From Patrick Bateman to Tom Ripley, on-screen psychopaths are usually male, not to mention violent criminals. 

This may fuel the assumption that the vast majority of psychopaths are men – but an academic now claims this may be misguided. 

Dr Clive Boddy, an expert at Anglia Ruskin University, says female psychopaths are 'more common than we think' because studies have long failed to identify them.