In particular, vowel sound and object size associations persist across languages. They show up in made-up words and in real ones—think cat versus the diminutive kitty. They don't require reading ability, as adults and small children make the same links. And they don't even require the ability to speak a specific language, according to new research from the Catholic University of Chile and the International School for Advanced Studies in Italy.
The scientists wondered whether 4-month-old infants would link vowel sound and object size. Babies listened to a series of nonsense syllables featuring O, A, I, and E sounds. Meanwhile, the infants' eye movements were tracked as they watched a screen presenting shapes of different sizes. The tots spent more time looking at larger shapes after hearing O and A sounds, and at smaller shapes after I and E sounds, indicating they made those same sound-size associations.
"The results show an inherent bias," says lead author Marcela Garay Peña. "Very early in development, an infant can infer the relationship between physical property and sound."
It's unknown why humans make connections between object size (and shape, taste, speed, etc.) and word sound. But Peña speculates that cross-sensory associations may be a tool to help us make sense of our surroundings. Being able to categorize objects according to the sound of their names, while also noticing corresponding physical attributes, may help reinforce conceptual ideas like "large" vs. "little." Ultimately, it might allow babies to start making predictions about their world. "An infant may exploit her knowledge about size/sound association to predict the names of new objects," Peña says.
It's unclear whether size/sound associations are built into our brains at birth. The infants in the study may already have learned the connections from adults. "Babies might notice the wider shape of a mother's mouth when cooing A or O sounds and the smaller shape during I or E syllables," she adds.
Further studies could even reveal whether animals make associations between sound and size. "Our study was small," Peña says, "but it opens the door to other research that can help us better understand human development." —Sarah Stanley
Sound is linked to sensory characteristics in more ways than one.
Taste: Sweet tastes are associated with vowel sounds in which the tongue is toward the back and roof of the mouth, as in the word shoe, explains Julia Simner, a University of Edinburgh researcher. Sour tastes match up with vowel sounds where the tongue is low (spa) or forward (span). We may associate pleasant tastes with soothing sounds.
Speed: Open vowel sounds (plod) are associated with slower movement, while I sounds (sprint) are paired with swifter movement, say New York University and University of Southern California researchers. They explored how cross-sensory associations can help companies create provocative product names—branding experts take note.
Color: In a Northwestern University study, subjects listened to sounds while watching visual stimuli. They associated changes in pitch, loudness, and timbre with changes in color. (The findings didn't link specific sounds with colors.) "Humans constantly seek patterns as we attempt to make sense of the world," says researcher Scott Lipscomb.
