A self-organized sentence processing theory of gradience: The case of islands

Formal theories of grammar and traditional parsing models, insofar as they presuppose a categorical notion of grammar, face the challenge of accounting for gradient effects (sentences receive gradient acceptability judgments, speakers report a gradient ability to comprehend sentences that deviate from idealized grammatical forms, and various online sentence processing measures yield gradient effects). This challenge is traditionally met by explaining gradient effects in terms of extra-grammatical factors, positing a purely categorical core for the language system. We present a new way of accounting for gradience in a self-organized sentence processing (SOSP) model. SOSP generates structures with a continuous range of grammaticality values by assuming a flexible structure-formation system in which the parses are formed even under sub-optimal circumstances by coercing elements to play roles that do not optimally suit them. We focus on islands, a family of syntactic domains out of which movement is generally prohibited. Islands are interesting because, although many linguistic theories treat them as fully ungrammatical and uninterpretable, experimental studies have revealed gradient patterns of acceptability and evidence for their interpretability. We describe the conceptual framework of SOSP, showing that it largely respects island constraints, but in certain cases, consistent with empirical data, coerces elements that block dependencies into elements that allow them.