terman’s urging, to avoid anti-Semitic bias despite not being Jewish.

He immediately took a professorship at the University of Wisconsin–Madison. When the psychology department would not give him lab space, he found an empty building nearby and, with graduate students, turned it into the Primate Laboratory, one of the first of its kind. About 40 students earned their PhDs there under his direction. He also served as head of the Army’s Human Resources Research branch, led the Division of Anthropology and Psychology of the National Research Council, consulted for the Army Scientific Advisory Panel, and was president of the American Psychological Association. His honors include election to the National Academy of Sciences, the American Philosophical Society, and the American Academy of Arts and Sciences, as well as the Howard Crosby Warren Medal, the National Medal of Science, and the Gold Medal from the American Psychological Foundation.

Harlow married his first wife, Clara Mears, in 1932. She had been one of Terman’s high-IQ students and later Harlow’s student before they became involved. They had two sons, Robert and Richard, and divorced in 1946. That same year he married child psychologist Margaret Kuenne, with whom he had two children, Pamela and Jonathan. Margaret died of cancer in 1971, and Harlow sank into depression, treated with electro-convulsive therapy. In 1972, he remarried Clara Mears. They lived in Tucson, Arizona, until his death in 1981. He was buried beside Margaret at Forest Hill Cemetery in Madison.

At Wisconsin, Harlow began studying nonhuman primates at the Henry Vilas Zoo, where he built the Wisconsin General Test Apparatus to examine learning, cognition, and memory. He noticed that monkeys developed strategies for his tests, a phenomenon he called "learning to learn" or "learning sets." This work bridged the Hull-Spence theory of trial-and-error learning and the Gestalt theory of sudden insight, showing the two were not in conflict.