Here visitors will watch the most exciting film ever! Will they yawn?

Yawns are contagious, although it is not clear why. Hearing, seeing, reading or simply thinking about yawns can make us yawn. Spontaneous yawning starts while we are still in the womb, but we are immune to yawn contagion until three or four years of age. According to some theories, yawning serves to cool and oxygenate the brain. As for being contagious, this phenomenon could be related to synchronisation of behaviour and communication.