Bowlby carried out the assessments for affectionless psychopathy and the family interviews himself so could have been biased in how he carried out the procedure and how he analysed the results
Strength/Limitation - Goldfarb's study
-Found lower IQ's in children from institutions compared to fostered children
-However the study is filled with confoundingvariables as other factors could have played a role in the development of the children (e.g. the children were war orphans who were traumatised and had poor after care)
Limitation - Confounding Variables
Children growing up from birth in poor quality institutions were deprived of many aspects of care, not just maternal care
Limitation - Lewis' study
-Partially replicated the 44thieves study on a larger scale, looking at 500 people
-Found that early prolonged maternal separation did not predict criminality or difficulty forming relationships
Limitation - Koluchova's Study
-Study of Czechtwin boys isolated from age 18months (locked in a cupboard)
-Later they were looked after by two loving adults and appeared to fullyrecover
-Sever deprivation can have positive outcomes provided that the child has some good socialinteraction and aftercare
-Suggests critical period is more of a sensitive one
Strength - Levy et al
-Showed that separating baby rats from their mother for as little as a day had a permanent effect on their social development
