With around one in every 100 people on the planet said to harbour some psychopathic tendencies, spotting these kinds of character traits can be a tricky business.
There are some tell-tale signs to look out for though, as previous studies have shown us.
Maybe they have a tendency to repeat certain, rather specific, phrases. They might keep up an unhealthy level of contact with their ex-partners. While in some instances, it might even come down to the fact they prefer a gin and tonic to a pint of lager.
Alternatively, as a new study has now revealed, it could simply come down to a limited sense of smell. That’s right: psychopaths struggle to disguish different smells.
Or at least that’s what research from the Department of Psychology at Macquarie University in Sydney, Australia claims.
To reach that conclusion, they tested how well 79 non-criminal psychopaths coped with smelling a variety of common aromas including fish, oranges and eggs.
What they found was that those test subjects with more prominent psychopathic traits like callousness and manipulation had a tougher time distinguishing between the different odours.
So how the hell does that work? According to the researchers, it could be down to the fact that psychopaths tend to have impaired functionality in the frontal part of their brains.
It’s this frontal lobe that is responsible for things like social behaviour, planning, decision-making and, of course, smelling stuff.
“Our findings provide support for the premise that deficits in the front part of the brain may be a characteristic of non-criminal psychopaths,” the study concluded.
“Olfactory measures represent a potentially interesting marker for psychopathic traits, because performance expectancies are unclear in odour tests and may therefore be less susceptible to attempts to fake good or bad responses.”
Though the research is still some way off being scientific fact, it does beg one question: does that mean psychopaths can’t tell when someone has farted?