Advaith Vijayasankaran

Investigating The Effects of Age and Bilingualism on Language Development

Started May 8, 2025

Abstract or project description

This secondary analysis study examines how age and bilingualism, particularly the linguistic distance between a bilingual infant’s two languages, influence infants’ preference for infant-directed speech (IDS). IDS, distinguished by exaggerated prosody and simplified syntax, is known to facilitate early language development. While infants generally prefer IDS to adult-directed speech (ADS), prior research has produced mixed findings regarding the effects of age and bilingual experience on this preference. I hypothesized that as the language distance of the languages a bilingual infant is exposed to increases, their IDS preference will increase as well. Using data from A Multilab Study of Bilingual Infants: Exploring the Preference for Infant-Directed Speech, which included 718 infants (333 bilingual, 384 monolingual) tested across 17 laboratories in seven countries, I tested whether IDS looking time and IDS preference (IDS looking time relative to adult-directed speech looking time)  varied as a function of age or language background. Results indicated no significant main effect of age, but monolingual infants demonstrated significantly longer IDS looking times than bilingual infants, without a substantial difference in IDS preference. This suggests that extended attention to IDS does not necessarily imply a stronger relative preference for it. In a secondary analysis, linguistic distance was coded on a scale of 1-3 based on how linguistically different a bilingual’s languages are. I found that infants learning closely related languages tend to show *both *a higher IDS preference and IDS looking time compared to infants learning more distantly related languages. These results do not support the view that infants’ preference for IDS represents a universal mechanism for language learning, as this study found that the languages a bilingual infant learns do influence that preference. Future research using larger samples that measure IDS preference in multiple languages is needed to clarify how bilingualism affects language development.