The Syntax-discourse Divide: Processing Ellipsis.

VP-ellipsis and sluicing are forms of ellipsis that can cross a sentence boundary. We present a series of comprehension studies on these forms of ellipsis to elucidate their processing and the relation of syntactic and discourse processing. One set of studies examines the hypothesis that the representation of elided material is syntactically structured. We present evidence supporting the hypothesis and tentatively attribute the effects to sharing of the structure of the antecedent constituent, with structure building or substitution of a variable for a constituent permitted if it is licensed by the syntactic principles of the language. Another set of studies tests the hypothesis that a new utterance is preferentially related to the main assertion of the preceding utterance, which is typically a constituent high in the syntactic tree. The results suggest that discourse processing differs from syntactic processing, where the most accessible material is recent material found low in the syntactic tree. A final set of studies examines the interplay of the syntactic processor, which may not violate "islands," and the discourse processor, which may, in the processing of ellipsis sentences involving islands. A novel explanation is offered for the observation (Ross 1967) that sluicing out of relative-clause islands is grammatical except when sprouting is required.