An experimental reassessment of complex NP islands with NP-scrambling in Japanese

There is little consensus in the Japanese syntax literature on the question of whether complex NPs with a complement clause headed by to yuu ‘that say’ are islands for NP-scrambling dependencies. To explore this question, we conducted two acceptability judgment experiments using the factorial definition of islands to test the island status of noun complements, relative clauses (which are complex NPs, but uniformly considered islands in the literature), and coordinated NP structures (which are also uniformly considered islands in the literature). Our first experiment yielded clear evidence that relative clauses and coordinated NPs are islands, and that noun complements are not. Our second experiment replicated the relative clause and coordinated NP results, but yielded an inconclusive null result for noun complements. Taken together, our results suggest either that noun complements are not islands, or that noun complements yield a small island effect that cannot be reliably detected at the typical sample sizes of 30-40 participants used here. We also investigated between- and within-participant variability in our results. We observe no evidence of increased between-participant variability for noun complements relative to other islands, and no increase of within-participant variability for noun complements relative to grammatical NP-scrambling, thus corroborating our conclusions. Our results have consequences for a number of issues that have been encoded in current syntactic theories of island effects, including the correlation between syntactic constituent complexity and island status (e.g., number of bounding nodes or phase heads), and the correlation between complementizer deletion and island status (e.g., the complement/adjunct distinction).