Lawyer-turned-author Susan Cain admits she’s an introvert and has encountered some challenges because of it. But she firmly believes that introverts have important contributions to make to U.S. business—value-added that employers usually aren’t aware of. That’s because employers have been trained, says Cain, to seek out extroverts.

Quiet: The Power of Introverts in a World That Can’t Stop Talking is Cain’s most recent book (Crown, 2012). In it, she describes the rise of extroverts, in what she calls “the culture of personality.” She refers to earlier examples, like Dale Carnegie, but her most compelling example is the Harvard Business School, where, she reports, a student told her, “This school is predicated on extroversion. Your grades and social status depend on it. It’s just the norm here.”

As a result, Cain writes, “The essence of the HBS education is that leaders have to act confidently and make decisions in the face of incomplete information.” However, in group exercises that depend on consensus, the loudest voices often prevail when the quieter ones are better informed or have better ideas. And that’s the thesis of Cain’s entire book—that teams, and businesses, dominated by the actions and opinions of extroverts, are often less innovative and successful than those that seek the input of introverts.

She writes movingly about Steve Wozniak, an electronic genius who pioneered word processors and computers for Hewlett Packard, beginning in the mid-1970s. Wozniak says in his autobiography, “Most inventors and engineers I’ve met are like me—they’re shy and they live in their heads.” Many if not most introverts prefer to work by themselves and have their best ideas when they’re allowed to do so.

If we understood the importance of this, Cain says, “We’d want to teach our kids to work independently. We’d want to give employees plenty of privacy and autonomy. Yet increasingly we do just the opposite.” We’ve become convinced of the value of what Cain calls the “New Groupthink” to solve problems and spawn new ideas. Many workers spend huge amounts of their time on teams, and they have less and less privacy in increasingly smaller personal workspaces.

Let’s look at brainstorming. Cain admits that generating ideas as part of a team is a corporate process that’s still very popular, and often called brainstorming. But research shows that, by and large, it doesn’t work as well as other methods. Psychologist Anders Ericsson has experimented with what he calls Deliberate Practice, which is best conducted alone.

His experiments showed that individuals who practiced their craft by themselves far excelled over those who practiced in groups: The reason is that, as Ericsson explains, when you practice deliberately, you identify the tasks or knowledge that are just out of your reach and strive to continually upgrade your performance.

By the same token, group brainstorming is less effective than many leaders believe. The earliest research to show this goes back to 1963 (!), when psychologist Marvin Donnette found that people got more and better ideas by themselves than in groups as small as four.

Researchers usually suggest three reasons for this:

1. Any group is likely to contain “social loafers”—people who sit back and let others do the work;
2. Only one person can speak at a time, forcing others to sit and listen passively, which is called “production blocking”; and
3. Some group members fear looking stupid in front of their peers, which is called “evaluation apprehension” and holds back some potential contributors.

But good leaders must have charisma, right? Meaning they must be extroverts, right? No, as it turns out, that’s wrong. Cain notes that the ranks of effective CEOs are full of such introverts as Charles Schwab, Bill Gates, Sara Lee CEO Brenda Barnes, and former Deloitte Touche Tohmatsu CEO James Copeland.

One study of 128 companies and their CEOs showed that extroverted leaders made more money than their quieter counterparts, but their companies didn’t do as well as those led by introverts.

Jim Collins, author of Good to Great, profiled CEOs who were known not for their charisma but for extreme humility combined with intense professional will. Their companies generated higher stock returns than those with flashier leaders.

Wharton management professor Adam Grant told Cain about one outstanding—and outstandingly introverted—leader. He is a U.S. Air Force wing leader, one rank below general. Being with people too much makes him lose focus, so he has trained himself to find time for thinking and recharging. He speaks quietly and is more interested in listening and gathering information than in asserting his own opinion. Introverted leaders draw the best from their subordinates.

The whole world doesn’t talk too much. The subtitle of Cain’s book is, according to her, misleading: It is Europe and North America that can’t stop talking. Asia, by contrast, tends toward a very different, much more respectful, culture, in which people listen much and speak little. Cain believes we Westerners would do well to take a page from the East’s book and tone ourselves down a bit. Who knows, we might learn something.