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Summary Article: Harlow, Harry F. (1905–1981)
from The Corsini Encyclopedia of Psychology and Behavioral Science

Harry Frederick Harlow, whose innovative studies of love and family propelled him into both fame and controversy, was born Harry F. Israel in the Iowa farm town of Fairfield. He changed his name to Harlow at the urging of his major professor at Stanford University, Lewis Terman, who told him that the Jewish sound of his name would make it difficult for him to get a job.

By the time he completed his PhD in 1930, the name change was official, and he had a solid job offer, as an assistant professor of psychology at the University of Wisconsin in Madison. He would remain at Wisconsin for more than 40 years, where he built a primate research program that continues today at both the Harlow Primate Laboratory and the Wisconsin Regional Primate Research Center.

Harlow had originally planned to continue rat studies he had begun at Stanford. But when he arrived in Madison, he learned that his department had closed down its rodent laboratory. For several years, he attempted makeshift animal experiments—a tiny rat colony in the basement of the administration building, a series of experiments with cats conducted in a spare room of a campus fraternity—but he finally settled on studying the apes and monkeys housed at Madison’s small zoo. His first doctoral student, the humanist psychology pioneer Abraham Maslow, worked with him there and focused his own dissertation on dominance strategies in nonhuman primates.

Harlow eventually persuaded the university to let him create an official primate research facility. Using student labor, his own money, and scavenged supplies, he cobbled together a facility out of an abandoned box factory near the edge of campus. He would later say that the close quarters and small number of monkeys that could be housed there led him to some of his most important discoveries.

In particular, because he was forced to use the same monkeys over and over, repeating the same tasks numerous times, he began to see that the animals were doing more than blind repetition. They showed knowledge from previous tests and applied it to the new ones. They became faster and faster at doing the tests, and quicker to correct themselves when presented with a new challenge. Harlow and his students built an elaborate device, called the Wisconsin General Test Apparatus (WGTA), to test monkeys on everything from shape sorting to pattern recognition. He published a series of papers arguing that this was evidence of cognitive ability—that, effectively, the monkeys learned to learn.

Those results, published in the early 1940s, were at first dismissed by the behavioral psychologists dominating the field. But as other researchers confirmed the results, Harlow began to gain attention as a promising researcher. He became president of the Midwest Psychological Association in 1947 and president of the APA’s Division of Experimental Psychology in 1950. By that time, though, Harlow had turned his attention to the line of research that would eventually bring him national acclaim.

In 1946, Harlow had divorced his first wife, Clara Mears, and then married a fellow faculty member from the educational psychology department, Margaret Kuenne. His second wife strongly encouraged him to explore family relationships in his monkey colony. The timing was excellent; Harlow had become disenchanted by the prevailing behaviorist models. He decided to take on a well-publicized theory that a relationship between mother and child was based mostly on biological drives, a kind of stimulus–response paradigm devoid of emotional connection.

For the first stage of the research, Harlow and his students built two surrogate mothers for comparison, one with a metal-wire body and the other with a soft cloth body, both the same size, both warmed by an electric bulb, and both equipped with a milk-bottle holder. They wanted to find out which surrogate the baby monkeys would prefer and whether what Harlow called “contact comfort” might be as powerful an effect as being fed. The studies showed that the infant monkeys clung almost constantly to the cloth mother, even when an adjacent wire mother held the milk bottle.

Harlow would go on to show that the ability to feel cuddled and comforted—or not—had a profound effect on normal development. In a series of experiments in which young monkeys were placed in a strange room with novel objects, for instance, he found that the “children” of a cloth mother were far more curious and willing to explore than those raised with only a wire substitute. The British psychiatrist John Bowlby credited Harlow’s work as some of the most important research to give credibility to his ideas about attachment theory.

Harlow was elected president of the American Psychological Association in 1958 and in a speech titled “The Nature of Love,” he urged his colleagues to abandon their resistance to the idea that such relationships were fundamental to human nature. “Psychologists, at least psychologists who write textbooks, not only show no interest in the origin and development of love and affection, but they seem determined to be unaware of its existence,” he complained.

For the rest of his career, Harlow worked to change that, focusing his research on the complexities of social relationships and continuing to use the rhesus macaques as a model in his growing laboratory. He looked at peer therapy, that is, whether friendship could help to correct social damage done by a family (the answer was yes), and he compared the social importance of mothers, fathers, siblings, and friends in shaping a developing individual. He publicly crusaded for his ideas, sided with Bowlby in emphasizing the fundamental importance of nuclear family relationships, and declared that no one grows up whole and happy “without a solid foundation of affection.” For both his work and his dedication to sharing it with the public, he was honored with the National Medal of Science in 1967.

But Harlow also took his experiments into darker areas of social behavior. He deliberately created abusive surrogate mothers (such as a cloth mother with brass spikes embedded) and studied the effects on child behavior. He also investigated the effects of extreme social isolation, at one point building an inverted pyramid-shaped device he called a “pit of despair,” in which he could isolate a young animal for weeks at a time. That work—and his tendency to describe the experiments with graphic precision—led him to become an obvious target for the emerging animal rights movement.

In 1974, Harlow, increasingly besieged by critics, decided to retire from the University of Wisconsin. His wife, Peggy, had died 2 years earlier, and he had remarried his first wife, Clara Mears, who encouraged him to choose a more peaceful life and a warmer climate. The Harlows moved to Tucson, where he took a research professor emeritus position at the University of Arizona. With the help of his wife and a former student, Stephen Bernstein, he worked on a collected volume of his research, published as The Human Model in 1979. But while in Arizona, he had been diagnosed with Parkinson’s disease, and his health steadily declined. He died December 6, 1981, at the age of 76.

Suggested Readings
  • Blum, D. (2002). Love at Goon Park: Harry Harlow and the science of affection. Boston: Perseus Books. .
  • Harlow, H. F. (1958). The nature of love. American Psychologist, 3(12).
  • Harlow, H. F., & Mears, C. (1979). The human model. New York: John Wiley & Sons. .
    University of Wisconsin–Madison
    Copyright © 2010 by John Wiley & Sons, Inc. All rights reserved.

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