An interesting section in the post cites research about " mirror neurons." Evidently the old saying "monkey see, monkey do" has scientific relevance. We learn from seeing other people, then copying them. As a survival tool, this served us well, back in the day.
It does not serve us well when we are around angry, negative people. Sometimes our brains pick up on things best left not repeated or mirrored. This resonates with the research in organizations that shows emotions are contagious, and the mood of the leader permeates the culture of the group.
When's the last time you became aware, as your mood was changing, that you might have picked up some 'bad vibes' in your environment?
Well, sometimes we generate our own bad moods ourselves, and the only negative person around is...ourself! Just remember, you can spread positivity just as easily as negativity, and it's a lot more fun.