Quiet: The Power of Introverts in a World That Can\'t Stop Talking pdfdrive com

Galen’s Prophecy
, “Carl
Jung’s descriptions of the introvert and extrovert, written over seventy-
five years ago, apply with uncanny accuracy to a proportion of our high-
and low-reactive adolescents.”
Kagan describes two of those adolescents—reserved Tom and
extroverted Ralph—and the differences between the two are striking.
Tom, who was unusually shy as a child, is good at school, watchful and
quiet, devoted to his girlfriend and parents, prone to worry, and loves
learning on his own and thinking about intellectual problems. He plans
to be a scientist. “Like … other famous introverts who were shy
children,” writes Kagan, comparing Tom to T. S. Eliot and the
mathematician-philosopher Alfred North Whitehead, Tom “has chosen a
life of the mind.”
Ralph, in contrast, is relaxed and self-assured. He engages the
interviewer from Kagan’s team as a peer, not as an authority figure
twenty-five years his senior. Though Ralph is very bright, he recently

---

failed his English and science classes because he’d been goofing around.
But nothing much bothers Ralph. He admits his flaws cheerfully.
Psychologists often discuss the difference between “temperament” and
“personality.” Temperament refers to inborn, biologically based
behavioral and emotional patterns that are observable in infancy and
early childhood; personality is the complex brew that emerges after
cultural influence and personal experience are thrown into the mix.
Some say that temperament is the foundation, and personality is the
building. Kagan’s work helped link certain infant temperaments with
adolescent personality styles like those of Tom and Ralph.
But how did Kagan know that the arm-thrashing infants would likely
turn into cautious, reflective teens like Tom, or that the quiet babies
were more likely to become forthright, too-cool-for-school Ralphs? The
answer lies in their physiologies.
In addition to observing the children’s behaviors in strange situations,
Kagan’s team measured their heart rates, blood pressure, finger
temperature, and other properties of the nervous system. Kagan chose
these measures because they’re believed to be controlled by a potent
organ inside the brain called the amygdala. 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.
The amygdala serves as the brain’s emotional switchboard, receiving
information from the senses and then signaling the rest of the brain and
nervous system how to respond. One of its functions is to instantly detect
new or threatening things in the environment—from an airborne Frisbee
to a hissing serpent—and send rapid-fire signals through the body that
trigger the fight-or-flight response. When the Frisbee looks like it’s
headed straight for your nose, it’s your amygdala that tells you to duck.
When the rattlesnake prepares to bite, it’s the amygdala that makes sure
you run.
Kagan hypothesized that infants born with an especially excitable

---

amygdala would wiggle and howl when shown unfamiliar objects—and
grow up to be children who were more likely to feel vigilant when
meeting new people. And this is just what he found. In other words, the
four-month-olds who thrashed their arms like punk rockers did so not
because they were extroverts in the making, but because their little
bodies reacted strongly—they were “high-reactive”—to new sights,
sounds, and smells. The quiet infants were silent not because they were
future 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