Cognitive Constraints on Syntactic Islands

Competence-based theories of island effects play a central role in generative grammar, yet the graded nature of many syntactic islands (Deane 1991; Kluender 1992) has never been properly accounted for. Indeed, syntactic accounts of island effects have persisted in spite of a wealth of data suggesting that island effects are not categorical in nature and that non-structural manipulations (i.e. ones leaving the island intact) can radically alter judgments of island violations. We argue here that processing (performance) factors have the potential to account for this otherwise unexplained variation in acceptability judgments. Processing factors are known to play a significant role in the perception of (un)acceptability (e.g. Chomsky & Miller, 1963); however, processing-based accounts of variation in acceptability judgments are not well-represented in the literature. Notably, syntactic island constructions are characterized by linguistic properties that are predicted to incur heavy processing costs and which have been noted by previous authors as markedly influencing acceptability judgments. Self-paced reading experiments and controlled acceptability studies are used here to explore the relationship between processing costs and judgments of acceptability. In each of the three self-paced reading studies, the data indicates that the processing cost of different types of island violations can be significantly reduced to a degree comparable to that of non-island filler-gap constructions by manipulating a single non-structural factor. Moreover, this reduction in processing cost is accompanied by significant improvements in acceptability. This evidence favors the hypothesis that island-violating constructions involve numerous processing pressures that aggregate to drive processing difficulty above a threshold so that a perception of unacceptability ensues. We also consider the extent to which competence-based theories can account for these and related results and the implications of these findings for syntactic theories of filler-gap dependencies.