Electrophysiological evidence of language switching for bidialectals: an event-related potential study

Language switching is an important issue in the study of bilinguals. However, how the nontarget language affects the production of the target language under the language switch condition is still unclear, especially for bilinguals who speak two dialects (bidialectals). In the present study, we investigate this issue by a picture-naming task and using an event-related potential (ERP) technique. Two groups of proficient bidialectals, Mandarin (L1)-Cantonese (L2) and Cantonese (L1)-Mandarin (L2), participated in the study. They were required to name pictures with Mandarin or Cantonese under language switching conditions and language nonswitching conditions. The results showed that participants of both groups showed significant longer reaction time, larger P200, and smaller N400 under language switching conditions than that under language nonswitching conditions, which reflects the language switching costs. Moreover, participants of the two groups showed different P200 and N400 between Mandarin-Cantonese (MC) switching conditions and Cantonese-Mandarin (CM) switching conditions. Specifically, MC bidialectals showed larger P200 under the CM condition than that under the MC condition, whereas CM bidialectals showed an opposite P200 pattern (CM conditionCM condition). These findings supported the language-unspecific selection theory. Overall, our study is the first to provide electrophysiological evidence of language switching between two dialects.