It’s natural to get affected by each other’s mood. Drains and Thunderstorms are two types of people. Drains are people who suck the energy out of you with their anger or anxiety or distress. One must focus on not being a drain and managing mental balance and equanimity. Thunderstorms are people who charge you with their positive energy.

Hume’s Philosophical Essay Concerning Human Understanding. The tape came in two versions, either happy or sad, but so subtly inflected that people were unaware of the difference unless they explicitly listened for it. As muted as the feeling tones were, students came away from the tape either slightly happier or slightly more somber than they had been before listening to it. Yet the students had no idea that their mood had shifted, let alone why.

The mood shift occurred even when the students performed a distracting task—putting metal pins into holes in a wooden board—as they listened. The distraction, it seems hampered intellectual understanding of the philosophical passage. But it did not lessen a whit how contagious the moods were: One way moods differ from the grosser feeling of emotions, psychologists tell us, has to do with the ineffability of their causes: while we typically know what has triggered an outright emotion, we often find ourselves in one or another mood without knowing its source.

The Würzburg experiment suggests, though, that our world may be filled with mood triggers that we fail to notice—everything from the saccharine Muzak in an elevator to the sour tone in someone’s voice.

Source: Social Intelligence by Daniel Goleman