Maria Popova mentions am Adam Grant study in reviewing Daniel H. Pink's "To Sell Is Human":

Another fascinating chapter reveals counterintuitive insights about the competitive advantages of introversion vs. extraversion. While new theories might extol the power of introverts over traditional exaltations of extraversion, the truth turns out to be quite different: Pink turns to the research of social psychologist Adam Grant, management professor at the Wharton School of Business at the University of Pennsylvania (my alma mater).

Grant measured where a sample of call center sales representatives fell on the introversion-extraversion spectrum, then correlated that with their actual sales figures. Unsurprisingly, Grant found that extraverts averaged $125 per hour in revenue, exceeding introverts’ $120. His most surprising finding, however, was that “ambiverts” — those who fell in the middle of the spectrum, “not too hot, not too cold” — performed best of all, with an hourly average of $155. The outliers who brought in an astounding $208 per hour scored a solid 4 on the 1-7 introversion-extraversion scale.

Pink synthesizes the findings into an everyday insight for the rest of us:

The best approach is for the people on the ends to emulate those in the center. As some have noted, introverts are ‘geared to inspect,’ while extraverts are ‘geared to respond.’ Selling of any sort — whether traditional sales or non-sales selling — requires a delicate balance of inspecting and responding. Ambiverts can find that balance. They know when to speak and when to shut up. Their wider repertoires allow them to achieve harmony with a broader range of people and a more varied set of circumstances. Ambiverts are the best movers because they’re the most skilled attuners.

Pink goes on to outline “the new ABCs of moving others” — attunement (“the ability to bring one’s actions and outlook into harmony with other people an with the context you’re [sic] in”), buoyancy (a trifecta of “interrogative self-talk” that moves from making statements to asking questions, contagious “positivity,” and an optimistic “explanatory style” of explaining negative events to yourself), and clarity (“the capacity to help others see their situations in fresh and more revealing ways and to identify problems they didn’t realize they had”).