Harlow’s Classic Studies Revealed the Importance of Maternal Contact

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Harry Harlow’s empirical work with primates is now considered a “classic” in behavioral science, revolutionizing our understanding of the role that social relationships play in early development. In the 1950s and 60s, psychological research in the United States was dominated by behaviorists and psychoanalysts, who supported the view that babies became attached to their mothers because they provided food. Harlow and other social and cognitive psychologists argued that this perspective overlooked the importance of comfort, companionship, and love in promoting healthy development.

Using methods of isolation and maternal deprivation, Harlow showed the impact of contact comfort on primate development. 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.

Harlow’s work showed that infants also turned to inanimate surrogate mothers for comfort when they were faced with new and scary situations. When placed in a novel environment with a surrogate mother, infant monkeys would explore the area, run back to the surrogate mother when startled, and then venture out to explore again. Without a surrogate mother, the infants were paralyzed with fear, huddled in a ball sucking their thumbs. If an alarming noise-making toy was placed in the cage, an infant with a surrogate mother present would explore and attack the toy; without a surrogate mother, the infant would cower in fear.

Together, these studies produced groundbreaking empirical evidence for the primacy of the parent-child attachment relationship and the importance of maternal touch in infant development. More than 70 years later, Harlow’s discoveries continue to inform the scientific understanding of the fundamental building blocks of human behavior.


Harlow H. F., Dodsworth R. O., & Harlow M. K. (1965). Total social isolation in monkeys. Proceedings of the National Academy of Sciences of the United States of America. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC285801/pdf/pnas00159-0105.pdf

Suomi, S. J., & Leroy, H. A. (1982). In memoriam: Harry F. Harlow (1905–1981). American Journal of Primatology, 2, 319–342. doi:10.1002/ajp.1350020402

Tavris, C. A. (2014). Teaching contentious classics. The Association for Psychological Science. Retrieved from https://www.psychologicalscience.org/observer/teaching-contentious-classics


Loved the simplicity of article but wanted to Apa cite it but didn’t see a name who wrote it

typed a partial comment and was disrupted and never got around to sending it. I tried to relocate it on my computer, but was not able. Could have been my thoughts. As a substitute teacher I see the results of giving a child a phone rather than giving a child love and all that goes with it. I see the predictions of Harry Harlow have come to pass. No absolutes, no positive examples, no investment of time, just looking for the allusive moment of quality time, that requires an investment TIME to be there for that moment in time. Any way I’m probably not the one you’re looking for.

The above summary fails to address any critique of Harlow’s legacy. Nothing about use of Harlow’s “pit of despair,” or his “rape rack” to use his own term? Nothing about beginning “his harsher isolation and depression experiments while “corrosively depressed” and “stumbling around drunk”? No concern about any possibility of sadism as “science”? No question of “how much suffering is justified by the imperatives of science”? For starters, see S. Hansen’s 11/13/2002 salon.com review of Deborah Blum’s Love at Goon Park, or the essay on Harlow in psychologist Loren Slater’s book, Opening Skinner’s Box.

Gigi, the sole reason for the experiment was not to root out sadism, it was to explain the need for attachment. Sorry about the special feelings you have for animals. It is a good point you let us see, you can now use that opportunity to show us sadism in regards to the research they made. I will search that article you point out to see what that author had to say about sadism.

I read these these experiments when they were published in the Scientific American journals.

I find he article a good review of the original work.

I worked in Harlow’s lab as as an undergraduate student in 1951/52. What I learned from this experience is the value of facts and verified statements about animal behavior. As a 20 year old kid discharged from the army, I was severely reprimanded for stating that a monkey had bit me in anger when I slapped its paw for trying to steal reasons out of lab coat. I was bitten but I invented the reason.
Our work was to flesh out the phylo-genetic scale. Along with just learning studies, with white rats as well.

And what did you discover?

Wow that’s amazing you worked in the lab, I think so just starting out in psychology and my first lesson was Harlow. It’s was very interesting learning about him, my only thought was the monkeys have to admit but that was done in those days. Thanks Sue


I agree that in this day and age, we would criticize this treatment. I have no doubt much of it still goes on, people still eat animals. That was a different time, we learn from the past so that we do not repeat it. But to be angry about the past or that someone could find the good research that was deemed from it is histrionic and a waste of positive energy.

Are you people insane? “I agree that in this day and age, we would criticize this treatment” I was raised in exactly in accord with Harlow’s experiments, denied human contact almost since birth. And you APPROVE of this?! “That was a different time, we learn from the past so that we do not repeat it.” Oh, you know so little. Look up “secure confinement” and consider what children face every day of their lives.

I agree with Harry’s theory.

I also find it sadistic or at least totally lacking in sensitivity and compassion to have torn these baby monkeys from their mothers to learn what.That they prefer warmth to a hard screen even when food is involved? It is this kind of thinking that leads to the willingness of politicians to separate families, putting children in cages so that they will be less likely to come to America for help. Truly sadistic!

I think we need like a chat forum for discussion about these issues honestly. I’d love to debate about this stuff actually and am wondering whether any means is sufficient. In regards to the actual experiment, Im not going to get my beliefs on ethical treatment mixed up and it did produce significant findings. I’m more upset about the actual findings themselves. It could also be because I see some very loose correlation between them and my life unfortunately. The published paper was definitely worth the read and I wish I didn’t.

I think the whole point is that the experiments show why politicians should NOT separate families etc.. it’s difficult to prove the effects of cruelty without being cruel. The alarming thing is how little has been learned from the sacrifice.
I know a young woman with learning difficulties, abandonment issues and probable RAD who is in care. She has created a fantasy world with cuddly toys. She is chastised for this by her ‘carers’ who confiscate them and make her feel guilty about her self. I am currently composing a letter for social services to intervene. I intend enclosing the above article.
Everyone who works in care should be made to read it!

I studied psychology as an undergrad several years ago, and of the cognitive development experiments that made it into academic text, Harlow’s was one that has always stuck in my mind. To refer to the outcomes and substantiated findings of studies such as these, without acknowledging the cruelty perpetuated in carrying them out, might be impossible. The two go hand in hand, and that’s the point. But years later, can we say the ends justified the means? Yes…and no. Studies such as this one, were done years ago, perhaps in a time with very different regulations; however, the findings are none the less very substantial. And, I personally believe could, and should, be referred to in the training of a variety of service and caregiver professions, as this last comment suggests. There is still much to be learned in Behavioral science area of study, but as a society in need of great change as a whole, we should be working to figure out how we can capitalize on the knowledge gained from past studies such as this one…as opposed to focusing solely on the conditions in which they were done in. That’s not to allow our emotions to diminish the importance of the findings, without putting them to good use in our everyday lives. The end goal being to make a positive difference in society moving forward.

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