Yawning is contagious among dogs and their owners

TOKYO, Aug. 8 (UPI) -- Yawning is contagious among people, and contagious among dogs and their owners, but not so much between a stranger and a dog, Japanese researchers say.

Teresa Romero and colleagues from the University of Tokyo said previous research showed dogs yawned in response to human yawns, but it was unclear whether this was a mild stress response or an empathetic response.

The researchers watched the dog owners or a stranger yawn, or mimic a yawning mouth movement.

The study, published in the journal PLoS One, found dogs yawned significantly more in response to their owners' yawns than to the strangers' yawns. The dogs also responded less frequently to the fake movements.

The researchers observed no significant differences in the dogs' heartbeat during the experiments, making it unlikely that their yawns were a distress response.

"Our study suggests that contagious yawning in dogs is emotionally connected in a way similar to humans," Romero said in a statement. "Although our study cannot determine the exact underlying mechanism operative in dogs, the subjects' physiological measures taken during the study allowed us to counter the alternative hypothesis of yawning as a distress response."