Schaffer’s stages of development

• Schaffer and Emerson proposed that attachments develop in four stages​

  
  

  • Asocial (first few weeks)
  • Indiscriminate Attachment (2-7 months)
  • Specific Attachment (7 months +)
  • Multiple Attachments

  
• A Strength of Schaffer & Emerson's study is it has good external validity. Schaffer and Emerson's study was carried out in the families own homes and most of the observations carried out were done by parents during ordinary activities and reported to researchers afterwards. This means the behavior of babies was unlikely to be affected by the presence of observers and so they'd behave naturally. This is a strength as we can say this study has good external validity.
• A strength of the study is it was carried out longitudinally meaning the childen were followed up and observed regularly. Longitudinal designs have better internal validity than cross- sectional designs as they don't have a cofounding variable of individual differences between participants. 
• A weakness of Schaffer & Emerson's study is it's limited sample characteristics. The sample size of both babies and their carers was good considering the large volume of data gathered, however all families involved were from the same district and social class in the same city and at a time over 50 years ago is a limitation. Child rearing practices vary from one culture to another and one historical Period to the next. This is a weakness as it means results don't necessarily generalize well to other social + historical context.