Yawning is contagious. If you see someone doing it, you're likely to feel a strong urge to do it, too. Some social scientists have speculated that this tendency to mimic a yawn is tied to empathy and our ability to connect with other people.
A new study indicates we're not born with this trait; it develops over time during the first few years of life. The researchers at the University of Connecticut found that most children aren't susceptible to contagious yawning until they're 4. What's more, young children with autism spectrum disorder (ASD) are less likely to imitate yawning than other kids the same age.
ASD includes a range of conditions that impair communication and social interaction. The diminished tendency to engage in a contagious yawn suggests autistic kids "may miss subtle cues that tie them emotionally to others," the researchers write in the journal Child Development. They said their study may provide guidance for approaches to working with these children so they focus more on such cues.