On one side of the dance floor, you have the life of the party and on the other side there's the wallflower. For years, the thinking was that you were one or the other. Leader or follower. Bold or shy. Extrovert or introvert.

Of course, it's not that simple. It never has been.

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Researchers have long identified an extrovert-introvert in-between, a more balanced and less harsh personality type called an ambivert. (The term could have been coined as far back as the 1920s, though some credit German-born psychologist Hans Eysenck in the 1940s.) The idea has gained more traction in recent years with a paper in the journal Psychological Science, written by Adam Grant, a professor at the Wharton School of Business at the University of Pennsylvania.

Most experts now agree that a large majority of people can't be labeled as extroverts (or, sometimes, extraverts) or introverts — though anyone can become extroverted or introverted in different situations. Instead, there is this sometimes silent majority that is neither the loud and obnoxious or the timid and meek. They're somewhere in the middle.

They are the ambiverts. And you might be one if …

1. You're really good at selling your point, and people seem to trust you.

Grant's dive into ambiversion looked specifically at salespeople and concluded that — get this — salespeople are more successful when they push less (back off, extroverts!) and listen more.

"Because they naturally engage in a flexible pattern of talking and listening, ambiverts are likely to express sufficient assertiveness and enthusiasm to persuade and close a sale," Grant wrote in the paper, "but are more inclined to listen to customers' interests and less vulnerable to appearing too excited or overconfident."

2. You get along well with the quiet co-worker and the brassy boss.

Extroverts, the theory goes, can spend too much time being the center of it all, meaning they miss out on much on the periphery. Introverts never get into the middle of it all. Rarely do the two types meet in any meaningful way. But ambiverts …

"It is like they're bilingual," behavior expert Daniel Pink, who hosts the National Geographic television series Crowd Control, told the Wall Street Journal. "They have a wider range of skills and can connect with a wider range of people in the same way someone who speaks English and Spanish can."

3. You're fine with meeting new people, but you might not go out of your way to do it.

A problem with ambiverts — according to Grant — is that, unlike their contemporaries on either ends of the personality spectrum, ambiverts are a little less decisive on what to do in certain situations. So even if it might be socially or somewhat politically advantageous to shake some hands and kiss some babies, in certain situations, at certain times, ambiverts might choose to lay back.

That's not ideal. But it’s not always bad, Grant told the Journal.

"Read each situation more carefully," Grant suggests to ambiverts, "and ask yourself, 'What do I need to do right now to be most happy or successful?'"

4. Given the choice of nightclubbing with friends or sitting home alone … well, it depends

Grant cites a study that refutes the idea that all extroverts need crowds and all introverts need solitude and time for reflection. The study found that both introverts and extroverts are most energized when they're being talkative or assertive.

The difference is how they react to all that incoming energy. Extroverts want more. After a while, introverts need a break.

"Extraverts crave stimulating activities like skydiving and stimulating beverages sold at Starbucks," Grant wrote in the Huffington Post. "Introverts are more likely to retreat to a quiet place, but they're very happy to bring someone else with them."

Ambiverts, on the other hand, can simply play it down the middle.

"Ambiverts are in that nice zone, in that sweet spot," psychologist Brian Little told the Huffington Post, "where they're able to act out of character as a pseudo-introvert or a pseudo-extravert, without paying the nervous system costs."

Pink has a four-minute quiz on his website to show people which end of the personality spectrum, extrovert or introvert, they fall on. What it really shows is that being somewhere in the middle — being an ambivert — is not a bad place to be at all.