Animal Studies of Attachment: Lorenz and Harlow

Attachment is a close, two-way emotional bond in which each individual treats the other as essential for emotional security. Studying it directly in human infants is slow and ethically limited, so early researchers turned to animals, whose attachments form quickly and can be manipulated experimentally.

Two classic studies dominate this part of the AQA specification, and you need both in detail:

Study	Animal	Key idea it demonstrated
Lorenz (1935)	Greylag geese	Imprinting during a critical period
Harlow (1958)	Rhesus monkeys	Contact comfort matters more than food

Between them, these studies challenged the older assumption that infants bond simply with whoever feeds them. Lorenz showed that a bird will attach to the first moving thing it sees rather than to a food source, and Harlow showed that a monkey will cling to a soft surrogate that gives no food at all. Both point to attachment being driven by something other than feeding.

The exam question almost always asks you to describe a study (AO1) and then evaluate it (AO3). Keep the two studies clearly separate: imprinting is Lorenz and geese; contact comfort is Harlow and monkeys.

Konrad Lorenz (1935) investigated imprinting using a clutch of greylag goose eggs, which he divided into two groups.

Procedure:

• Half the eggs were hatched with the natural mother present. This was the control group.
• Half were hatched in an incubator, where the first large moving object the goslings saw was Lorenz himself. This was the experimental group.

Findings:

• The incubator group imprinted on Lorenz and followed him everywhere. The control group followed their mother.
• When Lorenz mixed the two groups together, each gosling went straight back to its own "mother" figure: the control group to the goose, the experimental group to Lorenz.

Imprinting is the tendency to attach to and follow the first large moving object seen after hatching. Lorenz found this only happened during a critical period lasting from a few hours up to around two days after hatching. If imprinting did not occur inside this window, the goslings did not later attach at all.

Imprinting is not the same as human attachment. The gosling simply follows a moving object; there is no reciprocal emotional bond in the way there is between a human infant and caregiver.

Lorenz's most striking finding came later: imprinting did not just shape which object a bird followed as a chick, it also shaped its mating behaviour in adulthood. This is called sexual imprinting.

Birds that had imprinted on a particular type of object went on to direct their courtship behaviour towards that type of object rather than towards their own species. Lorenz described a peacock that had been raised in a reptile house, where the first moving things it saw after hatching were giant tortoises. As an adult, that peacock directed its courtship displays only at tortoises.

The general pattern of Lorenz's argument runs as follows:

Sexual imprinting shows imprinting has consequences that last into adulthood: the object imprinted on as a chick shapes who or what the adult bird tries to mate with.

Harry Harlow (1958) tested whether infant monkeys attach to whatever feeds them or to whatever gives them comfort. He reared infant rhesus monkeys with two wire "surrogate mothers".

Procedure:

• One surrogate was made of plain wire but had a feeding bottle attached, so it dispensed milk.
• The other surrogate was wrapped in soft cloth but gave no milk.

If attachment were about food, the monkeys should have preferred the wire mother. If it were about comfort, they should have preferred the cloth mother.

Findings:

Behaviour measured	Wire mother (milk)	Cloth mother (no milk)
Time spent clinging	Little	Most of the time
Where they went to feed	Here, briefly	—
Where they went when frightened	—	Ran here for comfort

The monkeys spent most of their time clinging to the cloth mother and only went to the wire mother to feed, returning to the cloth mother afterwards. When frightened by a mechanical toy, they ran to the cloth mother for security. This shows that contact comfort matters more than food for forming an attachment.

The single most important result: the monkeys attached to the mother that gave comfort, not the one that gave food. This directly contradicts the idea that infants bond with whoever feeds them.

Harlow did not stop at the surrogate preference; he followed the monkeys into adulthood, and the long-term effects were severe.

Monkeys reared with surrogate mothers alone, without contact with real monkeys, grew up socially and sexually abnormal. As adults they were:

• more aggressive and less sociable than normally-reared monkeys
• unable to mate normally or reluctant to do so
• poor and sometimes neglectful or violent parents when they did have offspring

Harlow also identified a critical period for attachment. He found that if an infant monkey formed an attachment within about 90 days, normal development was still possible. After this window, the damage caused by early deprivation was very difficult to reverse.

Aspect	Harlow's finding
What drives attachment	Contact comfort, not food
Long-term effect of neglect	Aggressive, socially and sexually abnormal adults
Critical period	About 90 days to form an attachment

Harlow's work reframed early care: infants need comfort and emotional contact, and a failure to provide this early on has lasting, hard-to-reverse consequences.

A strong answer weighs these studies rather than just describing them. Develop three or four of these points in the exam.

Generalising to humans is a problem for Lorenz. He studied birds, whose attachment system differs sharply from that of mammals. Human attachment is a two-way emotional bond, not the simple following response seen in geese, so imprinting findings may not transfer to people. Harlow's rhesus monkeys are mammals and far closer to humans, which gives his work more relevance to human attachment, though monkeys are still not human.

Harlow's research has real-world value. It transformed psychologists' understanding of the importance of early emotional care rather than mere feeding. This has influenced practices in childcare, in the design of care for orphaned or hospitalised children, and in the care of captive animals in zoos.

Harlow's study raises serious ethical issues. The monkeys suffered lasting distress and psychological harm, and many were permanently damaged. Because rhesus monkeys are similar enough to humans to suffer in comparable ways, this harm must be weighed against the theoretical and practical value of the findings.

There are confounding variables and challenges to both studies. In Harlow's study, the two surrogate heads looked different, so the monkeys' preference might partly reflect the more attractive-looking face rather than contact comfort alone. Some of Lorenz's conclusions have also been questioned: he claimed imprinting was permanent and irreversible, but Guiton found that chickens which imprinted on rubber gloves could later be encouraged to mate normally with other chickens, suggesting some imprinting can be reversed.

A balanced evaluation names both strengths (real-world value, closeness of monkeys to humans) and limitations (generalisation, ethics, confounding variables). Do not simply list criticisms.

1. Confusing imprinting with contact comfort

Imprinting is Lorenz and geese: following the first moving object during a critical period. Contact comfort is Harlow and monkeys: clinging to a soft surrogate for comfort. Swapping the researcher or the concept loses easy AO1 marks.

2. Saying Harlow's monkeys preferred the milk-giving mother

They did not. The monkeys clung to the cloth mother that gave no milk, and only visited the wire mother to feed. The whole point of the study is that comfort beat food.

3. Forgetting the critical-period detail

Both studies involve a critical period, but with different values. Lorenz found imprinting occurs within a few hours up to about two days; Harlow found monkeys needed to attach within about 90 days. Quoting the timeframe shows precise knowledge.

4. Over-generalising bird findings to humans without comment

If you use Lorenz to explain human attachment, you must add that birds differ from mammals and that human attachment is a reciprocal emotional bond, not simple following. Applying imprinting to humans uncritically is a weak point that examiners expect you to flag.

5. Only describing the studies and never evaluating

Psychology answers carry AO3 marks for evaluation. Describing Lorenz and Harlow without discussing generalisation, ethics, real-world value or confounding variables leaves those marks unclaimed.