Babies' behaviour towards humans and inanimate objects is similar, they have some preference for familiar adults and they are happier in the presence of other humans
Babies now display more observable social behaviours with a preference for people, they also recognise familiar adults and do not show stranger or separation anxiety
Stranger anxiety and separation anxiety when separated from a particular adult, the baby is said to have formed an attachment with primary attachment figure
60 babies from Glasgow (most from working class families), babies and their moths wet visited at their home every month for a year and then at 18 months
Separation anxiety was measured by asking mothers about their children experiences in every day life
Stranger anxiety was measured by asking mother questions about their children anxiety in response to unfamiliar adults
Most of the observations were made by the parents during ordinary activities, then reported to the researcher, this means the babies behaviour was unlikely to have been effected by the researcher, so it is likely the participants behaved normally
The same children were followed up and observed regularly, the quicker alternative would be to observe children at different ages (cross sectional design), however longitudinal studies have better internal validity because they dont have confounding variables of individual differences