The label ‘pathological liar’ gets thrown around a lot, especially in the direction of politicians or celebrities. Although it isn't a formal psychiatric diagnosis, it is a recognised concept that psychologists and psychiatrists have been interested in for a long time, at least since 1891 when the German psychiatrist Anton Delbrueck coined the label ‘Pseudologia fantastica’ to describe several of his patients who told an astonishing amount of fantastical lies (other similar psychological terms include ‘deception syndrome’ and ‘mythomania’). So why do people do it?

Worth noting is that while psychopaths and people with antisocial personality disorder can be inclined to excessive lying, most pathological liars are not psychopaths, nor do they necessarily have a personality disorder. Indeed, while psychopaths and people with an antisocial personality are typically manipulative and self-serving, pathological liars often lie for no apparent purpose.

Another key feature of pathological lying, as opposed to being a common-or-garden compulsive liar, is that the lies are often particularly bizarre or far-fetched.