Question: why , when other people mention the word " yawn " , or pretend to yawn , then other people feel forced to yawn aswell ???

Artem Evdokimov answered on 19 Jun 2012:

Great question 🙂

Erasmus noted that yawning is contagious all the way back in 1508. The reason why yawning is contagious is thought to be based in ‘mirroring’ action of neurons in the frontal cortex of people and certain other animals (dogs for example). There is a fairly strong link between the ability to yawn and the ability to feel empathy for others – autistic persons tend to exhibit a lot less ‘sympathy yawning’ than average. Yawning in sympathy is strongest when the initiator person is a family member or a close friend.

Incidentally, we are taught to cover our mouths as we yawn most likely due to an old superstition that demons may enter our bodies while our mouths are open…