A study from the University of Pisa (Italy) suggests that people are more likely to yawn in reaction to the yawn of a close relative than to a friend or stranger, according to the journal PLoS One .
The act of yawning has always been considered "contagious", since when someone in a group yawns around them other people do the same involuntarily. In addition, this reaction, common in about half of the population, is not unique to humans, but also exists in animals such as chimpanzees.
For the new study, the Italian researchers observed 109 men and women of a variety of nationalities in their daily activities and recorded the times contagious yawning occurred. The study found that they were more likely to occur among members of the same family, slightly less among friends , and still less among mere "acquaintances" and strangers.
Furthermore, the time elapsed between yawning and the imitation response was greater among acquaintances and strangers than among relatives , which "shows that the contagion of yawning is, above all, generated by the emotional closeness between individuals and not by other variables such as gender and nationality, "the researchers conclude.
