The amygdala is located deep in the limbic system, an ancient brain network found even in primitive animals like mice and rats. This network—sometimes called the “emotional brain”—underlies many of the basic instincts we share with these animals, such as appetite, sex drive, and fear.

Or at school you might have been prodded to come “out of your shell”—that noxious expression which fails to appreciate that some animals naturally carry shelter everywhere they go, and that some humans are just the same.

In China there was more emphasis on listening, on asking questions rather than holding forth, on putting others’ needs first. In the United States, he feels, conversation is about how effective you are at turning your experiences into stories, whereas a Chinese person might be concerned with taking up too much of the other person’s time with

The risk with our students is that they’re very good at getting their way. But that doesn’t mean they’re going the right way.

Nor are introverts necessarily shy. Shyness is the fear of social disapproval or humiliation, while introversion is a preference for environments that are not overstimulating. Shyness is inherently painful; introversion is not. One reason that people confuse the two concepts is that they sometimes overlap (though psychologists debate to what

the so-called Big Five traits: Introversion-Extroversion; Agreeableness; Openness to Experience; Conscientiousness; and Emotional Stability. (Many personality psychologists believe that human personality can be boiled down to these five characteristics.)

Studies have shown that performance gets worse as group size increases: groups of nine generate fewer and poorer ideas compared to groups of six, which do worse than groups of four. The “evidence from science suggests that business people must be insane to use brainstorming groups,” writes the organizational psychologist Adrian Furnham. “If you

Don is “a bitter introvert,” as he cheerfully puts it—bitter because the more time he spends at HBS, the more convinced he becomes that he’d better change his ways.

Aggressive power beats you up; soft power wins you over.”