A weakness?

-Lacks population validity -Consisted of only 60 working class mothers and babies from Glasgow - could form different attachments compared to wealthier families or in other countries -Sample was from the 1960s, parental care has changed significantly since then, more women going to work and children being cared outside of the home or fathers staying at home to caregive -Unable to generalise the results to parents and babies from other countries, backgrouds and historical contexts, sample was so unique so it is no comparable