THE ROLE OF STRUCTURAL INFORMATION IN THE RESOLUTION OF LONG-DISTANCE DEPENDENCIES

Abstract

The main question that this thesis addresses is: in what way does structural information enter into the processing of long-distance dependencies? Does it constrain the computations, and if so, to what degree? Available experimental evidence suggests that sometimes structurally illicit but otherwise suitable constituents are accessed during dependency resolution. Subject-verb agreement is a prime example (Wagers et al., 2009; Dillon et al., 2013), and similar effects were reported for negative polarity items (NPIs) licensing (Vasishth et al., 2008) and reflexive pronouns resolution (Parker and Phillips, 2017; Sloggett, 2017). Prima facie this evidence suggests that structural information fails to perfectly constrain real-time language processing to be in line with grammatical constraints. This conclusion would fall neatly in line with an assumption that human sentence processing relies on cue-based memory (e.g McElree et al., 2003; Lewis and Vasishth, 2005; Van Dyke and Johns, 2012; Wagers et al., 2009, a.m.o.), the key property of which is the fragility of memory search, which can return irrelevant results if they look similar enough to the relevant ones. The attractiveness of such an approach lies in its parsimony: there is independent evidence that general purpose working memory is cue-based (Jonides et al., 2008), so we do not need to postulate any language specific mechanisms. Additionally, the processing of multiple linguistic dependencies can be analyzed within the same theoretical framework. Cue-based approach has also been argued to be the best one in terms of its empirical coverage: some of the experimental evidence was assumed to only be explainable within it (the absence of ungrammaticality illusions in subject-verb agreement is the main example, to which we will return in more detail later). However, recently several other approaches have been suggested which would be able to ac- count for these cases (Eberhard et al., 2005; Xiang et al., 2013; Sloggett, 2017; Hammerly et al., draft.april.2018). These approaches usually assume separate processing mechanisms for different linguistic dependencies, and thus lose the parsimonious attractiveness of cue-based memory models. They also take a different stance on the role of structural information in real-time language processing, assuming that structural cues do accurately guide the dependency resolution. A priori there is no reason why they could not turn out to be true. But given the theoretical attractiveness of cue-based models in which structural information does not categorically restrain processing, it is important to critically evaluate these recent claims. In this thesis, we focus on reflexive pronouns and on the novel pattern reported in Parker and Phillips (2017) and Sloggett (2017): the finding that reflexive pronouns are sensitive to the properties of structurally inaccessible antecedents in some specific conditions (interference effect). The two works report consistent findings, but the accounts they give take opposite perspectives on the role of structural information in reflexive resolution. Our aim in this thesis is to assess the reliability of these findings and to experimentally investigate cases which would hopefully provide clearer evidence on how the structure guides reflexives processing. To this aim, we conduct two direct replications of Parker and Phillips (2017) and four novel experiments further investigating the properties of the interference effect. None of the six experiments provided strong statistical support for the previous findings. After ruling out several possible confounds and analyzing numerical patterns (which go in the expected direction and are consistent with previous results), we conclude that interference effect is likely real, but may be less strong than the previous studies would lead to believe. These results can be used for setting more realistic expectations for future studies regarding the size of the effect and statistical power necessary to detect it. With respect to our main goal of distinguishing between cue-based and alternative accounts of the interference effect, we tentatively conclude that cue-based approaches are preferred; however, one has to assume that some structural features are able to categorically rule out illicit antecedents. Further highly powered studies are necessary to verify and confirm these conclusions.