Avoiding gaps in Romance: a processing foundation for the Merge over Move principle?

Existing evidence suggests that the parser avoids positing a movement dependency if the grammar allows it. By investigating the processing of two syntactic ambiguities that have not been previously studied, we provide more conclusive evidence for this parsing bias in two Romance languages: French and Italian. In two acceptability judgment experiments and two self-paced reading studies, we found that sentences that involved a filler-gap dependency (indirect questions in Italian and free relatives in French) were dispreferred compared to sentences involving the same lexical material but no filler-gap dependency (declarative complement clauses in both languages). Crucially, the filler-gap dependency was not dispreferred when there was no available competitor. We discuss these results as also relevant for syntactic theory and for the questionable status of Merge over Move as a grammatical principle.