Psycholinguistic evidence for the optional movement of unaccusative subjects in Japanese

Abstract

One of the controversial issues surrounding unaccusativity in Japanese is the surface position of unaccusative subjects. While compelling evidence has been found that the theme subject of an unaccusative verb originates as an internal argument, it is still an open question whether or not the subject moves from its original position to a derived subject position. This article aims to contribute to this debate from a psycholinguistic perspective. We conducted two sentence-processing experiments in which causer adjuncts were used as an indicator of the surface position of the subject. Experiment 1 measured the processing time of unaccusative sentences with causer adjuncts, and it was revealed that sentences in which the causer adjunct preceded the theme subject were processed significantly faster than those in the other order. This result indicates that the canonical surface position of unaccusative subjects is below the adjunct and that subject movement is optional. In experiment 2, we examined whether the movement of unaccusative subjects is linked to givenness, a discourse-pragmatic factor that has been shown to be associated with scrambling. We found that the processing cost of the subject movement was reduced when the moved subject was marked as discourse given, which is consistent with previous studies on scrambled objects. Overall, our study supports the hypothesis that the unaccusative subject need not move to the derived subject position in Japanese.