There’s a yawning gulf between psychopaths
If you want to spot a psychopath, you could start by yawning at them. Scientists have found that the more psychopathic traits people have, the less likely they are to be afflicted by ‘‘contagious yawning’’.
To a greater or lesser degree, most people can be induced to yawn by seeing people yawning, or even just by thinking about yawning. This contagious yawning is common to many mammals, and is believed to serve a social purpose, perhaps by building empathy.
Researchers from Baylor University in Texas wanted to test this hypothesis by seeing if psychopaths were less affected by the yawns of others.
For the study, published in the journal Personality and Individual Differences, 135 students were tested for psychopathy.
This involved completing a test that measured traits such as ‘‘Machiavellian egocentricity’’, ‘‘coldheartedness’’ and ‘‘rebellious nonconformity’’. They were then shown a video in which people exhibited a variety of facial expressions, as well as yawning.
While this went on the researchers watched and recorded how often the students yawned.
What they found was that those who scored highly on the scale of ‘‘coldheartedness’’ were more than a third less likely to yawn.
Brian Rundle, a PhD student, said that the work helped to validate the idea that contagious yawning was about empathy.
‘‘There is a lot of educated speculation about this,’’ he said. ‘‘Why does our species yawn when we see somebody else yawn?
‘‘One of the biggest lines of evidence is that it is very much related to empathy – so what I wanted to do was test it in a population known for having a lack of empathy.’’
For the test of psychopathy, people were asked to say how much they agreed with statements such as ‘‘I cringe when an athlete gets badly injured during a game on TV’’, or ‘‘I do favours for people even when I know I won’t see them again’’. ‘‘A lot of these people are still very pleasant people, it is just clear they’re not able to connect with you as much as other people are,’’ Rundle said.
He added that his research should not mean that people who didn’t yawn when you yawned were definitely psychopathic.
‘‘While this is a really interesting finding, if you don’t respond to contagious yawn it doesn’t mean you have something wrong with you.’’
Why, though, would empathetic yawning be useful to humans?
‘‘That is a big question,’’ he said.
‘‘There’s some evidence to show that in baboons or dogs or chimps the alpha male tends to be the one to yawn first.’’
In our caveman past, a yawn from the chief could help synchronise behaviour. ‘‘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.’’