Early childhood experiences impact on personality development. Bowlby demonstrated in this 44 juvenile thieves study, that early childhood experiences play a vital role in the social development of children. Bowlby theorised that children who experience maternal deprivation during the critical time period are more likely to end up being affectionless psychopaths, have a negative internal working for relationships and be delinquent. He used this to support the idea of early childhood experience being crucial in the development of a healthy unconscious mind supporting a hard deterministic approach to later adult behaviour.However, Bowlby has been criticised for the use of non-experimental methods to collect his data