The effect of proficiency on phonological encoding in L2 speech production

During speech production, bilinguals need to encode target words phonologically before articulation, and the encoding units differ across languages. It remains an open question whether bilinguals employ the encoding unit in their L1 or L2 for phonological encoding. The present study examined the primary unit of phonological encoding in L2 speech production by Mandarin Chinese-English bilinguals with high and low L2 proficiency using the picture-word interference paradigm. Results revealed segmental priming effects with one or two segments and syllabic overlap at varied stimulus onset asynchronies (SOAs), for both groups in their L2 speech production. Additionally, the results demonstrated increasing effects with more overlapping segments for both groups, and the facilitation effects decreased as SOA increased. These results indicate that bilinguals encode English words with the segment as a primary planning unit regardless of their L2 proficiency. The time course of segmental encoding in L2 production is also discussed. © The Author(s), 2025. Published by Cambridge University Press.