Developmental Studies

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  • Created on: 25-04-15 11:35

Harlow (1959)

Aim: To find out whether baby monkeys would prefer a source of food or a source of comfort and protetction as an attachment figure.

Method: Lab experiment which raised rhesus monkeys in isolation. They had two 'surrogate' mothers. One was made of wire mesh and contained a feeding bottle, the other made of cloth but didn't contain a feeding bottle.

Results: Monkeys mostly clinged to the cloth surrogate, only using the wire surrogate to feed. Cloth surrogate seemed to give them comfort in new situations. Monkeys grew up and showed signs of social and emotional disturbance. The females were bad mothers who were often violent towards their offspring.

Conclusion: Infant monkeys formed more of an attachment with a figure that provided comfort and protection. Growing up in isolation affected their development.

EvaluationThe lab experiment structure makes it unlikely that results were affected by an unknown variable.

The findings of the study were applied to real life, and babies in hospital incubators are now given soft blankets.

It can be argued that the results of this study can't be generalised to human beings.

There are ethical issues of the study, due to the monkeys placement in a stressful situation.

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Ainsworth et al (1978)

Aim: To assess how children react under conditions of stress and to situations.

Method: Controlled observation, 12-18 month old infants left in a room with mothers. 8 different scenarios occured, such as a stranger approaching, infant being left alone, mother returning, etc. Infants' reactions constantly observed.

Results: About 15% of infants were 'insecure-avoidant(type A) - ignored their mother & didn't mind if she left. Stranger could comfort them. 

About 70% were 'securely attached(type B) - content with their mother, upset when she left, happy when she returned and avoided strangers. 

About 15% were 'insecure-resistant(type C) - uneasy around their mother and upset if she left. They resisted strangers and were also hard to comfort when their mother returned.

Conclusion: Infants showing different reactions to their carers have different types of attachment.

EvaluationThe research method used allowed control of the variables.

The laboratory-type situation made the study artificial, reducing the study's ecological validity.

The childrens' mothers may not have been their main attachment figures.

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Van Ijzendoorn and Kroonenberg (1988)

Aim: To study cross-cultural studies of attachment.

Method: Carried out meta-analysis of 32 studies of SST in different countries. They were analysed to find any overall patterns.

Results: The percentages of children classified as secure or insecure were very similar across the countries tested. Secure attachments most common. Some differences found in distribution of insecure attachments. In Western cultures, dominant insecure attachment was avoidant. In non-Western cultures, dominant type was resistant.

Conclusion: Cross-cultural similarities in raising children, producing common reactions to the 'strange situation'.


Using a different type of study may have revealed different patterns or types of attachment in different cultures.

The study assumes that different countries are the same thing as different cultures.

Meta-analyses can hide individual results that show an unusual trend.

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Robertson and Robertson (1968)

Aim: To develop a model for the process of disruption of attachment.

Method: A naturalistic observation which observed children who experienced from their carers. For example, a boy called John aged around 18 months stayed in a residential nursery for 9 days while his mother had another baby.

Results: John showed signs of passing through 'protest' for the first day or two. Then he showed despair by trying to get attention from nurses, but gave up when they were busy with other children. Then he showed detachment - he was more active and content. However, when his mother came to collect him, he was reluctant to be affectionate.

Conclusion: The short-term separation had very bad effects on John, including possible permanent damage to his attachment with his mothers.


John's reaction may have been due to his new environment or the fact that he was getting much less attention than he was used to.

There will have been little control of variables, making it difficult to replicate each individual situation.

Having taken place in a natural setting, the results will have ecological validity but will be less reliable.

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Bowlby (1944)

Aim: To study longer-term maternal deprivation

MethodCase studies were completed on 44 adolescents who had been referred to the clinic where Bowlby worked because they'd been stealing. There was a control group of 44 'emotionally disturbed' adolescents who didn't steal.

Results: 17 of the thieves had experienced frequent separations from their mothers before the age of two, compared with 2 in the control group. 14 of the thieves were diagnosed as 'affectionless psychopaths'. 12 of these 14 had experienced separation from their mothers.

Conclusion: Deprivation of the child from its main carer early in life can have very harmful long-term consequences.


Results indicate a link between deprivation and criminal behaviour.

Causal relationships can't be confirmed.

There may be other factors which caused the criminal behaviour.

Although case studies provide a lot of detailed information, the study relied on retrospective data, which may be unreliable.

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Curtiss (1977)

case study of a girl who had suffered extreme cruelty from her parents and never formed any attachments. She was discovered when she was 13 years old. She was physically underdeveloped and could only speak with animal-like sounds.

After a lot of help she later learned some language but her social and intellectual skills never seemed to fully develop.

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Koluchova (1976)

case study of two Czech twin boys. Their mother died soon after their birth. Their father remarried and their stepmother treated them very cruelly. They were often kept locked in a cellar, beaten, and had no toys.

They were found they were seven with rickets (a bone development disease caused by a lack of vitamin D), and very little social or intellectual development.

They were later adopted and made lots of progress. By adulthood they had above average intelligence and had normal social relationships.

Differences between this case and the case of Genie

  • The length of privation was shorter for the twins, allowing them more time to develop in a better environment.
  • Their experiences during isolation. The twins were kept together and may have attached to each other.
  • The quality of care they received after isolation- the twins were adopted while Genire was passed between psychologists and eventually put into an institution.
  • Individual differences, including ability to recover.
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Hodges and Tizard (1968)

Aim: To study the effects of institutional care on a child's development.

Method: A longitudinal study of 65 children placed in a residential nursery before they were four months old. They hadn't had the opportunity to form close attachments with any of their caregivers. By the age of four, some of the children had returned to their birth mothers, some had been adopted, and some stayed in the nursery.

Results: At 16 years old, the adopted group had strong family relationships, although compared to a control group of children from a 'normal' home environment, they had weaker peer relationships. Those sho stayed in the nursery or who returned to their mothers showed poorer relationships with family and peers than those who were adopted.

Conclusion: Children can recover from early maternal privation if they are in a good qualityloving environemnt, although their social development may not be as good as children who have never suffered privation.


A natural experiment, so it had high ecological validity.

Results supported by other studies.

The sample was quite small, making it difficult to generalise the findings.

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Clarke-Stewart et al (1994)

Aim: To study the positive effects of daycare.

Method: Used a series of separate observations. One experiment looked at the peer relationships of 150 children aged 2-3 years, who came from different social backgrounds. Another experiment studied the strength of attachment in a group of 18-month-old children. These children had at least 30 hours of daycare per week. The SST was used. Results were compared with those of children who had 'low intensity' day care (less than 10 hours per week).

Results: The 2-3 year olds who had experienced day care were good at coping with social situations and negotiating with each other. In the 'strange situation' experiment, the 18-month-olds who had high intensity daycare were juest as distressed when separated from their mothers as those who had low intensity day care.

Conclusion: Daycare can have a positive effect on the development of peer relationships in 2-3 year olds. Attachment in 18-month-olds is not affected by temporary separation.


The observations were controlled, so the study could be easily replicated.

Because the study was artificial, it lacks ecological validity and the results can't be generalised to other children.

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Shea (1981)

Aim: To study the positive effects of daycare.

Method: Videotaped infants aged between 3 and 4 in the playground during their first 10 weeks at nursery school. Their behaviour was assessed in terms of rough-and-tumble play, aggressionfrequency of poor interactiondistance from the teacher and distance from the nearest child.

Results: Over the 10 weeks the children's peer interaction increased and their distance from the teacher decreased. There was a decrease in aggression and an increase in rough-and-tumble play. The increase in sociability was more evident in children who attended daycare 5 days a week than in those who went 2 days a week.

Conclusion: Daycare causes children to become more sociable and less aggressive.


This was a naturalistic observation, meaning the study has high ecological validity because none of the behaviour was manipulated.

The study may have been affected by extraneous variables.

The behaviour was open to interpretation, so the findings could be biased - e.g. it could be difficult to differentiate between 'aggression' and 'rough-and-tumble play'.

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Belsky and Rovine (1988)

Aim: To identify negative effects of daycare.

Method: Infants placed in SST to assess how secure their attachments to their mothers were. One group had experienced no day care and one had experienced at least 20 hours of day care per week before their first birthday.

Results: The infants who had received daycare were more likely to have an insecure attachment type. They were 'insecure-avoidant' - ignored their mother and didn't mind if she left, or 'insecure-resistant' - uneasy around their mother and upset if she left. Those who hadn't had day care were more likely to be securely attached.

Conclusion: Daycare has a negative effect on an infant's social development.


The SST is a controlled observation, so there was good control of the variables.

However, this means that the study lacks ecological validity, because it creates an artificial situation.

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