Emeroy Bernardo enjoys spending time alone, meditating, exercising and working. When he goes out for dinner or drinks with friends, he sometimes quietly observes people’s facial expressions and body language. Often when he’s shopping or running errands, he ignores people he knows—pretending he doesn’t see them—to avoid small talk.

Still, the 27-year-old dance instructor who lives in Glendale Calif., considers himself friendly and meets new people almost everywhere—at the gym, at Starbucks , waiting to board a plane. At parties, Mr. Bernando is often the guy who starts a dance circle and then shows off his break-dancing moves.

Is Mr. Bernardo an introvert or an extrovert?

He is an ambivert, a solid mix of both.

The personality traits of extroversion and introversion fall on a spectrum, and most of experts’ focus has been on the two ends. Now, social psychologists, behavioral scientists and business experts are taking a closer look at the overlooked category smack in the middle—ambiversion—and deciding that people with this trait may have some personal and professional advantages for being adaptable.