The window to the bilingual mind: Eye movements reveal psycholinguistic grain sizes of bilingual spoken word recognition

Although there are common phonological units across different languages, previous studies have shown that individual differences of language proficiency affect sound unit preferences in monolingual and bilingual speakers. The cross-language lexical activation of phonological representations in bilingual minds can provide a great opportunity for testing hypotheses about how this key factor modulates the cross-linguistic phonological transfer across languages. In this study, I used the eye-tracking technique and quantitative methods (i.e., growth curve analysis and multilevel regression) to examine how individual differences in language proficiency affect cross-language phonological unit size transfer in Chinese-English bilinguals. Participants heard a spoken word and were asked to identify its corresponding picture from an array that included a target picture, a within-language phonological competitor picture, and two phonologically unrelated control pictures. Growth curve analysis was used to analyze the proportion of eye fixations to target and competitor pictures during spoken word recognition. I found that Chinese-English bilinguals with increased English proficiency showed higher fixation proportions to smaller Chinese phonological units (i.e., onset and rime units), even though these units are not major processing units for Chinese spoken word recognition. This result suggested that the variation of the second language (L2) English proficiency modulated the first language (L1) Chinese phonological sensitivity to finer-grained unit sizes. Moreover, Chinese-English bilinguals demonstrated higher fixation proportions to the L1 phonological unit (i.e., the consonant–vowel unit, CV unit) when they recognized L2 spoken words, reflecting the idea that the CV unit was transferable across language boundaries, from Chinese to English. This transfer pattern suggests that Chinese-English bilinguals might employ both L1 and L2 phonological units while recognizing spoken words. Together, the findings provide evidence that bilinguals co-activated L1 and L2 phonological units and that the cross-linguistic phonological transfer was modulated by individual differences in language proficiency