-Written by Katie Little ‘18
In 1958, psychologists generally believed that behavior was primarily motivated by survival related drives, such as hunger, thirst, pain, and sex. They determined that all other motives, including love, were secondary to these basic drives and therefore based upon them. From this perspective, the love between a mother and her child would be based on a learned association between the mother and nourishment through breast feeding, as well as protection from harm. However, Harry Harlow observed something rather unusual in rhesus monkeys that raised some concern about this simplistic model of mother-infant bonds and love as a whole.
Before Harlow decided to study affection, he already had experience working with baby rhesus monkeys. He separated the monkeys from their mothers shortly after their births, and he kept them in cages with a gauze pad to cover the wire floors. The psychologists noticed that the monkeys became very attached to their gauze pads, to the point of throwing tantrums when the pad was taken away to be cleaned.
From this, Harlow began to wonder what role contact comfort might play in mother-infant bonds. To conduct his experiment, he created two artificial surrogate mothers for a group of 8 baby monkeys. He created one out of a block of wood covered in terry cloth; the other model was made out of wire mesh. Both surrogate mothers were placed in front of light bulbs to radiate heat to keep the babies warm. To feed the baby monkeys, 4 monkeys were placed in a condition where the soft, terry cloth mother was fitted with a bottle to provide milk. The other 4 monkeys received milk from the wire mother; however, both groups of monkeys were placed in cages with both mothers present.
If mother-infant bonding was solely driven by biological needs, such as nourishment, we would expect the 4 baby monkeys receiving milk from the terry cloth mother to spend their time clinging to that surrogate and the 4 baby monkeys receiving milk from the wire mesh mother to primarily choose to cling to the wire mesh mother. However, Harlow’s suspicion about the importance of contact comfort seemed to be correct; both groups of baby monkeys spent the vast majority of their time clinging to the soft, terry cloth mothers, regardless of which mother provided milk.
Harlow continued his experiments in a variety of different conditions. For example, he put the terry cloth mother in a clear glass box so the monkeys could not touch her. Even without the contact, the monkeys still interacted with the mother in the box, indicating that they had developed a special bond to her that transcended even their desire for comfort.
His experiments continue to fuel attachment research today and laid the groundwork for researchers like Mary Ainsworth. (For more information, please see the blog post titled “Mary Ainsworth and the Strange Situation Procedure.”)
To watch a video of Harlow’s monkeys, please see below:
Harlow, H. F. (1958). The nature of love. American Psychologist, 13, 673-685.
H., C. [Casper H.]. (2008, April 14). Food or Security? Harlow’s study on monkeys’ attachment [Video file]. Retrieved from https://www.youtube.com/watch?v=hsA5Sec6dAI
Image found: https://openclipart.org/detail/194520/cartoon-monkey