What makes a person yawn when they see someone else yawn?

Yawning when seeing someone else yawn is often attributed to a phenomenon known as contagious yawning. This behavior is thought to be linked to social bonding and empathy, as it is more common among individuals who are closely connected or have strong social ties. It may also be related to mirror neurons in the brain, which trigger similar actions in response to observing others. This response can serve as a way to promote alertness and synchrony within a group.