EVENT-RELATED BRAIN POTENTIALS AND CASE INFORMATION IN SYNTACTIC AMBIGUITIES

In an ERP study, German sentences were investigated that contain a cas e-ambiguous NP that may be assigned accusative or dative case. Sentenc es were disambiguated by the verb in final position of the sentence. A s our data show, sentences ending in a verb that assigns dative case t o the ambiguous NP elicit a clear garden-path effect. The garden-path effect was indicated by a broad centro-posterior negative shift that o ccurred between 300 and 900 msec after the dative-assigning verb was p resented. No enhanced P600 following the misanalysis was observed. Nou n phrases whose case ambiguity was resolved in favor of accusative cas e and unambiguously dative-marked NPs did not trigger significant ERP differences. We will discuss the implications of our results for parsi ng and its neuropsychological correlates. The results of this study su pport a parser design according to which the so-called structural case (nominative or accusative) is assigned without any delay in the absen ce of morpho-lexical counterevidence. It is argued that the enhancemen t of a negative ERP component with a ''classical'' N400 topography ref lects the difficulty of reanalysis due to reaccessing morpho-lexical i nformation that lies outside the domain of the parsing module. Consequ ently, ERP responses to garden-path effects are not confined to a late positivity but vary depending on the level of processing involved in reanalysis. The fact that garden-path effects may also elicit an N400 can be linked to the nonhomogeneous linguistic properties of the const ructions from which they arise.