The acceptance of pre- and postverbal subjects by L1 and L2 Italian speakers: The role of unaccusativity and information structure

An open question in second language research is how much L2 speakers are sensitive to syntactic and discourse-related factors when parsing word order alternations. The Interface Hypothesis predicts difficulty when mapping discourse onto syntax, while other accounts predict stronger reliance on contextual information to compensate for difficulties with syntactic representation. We examined these accounts by testing the acceptability of pre- and postverbal subject sentences in Italian as a function of their discourse-related conditions (broad vs. narrow focus) and the syntactic structure in which they appeared (transitive vs. unaccusative). The canonical subject position in Italian is preverbal, but postverbal subjects are licensed in narrow focus in transitive structures, and in both broad and narrow focus in unaccusative structures. We compared transitive structures with clitic left-dislocation (OClitVS) with unaccusative structures with locative inversion (LocVS). A speeded acceptability judgment task revealed qualitatively similar effects of information structure and unaccusativity constraints on word order in the judgments of both first (L1) and second language (L2) speakers of Italian (with L1 German). However, L2 speakers accepted OClitVS structures in broad focus more often than L1 speakers, in line with the Interface Hypothesis. L2 speakers also took longer to judge LocVS structures, in line with accounts predicting difficulty at the syntactic level. An exploratory cluster analysis revealed that the overacceptance of OClitVS structures in broad focus was modulated by L2 proficiency and exposure, while there was no evidence of similar effects for the delayed judgments of LocVS structures. Results from preverbal subject sentences revealed that canonicity was a stronger cue for acceptance than discourse appropriateness in both L1 and L2 speakers.