ERP evidence for different strategies in the processing of case markers in native speakers and non-native learners

For native Japanese participants the general ERP response to the case violations was an N400-P600 pattern. Double accusatives led to an additional enhancement of the P600 amplitude. For the learners a native-like P600 was present for double accusatives and for double nominatives. The additional negativity, however, was present in learners only for double nominative violations, and it was characterized by a different topographical distribution.The results indicate that native listeners use case markers for thematic as well as syntactic structure building during incremental sentence interpretation. The modulation of the P600 component for double accusatives possibly reflects case specific syntactic restrictions in Japanese. For adult language learners later processes, as reflected in the P600, seem to be more native-like compared to earlier processes. The anterior distribution of the negativity and its selective emergence for canonical sentences were taken to suggest that the non-native learners resorted to a rather formal processing strategy whereby they relied to a large degree on the phonologically salient nominative case marker.Case marking is an important linguistic property shared by many languages in the world. In languages that allow free word order, such as Japanese and German, the correct interpretation of case markers is critical for sentence comprehension. For example, in Japanese the meanings of the sentences in (1) and (2) can only be distinguished by the correct interpretation of the nominative (nom.) and accusative (acc.) case markers, ga and o.(1) 'Gakusei-ga kentikuka-o tasuketa.' (Canonical)Student (nom.) architect (acc.) helpedA student helped an architect.(2) 'Gakusei-o kentikuka-ga tasuketa.' (non-canonical)Student (acc.) architect (nom.) helpedAn architect helped a student.While previous psycho- and neurolinguistic studies have shed some light on how case markers are used during online sentence comprehension in a native language (L1) [1-6], not