Welcome to The Edge, a show that aims to explore the unique talent and occasional darkness that drives elite performance in the worlds of sport, politics and music. This week Joey Barton sits down to talk to Dr Kevin Dutton, a psychologist and writer, specialising in the study of psychopathy.

You can take Kevin's psychopath test here: http://www.kevindutton.co.uk/test/the-psychopath-challenge/