Bilingual individuals need to switch their languages to understand different language information in daily life, which is called bilingual comprehensive switching. Prior studies mainly focused on whether the non-target language was activated when bilinguals intended to understand the target language, while inconsistent results were concluded for methodological ambiguities in paradigms. Therefore, this study was designed to further investigate the activation of non-target language in language comprehension with an immediate cross-language priming paradigm and event-related brain potential (ERP) technique.
Twenty Chinese-English bilinguals participated in Experiment 1 where the phonological decision task was conducted, and sixteen Chinese-English bilinguals participated in Experiment 2 where the conceptual decision task was conducted. All of participants were Chinese natives, and English was their unskilled second language. In each experiment, target words (one language) were presented immediately after prime words (another language) which were phonologically related with the translation equivalents of target words (Experiment 1) or semantically related with the translation equivalents of target words (Experiment 2). Participants were instructed to make phonological decision (Experiment 1) or conceptual decision (Experiment 2) to all words presented on the screen. The behavior data and ERP data were recorded and analyzed with target words.
The results showed that, in experiment 1, there were no RTs or P200 difference between phonologically related target words and phonologically unrelated target words no matter the switching direction was L1–L2 or L2–L1. So there was no evidence of cross-language phonological priming, suggesting that the phonological representation of non-target language was not automatically activated when the target words were processed at lexical level. And in experiment 2, significant cross-language semantically priming was found on both behavior and ERP data. Semantically related target words produced faster RTs and a smaller amplitude N400 than semantically unrelated target words in both switching direction. More importantly, the results provided evidence for the priming asymmetry, with larger priming from L1 to L2 than the reverse, and different spatial and temporal N400 priming effect (the ERP difference between two types of target words) between two switching direction. N400 priming effect was distributed towards more posterior sites for L2–L1 switching during the typical N400 window (300-500ms), and N400 priming effect for L1–L2 switching was distributed to more anterior sites, but lasted to 500-700 ms.
In conclusion, results from the current study provide evidence for the semantic activation of non-target Language during the conceptual decision task, and the semantic activation was asymmetry between L1–L2 and L2–L1. But no evidence was found for the lexical activation of non-target Language during the phonological decision task.