Some findings reveal extroverts as more adept at reading nonverbal cues, and attribute this to the extrovert's greater interest and experience with social interactions. Another line of research using subliminal images of facial emotion found introverts to be more sensitive to the differences, and hypothesized that this may be why introverts regulate the amount of incoming social information.

Extroverts are more attuned to social rewards, so they are more likely to flash a smile for effect. A notable exception are introverts - like me - whom I call "socially accessible" introverts. We have been trained well to smile and nod, which can place a burden on our processing efforts.

I am rarely bored alone; I am often bored in groups and crowds.

A shy kid might look longingly at other kids playing in the schoolyard, afraid and unsure about how to approach them, but an introvert is perfectly content on her own.

When an introvert cares about someone, she also wants contact, not so much to keep up with the events of the other person's life, but to keep up with what's inside: the evolution of ideas, values, thoughts, and feelings.

America is a noisy culture, unlike, say, Finland, which values silence. Individualism, dominant in the U.S. and Germany, promotes the direct, fast-paced style of communication associated with extraversion. Collectivistic societies, such as those in East Asia, value privacy and restraint, qualities more characteristic of introverts.

Introvert, her brain responds with a high level of activity, it is as if several lights start flashing on a control panel.