Why is yawning more contagious for some people and not others? The reason may be empathy. Researchers have found that people who score high on empathy are more likely to stretch their jaws when they see others doing so. The same research found that people with mild schizotypal traits— healthy individuals that exhibit traits associated with schizophrenia—were less likely to yawn when they see others do it.
Steven Platek, Ph.D., at Drexel University in Philadelphia, Pennsylvania, had 65 subjects watch videos of people laughing, yawning and staring blankly. "Those who showed contagious yawning were more likely to perform better on our empathy test than those who did not," says Platek. Forty percent of the subjects yawned in reaction to the videos; while subjects who were less likely to yawn showed some schizotypal traits. While none of the subjects were found to be schizophrenic, Platek notes that a yawn test may help identify some people with the disorder.
Though a common characteristic of schizophrenia is lack of empathy, people who don't yawn should not consider themselves schizotypal. The research was presented at the Eastern Psychological Association Annual Meeting in Baltimore, Maryland.