Within the speech production literature, the debate between the language-universal vs. language-specific functional unit of phonological encoding can also benefit from further research on bilingual speakers, especially bilingual speakers of languages which have been proposed to have different functional units of phonological encoding. In a masked priming experiment, native Mandarin speakers who were highly proficient in English, showed phoneme onset priming in their production of English (Verdonschot et al., 2013). For highly proficient Japanese-English bilinguals the same pattern was revealed, showing sensitivity to the phoneme onset in English (Ida et al., 2015; Nakayama et al., 2016). This suggests that native speakers of a syllabic/moraic language can employ different processing units depending on the language used (i.e., a phoneme-sized unit for phonological encoding in English). Interestingly, while the Japanese-English bilinguals adhered to their native mora-based processing strategy in Japanese (Ida et al., 2015), Mandarin-English bilinguals showed phoneme onset priming even in their production of Chinese (although contingent upon syllable structure sharing between the prime and target) instead of only syllable priming (Verdonschot et al., 2013). One question that arises is what might have modulated the adaptive behavior of bilingual speakers. The question may be adjudicated with more insights from neurophysiological studies.