We next tried to define what characteristics distinguished the smarter teams from the rest, and we were a bit surprised by the answers we got. We gave each volunteer an individual I.Q. test, but teams with higher average I.Q.s didn’t score much higher on our collective intelligence tasks than did teams with lower average I.Q.s. Nor did teams with more extroverted people, or teams whose members reported feeling more motivated to contribute to their group’s success.

Instead, the smartest teams were distinguished by three characteristics.

First, their members contributed more equally to the team’s discussions, rather than letting one or two people dominate the group.

Second, their members scored higher on a test called Reading the Mind in the Eyes, which measures how well people can read complex emotional states from images of faces with only the eyes visible.

Finally, teams with more women outperformed teams with more men. Indeed, it appeared that it was not “diversity” (having equal numbers of men and women) that mattered for a team’s intelligence, but simply having more women. This last effect, however, was partly explained by the fact that women, on average, were better at “mindreading” than men.

--Anita Wooley, Thomas W. Malone. and Christopher Chabris, Why Some Teams Are Smarter Than Others, New York Times, January 16. 2015