Animal studies of attachment: Lorenz and Harlow Flashcards
(7 cards)
What is imprinting
Imprinting is when an animal such as a bird will strongly attach to the first object that they encounter. The infant animal will then follow this object.
Imprinting: Lorenz (1932)
Aim and procedure
Lorenz (1932)- Lorenz aimed to investigate the mechanisms of imprinting. Lorenz took a large clutch of goose eggs and kept them until they were about to hatch out. Half of the eggs were then placed under a goose mother, while Lorenz kept the other half in an incubator beside himself for several hours.
When the geese hatched the young birds regarded Lorenz as their mother and followed him accordingly. The other group followed the mother goose.
Lorenz found that geese follow the first moving object they see, during a 12-17 hour critical period after hatching. This process is known as imprinting, and suggests that attachment is innate and programmed genetically.
Imprinting has consequences, both for short term survival, and in the longer term forming internal templates for later relationships. Imprinting occurs without any feeding taking place. If no attachment has developed within 32 hours it’s unlikely any attachment will ever develop.
To ensure imprinting had occurred Lorenz put all the goslings together under an upturned box and allowed them to mix. When the box was removed the two groups separated to go to their respective ‘mothers’ - half to the goose, and half to Lorenz.
Imprinting does not appear to be active immediately after hatching, although there seems to be a critical period during which imprinting can occur. Hess (1958) showed that although the imprinting process could occur as early as one hour after hatching, the strongest responses occurred between 12 and 17 hours after hatching, and that after 32 hours the response was unlikely to occur at all. Lorenz and Hess believe that once imprinting has occurred it cannot be reversed, nor can a gosling imprint on anything else.
conclusion of Lorenz (1932)
Lorenz concluded that the process of imprinting is a strong biological feature of attachment in certain birds, and that imprinting occurs based on the first object rather than on other cues such as scent or sound. This would explain why goslings imprint after a matter of minutes due to their increased mobility; human babies are born immobile and therefore there is less call for them to form an attachment straight away, and so, this develops later (7-9 months). It supports the view that having a biological basis for an attachment is adaptive as it promotes survival. The longevity of the goslings’ bond with Lorenz would support the view that, on some level, early attachment experiences do predict future bonds.
Aim of Harlow (1958)
Harlow (1958)- Harlow aimed to study the mechanisms by which newborn rhesus monkeys bond with their mothers. 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.
Harlow (1958) :
Eight of the monkeys could get milk from the wire mother
Eight monkeys could get milk from the cloth mother
The animals were studied for various length of time.
Both groups of monkeys spent more time with the cloth mother (even if she had no milk). The infants of the second 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 behavior between the monkeys who had grown up with surrogate mothers and those with normal mothers.
He found that (for the surrogate mother monkeys):
They were much more timid (though monkeys with access to a cloth mother were less timid than those without, who were very distressed).
They didn’t know how to act with other monkeys.
They were easily bullied and wouldn’t stand up for themselves.
They had difficulty with mating.
The females were inadequate mothers.
These behaviors 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.
Conclusion of Harlow (1958)
Harlow concluded that “contact comfort” (provided by the cloth mother) 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 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.
This study suggests that Rhesus macaques and potentially other primates such as humans have a biological (nature) need for physical contact and will attach to whatever provides comfort rather than food, going against the behaviourist theory of attachment (see below).
Evaluation of animal studies
There are serious ethical concerns about the level of suffering that primates endures in Harlow’s experiments as he intentionally orphaned infants and subjected them to high levels of stress. Some of Harlow’s other experiments were more extreme and lead in part to a negative view of psychology as a field of research, though this also lead to changed ethical standards.
Similarly, as Lorenz’s experiment had a permanent and irreversible negative effect on the geese (for example those that imprinted to him were less able to mate with their own kind) so was very unethical.
There are problems with generalising findings on attachment from animal studies to humans infants, as geese are very different in evolutionary terms, and whilst monkeys are similar genetically to humans, there are still significant differences in both biology and cultural/social environments.
Knowledge gained form Harlow’s studies has been applied effectively to the early childcare of human infants. For example contact between mothers and babies is encouraged in the first few hours after birth to promote attachment, and social workers investigate cases of infant neglect as they understand the long term damage that can result from this. It has also been argued that the long-term benefit to millions of human infants resulting from Harlow’s research justifies the studies in terms of cost-benefit analysis.
