Yawning is CONTAGIOUS. I've gotten in accidental yawning warns before and it lasts forever. (I yawned as I typed that sentence. ~Rose)
Well, you be able to spot a psychopath by the way they yawn.... or lack of yawning. Contagious yawning has been linked to empathy and since psychopaths lack empathy, there is a lower chance for them to catch a yawn. This is according to a 2015 study.
Now, don't get it twisted, it's not necessarily a determining factor, but it could be a symptom. Professor and Scientist, Jennifer Golbeck, said quote, "Of course, this is not a diagnostic tool for psychopathy, but it is an interesting connection, showing how these personality traits affect various behaviors in unexpected ways."
How many times have you yawned just from this article?
Source: Your Tango