Everyone is different from each other for their behavior and nature and we know that some of us are introvert who speak less and listen more. This link describes the introvert humor in an interesting manner. The introvert ones are always in interesting for their silent behavior and we often think what they are thinking of.
If you want to know what are their choices and what they think of when someone is talking then you can go through this link. The graph is also designed to describe the nature of the introvert personalities. via mymodernmet