Could this common reaction reveal whether or not you're a psychopath?

Right...

There is a lot of information out there about psychopaths and how to work out whether or not you know one. One study revealed how to tell if your workmate is a psychopath, and another suggested that psychopaths most enjoy these two pop songs.

There's also research that suggests if this is your partners usual coffee order, they could be a psychopath.

Yes, really.

But if you're unsure of someone's musical taste, and if your other half doesn't even drink coffee, how can you tell?

A new study has determined one very simple way to tell if someone is a psychopath. And it's something most people do pretty regularly.

Can you guess what it is? Yawning.

Research published in Personality and Individual Differences showed that when we see someone else yawning, we tend to find we've got one coming on ourselves. Why? Because a mirroring yawn is seen as empathetic and a sign of bonding. We're not alone, either - lots of social animals behave this way.

However, psychopaths lack empathy, meaning that they're less likely to yawn back at you.

Brian Rundle, lead researcher, explained: 'You may yawn, even if you don’t have to. We all know it and always wonder why.

'I thought, "If it’s true that yawning is related to empathy, I’ll bet that psychopaths yawn a lot less." So I put it to the test.'

The experiment saw 135 college students take part in a test, answering 156 questions before being shown videos of other people reacting to situations. The clips showed people laughing, yawning, or staying neutral, and the results showed that participants who were less empathetic were unlikely to yawn, even after seeing someone else doing it.

So the next time you yawn, take a quick look and see whether the people around you do the same.

But before you start accusing anyone who doesn't yawn of being a psychopath, Rundle warns: 'The take-home lesson is not that if you yawn and someone else doesn’t, the other person is a psychopath.

'A lot of people didn’t yawn, and we know that we’re not very likely to yawn in response to a stranger we don’t have empathetic connections with.

'But what we found tells us there is a neurological connection — some overlap — between psychopathy and contagious yawning. This is a good starting point to ask more questions.'

Noted.