Animal studies of attachment

• Lorenz and Harlow conducted animal studies into attachment.
• Lorenz (1952) conducted a lab experiment in which goslings were hatched either with their mother or in an incubator. Once hatched, the goslings followed the first moving object they saw and this was Lorenz for the goslings hatched in the incubator, while the others followed their mother.
• Lorenz (1952) found that even when the 2 groups (hatched in an incubator or hatched with their mother) were mixed, the experimental group continued to follow Lorenz while the control group continued to follow their mothers.
• Lorenz (1952) concluded that the phenomenon he saw is called imprinting and he identified a critical period for this to occur, which can be as brief as a few hours after birth depending on the species. This suggests that organisms having a biological basis for an attachment is adaptive as it promotes survival.
• Lorenz also investigated the relationship between imprinting and adult mate presences. He observed that birds that imprinted on a human would often later display courtship behaviour towards humans.​
• SEXUAL IMPRINTING CASE STUDY:​

  • Lorenz (1952) described a peacock that had been reared in the reptile house of a zoo where the first moving 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 has meant he had undergone sexual imprinting.​
• Harlow (1958) investigated the importance of contact comfort. Harlow observed that newborns kept alone in a bare cage usually died but that they tended to survive if given something soft like a cloth to cuddle.​
• Harlow (1958) reared 8 rhesus monkeys with two wire model 'mothers'.

  • One made of wire that dispensed milk (the feeding mother).
  • One covered in soft cloth that did not dispense milk (the comfort mother).

  Harlow observed how much time the monkeys spent with each surrogate and their response in stressful situations (e.g. when a frightening object was introduced).
• Harlow (1958) found that the infant rhesus monkeys showed attachment behaviour towards the cloth-covered surrogate mother in preference to the wire surrogate mother. Also, the infant rhesus monkeys sought comfort from the cloth-covered surrogate mother when frightened regardless of which surrogate mother dispensed milk.
• Harlow also investigated maternally deprived monkeys as adults.

  • Harlow et al. also followed the monkeys who had been deprived of a ‘real’ mother into adulthood to see if the early maternal deprivation had a permanent effect
  • He found that monkeys reared with wire monkeys only displayed dysfunctional adult behaviour such as: being more aggressive, less sociable, difficulty mating and female monkeys neglected/attacked/killing their young.
• Harlow concluded that there was a critical period for attachment - a mother figure had to be introduced to an infant monkey within 90 days for an attachment to form. After this time, attachment was impossible and the damage done by early deprivation became irreversible.
• A weakness of Lorenz's study is that it is difficult to generalise its findings to humans. This is because the mammalian attachment system is quite different from that of birds. This is because mammalian mothers show more emotional attachment to young than birds do, and mammals may be able to form attachments at any time. This means that Lorenz's conclusions cannot be easily applied and explain why humans form attachments.
• Another weakness of Lorenz's study of attachment is that some of his conclusions have been doubted. Guiton et al provided contradictory evidence when they found that chickens imprinted on yellow washing-up gloves would try to mate with them as adults, but that with experience they eventually learned to prefer mating with other chickens. This contradictory evidence suggests that the effects of imprinting are not as permanent or irreversible as Lorenz implied, thereby challenging his conclusions about early attachment.
• One weakness of Harlow's study into attachment is its ethical issues. This is because the 16 rhesus monkeys were separated from their mother at birth, without their consent, and were instead reared with wire surrogate mothers as part of the experiment. This weakens Harlow's study as the monkeys suffered greatly and suffered long-term impacts such as dysfunctional behaviour in adulthood. Therefore, it can be argued that it is unethical to cause harm to animals in research to learn about human attachment.
• A strength of Harlow's research into attachment is that it has real-life application. For example, the findings have helped social workers understand risk factors in child neglect, like lack of contact comfort, and abuse and intervene quickly to prevent the dysfunctional adult behaviour Harlow observed in maternally deprived monkeys (Howe 1998). This strengthens Harlow's study because it has practical value and has proved useful.