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

Here the author examines ways that free will can overcome the genetic proclivity discussed in the previous chapter. Cain meets with Jerome Kagan’s protégé Carl Schwartz, a doctor at Massachusetts General Hospital in Boston. He continued research on Kagan’s subjects into their adulthood, but with the aid of a functional magnetic resonance imaging (fMRI) machine to assess brain function. As Schwartz showed introverts pictures of people’s faces, the fMRI registered high activity in an area of the brain called the amygdala. The amygdala is an almond-shaped organ in the limbic system, an ancient part of the brain that controls emotion and behavior. It regulates, for instance, the “fight or flight” instinct of many animals.

However, a newer part of the brain, the frontal cortex, can override the impulses of the amygdala. This is what happens when introverted people learn to overcome their fears of, say, public speaking, allowing them to adapt their behavior as needed. The same goes for extroverts, who can adopt some habits of introverts that don’t come naturally to them. For either group, though, the ability to stretch their personalities has limits; Cain likens this to a rubber band that can stretch only so far. Plus, one’s natural impulses never go away. In an experiment with rats, when researchers detached the connection between the amygdala and frontal cortex, so that the latter’s input was cut off, they discovered that an earlier learned fear was still present.

Another study done in the 1960s by Hans Eysenck examined varying levels of stimulation in the brains of introverts and extroverts. Eysenck thought that people sought the right levels of stimulation for them based on how their brains processed such stimulation. He surmised that a part of the brain stem called the ascending reticular activating system (ARAS) was more open in introverts than in extroverts, allowing in more stimulation, and that this caused introverts to balance things with less stimulating environments. Later research indicated a more complex picture than that, but the basic premise holds. As Cain writes,

Whatever the underlying cause, there’s a host of evidence that introverts are more sensitive than extroverts to various kinds of stimulation, from coffee to a loud bang to the dull roar of a networking event—and that introverts and extroverts often need very different levels of stimulation to function at their best (123-24).

The implication of the research is that people regulate their levels of stimulation to find their own preferred sweet spot, so they are neither frazzled nor bored.

In Chapter 6, Cain discusses how extroverts and introverts complement each other in animal societies. The thread running throughout is the relationship between Franklin Roosevelt, an extrovert, and his wife Eleanor Roosevelt, an introvert. Eleanor intuited the feelings and needs of others and communicated this to Franklin; she was, in effect, his eyes and ears on the ground whose insights helped him greatly as a politician.

Cain relates a personal anecdote about attending a weekend event accommodating the needs of introverts. It included casual interactions with others, lots of downtime to use as one wished, nothing forced. The event’s keynote speaker, Elaine Aron, discussed her research that led her to identify 27 traits that contribute to a personality that she calls highly sensitive. Echoing what Cain writes about Eleanor Roosevelt, these traits include having very strong emotions, thinking in a complex manner, being highly empathic, and noticing subtle details.

Other research done on highly sensitive types reveals that such people also have a strong conscience: They worry more about things they’ve done wrong and are more likely to do the right thing even when no one is watching. They also tend to be literally thin-skinned, experiencing what lie detector tests look for—changes to skin temperature and levels of moisture from sweating. Extroverts exhibit fewer such outward signs of agitation. Although this might seem to be an advantage, there is social value in introverts’ visible reactions. Blushing from embarrassment or guilt is something we cannot control, so there’s no way to hide it. This signals genuine remorse and a willingness to make amends, which brings people together.

Still, Cain wonders how highly sensitive people managed to survive the harsh sorting-out process of evolution, as the qualities of extroverts often seem better suited to survival. The truth is that animal species have a mix of attributes, each useful in different situations. This is referred to as the trade-off theory of evolution. In this case, sometimes it’s better to hang back and watch, other times to be bold and take action. Although evolutionary biologists have traditionally focused on individual behavior, recently they’ve paid more attention to groups. For example, more sensitive and watchful antelopes that notice predators earlier are as important to the herd as the bolder, more active ones that focus on finding food. As a result of the strengths of each, both types survive and continue to disseminate their genes. Applied to humans, evidence suggests that nomads benefit from extroversion, as high-energy hunting and gathering is needed, while settled groups of people benefit from introversion, which allows for the patience necessary to stay put and raise crops.

Cain ends the chapter by returning to her weekend retreat. It’s an introvert’s dream, with nothing to inhibit or interrupt their preferred lifestyle. It may even be a little too perfect in that regard. She comes to miss extroverted types like her husband, whom she admires for the qualities that she lacks. The two types, she concludes, complement each other—just like Franklin and Eleanor Roosevelt.

This chapter examines the introvert-extrovert divide through the lens of finance, particularly as practiced from the late 1990s to the 2008 crash. Cain opens with an anecdote of an investor who made a series of risky investments in 2008, losing big with each one, and in the process squandering most of his retirement savings. The author is curious to know why someone would do this—returning to the well of failure time and again.

Research shows that much of it has to do with something called reward sensitivity. Extroverts seek the rush of reward more than introverts do, even in the face of setbacks. Studies indicate that, in extroverts, the older limbic system (discussed in Chapter 5), which controls emotions and impulses, is not as restricted by the decision-making neocortex as much as it is in introverts. Moreover, the pathways of dopamine, a chemical in the brain associated with feelings of euphoria, are more active in extroverts. Thus, extroverts get more of a buzz from risky behavior.

The years leading to the financial crash of 2007-2008 were a perfect storm of encouragement for such risk-taking. The market’s upswing during these years brought extroverts to the fore in many businesses and organizations because risky investments paid off for so long that a bullish outlook prevailed. Extroverts promised results and delivered. Meanwhile, introverts who advised caution were deemed too pessimistic. Their voices got drowned out as more extroverted individuals rose to leadership positions. In the end, it turned out that the introverts had raised some good questions and the extroverts had missed a number of obvious warning signs.

Research by psychologist Joseph Newman tries to explain why the buzz in reward-sensitive individuals (i.e., extroverts) gets in the way of good judgment. Newman learned that it has to do with whether one pauses to reassess after a setback. Introverts generally do, while extroverts do not—as the power of a potential reward is too great, pushing them on. One of Newman’s studies showed that when playing a game, if extroverts were forced to pause after a mistake, they went on to do just as well as introverts; when not forced to pause, the extroverts’ results were worse. In addition, introverts tend to have more patience and persistence for any given task, allowing them to perform better in the long run at things like academic achievement. This means they “sometimes outperform extroverts even on social tasks that require persistence” (169).

Cain then discusses why introverts get so involved in their work, when it would seem that this should only be the case for reward-sensitive extroverts. There are two likely reasons. One is that reward-sensitivity works on a continuum, so each person is a mix of attributes. The second derives from psychologist Mihaly Csikszentmihalyi’s research into flow: “the fulfillment that comes from absorption in an activity outside yourself” (172), something that introverts are especially good at.