People with psychopathic traits are less affected by others' yawns, a 2015 study finds.
Contagious yawning has been linked to empathy levels in several studies, though not all research supports the association. However, new research in the journal Personality and Individual Differences finds that people with psychopathic traits—especially a lack of empathy—are not as susceptible to catching a case of the yawns ... at least among college students, the only group tested.
Researchers from Baylor University in Texas tried to provoke 135 students to yawn in reaction to someone else’s yawn. Each of the participants also completed a questionnaire regarding their personality traits, measuring psychopathic characteristics like selfishness, tendency to be manipulative, impulsivity, and a lack of empathy. Then they sat at a computer and watched 10-second video clips of facial movements, including yawning. Electrodes were attached to their faces just under the lower eyelids, on their foreheads, on the outer corners of their eyes, and on their fingertips to measure their movements in reaction to the videos.
The higher the participants rated on measures of cold-heartedness, the less likely they were to catch another person’s yawn. Granted, people are less likely to feel empathy with a stranger they’re watching in a video than with someone they know, and the sample size was pretty small, so Baylor University probably isn’t full of a bunch of raging psychopaths. And not yawning when others do it doesn’t mean you should run off for a psych evaluation. "But what we found tells us there is a neurological connection—some overlap—between psychopathy and contagious yawning,” study author Brian Rundle says.