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.