-data collected by Schaffer and Emerson may be unreliable as it is based on the mothers' report of their infants, some mothers are less sensitive than others.
-Sample is biased as it was from a working class population so the findings cant be generalised
-there are cultural differences in the upbringing of a child therefore this stage model only applies to individualist cultures.
-'stage theories' suggest development is inflexible therefore this is problematic as if they become a standard by which families are judged this may lead to them being classed as abnormal.