One of language's great strengths is its flexibility—words can mean anything we want them to. But not all vocabulary is arbitrary. And according to a paper published in April in the Journal of Personality and Social Psychology, certain types of names are more likely to be given to boys versus girls, based merely on properties of their sound.

For decades researchers have discussed the role of sound symbolism, in which the sound of a word carries meaning regardless of its definition. The most famous example is the bouba/kiki effect: people across cultures and ages associate the made-up word bouba with round objects and kiki with spiky ones. As another example, the open volume in the mouth when pronouncing vowels expresses size; think of how big an event is evoked by splosh versus splish. To explore sound symbolism, Michael Slepian, the new paper's lead author and a researcher at Columbia Business School, says he wanted to “look to a place where people give new names to things all the time: other people.” He and his collaborator at Columbia, Adam Galinsky, also wondered if sounds could convey social information.

In one study, the researchers analyzed 270 million recorded baby names in the U.S. from 1937 to 2013. They found that boys were more likely than girls to receive names beginning with “hard” (voiced) phonemes, which vibrate the vocal cords, such as the A in Adam and the B in Brian. Names starting with “soft” (unvoiced) phonemes, such as the F in Fiona or the H in Heather, were more often assigned to girls than to boys.

In several online experiments, the researchers also showed that people in both the U.S. and India perceived voiced names—whether real or invented, boys' names or girls'—as “harder” than unvoiced ones and thus more masculine. The sound-gender association was strongest in those who most highly endorsed the stereotype of men as tough and women as tender.

Slepian suggests that parents choosing baby names might use this information to play into gender norms—or to buck them.

The First Sound Matters

If a name's initial phoneme is “voiced,” meaning it vibrates the vocal cords, it tends to be judged as “harder” and more masculine. Unvoiced phonemes, formed purely with the tongue and lips, tend to be judged as “softer” and more feminine. Here are some typical—and atypical!—examples:

VOICED UNVOICED ADAM CAROL BARBARA CHARLES DAVID FELICIA EDWARD HOPE GREGORY KATHARINE GERALD PATRICK IAN PHOEBE JESSICA QUEENIE LUKE SARAH MICHAEL SHARON NICHOLAS TINA OWEN THEO ROBERT ULYSSES VINCENT WILLIAM YVETTE ZACHARY

Mouth movements influence word meaning in other ways, too: Words that move from the throat to the lips, such as “gap” and “cab,” are more often associated with avoidance or pushing away. Words that move inward, however, such as “pick” and “big,” tend to suggest approachability.