You Can Spot A Psychopath If He Doesn't Yawn Back At You

You can spot a psychopath by yawning at him. If he does not yawn back, you know that he is a psychopath, and anti-social, according to dailymail.

While 'contagious yawning' is normal among mammals, psychopaths do not exhibit it.

The researchers from Baylor University in Texas published their findings in the journal Personality and Individual Differences.

They tested 135 students for "Machiavellian egocentricity", which means a tendency to go only on "personal needs, cold-heartedness and rebellious nonconformity".

Studies show that when they watch people yawning, most will show symptoms of yawning as well as tiredness. The students were shown video clips of people who varied their facial expressions, including yawning.

In varying degrees, most people can be induced to yawn by seeing or just thinking about yawning., according to TheTimes.

The ones who showed the most "cold-heartedness" were least likely to yawn.

Brian Rundle, a PhD student who was part of the study, said: "One of the biggest lines of evidence is that (contagious yawning is) very much related to empathy. While this is a really interesting finding, it doesn't mean that if you're not affected by a contagious yawn there's something wrong with you."

He added, "There's some evidence that to show that in baboons or dogs or chimps the alpha male tends to yawn first. If you're sitting around the campfire it cues everyone else to yawn, and instead of going to bed at separate times they all do it at the same time."