Animal Studies of Attachment

Research on attachment has not been limited to human participants. Some of the most influential studies in attachment theory were conducted using animal subjects — particularly geese and rhesus monkeys. These studies have provided crucial insights into the nature of attachment, the mechanisms underlying bond formation, and the consequences of disrupted early relationships. However, they also raise significant ethical and methodological questions about generalising animal findings to humans.

Key Definition: Imprinting is a form of attachment observed in some species (especially birds) in which the young animal forms an attachment to the first moving object it encounters during a critical period shortly after birth or hatching.

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Spec Mapping

This lesson addresses the AQA 7182 Paper 1 requirement to know and evaluate animal studies of attachment, specifically the work of Lorenz and Harlow. The specification expects you to use these studies for two purposes: first, to understand mechanisms of attachment that are hard to study experimentally in humans (the critical period, the role of contact comfort, the effects of deprivation); and second, to evaluate the studies methodologically and ethically, including the central problem of generalising from non-human animals to humans. These studies also provide the empirical springboard for Bowlby's evolutionary, monotropic theory (next lessons), so the synoptic value of getting them right is high.

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Lorenz's Research on Imprinting (1935)

Konrad Lorenz (1935) conducted a classic study of imprinting using greylag geese.

• Aim: To investigate the phenomenon of imprinting — whether young precocial birds form an attachment to the first moving object they encounter, and the conditions under which this occurs.
• Procedure: Lorenz divided a large clutch of greylag goose eggs into two groups. One group was hatched naturally by the mother goose in her presence. The other group was hatched in an incubator, so that the first large moving object the goslings saw on hatching was Lorenz himself. He then marked the two groups to tell them apart, placed them together under an upturned box, and released them with both the mother goose and Lorenz present.
• Findings: The incubator group followed Lorenz everywhere and showed no recognition of their natural mother; the naturally hatched group followed the mother goose. When the groups were mixed and then released, they immediately separated — each gosling went to its respective "mother." Imprinting was rapid, did not depend on feeding, and once established could not be reversed.
• Conclusion: Imprinting is an innate, biologically prepared form of attachment that occurs during a narrow critical period and is directed at the first suitable moving stimulus, regardless of whether that stimulus provides food.

Lorenz identified several key features of imprinting:

Feature	Description
Critical period	Imprinting must occur within a restricted time window, which Lorenz suggested was within hours of hatching (very roughly the first day or so in geese). If no attachment was formed during this period, it would not occur at all.
Irreversibility	Once imprinting had occurred, Lorenz argued it could not be reversed. The goslings did not later switch their attachment to the mother goose or any other object.
Long-term / sexual imprinting	Lorenz proposed that early imprinting also influenced mate choice in adulthood (sexual imprinting). Animals that imprinted on a member of another species, or on a human, would later direct courtship towards that species rather than their own.

A Remarkable Case Study

Lorenz described the case of a peacock that had been reared in the reptile house of a zoo, where the first moving objects it saw were giant tortoises. In adulthood, this peacock directed its courtship displays exclusively towards giant tortoises, ignoring peahens. This case powerfully illustrates the lasting effects of sexual imprinting and the way the critical-period stimulus can shape behaviour for life.

graph TD
    A[Egg hatches] --> B{First moving object<br/>seen within critical period?}
    B -- Yes --> C[Imprinting occurs<br/>on that object]
    B -- No imprinting in window --> D[Attachment fails<br/>to form normally]
    C --> E[Following behaviour<br/>in infancy]
    C --> F[Sexual imprinting:<br/>mate preference in adulthood]

Exam Tip: When evaluating Lorenz's work, remember that imprinting in birds is a very different process from attachment in humans. Imprinting is rapid and tied to a brief critical period; human attachment develops gradually over months. Be cautious about drawing direct parallels.

Why Lorenz's Study Mattered

Lorenz's work did more than describe a curious behaviour in geese. It established ethology — the study of animal behaviour in natural conditions — as a serious science, and it introduced two ideas that became central to attachment theory. The first is that some attachments are innate rather than learned: the goslings did not have to be trained or fed to follow their attachment figure; the bond formed almost instantly on the basis of a built-in predisposition. The second is the critical period: the idea that a behaviour can only develop within a fixed, biologically determined window. Bowlby borrowed both ideas directly, proposing that human attachment is likewise innate and adaptive and is most readily formed within a critical (later softened to "sensitive") period. The detailed strengths and limitations of Lorenz's work are developed in the AO3 section below, where the central issues are generalisability from birds to mammals and humans, and Guiton's (1966) challenge to the claim of irreversibility.

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Harlow's Research on Rhesus Monkeys (1958)

Harry Harlow (1958) conducted a series of experiments on rhesus monkeys that fundamentally challenged the dominant learning theory (cupboard love theory) of attachment, which claimed that infants attach to whoever feeds them.

• Aim: To test whether attachment in infant monkeys is driven by the provision of food or by "contact comfort" — the comfort derived from soft physical contact.
• Procedure: Harlow reared infant rhesus monkeys with two wire surrogate "mothers." One was made of bare wire mesh; the other was wire covered in soft terry cloth. In one condition the wire mother dispensed milk through a bottle; in another condition the cloth mother dispensed the milk. Harlow measured how much time the infants spent on each surrogate and observed their behaviour when frightened and when exploring.
• Findings: Regardless of which surrogate provided milk, the infants spent the great majority of their time clinging to the soft cloth mother, going to the wire mother only to feed when she was the food source, and then returning to the cloth mother. When frightened by a mechanical, noise-making toy, the infants fled to the cloth mother for comfort; with the cloth mother present, they were more willing to explore, using her as a secure base.
• Conclusion: Contact comfort, not food, is the primary basis of attachment in infant monkeys. This directly contradicts the learning-theory claim that attachment forms because the caregiver provides food.

Observation	Result
Time spent with each mother	Regardless of which mother provided food, the infants spent most of their time on the cloth mother, visiting the wire mother only briefly to feed when she was the food source.
Response to a frightening stimulus	When a mechanical, noisy toy was introduced, the infants ran to the cloth mother for comfort (a secure base), irrespective of which mother fed them.
Exploration	Infants with access to the cloth mother explored more confidently, returning to her periodically; infants with only a wire mother explored little and appeared distressed.

Key Definition: Contact comfort is the comfort derived from physical, tactile contact with a soft, warm caregiver. Harlow's research demonstrated that contact comfort, not food, is the primary basis for attachment.

The Critical Period and Long-Term Effects

Harlow also followed his monkeys into adulthood and investigated the effects of early maternal deprivation on later social development. He found that:

• Monkeys reared with the cloth surrogate but without real social contact still grew up socially abnormal — surrogate "mothering" was not sufficient for normal development.
• The capacity to recover depended on how long deprivation lasted. There appeared to be a critical period of roughly the first few months: monkeys deprived for shorter periods and then given peer contact could recover much better than those deprived for longer.
• Monkeys deprived for around the first six months or more showed severe, often irreversible social and emotional disturbance: they were aggressive or fearful with peers, unable to mate normally, and engaged in self-directed behaviours such as rocking and self-clasping.

The exploration findings deserve emphasis because they introduced the idea of the secure base that runs through the rest of the topic. A frightened infant who can flee to a comforting figure, and an infant who will venture out to explore only when that figure is present, is using the attachment figure as a base of security — exactly the behaviour Ainsworth would later operationalise in the Strange Situation with human infants. Harlow's monkeys thus supplied an animal demonstration of secure-base behaviour and of the link between felt security and confident exploration, which is one reason the study influenced Bowlby and Ainsworth so heavily.

When the most severely deprived females were made to breed (they would not mate willingly, and were impregnated using a restraining apparatus), they became neglectful or abusive towards their own offspring — Harlow termed them "motherless mothers." This demonstrated the intergenerational transmission of disrupted early attachment, a striking parallel to Bailey et al.'s human finding (see Bowlby's theory) that mothers' own attachment histories predict their infants' attachment.

Duration of Early Isolation/Deprivation	Effect on Later Behaviour
Shorter periods (a few months)	Social difficulties that were largely recoverable with subsequent peer contact
Around 6 months or more	Severe social abnormality that was largely irreversible
Prolonged total isolation	Profound, lasting dysfunction; self-harm; inability to mate or parent ("motherless mothers")

Exam Tip: When discussing ethical issues in Harlow's study, make sure you explain why the ethical concerns matter (e.g., lasting harm, inability of animals to consent) rather than simply stating "it was unethical." Link ethical points to the cost-benefit argument: the knowledge gained versus the suffering caused.

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Comparing Lorenz and Harlow

Feature	Lorenz (1935)	Harlow (1958)
Species studied	Greylag geese (a precocial bird)	Rhesus monkeys (a primate)
Type of bond studied	Imprinting	Contact-comfort attachment
Key finding	Attachment occurs during a critical period; the first moving object becomes the attachment figure	Contact comfort, not food, is the basis of attachment
Critical period	Hours after hatching	The first few months of life
Reversibility	Claimed irreversible (challenged by Guiton, 1966)	Recoverable if brief; largely irreversible after ~6 months
Role of feeding	Irrelevant to imprinting	Irrelevant to attachment; comfort matters more
Ethical issues	Relatively minor — geese observed in semi-natural conditions	Severe — monkeys experienced lasting psychological harm
Generalisability to humans	Limited — bird imprinting is very different from mammalian attachment	Greater — rhesus monkeys are primates, but still not human

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Synoptic Links

• Bowlby's evolutionary theory of attachment: Both studies were formative for Bowlby. Lorenz's critical period directly inspired Bowlby's notion of a critical/sensitive period in human attachment, and Harlow's contact-comfort finding supported Bowlby's claim that attachment is an innate, adaptive system rather than a learned association with food.
• A-Level Biology — evolution and natural selection: Imprinting is a textbook example of an innate, genetically programmed behaviour that has been naturally selected because it keeps vulnerable young close to a protective adult, raising survival and hence reproductive success. The biology of inherited, species-typical behaviour and the concept of fitness map directly onto the evolutionary explanation of attachment.
• The learning theory of attachment vs the behaviourist approach: Harlow's monkeys are the classic refutation of the cupboard-love account derived from operant and classical conditioning. The food-providing wire mother should, on a strict learning account, have become the attachment figure; she did not. This is a powerful synoptic illustration of the limits of behaviourism.
• Research methods and the use of animals: This topic is the natural home for evaluating the scientific and ethical status of animal research — controlled laboratory experimentation (Harlow), naturalistic observation (Lorenz), the difficulty of extrapolating across species, and the cost-benefit framework and 3Rs (Replacement, Reduction, Refinement) that govern modern animal-research ethics.
• The nature-nurture debate: these studies are strongly nativist — they locate attachment in innate, evolved mechanisms (imprinting, contact comfort, critical periods). Yet Guiton's reversibility finding and Harlow's partial rehabilitations show that experience can modify even these "hard-wired" systems, illustrating that the most defensible position is interactionist. This connects directly to the way the nature-nurture debate is examined as a synoptic issue across the whole specification.

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Evaluation (AO3)

The use of animals can be scientifically justified on practical and theoretical grounds, which is the necessary counterweight to the ethical critique. Animals have shorter lifespans and faster development, allowing longitudinal effects (such as the consequences of early deprivation across a lifetime) to be observed within a feasible timeframe, and they permit experimental manipulations — deliberately controlling who rears an infant, or separating food from comfort — that could never be performed on human children. There is also an evolutionary continuity argument: because attachment is proposed to be an adaptive system shared across many species, studying it in animals can illuminate the general mechanism. None of this dissolves the ethical problem, but a top-level evaluation recognises that the case for animal research rests on these methodological advantages, and then asks whether they are sufficient to outweigh the harm — rather than treating "it used animals" as an automatic criticism.