Children, like adults, use three visible cues—race, gender and age—to arrange their social world. They prefer to make friends with kids similar to them on these traits. New research shows that verbal accents may be equally important in guiding youngsters’ social decisions—in fact, accents may be even more important than race.

Working at Harvard University, developmental psychologist Katherine D. Kinzler and her colleagues first showed American five-year-olds photographs of different children paired with audio clips of voices and asked which ones they preferred as a friend: a child who spoke English, one who spoke French, or one who spoke English with a French accent. Even though the subjects understood the French-accented English, they were almost four times more likely to choose the native English speaker as a friend.

Going one step further, Kinzler and her team showed that an accent is more meaningful than race in signifying whether someone belongs in your social group. Replicating previous research, they found that under silent conditions children chose as potential friends children of the same race. Yet when the potential friends spoke, white children preferred a black child speaking with a native accent over a white child who spoke English with a foreign accent.

Why was accent more important than race? “Race, as a psychological category, may be relatively modern in terms of human evolution,” explains Kinzler, now at the University of Chicago. In prehistoric times, “a neighboring group might have sounded different even if they did not look different,” she says. Preference for our own race might have developed later, after the more ancient preference for our own accent. The next step is to see whether living in bilingual or multilingual countries might change this early inclination.