Animal studies of attachment

• Lorenz’s research:


  Lorenz observed imprinting by randomly dividing a clutch of goose eggs in half. 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 Findings:


  The incubator group followed Lorenz everywhere and the control group followed their mother. When the two groups were mixed up the control group continued to follow the mother and the experimental group followed Lorenz.
• Imprinting= bird species that are mobile from birth attach to and follow the first moving object they see.
• Lorenz’s findings:

  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). If imprinting does not occur within that time Lorenz found that chicks did not attach themselves to a mother figure.
• Sexual imprinting:


  Lorenz also found that birds that imprinted on a human would often later display courtship behaviour towards humans.
• Sexual imprinting:


  Lorenz found a peacock that had been reared in a reptile house of a zoo where the first moving object it saw after hatching were giant tortoises would only direct courtship behaviour towards giant tortoises as an adult.
• Harlow’s research:


  Harlow used 16 baby rhesus monkeys and two artificial mothers, one made of wire and dispensed milk and one covered in cloth.
• Harlow’s findings:


  The baby monkeys cuddled the cloth-covered mother in preference to the plain-wire mother (especially when frightened) regardless of which mother dispensed milk. This showed that ‘contact comfort’ was of more importance to the monkeys than food.
• Harlow also concluded there was a critical period for attachment formation like Lorenz. 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.
• Support for the concept of imprinting:

  Study by Regolin and Vallortigara supports Lorenz’s ideas. They exposed chicks to simple shape combinations that moved. The chicks were shown a range of shape combinations that were 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.
• However, Lorenz’s ideas cannot be generalised to humans as the mammalian attachment system is quite different and more complex than that in birds. For example, in mammals attachment is a two-way process (it is not just the young who become attached, mammalian mothers also show an emotional attachment to their young).
• Harlow's research has helped social workers and psychologists understand that a lack of bonding experience may be a risk factor in child development allowing them to intervene. We also now understand the importance of attachment figures for baby monkeys in zoos and breeding programmes.
• Although rhesus monkeys are much more similar to humans than Lorenz’s birds, the human brain and human behaviour is still more complex than that of monkeys. This means it may not be appropriate to generalise Harlow’s findings to humans.
• Harlow's research:


  Harlow found that early maternal deprivation had severe consequences. The monkeys reared with 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. When they became mothers, some of them neglected their young and others attacked and even killed them.