The object before subject bias and the processing of double-gap relative clauses in Japanese

We report a fragment-completion questionnaire and a self-paced reading experiment investigating relative clauses in Japanese that contain two extraction sites in the same clause. The results indicate that in such double-gap relative clauses there is a preference to fill the object position before the subject position. Previous factors, especially those related to working memory resources, which have often been implicated in extraction preferences, do not predict the patterns observed. The results support the proposal that the accessibility of extraction sites in relative clauses is inversely correlated to the order in which semantic roles are preferentially assigned. We discuss ways of incorporating such a constraint in previous proposals such as expectation-based models.