quiet-the-power-of-introverts-in-a-world-that-cant-stop-talking-susan-cain

introverts—just the opposite—but because
they had nervous systems that
were unmoved by novelty.
The more reactive a child’s amygdala,
the higher his heart rate is likely
to be, the more widely dilated his eyes,
the tighter his vocal cords, the more
cortisol (a stress hormone) in his
saliva—the more jangled he’s likely to
feel when he confronts something new
and stimulating. As high-reactive infants
grow up, they continue to confront
the unknown in many different
contexts, from visiting an amusement
park for the first time to meeting new
classmates on the first day of kindergarten.
We tend to notice most a child’s
reaction to unfamiliar people—how
does he behave on the first day of
school? Does she seem uncertain at
birthday parties full of kids she doesn’t
know? But what we’re really observing
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