AO1
Harlow wanted to study the mechanisms by which newborn rhesus monkeys bond with their mothers.

These infants were highly dependent on their mothers for nutrition, protection, comfort and socialisation. What, exactly, though, was the basis of this bond?

The behavioural theory of attachment would suggest that an infant would form an attachment with a carer that provides food. In contrast, Harlow's explanantion was that attachment develops as a result of the mother providing comfort, suggesting that infants have an innate need to touch and cling to something for emotional comfort.

Procedure
16 monkeys were separated from their mothers immediately after birth and placed in cages with access to two surrogate mothers, one made of wire and one covered in soft terry towelling cloth.

Eight of the monkeys could get milk from the wire mother.
Eight of the monkeys could get milk from the cloth mother.

The animals were studied for various length of time.

Results
Both groups of monkeys spent more time with the cloth mother (even if the wire mother was the one with the milk). The infants of the first group would only go to the wire mother when hungry. Once fed they would return to the cloth mother for most of the day. If a frightening object was placed in the cage the infant took refuge with the cloth mother. The infant would explore more when the cloth mother was present.
Then Harlow observed the difference in behaviour between the monkeys who had grown up with the surrogate mothers and those with normal mothers. They found that:

They were much more timid.
They didn't know how to behave with other monkeys and could be aggressive.
They had difficulty with mating.
The females were "inadequate" mothers - some even killing their offspring.

These behaviours were observed only in the monkeys who were left with the surrogate mothers for more than 90 days. For those left less than 90 days, the effects could be reversed if placed in a normal environment where they could form attachments.

Harlow concluded that "contact comfort" (provided by the cloth mt=other) was more important than food in the formation of attachment. This also shows that contact comfort is preferable to food but not sufficient for healthy development.

He also concluded that early maternal deprivation leads to emotional damage but that its impact could be reversed in monkeys if an attachment was made before the end of the critical period. However if maternal deprivation lasted until after the end of the critical period then no amount of exposure to mothers or peers could alter the emotional damage that had already occurred.

Harlow found therefore that it was social deprivation rather than maternal deprivation that the young monkeys were suffering from. When he brought some other infant monkeys up on their own, but with 20 minutes a day in a playroom with three other monkeys, he found they grew up to be quite normal emotionally and socially.

	Created by Tom Povey over 10 years ago

Harlow and Lorenz