Biography of Psychologist Harry Harlow

Harry Harlow was an American psychologist who is best-remembered for his series of controversial and often outrageously cruel experiments with rhesus monkeys. In order to study the effects of maternal separation and social isolation, Harlow placed infant monkeys in isolated chambers.

Some variations of the experiments involved placing the monkeys with surrogate mothers made of either wire or cloth to see which the young monkeys preferred. In other instances, the monkeys were raised in total isolation for as long as 24 months, leading to profound and lasting emotional disturbances. 

Best known for his social isolation experiments with rhesus monkeys, Harlow's research contributed a great deal to our understanding of the importance of caregiving, affection, and social relationships early in life. In one review of the most eminent psychologists of the 20th century, Harlow was ranked 26th out of 100.

Harry Harlow was born on October 31, 1905, in Fairfield, Iowa. He died on December 6, 1981, in Tucson, Arizona.

Harry Harlow (born Harry Israel) grew up in Iowa and later went on to attend Reed College in Portland, Oregon, for one year. After passing a special aptitude test, he enrolled at Stanford University where he started out as an English major. His grades were so bad that after one semester he switched to the study of psychology.

While at Stanford, Harlow studied with psychologist Lewis Terman, who had helped develop the Stanford-Binet intelligence test. In 1930, he earned his Ph.D. in psychology and later changed his last name from Israel to Harlow.

After graduating from Stanford, Harlow was offered a position at the University of Wisconsin-Madison. While at the school, he established the pioneering Primate Laboratory where he would perform his controversial social isolation experiments. Harlow's classic series of experiments were conducted between 1957 and 1963 and involved separating young rhesus monkeys from their mothers shortly after birth. The infant monkeys were instead raised by surrogate wire monkey mothers.

In one version of the experiment, one of the "mothers" was made entirely from the wire while the other was covered with a soft cloth. Harlow found that regardless of whether or not the cloth-covered mother provided food, the infant monkeys would cling to her for comfort. On the other hand, the monkeys would only select the wire mother when she provided food.

Harlow presented his results at the annual convention of the American Psychological Association in 1958 and also reported his findings in his classic article entitled "The Nature of Love" in the journal American Psychologist.

Later experiments looked at social isolation by raising rhesus monkeys either in total or partial isolation. Harlow and his students found that such isolation led to a variety of negative outcomes including severe psychological disturbances and even death.

Harlow's experiments were shocking and controversial. Most would be considered unethical by today's standards. However, his research played an important role in shaping our understanding of child development. Prevailing thought during Harlow's time suggested that paying attention to young children would "spoil" them and that affection should be limited. Harlow's work instead demonstrated the absolute importance of developing safe, secure, and supportive emotional bonds with caregivers during early childhood.

Many experts at the time also believed that feeding was the primary force between the mother-and-child bonds. Harlow's work suggested that while feedings are important, it is the physical closeness and contact that provides the comfort and security that a child needs for normal development. Harlow's work along with that of other researchers including psychologist John Bowlby and pediatrician Benjamin Spock helped spark a revolution in our approach to childcare and child-rearing.

• Harlow HF. The effect of large cortical lesions on learned behavior in monkeys. Science. 1950;112(2911):428.
• Harlow HF, Woolsey CN. Biological and Biochemical Bases of Behavior. University of Wisconsin Press; 1958.
• Harlow HF, Baysinger CM, Plubell PE. A variable-temperature surrogate mother for studying attachment in infant monkeys. Behavior Research Methods. 1973;5(3):269-272.
• Harlow HF. Lust, latency, and love: Simian secrets of successful sex. Journal of Sex Research. 1975;11(2):79-90.

• Harlow HF. The nature of love. American Psychologist. 1958;13:673-685.
• Blum D. Love at Goon Park. New York: Perseus Publishing; 2002.