Harry Harlow, “The Nature of Love,” 1958
In his most famous study, Harry Harlow raised rhesus monkeys in an environment with two surrogate “mothers,” (both inanimate doll-like figures). One was made of wire and provided milk, and the other was made of cloth, but provided no sustenance. Overwhelmingly, the monkeys chose to spend time with the cloth monkey, leaving it only when they needed milk.
Harlow also decided to test which “mother” they would prefer when scared, one that provides sustenance or one that provides only contact comfort. He placed a loud toy in the cage with the monkeys to frighten them. All of the monkeys ran to the cloth mother, and were calmed by its touch enough to feel confident enough to approach the toy.
Later in life, when the rhesus monkeys had grown, they were totally unable to behave normally around their peers and either ignored or abused their own children. Their immune systems were compromised and they behaved erratically, circling in their cages, self-mutilating, and staring blankly.
This study and similar ones that he conducted fundamentally changed the way nurseries and orphanages were run in America. Before the study, psychologists did not understand how important physical touch was to infants’ development and advised against touching infants too much. Psychologists now know how detrimental this can be to a child’s development and recommend skin-to-skin contact with the infant as much as possible in early development.