Separating syntactic memory costs and syntactic integration costs during parsing: the processing of German WH-questions

Event-related brain potentials (ERPs) were recorded while participants processed case-unambiguous German subject and object WH-questions with either a long or a short distance between the WH-filler and its gap. A sustained left anterior negativity was observed for object questions with long filler-gap distance but not for short object questions. This negativity was modulated by individual differences in working memory capacity. No comparable negativity was elicited by WHETHER-questions which did not contain a filler-gap dependency. A positive-going ERP effect was observed for short and long object WH-questions at the position of the second noun phrase. We interpret the sustained negativity as reflecting working memory processes required for maintaining the dislocated object in memory. Processing costs associated with integrating the stored element into the phrase structure representation are indicated by the local positivity. These results support the notion of separable syntactic working memory and syntactic integration cost components as causes of processing difficulty in complex sentences. 2002 Elsevier Science (USA). All rights reserved.