The role of inhibitory control in the phonological processing of bilinguals during language switching

Bilingual individuals demonstrate the capacity to choose the intended language while inhibiting interference from unintended languages, sparking debates on the cognitive mechanism responsible for this successful selection. While most studies have focused on inhibition at the lemma level, fewer have delved into the cognitive mechanisms of language switching at the phonological level, with even fewer exploring the direct relationship between inhibition ability and switch costs at the phonetic level. This study aimed to investigate the occurrence of inhibitory control at the phonetic level during speech production when transitioning between Chinese and English. Employing a mixed design with both within-subjects and between-subjects components, the study involved switch and non-switch trials in both L1-L2 and L2-L1 transitions, across three groups categorized by inhibition ability levels (high, mid, and low). The investigation unfolded in two main parts: firstly, scrutinizing the impact of language switching on specific phonetic features in a cued picture naming task; and secondly, exploring the potential direct link between inhibition ability and switch costs at the phonetic level, specifically focusing on the voice onset time of stops. The results unveiled asymmetrical switch costs in the voice onset time of stops when transitioning into the dominant language (L1) for Chinese-English bilinguals, indicating a robust manifestation of inhibitory control at a specific linguistic juncture. Furthermore, a notable correlation emerged between inhibition abilities and switch costs (VOT cost), showcasing that stronger inhibition abilities correlated with reduced costs in voice onset time. Thus, the study suggests that inhibitory control may be imperative in bilingual language tasks, aiding in the suppression of cross-linguistic phonetic influences, and that enhanced inhibition abilities could mitigate the impact of the other language during language switching for Chinese and English bilinguals.