Animal studies in attachment

• A01 - Lorenz

  Imprinting 

  • An innate readiness to develop a strong bond with the mother which takes place during a specific time in development.
  • Probably during the first few hours after birth/hatching.
  • If it doesn’t happen at this time it’ll probably not happen.
• Lorenz - procedure

  • Lorenz randomly divided a 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 - findings

  • The incubator group followed Lorenz everywhere
  • The control group who 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
• Lorenz - findings

  • Lorenz noted that this process of imprinting is restricted to a very definite period of the young animal’s life – called a CRITICAL PERIOD (e.g. a few hours after hatching).
  • If a young animal is not exposed to a moving object during this early critical period the animal will not imprint.
• Long lasting effects

  Lorenz noted several features of imprinting:

  • The process is irreversible and long lasting.
  • Early imprinting has an effect on later mate preference, called sexual imprinting.
  • Animals (especially birds) will choose to mate with the same kind of object upon which they were imprinted.
  • In a case study, the first moving objects a peacock saw after hatching were giant tortoises. As an adult, the peacock was only interested in giant tortoises. This meant it had undergone sexual imprinting.
• AO1 - Harlow

  Harlow (1959) carried out the most important animal research on attachment. He wanted to demonstrate that mother love (attachment) was not based on the feeding bond between mother and infant (as predicted by the learning theory). Harlow worked with monkeys – much more similar to humans than Lorenz’s birds.
• Harlow procedure

  • Harlow created two wire ‘mothers’ -“ one wire mother was wrapped in soft cloth, the other was just wire.
  • 8 monkeys were studied for 165 days.
  • For 4 monkeys, a milk bottle was on the cloth-covered mother
  • For the other 4 monkeys, the milk bottle was on the wire mother.
  • The amount of time each infant spent with the two mothers was measured.
  • Observations were also made of the monkey infants’ responses when frightened, e.g. by a mechanical teddy bear.
• Harlow findings

  • All 8 monkeys spent most of their time with the cloth-covered mother whether or not it had the feeding bottle.
  • Those feeding from the wired mother only spent a short amount of time there.
  • The baby monkeys cuddled the soft cloth mother in preference to the wire one and sought comfort from the cloth one when frightened.
• Harlow conclusions

  • These findings suggest that infants do not develop an attachment to the person who feeds them but to the person offering contact comfort. 
• Long lasting effects

  • Harlow continued to study his monkeys as they grew up
  • The motherless monkeys, even those who had contact comfort, developed abnormally
  • Socially abnormal and sexually abnormal
  • There was a critical period for these effects 
  • If the motherless monkeys spent time with their monkey ‘peers’ they seemed to recover - “ but only if this happened before they were 3 months old.
  • Having more than 6 months with only a wire mother was something they did not appear able to recover from
• Lorenz AO3

  Research Support for Imprinting

  • One strength of Lorenz’s research comes from later research support
  • Guiton (1966) found that when chicks were exposed to yellow rubber gloves for feeding them during their first few weeks, they became imprinted on the gloves.
  • Young animals aren’t born with predisposition to imprint on specific object - “ imprint on any moving object during critical period.
  • Male chickens later tried to mate with the gloves
  • These findings supports the findings of Lorenz, suggesting that attachment behaviours such as imprinting are innate
• Lorenz AO3

  Criticism of Imprinting

  Criticism of Lorenz's Imprinting Research

  • Lorenz's original concept of imprinting suggests irreversible imprinting on the nervous system.

  • Hoffman (1996) argues imprinting is a 'plastic and forgiving' mechanism.

  • Guiton (1966) found imprinting could be reversed in chickens, suggesting imprinting may not be different from other learning methods.
• Harlow A03

  Confounding variable

  Harlow's Research Criticism

  • Lack of control over two'mothers'.

  • Different head types for each wired mother.

  • Possible independent variables: type of head and cloth coverage.

  • Monkeys may prefer cloth-covered mother due to attractive head.

  • Study lacks internal validity.

  • Doesn't measure attachment development to caregivers or comforters.
• Harlow AO3

  • limitation - Generalization issue: Human behavior differs significantly from animals.

  • Harlow's research supports Schaffer and Emerson's findings: Infants aren't most attached to caregivers.

  • Conclusions should be treated cautiously unless replicated in humans.
• Harlow A03

  Ethics 

  • A final consideration of animal research is the ethical implications of experimenting on animals
  • Harlow’s study created lasting emotional harm as the infant monkeys later found it difficult to form relationships with their peers
  • However, some psychologists argue that animal research can be justified in terms of the effect it has on our knowledge of attachment 
  • For example, Harlow’s research has been used to offer better care for human infants
  • This suggests that the benefits of animal research into attachment may outweigh costs