This is a review of Susan Cain’s Quiet: The Power of Introverts in a World That Can’t Stop Talking (2012).


Being an introvert in almost every way, I wasn’t expecting to learn too much about my own behavior from the book. Indeed, the personality descriptions and key features of introversion are mentioned in the book. There was, however, still much to learn about introversion vs extroversion from a societal perspective.

What got me interested in the book was a line from Amazon’s interview:

Q: Why did you write the book?
A: For the same reason that Betty Friedan published The Feminine Mystique in 1963. Introverts are to extroverts what women were to men at that time–second-class citizens with gigantic amounts of untapped talent. Our schools, workplaces, and religious institutions are designed for extroverts, and many introverts believe that there is something wrong with them and that they should try to “pass” as extroverts. The bias against introversion leads to a colossal waste of talent, energy, and, ultimately, happiness.

I had never thought about this before. After all, introversion is almost a societal taboo: from the first day of school to the last day of one’s job, there are boundless social encouragements to be an extrovert—or at least to pretend to be an extrovert. I’ll go through some of the book’s main results.

The Team Environment

One of the most interesting points of the book is that extroverts are overrated in teamwork skills. Cain relates a game called the Subarctic Survival Situation, given to incoming students at the Harvard Business School. Individuals within a team are supposed to rank the items in a list of tools based on which would be the most important for survival in a freezing condition. Then the team can collaborate and come up with a team ranking. If the team ranking is better than every individual’s ranking, the team is said to have synergy and be successful. Otherwise, if one person on the team had a better individual ranking than the team ranking, it means the team did not cooperate well enough.

In this game, those who were the most assertive (i.e. the extroverts) dominated the discussions. As a result, sometimes when one person who may have had tons of wilderness experience speaks too softly, they are ignored and the team fails. An interview with a participant in the game:

“Our action plan hinged on what the most vocal people suggested,” recalls the classmate. “When the less vocal people put out ideals, those ideas were discarded. The ideas that were rejected would have kept us alive and out of trouble, but they were dismissed because of the conviction with which the more vocal people suggested their ideas. Afterwards they played us back the videotape, and it was so embarrassing.” (50)

Here are more unsurprising results:

If we assume that quiet and loud people have roughly the same number of good (and bad) ideas, then we should worry if the louder and more forceful people always carry the day. This would mean that an awful lot of bad ideas prevail while good ones get squashed. Yet studies in group dynamics suggest that this is exactly what happens. We perceive talkers as smarter than quiet types—even though grade-point averages and SAT and intelligence test scores reveal this perception to be inaccurate. In one experiment in which two strangers met over the phone, those who spoke more were considered more intelligent, better looking, and more likable. (51)

And yet more:

All of this would be fine if more talking were correlated with greater insight, but research suggests that there’s no such link. In one study, groups of college students were asked to solve math problems together and then to rate one another’s intelligence and judgment. The students who spoke first and most often were consistently given the highest ratings, even though their suggestions (and math SAT scores) were no better than those of the less talkative students. These same students were given similarly high ratings for their creativity and analytical powers during a separate exercise to develop a business strategy for a start-up company.  (51)

In addition, Cain cites studies which show that extroverts and introverts both make good leaders, but of different people. Extroverts were more effective when leading passive types, that is, those who did their job without exercising initiative. However, introverts were more effective when leading those who did actively try to improve work performance. This makes sense. Those who are more passive may need extra guidance, while those who take initiative don’t need to be bogged down by micromanagement.

The style of “groupthink” took its own chapter: “When Collaboration Kills Creativity.” Study after study show that ideas might be better if extroverts weren’t so overvalued.

Physiological Differences

Cain cites the work of Jerome Kagan, a developmental psychologist, who was able to successfully predict whether babies would turn into extroverts or introverts based on reactiveness.  Counterintuitively, it was the high-reactive who became introverts. It makes sense though, as the high-reactive are more moved by external stimuli, while the low-reactive are unfazed. Hence the low-reactives are the extroverts: they handle unfamiliar social situations with calm, while the high-reactives tend to stay away from such situations.

Some of the evolutionary principles behind the different behaviors are also explored.

In fact, public speaking anxiety may be primal and quintessentially human, not limited to those of us born with a high-reactive nervous system. One theory, based on the writings of the sociobiologist E.O. Wilson, holds that when our ancestors lived on the savannah, being watched intently meant only one thing: a wild animal was stalking us. And when we think we’re about to be eaten, do we stand tall and hold forth confidently? No. We run. In other words, hundreds of thousands of years of evolution urge us to get the hell off the stage, where we can mistake the gaze of the spectators for the glint in a predator’s eye. (107)

The difference can be detected even in something as innocuous as noise sensitivity:

In another famous study, introverts and extroverts were asked to play a challenging word game in which they had to learn, through trial and error, the governing principle of the game.  While playing, they wore headphones that emitted random bursts of noise.  They were asked to adjust the volume of their headsets up or down to the level that was “just right.”  On average, the extroverts chose a noise level of 72 decibels, while the introverts selected only 55 decibels.  When working at the volume that they had selected—loud for the extroverts, quiet for the introverts—the two types were about equally aroused (as measured by their heart rates and other indicators).  They also played equally well.

When the introverts were asked to work at the noise level preferred by the extroverts, and vice versa, everything changed.  Not only were the introverts over-aroused by the loud noise, but they also underperformed—taking an average of 9.1 trials rather than 5.8 to learn the game.  The opposite was true for the extroverts—they were under-aroused (and possibly bored) by the quieter conditions, and took an average of 7.3 trials, compared with the 5.4 they’d averaged under noisier conditions. (124)


How do introverts and extroverts compare on academic tasks?

Introverts’ disinclination to charge ahead is not only a hedge against risk; it also pays off on intellectual tasks. Here are some of the things we know about the relative performance of introverts and extroverts at complex problem-solving. Extroverts get better grades than introverts during elementary school, but introverts outperform extroverts in high school and college. At the university level, introversion predicts academic performance better than cognitive ability. One study tested 141 college students’ knowledge of twenty different subjects, from art to astronomy to statistics, and found that introverts knew more than the extroverts about every single one of them. Introverts receive disproportionate numbers of graduate degrees, National Merit Scholarship finalist positions, and Phi Beta Kappa keys. (167)

The following contains what I found to be perhaps the most significant result:

Introverts are not smarter than extroverts. According to IQ scores, the two types are equally intelligent. And on many kinds of tasks, particularly those performed under time or social pressure or involving multitasking, extroverts do better. Extroverts are better than introverts at handling information overload. Introverts’ reflectiveness uses up a lot of cognitive capacity, according to Joseph Newman. On any given task, he says, “if we have 100 percent cognitive capacity, an introvert may have only 75 percent on task and 25 percent off task, whereas an extrovert may have 90 percent on task.” This is because most tasks are goal-directed. Extroverts appear to allocate most of their cognitive capacity to the goal at hand, while introverts use up capacity by monitoring how the task is going.

This speaks very true for me.

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