Blurred linguistic boundaries: Overlapping neural signatures of syntactic processing in second language and regional variant

The main objective of this study is to examine the patterns of syntactic processing in bidialectalism through an event-related potential (ERP) approach. By analyzing the neural response patterns of bilectals during the processing of syntactic violations, we gained valuable insights into the characteristics of syntactic processing in bidialectalism. These characteristics were then compared to those of bilinguals based on previous research findings. We ultimately discovered that the syntactic processing patterns of bilectals and bilinguals overlapped significantly and that both their neural responses to syntactic violations are significantly influenced by cross-linguistic interference (CLI). In addition, several linguistic factors, such as nativeness, syntactic distance (typological distance) between languages/dialects, linguistic dominance, and linguistic exposure, were found to greatly influence the direction and extent of CLI transfer, particularly at the processing level. Overall, the present study primarily discusses the overlapping neural signatures of syntactic processing found between bilectals and bilinguals. These overlaps are connected to the sociolinguistic interpretation of bidialectalism, implying that there exists no intrinsic disparity between bidialectalism and bilingualism, but rather quantitative differences, suggesting that the boundaries between them are blurred. The present study is a quantitative study using a highly temporal-resolution electroencephalographic (EEG) technique to capture the brain activity of bilectals during sentence processing, and the obtained EEG signals were quantified and employed in regression analysis. Given that Norway has a dialectal usage profile that aligns well with the current study, 101 Norwegian bilectals are recruited for this study. In the experiment, the sentences presented to participants have manipulated in terms of gender or number agreement between subject nouns and predicate adjectives and presented in the form of visual stimuli. Participants’ neural responses during the processing of these sentences are quantified and serve as dependent variables to examine the impacts of various factors on bilectals’ syntactic processing. In conclusion, our main findings can be summarized as follows: a) both bilectals and bilinguals’ L2/D2 syntactic processing can achieve a native-like pattern with the modulation of linguistic exposure, b) bilectals exhibit two dialect-independent syntactic representations, c) the effects of CLI in bilectals are bidirectional and can be observed at a processing level, and d) the syntactic processing of bilectals can be influenced by the CLI transferred from official language, such as English. In summary, the syntactic processing between bidialectalism and bilingualism shows many overlaps at the level of online processing