Why are yawns contagious? New research finds clues

The "contagiousness" of yawns may be rooted in primitive brain reflexes, British researchers report.

Echophenomena is the term for contagious movements such as yawns. Humans tend to yawn when they see others yawn, and so do chimpanzees and dogs.

Researchers at the University of Nottingham wondered where the roots of this type of echophenomena are located. They examined 36 adults as they looked at video clips of people yawning. The participants were told to either try to stop themselves from yawning or just let it happen.

The researchers found that it's hard to resist yawning when you see someone yawn, and the urge to yawn gets stronger when you're told not to do it. The researchers also found that people differ in their vulnerability to yawns.

"We suggest that these findings may be particularly important in understanding further the association between motor excitability and the occurrence of echophenomena in a wide range of clinical conditions... such as epilepsy, dementia, autism and Tourette syndrome," said study leader Stephen Jackson. He's a professor of cognitive neuroscience at Nottingham.

The researchers also tried to manipulate contagious yawning through a kind of electrical stimulation.

"This research has shown that the 'urge' is increased by trying to stop yourself. Using electrical stimulation, we were able to increase excitability and in doing so increase the propensity for contagious yawning," said Georgina Jackson, a professor of cognitive neuropsychology.

"In Tourette's, if we could reduce the excitability we might reduce the tics, and that's what we are working on," she said in a Nottingham news release.

The work with electrical stimulation suggests that the brain's primary motor cortex plays a role in contagious yawning, the researchers said.

The findings were published Aug. 31 in the journal Current Biology.