Storage and integration in the processing of filler-gap dependencies: an ERP study of topicalization and wh-movement in German.

We recorded event-related brain potentials (ERPs) during the processing of unambiguous German sentences containing different types of filler-gap dependency. Both topicalization constructions and wh-questions were found to elicit a left-anterior negativity (LAN) prior to the processing of the subcategorizing verb, relative to a gap-free control condition. At the subcategorizing verb, sentences containing a wh-dependency produced a parietal positivity (P600) relative to topicalization structures. These results support the claim that separable parsing processes are involved in the processing of syntactic dependencies, with working memory based processes being reflected in an LAN, and the relative difficulty of integrating the filler with its subcategorizer reflected in a P600. Integration cost but not memory cost was found to be influenced by the type of filler-gap dependency involved.