The L2 accent effect in the processing of grammatical and phonological violations. A German-Polish ERP study

L2 accents can hinder comprehension, but their impact on violation processing has not yet been fully clarified. This study examined how L2 accents shape the processing of grammatical and phonological violations in German and Polish. Using ERPs, we analysed neural responses reflecting early phonological analysis (PMN), lexical-semantic integration (N400), and late reanalysis (P600). Prior studies reported diminished ERP effects for grammatical deviations under L2-accented speech. We expected similar modulations for phonology. The results differed between languages: Polish listeners exhibited an early negativity to phonological violations limited to L2-accented input, whereas Germans did not. Independently of L2 accent, both violation types elicited an enhanced N400 effect across languages, though in German the effect was delayed. Finally, both violations elicited an increased late positivity, which was attenuated by L2-accentedness in German but not in Polish. The findings indicate that L2 accents do not uniformly reduce violation processing but interact with language-specific properties.