Lesson 10 Animal Studies Flashcards
Harlow (1959) procedure
Harlow created two wire ‘mothers’. One wire mother was wrapped in a soft cloth. Eight infant rhesus monkeys were separated from their mother at birth and were studied for a period of 165 days. They were placed in a cage with the two wire mothers. Four of the monkeys received milk from the cloth mother, the other four received milk from the exposed wire mother. During the 165 days, the time that the monkeys spent with each of the two mothers was measured. Observations were made of the monkey’s responses to being frightened by a mechanical teddy bear and how they coped with exploring a new room full of unfamiliar toys
Harlow (1959) findings
All eight monkeys spent most of their time on the soft cloth mother, regardless of whether this mother was the one with the feeding bottle or not. Those monkeys who were fed by the exposed wire mother only stayed on it long enough to get milk and then returned to the soft cloth mother. When frightened by a mechanical teddy bear all monkeys clung to the soft cloth mother, and when playing with new objects the monkeys kept one foot on the soft cloth mother. When placed in a new environment they were not confident enough to explore the room unless the soft cloth mother was with them.
Harlow (1959) Long term effects
Harlow (1959) continued to study the eight monkeys as they grew up. The monkeys developed abnormally, they froze or fled when approached by other monkeys. They did not show normal mating behaviour and did not cradle their own babies. If the monkeys spent time with other monkeys then they could recover but only if this happened before they were three months old. Having more than three months with only a wire mother was something they could not recover from.
Advantages of Harlow (1959)
+ This study has implications for theories for attachment. Harlow’s suggestion that comfort/sensitive responsiveness is more important than food contradicts learning theory.
+ This study highlights the implications of early neglect and the long-term consequences of poor attachment in childhood for future relationships. This fits with Bowlby’s maternal deprivation theory. However, in humans this may be more of a sensitive period as studies have demonstrated how children have been able to recover from early deprivation (e.g. Romanian orphan studies).
+ Schaffer and Emerson (1964) also found that food is not necessary for attachment to form. They discovered that babies are often attached to people who play with them, rather than people who feed them. In 39% of cases even though the mother was the one who fed the baby the baby was more attached to someone else.
Disadvantages of Harlow (1959)
- This study could be considered to be unethical. The monkeys were removed from their mothers, which would have been very traumatic, and they were then deliberately scared to see how they would react. This led to long-term emotional harm, when these monkeys were older and encountered other monkeys they either froze or fled. They also had difficulty caring for their own young (did not cradle them) as they had not been cared for themselves.
Lorenz (1939) procedure
Konrad Lorenz was an ethologist (they study animal behaviour in their natural environment). He wanted to investigate imprinting (the instinct in several species of animals to attach to the first moving thing they see after they are born). Lorenz (1935) took a clutch of Gosling (Goose) eggs and divided them into two groups. One group was left to hatch with their natural mother present, while the other eggs were placed in an incubator. When the eggs in the incubator hatched the first moving thing they saw was Lorenz. Lorenz marked the two groups to distinguish between them and placed them all together again.
Lorenz (1939) findings
The Goslings quickly divided themselves up, one group following their natural mother and the other (the ones from the incubator) following Lorenz. The Goslings that had been in the incubator showed no recognition of their natural mother. Lorenz found that that this process of imprinting is restricted to a very definite period of a young animal’s life, called a critical period. If a young animal is not exposed to a moving object during this early critical period then the animal will not imprint. Animals imprint on consistently moving objects during their first two days. Imprinting is similar to attachment in that it binds an animal to a caregiver in a special relationship. Lorenz (1935) had to teach the goslings how to swim and they would always return to him when he called.
Lorenz (1939) long term effects
Lorenz (1935) noted several features of imprinting, for example the process is irreversible and long lasting. One of the Geese that imprinted on him, called Martina, used to sleep on his bed every night. Lorenz (1935) also discovered that this early imprinting had an effect on later mate preferences, called sexual imprinting. Animals (especially birds) will choose to mate with the same kind of object upon which they were imprinted.
Advantages of Lorenz (1935)
+ Imprinting is similar to the idea of a critical period in Bowlby’s maternal deprivation theory. In both cases there is a ‘window of opportunity’ in which attachments must be formed otherwise there will be negative long-term consequences.
+ Other studies support the idea that animals are born with an instinct to attach to the first moving object they see. Gutton (1966) demonstrated that chickens exposed to yellow rubber gloves during feeding in their first few weeks of life imprinted on the gloves.
Disadvantages of Lorenz (1935)
- Imprinting is more reversible than Lorenz thought. Gutton (1966) found that he could reverse the imprinting in chickens that had initially tried to mate with the yellow rubber gloves. After spending time with their own species they were able to engage in normal sexual behaviour with other chickens.
- It is problematic to extrapolate the findings from animal studies to attachment in human infants. What applies to a non-human species does not necessarily apply to human infants. Humans are physiologically very different from monkeys/geese as well as having several other influences that monkeys/geese do not have, such as culture, society, peers, upbringing etc. The attachment bond between human infants and their attachment figures is far more complex than it is in monkeys/geese. For instance, there are several different types of attachment styles that human infants can have (e.g. secure, avoidant, resistant). There is an argument that, of the two, Harlow’s study may be more relevant to human experience as it uses a mammalian species.
