animal studies of attachment

animal studies

In psychology these are studies carried out on non-human animal species rather than on humans, either for ethical or practical reasons - practical because animals breed faster and researchers are interested in seeing results across more than one generation of animals.

Lorenz’s research

Imprinting

aim → to identify the relationship between infant animals and their mothers.

Procedure → Lorenz conducted an experiment in which he randomly divided a large clutch of goose eggs. Half the eggs were hatched with the mother goose in their natural environment. The other half hatched in an incubator where the first moving object they saw was Lorenz.

Findings → The incubator group followed Lorenz everywhere whereas the control group, hatched in the presence of their mother, followed her. When the two groups were mixed up the control group continued to follow the mother and the experimental group followed Lorenz.

This phenomenon is called imprinting - whereby bird species that are mobile from birth (like geese and ducks) attach to and follow the first moving object they see. Lorenz identified a critical period in which imprinting needs to take place. Depending on the species this can be as brief as a few hours after hatching (or birth). If imprinting does not occur within that time Lorenz found that chicks didn’t attach themselves to a mother figure.

Sexual imprinting

Lorenz also investigated the relationship between imprinting and adult mate preferences. He observed that birds that imprinted on a human would often later display courtship behaviour towards humans.

In a case study Lorenz (1952) described a peacock that had been reared in the reptile house of a zoo where the first moving objects the peacock saw after hatching were giant tortoises. As an adult this bird would only direct courtship behaviour towards giant tortoises. Lorenz concluded that this meant the peacock had undergone sexual imprinting.

Harlow’s research

Harlow worked with rhesus monkeys, which are much more similar to humans than Lorenz's birds.

The importance of contact comfort

Harlow observed that newborns kept alone in a bare cage often died but that they usually survived if given something soft like a cloth to cuddle.

Procedure → Harlow (1958) tested the idea that a soft object serves some of the functions of a mother. In one experiment he reared 16 baby monkeys with two wire model 'mothers'. In one condition milk was dispensed by the plain-wire mother whereas in a second condition the milk was dispensed by the cloth-covered mother.

Findings → The baby monkeys cuddled the cloth-covered mother in preference to the plain-wire mother (spent most of their time with the cloth mother, often up to 20hrs a day) and sought comfort from the cloth one when frightened (e.g. by a noisy mechanical teddy bear) regardless of which mother (cloth-covered or plain-wire) dispensed milk. This showed that 'contact comfort’ was of more importance to the monkeys than food when it came to attachment behaviour.

Maternally deprived monkeys as adults

Harlow and colleagues also followed the monkeys who had been deprived of a 'real' mother into adulthood to see if this early maternal deprivation had a permanent effect. The researchers found severe consequences. The monkeys reared with plain-wire mothers only were the most dysfunctional.

However, even those reared with a cloth-covered mother didn’t develop normal social behaviour. These deprived monkeys were more aggressive and less sociable than other monkeys and they bred less often than is typical for monkeys, being unskilled at mating. When they became mothers, some of the deprived monkeys neglected their young and others attacked their children, even killing them in some cases.

The critical period for normal development

Like Lorenz, Harlow concluded that there was a critical period for attachment formation - a mother figure had to be introduced to a young monkey within 90 days for an attachment to form. After this time attachment was impossible and the damage done by early deprivation became irreversible.

AO3 - strength of Lorenz’s research

Regolin and Vallortigara (1995) conducted a study which supports Lorenz's idea of imprinting. Chicks were exposed to simple shape combinations that moved, such as a triangle with a rectangle in front. A range of shape combinations were then moved in front of them and they followed the original most closely.

This supports the view that young animals are born with an innate mechanism to imprint on a moving object present in the critical window of development, as predicted by Lorenz.

AO3 - limitation of Lorenz’s research

The mammalian attachment system is quite different and more complex than that in birds. e.g. in mammals attachment is a two-way process, so it isn’t just the young who become attached to their mothers but also the mammalian mothers show an emotional attachment to their young.

This means that it is probably not appropriate to generalise Lorenz's ideas to humans.

AO3 - strength of Harlow’s research

important real-world applications.

e.g. it has helped social workers and clinical psychologists understand that a lack of bonding experience may be a risk factor in child development allowing them to intervene to prevent poor outcomes (Howe 1998). We also now understand the importance of attachment figures for baby monkeys in zoos and breeding programmes in the wild.

This means that the value of Harlow's research is not just theoretical but also practical.

AO3 - limitation of Harlow’s research: psychological harm on the monkeys

animal studies are practical in many ways. not many demand characteristics, investigator effects, etc. also, animals breed very quickly. over a short period of time a researcher can have many generations of animals. so, they can track development and how behaviour changes over time.

but, the monkeys suffered greatly in terms of emotional separation from their biological mother at such an early age due to the procedure Harlow used. if the primates are considered to be sufficiently human-like to generalise the results beyond the sample used then the effects of psychological harms that they’ll have endured are similar to that of a human baby.

cost-benefit analysis → his findings and conclusions have important theoretical and practical applications.