Islands in the grammar? Standards of evidence

When considering how a complex system operates, the observable behavior depends upon both architectural properties of the system and the principles governing its operation. As a simple example, the behavior of computer chess programs depends upon both the processing speed and resources of the computer and the programmed rules that determine how the computer selects its next move. Despite having very similar search techniques, a computer from the 1990s might make a move that its 1970s forerunner would overlook simply because it had more raw computational power. From the naïve observer’s perspective, however, it is not superficially evident if a particular move is dispreferred or overlooked because of computational limitations or the search strategy and decision algorithm. In the case of computers, evidence for the source of any particular behavior can ultimately be found by inspecting the code and tracking the decision process of the computer. But with the human mind, such options are not yet available. The preference for certain behaviors and the dispreference for others may theoretically follow from cognitive limitations or from task-related principles that preclude certain kinds of cognitive operations, or from some combination of the two. This uncertainty gives rise to the fundamental problem of finding evidence for one explanation over the other. Such a problem arises in the analysis of syntactic island effects – the focu

The source ambiguity problem: Distinguishing the effects of grammar and processing on acceptability judgments

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

Cognitive constraints and island effects

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 nonstructural manipulations that leave island structures intact can radically alter judgments of island violations. We argue here, building on work by Paul Deane, Robert 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 that 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 nonisland filler-gap constructions by manipulating a single nonstructural 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, resulting in unacceptability. We examine the implications of these findings for the grammar of filler-gap dependencies

Structured Access in Sentence Comprehension

This thesis is concerned with the nature of memory access during the construction of long-distance dependencies in online sentence comprehension. In recent years, an intense focus on the computational challenges posed by long-distance dependencies has proven to be illuminating with respect to the characteristics of the architecture of the human sentence processor, suggesting a tight link between general memory access procedures and sentence processing routines (Lewis & Vasishth 2005; Lewis, Vasishth, & Van Dyke 2006; Wagers, Lau & Phillips 2009). The present thesis builds upon this line of research, and its primary aim is to motivate and defend the hypothesis that the parser accesses linguistic memory in an essentially structured fashion for certain long-distance dependencies. In order to make this case, I focus on the processing of reflexive and agreement dependencies, and ask whether or not non-structural information such as morphological features are used to gate memory access during syntactic comprehension. Evidence from eight experiments in a range of methodologies in English and Chinese is brought to bear on this question, providing arguments from interference effects and time-course effects that primarily syntactic information is used to access linguistic memory in the construction of certain long-distance dependencies. The experimental evidence for structured access is compatible with a variety of architectural assumptions about the parser, and I present one implementation of this idea in a parser based on the ACT-R memory architecture. In the context of such a content-addressable model of memory, the claim of structured access is equivalent to the claim that only syntactic cues are used to query memory. I argue that structured access reflects an optimal parsing strategy in the context of a noisy, interference-prone cognitive architecture: abstract structural cues are favored over lexical feature cues for certain structural dependencies in order to minimize memory interference in online processing

How do individual cognitive differences relate to acceptability judgments?: A reply to Sprouse, Wagers, and Phillips

Sprouse, Wagers, and Phillips (2012) 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 they 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

The Varying Roles of Morphosyntax in Memory and Sentence Processing: Retrieval and Encoding Interference in Brazilian Portuguese

Cue-based retrieval models have largely been adopted as a description of how linguistic content is retrieved from memory. Under this framework, a retrieval cue is projected at the site of a dependency and matched with its target using a parallel matching procedure (e.g., Van Dyke and Lewis, 2003). Although this is a highly efficient mechanism, retrieval difficulties occur when there are multiple items stored in memory that serve as potential matches for the retrieval cue(s), which is known as similarity-based interference (SBI). Several studies have demonstrated that a wide variety of linguistic information can generate SBI effects, but the theory of what serves as a retrieval cue is still relatively unknown (Van Dyke and Johns, 2012). Moreover, recent empirical evidence has proposed the similarity-based interference can arise from another source: the encoding mechanism (e.g., Villata et al., 2018). Three hypotheses are addressed regarding three potential retrieval mechanisms: (1) a retrieval mechanism that only relies on cues relevant to the dependency being resolved, (2) one that is sensitive to all of the features overlapping between a target and distractor(s), or (3) a mechanism that is primarily sensitive to relevant features but produces additive interference effects for irrelevant features. Moreover, a fourth hypothesis investigates if similarity-based interference also arises from the encoding mechanism. In an attempt to disentangle whether sentence processing disruptions occur as a result of retrieval mechanism (1) + encoding interference or due to one of the other mechanisms, 7 self-paced reading experiments were conducted on Brazilian Portuguese. In all of the studies, number was a relevant feature for the resolution of the grammatical dependency (subject-verb dependency in relative clauses or wh-remnant-correlate pairing in sluices) and gender features varied in their relevance. The rationale behind using these dependencies and features was to test whether syntactically relevant features produced stronger interference effects than irrelevant features and to propose why these results differed. Any findings that showed that irrelevant feature (gender) matches caused reading time slowdowns or decreased comprehension question accuracy before the retrieval site were interpreted as encoding interference.Although results vary across studies, the findings in this thesis provide the most support for a combination of retrieval (mechanism 1) and encoding interference. Although the other two retrieval mechanisms cannot be completely ruled out at this time, the evidence that gender produces earlier and weaker effects reminiscent of encoding interference and that number produced interference reflective of retrieval interference are novel

Retrieval Effects in Sentence Parsing and Interpretation

This dissertation is an investigation into the memory mechanisms that support parsing and how they constrain parsing success. Constraints can occur from two directions: the ability to store items participating in grammatical dependencies, or else the dependencies themselves, and the ability to retrieve items required for creating grammatical dependencies. A review of available evidence regarding memory constraints on parsing suggests that although attention has more often been focused on the storage constraints on parsing, the evidence is actually more consistent with a retrieval account of parsing breakdown. I present a framework for investigating retrieval effects in parsing, based on existing models of associative memory retrieval and illustrate how the work traditionally carried out by the parser can be understood as an instance of working memory retrieval. Five experiments present new evidence in support of the retrieval approach. Two of these illustrate effects of semantic interference, in which semantic properties of candidate NPs affect the ability to complete grammatical dependencies, and the remaining three illustrate effects of referential interference, in which the availability of items in the situation model affect parsing success. It is argued that storage accounts of parsing breakdown cannot account for these results, promoting the conclusion that an associative memory mechanism underlies both parsing and sentence interpretation