Harlow's Monkeys: Why Comfort Beat Food

In the late 1950s, at the University of Wisconsin, infant rhesus monkeys were given a choice between two artificial "mothers." One was built of bare wire mesh and held a bottle of milk. The other was wrapped in soft terry cloth and offered nothing to eat at all.

The infants chose the cloth mother — overwhelmingly, and around the clock. That result, reported by Harry Harlow in his 1958 address "The Nature of Love", upended what mainstream psychology believed about why children love their parents. It is also a study with a real ethical cost — one that belongs in the story, not in a footnote. This article covers both: what the experiments showed, what they did to the animals involved, what they changed, and what they still say about the human need for comfort.

What Did Harlow's Monkey Experiments Actually Show?

To understand why the result landed like a bomb, you need the theory it demolished. At mid-century, the dominant view — shared, unusually, by behaviourists and psychoanalysts alike — was what critics nicknamed "cupboard love": an infant bonds to its mother because she is the source of food. Affection was treated as a by-product of feeding, and sometimes as a hazard. John B. Watson, the founder of behaviourism, had spent the 1920s warning parents in print against excessive hugging and kissing, which he argued bred weakness and dependence.

Harlow separated infant rhesus monkeys from their mothers and raised them with the two surrogates. If cupboard love were right, the infants should have bonded to whichever surrogate fed them. Instead:

• →Infants spent up to eighteen hours a day clinging to the cloth mother, visiting the wire mother only long enough to feed — even when the wire mother was the sole source of milk.
• →When frightened — Harlow used a mechanical toy that banged a drum — the infants ran to the cloth mother and calmed against her, not the one that fed them.
• →With the cloth mother present, infants would gradually leave her to explore a strange room, returning to her between forays. Without her, they froze, rocked, and cried.

Harlow called the phenomenon contact comfort: the soothing of soft, warm physical contact is not a by-product of feeding but a need in its own right — and, in these infants, a stronger driver of the bond than food itself. That last observation — the cloth mother as a base to explore from — is essentially the "secure base" idea that Mary Ainsworth would later build into the Strange Situation.

Why Were Harlow's Monkey Experiments So Controversial?

Because of what they cost the animals, and because Harlow kept going well past the point the central question was answered.

Every infant in these studies was separated from its mother at birth — that separation was the experiment. Monkeys raised with only surrogates, however soft, grew into socially damaged adults: withdrawn, unable to relate normally to other monkeys, and in some cases neglectful or dangerous as parents themselves. And Harlow escalated. His later work confined monkeys in total-isolation chambers for months — devices to which he gave deliberately brutal nicknames — producing profoundly disturbed animals, some of whom never recovered. He was openly indifferent to the emerging criticism, and the criticism came from inside the field as well as outside it: his former student John Gluck, who became a research ethicist, reckons with the laboratory's practices in Voracious Science and Vulnerable Animals (2016), and Deborah Blum's history Love at Goon Park (2002) documents the science and the suffering side by side.

Harlow's laboratory became a rallying point for the modern animal-welfare movement, and the reaction it provoked helped drive the oversight system that exists now — ethics committees, welfare standards, and in Canada the Canadian Council on Animal Care. Under today's review, these experiments would not be approved. An honest account holds both facts at once: the findings are foundational, and they were bought at a price that a field with better ethics would not have paid. Pretending otherwise — in either direction — distorts the record.

What Did Contact Comfort Change?

Almost everything about how institutions treated the parent-child bond.

John Bowlby had already argued, in his 1951 report for the World Health Organization on maternal care, that children deprived of a consistent caregiver suffered real developmental harm — but he was arguing largely from observation, against a sceptical establishment. Harlow's data gave the claim experimental teeth: here was the bond forming, measurably, around comfort rather than calories. The two men corresponded, and attachment theory — later tested in humans by Ainsworth — took much of its early legitimacy from those wire-and-cloth studies. The Association for Psychological Science has a good short account of the studies and their influence.

The practical aftershocks reached ordinary life. Hospitals, which had restricted parents' visits to sick children on hygiene grounds, moved toward keeping parents present. Childcare advice reversed course from Watson-era warnings: holding, rocking, and comforting a child stopped being framed as spoiling. And the descendants of contact comfort are still arriving — the World Health Organization now recommends "kangaroo mother care," prolonged skin-to-skin contact, as standard care for preterm and low-birth-weight babies.

Is There Hope If Early Comfort Was Missing?

One late chapter of this research gets far less attention than the wire mother, and it is the most humane thing Harlow's lab produced. Stephen Suomi and Harlow (1972, Developmental Psychology) took monkeys damaged by months of isolation and paired them with younger, gentler "therapist" monkeys — infants who clung and played without threatening. Over months of that patient contact, the isolated monkeys recovered much of their social behaviour. The damage that looked permanent turned out, under the right relational conditions, to be substantially reversible.

A caution is required here: rhesus monkeys are not people, and animal findings inform our understanding of humans rather than prove anything about them. But the direction of the finding — that what was broken in relationship showed real capacity for repair in relationship — is the same premise underneath attachment-based therapy: patterns built around absent or unreliable comfort are not treated as fixed, and the working relationship itself is part of how they are re-examined.

What Does This Mean for Adults Today?

Strip away the monkeys and the mid-century apparatus, and the finding is about something adults still get wrong about themselves: the need for comfort is not weakness, and it is not something maturity is supposed to grow out of. Harlow's infants had food, warmth, and safety in every technical sense. What they sought — what organized their whole behaviour — was contact.

Adults run the same pattern in subtler forms. Much of what looks like a fight about chores or phones or in-laws is, underneath, one person reaching for reassurance and the other not recognizing the reach — a dynamic that sits at the centre of couples counselling. People who learned early that comfort was unreliable often become adults who cannot ask for it, and then read their own loneliness as a personal defect rather than an unmet need. And chronic loneliness itself is now taken seriously as a health concern, not a character flaw.

Therapy, including virtual therapy, does not supply physical comfort — no serious therapist claims otherwise. What it works on is the relational half of the equation: noticing the reach, saying the need out loud, and building relationships where comfort is available and accepted, in both directions.

When to Reach Out

If asking for comfort feels impossible, if closeness reliably turns into conflict, or if self-sufficiency has quietly become isolation, those are workable problems — not personality verdicts. You do not need to know the theory to start the conversation.

If you are in crisis right now, call or text 9-8-8, the 9-8-8 Suicide Crisis Helpline, available across Canada at no cost, any time. In British Columbia you can also call 1-800-SUICIDE (1-800-784-2433).

A Low-Pressure First Step

TEO Counselling offers virtual sessions across British Columbia, Ontario, Alberta, Saskatchewan, Manitoba, and Newfoundland and Labrador, and a free 15 minute consultation to ask about approach, training, and fit — a conversation, not a commitment. Book a free consultation through the Jane booking platform, or call (519) 760-5211.

You don't have to carry it alone.