Harry Harlow (1905-1981)

Harry Harlow received his B.A. and Ph.D. in psychology from Stanford University and then joined the faculty at the University of Wisconsin, where he established the Psychology Primate Laboratory. When Harlow's lab joined the Wisconsin Regional Primate Laboratory in 1964, Harlow became the director of the merged research center. He is most famous for his scientific study of love. Starting in 1957, Harlow systematically manipulated the rearing conditions of baby rhesus monkeys. Some were reared with mothers, others without. Harlow provided "surrogate mothers" either of terry cloth wrapped around a sloped wooden block or of wire mesh. Nippled bottles that fed milk on schedule were attached to the upper thoracic section of the surrogates.

Harlow's findings disproved predictions by reinforcement theorists that love is a secondary or derived drive associated with the reduction of hunger/thirst. Whether they received milk exclusively from a wire mother or a cloth mother, babies clung to the cloth mother up to eighteen hours a day. Nursing seemed primarily to ensure frequent and intimate body contact of infant with mother. At 250 days, monkeys reared alone initially showed fear and disturbance when presented with a cloth mother, but gradually learned to play on her and use her for comfort when frightened. Harlow's primate findings provided early confirmation of later attachment research. When frightened or upset, securely attached human infants demand and obtain comfort from proximity to their mothers. The cloth mother served as a comfort in open field tests. Scary toys such as a wind-up, drumming teddy bear frightened the infant monkeys. They screamed and cowered while crouching immobilized. But when the cloth surrogate mother was present, the baby would climb on and clutch her, then relax enough to explore the room and toys adventurously. Total emotionality scores were cut in half when the cloth mother was present, but not when a cloth diaper was present.

Harlow demonstrated the staying power of infant monkey "love" by removing some infants from their cloth surrogates for five months. Reunion episodes revealed that deprivation had intensified the tie to the "mother." Reunited monkeys clung to the cloth mother and would not descend for exploration during three-minute test sessions.

Baby monkeys without playmates or real mothers behaved in socially incompetent ways. Six months of social isolation rendered the animals permanently inadequate socially. Infant-infant play was slower for cloth-mother-reared infants, who caught up in about a year. Sexual behaviors were abnormal for the surrogate Harry Harlow's primate studies offered important insights into issues such as human maltreatment of infants and familial love. (Harlow Primate Laboratory, University of Wisconsin) reared monkeys. If impregnated, mothers behaved quite abnormally. Infants of motherless mothers showed extremes of sexuality and aggressiveness. This primate research contributed clinical insights to issues of human maltreatment of infants.

Harlow's work won him election to the National Academy of Sciences. He received the National Medal of Science in 1967 and the Gold Medal Award of the American Psychological Association in 1973.