Animal studies Flashcards
Lorenz’s research (1952) - imprinting
-First observed the phenomenon of imprinting when he was a child and a neighbour gave him a newly hatched duckling that then followed him around
Lorenz’s research (1952) - procedure
- As an adult researcher Lorenz set up a classic 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
Lorenz’s research (1952) - findings
- The incubator group followed Lorenz everywhere
-But the control group, hatched in the presence of their mother, followed her
-Two group were mixed up - the control group continued to follow the mother and the experimental group followed Lorenz - Called imprinting- 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 - chicks did not attach themselves to a mother figure
Lorenzs (1952) - sexual imprinting
-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 has been reared in the reptile 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
Research support for Lorenz
- A study of Regolin & Vallortigara (1995) supported imprinting
- Chicks were exposed to simple shape combination that moved - a triangle with a rectangle in front of the chicks but they followed the original shape most closely
-This supports the view that young animals are born with an innate mechanism to imprint on a moving object present in a critical window of development (predicted by Lorenz)
Limitation to Lorenz
- The attachment in mammals is very different and more complex than that of birds
- Mammals attachment is a two-way process with both the mother and young showing attachment
-Therefore it is probably not appropriate to generalise Lorenz’s study to humans
Limitation of Lorenz 2 - imprinting as permanent has been questioned
- Guiton et al (1966) - found that chickens imprinted on yellow washing up gloves would later try to mate with them as Lorenz predicted
- However, with experience they eventually learned to prefer mating with other chickens
Now it is understood that imprinting is a ‘more plastic and forgiving mechanism’ - Hoffman (1996)
Harlow (1958) - importance of contact comfort
- Harlow observed that new-borns kept alone in a bare cage often died but that they usually survived if given something soft like a cloth to cuddle
Harlow (1958) - procedure
- 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
Harlow (1958) - findings
- The baby monkeys cuddled the cloth-covered mother in preference to the plain-wire mother and sought comfort from the cloth one when frightened (eg. 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
Harlow (1958) - 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 monkeys reared with the plain-wire mothers only were the most dysfunctional
- However, even those reared with a cloth-covered mother did not 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
Harlow - critical period of normal development
- 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
Evaluation - strength of real world applications
- His work had theoretical value because it refuted ‘cupboard love theory’ that attachment develops as a result of feeding
- Helped social workers and clinical psychologists understand that a lack of bonding experience is a risk factors in child development allowing them to intervene to prevent poor outcomes (Howe, 1998)
-We also now understand the importance at attachment figures for baby animals in zoos and breeding programmes in the wild
Limitation to Harlow - generalisability to humans
- Can we generalise the findings of the Rhesus monkey’s to humans?
- Monkey’s are more human like than birds and all mammals share some common attachment behaviours
- However, the human brain and human behaviour is still more complex than monkeys
Therefore, it may not be appropriate to generalise Harlow’s findings to humans
Harlow - ethical positives
-Understanding effects of attachment
-Disproved the ‘cupboard love’ theory
-Demonstrated the importance of quality of early experiences
-Research such as Harlow’s has helped social workers understand risk factors
In child neglect and abuse and so to intervene to prevent it
-Also important in changing policies - regarding animals in captivity -recognition of cruelty
