P600 responses reveal cross-linguistic co-activation: Grammatical gender processing in Turkish-German bilinguals

This study investigates the neural processing of grammatical gender incongruencies in German in Turkish-German bilinguals using event-related potentials (ERPs) using a connected speech paradigm, taking into account the potential influence of the absence of grammatical gender in their first language (L1; Turkish) on this process. Participants listened to short stories in German that introduced a person or an inanimate object as a referent, followed later by a gendered pronoun that was either congruent or incongruent with the referent's grammatical gender. For bilingual participants, half of the trials were presented entirely in German, and the other half included a language switch whereby: the first part including the referent was presented in Turkish, while the second part including the critical pronoun was in German. German monolinguals served as a control group and listened to the same stories entirely in German. ERP results revealed a robust P600 effect in monolinguals for gender incongruencies both in conditions involving personal and inanimate referents. Bilinguals exhibited a P600 effect only for personal referents in non-switch trials, indicating sensitivity to semantically grounded gender but reduced responsiveness to purely syntactic gender incongruencies. No P600 effect was observed in switch trials, suggesting cross-linguistic interference from Turkish in processing gender information in German. These findings highlight that bilinguals' L1 continues to influence second language (L2) processing, even in early, highly proficient speakers. While monolinguals processed syntactic gender with and without semantic cues similarly, bilinguals relied more on semantic information. Language switching further influenced processing, demonstrating the dynamic effects of cross-linguistic interference. This study underscores the interplay between structural linguistic differences in bilinguals and offers insights into the cognitive and neural mechanisms of bilingual language adaptation. It advances understanding of how bilinguals process gender incongruencies in structurally distinct languages, emphasizing the impact of L1 on L2 even in dominant L2 environments.