Usefulness (real world application). For example the key defining characteristic of antisocial personality disorder is the failure to conform to culturally acceptable ethical behaviour, i.e reckless, aggression. All the examples stated are signs of deviation from social norms and being able to identify such deviation is useful in clinical practise. Therefore this suggest that deviations from social norms has made a valuable contribution in psychiatry and classifying mental health disorders which will enable psychiatrists, implement treatments