Individual variation in epenthetic vowel production by Brazilian Portuguese–Japanese bilinguals

Brazilian Portuguese (BP) and Japanese have phonological repair strategies that involve vowel epenthesis in illicit consonant clusters, but whereas BP inserts /i/, Japanese inserts /ɯ/ as a default. For example, a loanword like ‘TikTok’ is typically produced as /ti.ki.tɔ.ki/ in BP and as /tik.kɯ.tok.kɯ/in Japanese. Here, we ask whether balanced BP–Japanese bilinguals apply their language-specific repair strategies separately, or whether one language’s strategy ‘spills over’ into the other, and if such spillover occurs, which individual factors predict its likelihood. Twenty-two BP–Japanese bilinguals participated in a production task in which they were presented with stimuli containing illicit consonant clusters, e.g., /agbo/, and produced these forms within a BP or Japanese carrier sentence. A model predicting the likelihood of epenthesis type revealed that speakers mostly applied language-specific strategies separately, i.e., /i/-epenthesis in the BP sentences and /ɯ/-epenthesis in the Japanese sentences. However, in some cases, we observed ‘spillover’, e.g., /i/-epenthesis in Japanese or /ɯ/-epenthesis in BP. Individual variation in language dominance, aggregate immersion, and phonolexical perception acuity predicted the likelihood of such spillover. These findings contribute new production data to a growing body of literature on individual variation in bilinguals’ language-specific phonotactics.