The Changing Frequency and Functions of Onomatopoeia in Early Interactions: From First Words to Vocabulary Spurt

Onomatopoeia – words that mimic sounds like vroom , quack , and beep – are prominent in early vocabularies across languages. Their phonological simplicity may facilitate early production, but they also occur in rich, multimodal caregiver–infant interactions, suggesting a broader communicative role. Using a naturalistic video corpus, we analysed spontaneous interactions between 6 English-speaking parent–child dyads from the onset of word production up to 500 infant word types. Onomatopoeia constituted a higher proportion of infants’ early vocabularies than later ones and were more likely than conventional words to be reduplicated and produced with playful prosody by both infants and caregivers. Onomatopoeic words co-occurred with iconic gestures in caregiver speech more often than conventional words did, whereas pointing was more tightly linked to conventional words for both infants and caregivers. Enactment – such as performing animal sounds – was the most frequent function of onomatopoeia for both infants and caregivers, although infants used onomatopoeia as referential labels more often than caregivers. In addition, caregivers increasingly used onomatopoeia to refer to non-present referents as children’s vocabulary grew, highlighting a developmental shift in communicative use. These findings suggest that onomatopoeia support early engagement and participation in social routines, functioning not only as lexical placeholders but as enactments that allow infants and caregivers to co-perform meaning. We argue that onomatopoeia are prevalent in early interactions because they feature in rich exchanges that are socially rewarding for both infants and caregivers.