yawning-contagious-you-cant-control-it-study-finds-2585278

"Contagious yawning, in which yawning is triggered involuntarily when we observe another person yawn, is a common form of echophenomena -- the automatic imitation of another's words (echolalia) or actions (echopraxia)," the study said. Telling the participants to stifle their yawns only increased their urge to yawn, the researchers found. As the researchers used TMS, it was also possible to increase the "excitability" in the motor cortex and thus even increase people's tendency to contagious yawns. When the researchers applied electrical currents to the motor cortex in their experiments, the urge to yawn among the participants increased.