Competence-based theories of island effects play a central role in generative grammar, yet the graded nature of many syntactic islands has never been properly accounted for. Categorical 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 that leave island structures intact can radically alter judgments of island violations. We argue here, building on work by Deane, Kluender, and others, that processing factors have the potential to account for this otherwise unexplained variation in acceptability judgments. We report the results of self-paced reading experiments and controlled acceptability studies which explore the relationship between processing costs and judgments of acceptability. In each of the three self-paced reading studies, the data indicate 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 examine the implications of these findings for the grammar of filler-gap dependencies.*

Mental representations formed from words or phrases may vary considerably in their feature-based complexity. Modern theories of retrieval in sentence comprehension do not indicate how this variation and the role of encoding processes should influence memory performance. Here, memory retrieval in language comprehension is shown to be influenced by a target’s representational complexity in terms of syntactic and semantic features. Three self-paced reading experiments provide evidence that reading times at retrieval sites (but not earlier) decrease when more complex phrases occur as filler-phrases in filler-gap dependencies. The data also show that complexity-based effects are not dependent on string length, syntactic differences, or the amount of processing the stimuli elicit. Activation boosting and reduced similarity-based interference are implicated as likely sources of these complexity-based effects.

Judgments of linguistic unacceptability may theoretically arise from either grammatical deviance or significant processing difficulty. Acceptability data are thus naturally ambiguous in theories that explicitly distinguish formal and functional constraints. Here, we consider this source ambiguity problem in the context of Superiority effects: the dispreference for ordering a wh-phrase in front of a syntactically “superior” wh-phrase in multiple wh-questions, e.g. What did who buy? More specifically, we consider the acceptability contrast between such examples and so-called D-linked examples, e.g. Which toys did which parents buy? Evidence from acceptability and self-paced reading experiments demonstrates that (i) judgments and processing times for Superiority violations vary in parallel, as determined by the kind of wh-phrases they contain, (ii) judgments increase with exposure while processing times decrease, (iii) reading times are highly predictive of acceptability judgments for the same items, and (iv) the effects of the complexity of the wh-phrases combine in both acceptability judgments and reading times. This evidence supports the conclusion that D-linking effects are likely reducible to independently motivated cognitive mechanisms whose effects emerge in a wide range of sentence contexts. This in turn suggests that Superiority effects, in general, may owe their character to differential processing difficulty.*

Sprouse, Wagers, & Phillips (in press) carried out two experiments in which they measured individual differences in memory to test processing accounts of island effects. They found that these individual differences failed to predict the magnitude of island effects and construe these findings as counterevidence to processing-based accounts of island effects. Here, we take up several problems with their methods, their findings, and their conclusions.First, the arguments against processing accounts are based on null results using tasks that may be ineffective or inappropriate measures of working memory (the n-back and serial recall tasks). The authors provide no evidence that these two measures predict judgments for other constructions that are difficult to process and yet are clearly grammatical. They assume that other measures of working memory would have yielded the same result, but provide no justification that they should. We further show that whether a working memory measure relates to judgments of grammatical, hard-to-process sentences depends on how difficult the sentences are. In this light, the stimuli used by the authors present processing difficulties other than the island violations under investigation and may have been particularly hard to process. Second, the Sprouse et al. results are statistically in line with the hypothesis that island sensitivity varies with working memory. Three out of the four island types in their Experiment 1 show a significant relation between memory scores and island sensitivity, but the authors discount these findings on the grounds that the variance accounted for is too small to have much import. This interpretation, however, runs counter to standard practices in linguistics, psycholinguistics, and psychology. *

In explicit memory recall and recognition tasks, elaboration and contextual isolation both facilitate memory performance. Here, we investigate these effects in the context of sentence processing: targets for retrieval during online sentence processing of English object relative clause constructions differ in the amount of elaboration associated with the target noun phrase, or the homogeneity of superficial features (text color). Experiment 1 shows that greater elaboration for targets during the encoding phase reduces reading times at retrieval sites, but elaboration of non-targets has considerably weaker effects. Experiment 2 illustrates that processing isolated superficial features of target noun phrases—here, a green word in a sentence with words colored white—does not lead to enhanced memory performance, despite triggering longer encoding times. These results are interpreted in the light of the memory models of Nairne, 1990, 2001, 2006, which state that encoding remnants contribute to the set of retrieval cues that provide the basis for similarity-based interference effects.