Harlow monkey study

What did Harlow (1958) aim to investigate?

Harlow aimed to study the mechanisms by which newborn rhesus monkeys bond with their mothers, particularly whether attachment is based on food or comfort (contact comfort).

What was the procedure of Harlow’s study?

• 16 rhesus monkeys separated from biological mothers at birth

• Placed in cages with two surrogate mothers:

  • Wire mother (sometimes provided milk)

  • Cloth mother (covered in soft terry towelling, sometimes no milk)

• 8 monkeys fed from wire mother

• 8 monkeys fed from cloth mother

• Behaviour observed over various time periods

What were the findings about attachment preference?

• All monkeys spent more time with the cloth mother, regardless of which provided milk

• Monkeys fed by wire mother only visited it when hungry, then returned to cloth mother

• Shows attachment is based on contact comfort, not food

What did Harlow find about emotional security and exploration?

• When frightened, monkeys sought refuge with the cloth mother

• Monkeys were more willing to explore the environment when the cloth mother was present

• Suggests the caregiver acts as a secure base

What long-term effects were observed in monkeys raised with surrogate mothers?

Monkeys raised without real mothers showed:

• Increased timidity (especially without cloth mother)

• Poor social behaviour (didn’t know how to interact with other monkeys)

• Easily bullied, lacked aggression

• Difficulty mating

• Females were inadequate mothers

How did duration of deprivation affect outcomes?

• If deprivation lasted less than 90 days, effects could be reversed with normal social interaction

• If deprivation lasted more than 90 days (critical period), damage was permanent

• Suggests existence of a critical period for attachment

What is “contact comfort” and why is it important?

• Contact comfort = physical comfort provided by soft tactile contact (cloth mother)

• Found to be more important than food in forming attachment

• However, not sufficient alone for normal emotional development

What did Harlow conclude about deprivation?

• Early maternal deprivation causes emotional damage

• Effects can be reversed only within the critical period

• After this, damage is irreversible

• Highlighted importance of early attachment experiences

What did Harlow find about social vs maternal deprivation?

• Concluded it was social deprivation, not just maternal deprivation, causing damage

• Monkeys raised alone but given 20 minutes daily play with others developed normally

• Shows importance of peer interaction in development

How does Harlow’s study challenge behaviourist theory of attachment?

• Behaviourism argues attachment is based on food (cupboard love theory)

• Harlow showed monkeys preferred comfort over food

• Suggests attachment is biologically driven (nature) rather than learned

What are the implications of Harlow’s research for humans?

• Suggests humans have a biological need for physical contact

• Early attachment is crucial for emotional and social development

• Supports importance of caregiver sensitivity and bonding