Where Introverts Reside

I overheard a conversation at work today. My boss was walking to a conference room with another colleague.

My boss said, "You won't have to talk for long, don't worry. I told them you're a man of few words."

And then I wondered, is my colleague an introvert? It's hard to guess, sometimes. Introversion seems like a secret world; I'm always on the lookout for clues to who else resides there.