Processing syntactic violations in the non-native language: Different behavioural and neural correlates as a function of typological similarity?

Despite often featuring in theoretical accounts, the exact impact of typological similarity on non-native language comprehension and its corresponding neural correlates remains unclear. We examined the modulatory role of typological similarity in syntactic violation processing in the non-native language Spanish, for example [el volcán] versus [^∗la volcán], and in cross-linguistic influence. Participants were Italian late learners of Spanish (similar language pair) or German late learners of Spanish (less similar language pair). We measured P600 amplitudes, accuracy and response times. In line with our predictions, we found a larger P600 effect and differential CLI effects for Italian-Spanish speakers compared to German-Spanish speakers. Behaviourally, Italian-Spanish speakers responded slower compared to German-Spanish speakers. Together, these results indicate typological similarity effects in non-native comprehension as reflected in a processing advantage for typologically similar languages, but only at the neural level. These findings have critical implications for the interplay of different languages in the multilingual brain. © The Author(s), 2025.