Aim: To investigate the formation of early attachments (in particular, the age they were formed).
They used a sample of 60 babies from Glasgow, with the majority being from working-class families
This was a longitudinal study where the babies and mothers were being studied every month for the first year and then again at 18 months.
They assessed separation anxiety/protest; through infant being left alone in a room, left in the pram outside the shops, left in the cot at night etc.
They used observations and interviews with the mothers.
Also assessed stranger anxiety with the researcher starting home visits by approaching the infant, to see if they got distressed.
Found that between 25-32 weeks, about 50% of babies shoed separation anxiety towards their caregiver (usually the mother).
Attachment tended to be to the caregiver who was most interactive and sensitive to the infants' signals and facial expression (reciprocity).
By 40 weeks, 80% of babies had a specific attachment (to the primary caregiver) and almost 30% displayed multiple attachments.
This suggests that there is a pattern of attachment common to all infants which is biologically controlled.
Furthermore, attachments are more easily made with those who are sensitive, for example recognising and responding appropriately to an infant's needs, rather than those spending the most time with a child.
Evaluation
Good external validity: Observations were in participants' natural environment.
Limited sample characteristics: All families were from the same area over 50 years ago, so may lack generalisability.
Longitudinal design: Same participants were observed at each age, eliminating individual differences as a confound.