The good news, then, is that in some sense we are all born to sell and equipped to lead. And that means a hidden but urgent challenge for organizations of every kind is to shatter the stereotype of who’s an effective leader. When we choose leaders, as when hiring managers choose salespeople, we’re understandably drawn to the gregarious, friendly types with their comfortable patter and ready smiles. But are they really the best?

Spend a day with any leader in any organization, and you’ll quickly discover that the person you’re shadowing, whatever his or her official title or formal position, is actually in sales. These leaders are often pitching customers and clients, of course. But they’re also persuading employees, convincing suppliers, sweet-talking funders or cajoling a board. At the core of their exalted work is a less glamorous truth: Leaders sell.

So what kind of personality makes the best salesperson — and therefore, presumably, the most effective leader?

Most of us would say extroverts. These wonderfully gregarious folks, we like to think, have the right stuff for the role. They’re at ease in social settings. They know how to strike up conversations. They don’t shrink from making requests. Little wonder, then, that scholars such as Michael Mount of the University of Iowa and others have shown that hiring managers select for this trait when assembling a sales force.

The conventional view that extroverts make the finest salespeople is so accepted that we’ve overlooked one teensy flaw: There’s almost no evidence it’s actually true.

When social scientists have examined the relationship between extroverted personalities and sales success — that is, how often the cash register rings — they’ve found the link to be, at best, flimsy. For instance, one of the most comprehensive investigations, a meta-analysis of 35 studies of nearly 4,000 salespeople, found that the correlation between extroversion and sales performance was essentially zero (0.07, to be exact).

Does this mean instead that introverts, the soft-spoken souls more at home in a study carrel than on a sales call,are more effective? Not at all.

The answer, in new research from Adam Grant, the youngest tenured professor at the University of Pennsylvania’s Wharton School of Management, is far more intriguing. In a study that will be published later this year in the journal Psychological Science, Grant collected data from sales representatives at a software company. He began by giving reps an often-used personality assessment that measures introversion and extroversion on a 1-to-7 scale, with 1 being most introverted and 7 being most extroverted.

Then he tracked their performance over the next three months. The introverts fared worst; they earned average revenue of $120 per hour. The extroverts performed slightly better, pulling in $125 per hour. But neither did nearly as well as a third group: the ambiverts.

Read More