schaffers stages of attachment

• Glasgow study by Schaffer- 60 mother and infant pairs from working class families in Glasgow were interviewed observed and the mothers were interviewed, by 6 months 50% of the infants had shown separation anxiety, by 10 months 80% specific attachment and 30% multiple, by 18 months at least two,
• evaluation of Schaffer's study- biased sample as only from working class families in Glasgow so lacks external validity, also lacks internal validity as relied on mothers answers in interviews which may have been subject to social desirability, however observations were made in their own homes to measure behaviour in a familiar setting which improves ecological validity