When we hear the word "leader," what's the first thing that comes to mind?

Often, we will conjure up the image of a smooth-talking man in a Tom Ford suit. He is laughing, mid-conversation with a subordinate, and patting his colleague sternly on the shoulder.

It's nothing new. In our minds, the word "leader" has grown synonymous with the words "outgoing" and "assertive." We think of business leaders and corporation tycoons almost the way we think of salesmen--as people who feel comfortable making requests and marketing in a social setting.

The only problem with this perception is that there is no scientific evidence that it's actually right.

A meta-analysis performed by professors at Michigan State University has shown that the trait of extroversion aids in many aspects of the workplace but has essentially zero correlation to sales performance.

A compelling study by Adam Grant tells us just that. Grant--who has been recognized as the University of Pennsylvania's Wharton School of Business's top-rated teacher and one of the world's top 40 business professors under 40--collected data from sales reps at a software company.

He gave them personality assessment tests to determine where they fell on the scale of 1-7, with 1 being very introverted and 7 being the most outgoing. When he checked in on their performance for the next three months, however, it was clear that both introverts and extroverts were pulling almost the same average revenue per hour.

Introverts were earning $120 an hour. Extroverts made $125 an hour. Ambiverts, however, were earning hourly revenue of $155 an hour--24% better than the average extrovert.

Ambiverts, in case you've never heard this term before, are those who rank on the scale somewhere between 3-5. They're not overwhelmingly loud and aggressive, like many extroverts are perceived to be. They're not so soft-spoken that their points never get across.

They're right in the middle, able to obtain respect without being domineering and able to connect without being pushovers.

In fact, those who made the most, earning an average of $208 per hour, scored at a 4.0--right in the middle of the scale.

What's even better news? Grant found that the distribution of introverts and extroverts in society is largely the same as that of his study. A couple of us fall at either extreme but, for the most part, the vast majority of us can be found somewhere in the middle.

So maybe--in this case--it is better to enjoy being somewhat moderate.

Here, in the majority of the population, we have somehow found the perfect balance.