Learning two languages from birth shapes pre-attentive processing of vowel categories: Electrophysiological correlates of vowel discrimination in monolinguals and simultaneous bilinguals

Using event-related brain potentials (ERPs), we measured pre-attentive processing involved in native vowel perception as reflected by the mismatch negativity (MMN) in monolingual and simultaneous bilingual (SB) users of Canadian English and Canadian French in response to various pairings of four vowels: English /u/, French /u/, French /y/, and a control /y/. The monolingual listeners exhibited a discrimination pattern that was shaped by their native language experience. The SB listeners, on the other hand, exhibited a MMN pattern that was distinct from both monolingual listener groups, suggesting that the SB pre-attentive system is tuned to access sub-phonemic detail with respect to both input languages, including detail that is not readily accessed by either of their monolingual peers. Additionally, simultaneous bilinguals exhibited sensitivity to language context generated by the standard vowel in the MMN paradigm. The automatic access to fine phonetic detail may aid SB listeners to rapidly adjust their perception to the variable listening conditions that they frequently encounter.