Harry Harlow’s experiments on love and affection

Rhesus monkey clings to surrogate mother.

I have  just run across this experiment in the psychology of mother love and it is fascinating. This is from Harlow’s Classic Studies Revealed the Importance of Maternal Contact. What amazes me is the criticism he endured for his supposed cruelty to animals.

Infant rhesus monkeys were taken away from their mothers and raised in a laboratory setting, with some infants placed in separate cages away from peers. In social isolation, the monkeys showed disturbed behavior, staring blankly, circling their cages, and engaging in self-mutilation. When the isolated infants were re-introduced to the group, they were unsure of how to interact — many stayed separate from the group, and some even died after refusing to eat.

Even without complete isolation, the infant monkeys raised without mothers developed social deficits, showing reclusive tendencies and clinging to their cloth diapers. Harlow was interested in the infants’ attachment to the cloth diapers, speculating that the soft material may simulate the comfort provided by a mother’s touch. Based on this observation, Harlow designed his now-famous surrogate mother experiment.

In this study, Harlow took infant monkeys from their biological mothers and gave them two inanimate surrogate mothers: one was a simple construction of wire and wood, and the second was covered in foam rubber and soft terry cloth. The infants were assigned to one of two conditions. In the first, the wire mother had a milk bottle and the cloth mother did not; in the second, the cloth mother had the food while the wire mother had none.

In both conditions, Harlow found that the infant monkeys spent significantly more time with the terry cloth mother than they did with the wire mother. When only the wire mother had food, the babies came to the wire mother to feed and immediately returned to cling to the cloth surrogate.

This is what he said in reply to his critics:

Remember, for every mistreated monkey, there are a million mistreated children. If my work will point this out, and save only one million human children then I can’t get overly concerned about ten monkeys.

At least his colleagues seemed to understand the nature and importance of his work.

In 1958, Harlow was elected president of the American Psychological Association. At the APA’s annual meeting on August 31 of that year, he delivered a seminal paper titled “The Nature of Love,” cited in Love at Goon Park (public library) — Deborah Blum’s masterful chronicle of how Harlow pioneered the science of affection.

This is the experimental result that mattered.

His most famous experiment involved giving young rhesus monkeys a choice between two different “mothers.” One was made of soft terrycloth but provided no food. The other was made of wire but provided nourishment from an attached baby bottle.

Harlow removed young monkeys from their natural mothers a few hours after birth and left them to be “raised” by these mother surrogates. The experiment demonstrated that the baby monkeys spent significantly more time with their cloth mother than with their wire mother.

In other words, the infant monkeys went to the wire mother only for food but preferred to spend their time with the soft, comforting cloth mother when they were not eating. Harlow concluded that affection was the primary force behind the need for closeness.

I suspect this is as much true for adults as it is for children.

Children at the Home Hospital for Irrecoverable Children in Sighetu Marmaţiei, Romania, in September 1992

But no sooner to I come across that, I came across this: 30 Years Ago, Romania Deprived Thousands of Babies of Human Contact. And there, in the midst of the story there was this:

Neuroscientists tended to view “attachment theory” as suggestive and thought-provoking work within the “soft science” of psychology. It largely relied on case studies or correlational evidence or animal research. In the psychologist Harry Harlow’s infamous “maternal deprivation” experiments, he caged baby rhesus monkeys alone, offering them only maternal facsimiles made of wire and wood, or foam and terry cloth.

Why use monkeys when you can use real children.

By design, 68 of the children would continue to receive “care as usual,” while the other 68 would be placed with foster families recruited and trained by BEIP. (Romania didn’t have a tradition of foster care; officials believed orphanages were safer for children.) Local kids whose parents volunteered to participate made up a third group. The BEIP study would become the first-ever randomized controlled trial to measure the impact of early institutionalization on brain and behavioral development and to examine high-quality foster care as an alternative.

And then they were assessed and then re-assessed again.

When the children were reassessed in a “strange situation” playroom at age 3.5, the portion who displayed secure attachments climbed from the baseline of 3 percent to nearly 50 percent among the foster-care kids, but to only 18 percent among those who remained institutionalized—and, again, the children moved before their second birthday did best. “Timing is critical,” the researchers wrote. Brain plasticity wasn’t “unlimited,” they warned. “Earlier is better.”

The benefits for children who’d achieved secure attachments accrued as time went on. At age 4.5, they had significantly lower rates of depression and anxiety and fewer “callous unemotional traits” (limited empathy, lack of guilt, shallow affect) than their peers still in institutions. About 40 percent of teenagers in the study who’d ever been in orphanages, in fact, were eventually diagnosed with a major psychiatric condition. Their growth was stunted, and their motor skills and language development stalled. MRI studies revealed that the brain volume of the still-institutionalized children was below that of the never institutionalized, and EEGs showed profoundly less brain activity. “If you think of the brain as a light bulb,” Charles Nelson has said, “it’s as though there was a dimmer that had reduced them from a 100-watt bulb to 30 watts.”

And then later in the article we come to this.

As early as 2003, it was evident to the BEIP scientists and their Romanian research partners that the foster-care children were making progress. Glimmering through the data was a sensitive period of 24 months during which it was crucial for a child to establish an attachment relationship with a caregiver, Zeanah says. Children taken out of orphanages before their second birthday were benefiting from being with families far more than those who stayed longer. “When you’re doing a trial and your preliminary evidence is that the intervention is effective, you have to ask, ‘Do we stop now and make the drug available to everyone?’ ” he told me. “For us, the ‘effective drug’ happened to be foster care, and we weren’t capable of creating a national foster-care system.” Instead, the researchers announced their results publicly, and the next year, the Romanian government banned the institutionalization of children under the age of 2. Since then, it has raised the minimum age to 7, and government-sponsored foster care has expanded dramatically.

But in the end, both sets of children ended up damaged. This is a passage towards the end of the article.

The neuropsychologist Ron Federici was another of the first wave of child-development experts to visit the institutions for the “unsalvageables,” and he has become one of the world’s top specialists caring for post-institutionalized children adopted into Western homes. “In the early years, everybody had starry eyes,” Federici says. “They thought loving, caring families could heal these kids. I warned them: These kids are going to push you to the breaking point. Get trained to work with special-needs children. Keep their bedrooms spare and simple. Instead of ‘I love you,’ just tell them, ‘You are safe.’ ” But most new or prospective parents couldn’t bear to hear it, and the adoption agencies that set up shop overnight in Romania weren’t in the business of delivering such dire messages. “I got a lot of hate mail,” says Federici, who is fast-talking and blunt, with a long face and a thatch of shiny black hair. “ ‘You’re cold! They need love! They’ve got to be hugged.’ ” But the former marine, once widely accused of being too pessimistic about the kids’ futures, is now considered prescient.

Federici and his wife adopted eight children from brutal institutions themselves: three from Russia and five from Romania, including a trio of brothers, ages 8, 10, and 12. The two oldest weighed 30 pounds each and were dying from untreated hemophilia and hepatitis C when he carried them out the front door of their orphanage; it took the couple two years to locate the boys’ younger brother in another institution. Since then, in his clinical practice in Northern Virginia, Federici has seen 9,000 young people, close to a third of them from Romania. Tracking his patients across the decades, he has found that 25 percent require round-the-clock care, another 55 percent have “significant” challenges that can be managed with adult-support services, and about 20 percent are able to live independently.

Harry Harlow was not just right, he was more right than he would ever know. It is common sense and indeed obvious; it is very hard to provide warmth outside a family relationship.

1 thought on “Harry Harlow’s experiments on love and affection

  1. Pingback: Harry Harlow’s experiments on love and affection - The Rabbit Hole

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