Bowlby's 44 thieves research(1944)
44 teenage delinquents who were accused of stealing, interviewed for signs of prolonged separation from mothers, control group of 44 non-criminal teenagers with emotional problems were assessed to see if maternal deprivation occurred in them
14/44 thieves were affectionless psychopaths and 17/44 had maternal separation whereas the control group 2/44 had maternal separation and 0/44 were affectionless psychopaths
showed that prolonged separation/deprivation caused affectionless psychopathy, emphasises the importance of attachment during the critical period