Dynamic integration of pragmatic expectations and real-world event knowledge in syntactic ambiguity resolution

Dynamic Integration of Pragmatic Expectations and Real-World Event Knowledge in Syntactic Ambiguity Resolution Klinton Bicknell (kbicknell@ling.ucsd.edu) Department of Linguistics, UC San Diego 9500 Gilman Drive #108, La Jolla, CA 92093-0108 USA Hannah Rohde (hannah@northwestern.edu) Department of Linguistics, Northwestern University 2016 Sheridan Road, Evanston, IL 60208 USA Abstract This paper presents the results of a sentence completion study and a self-paced reading experiment involving a relative clause attachment ambiguity. Our results provide evidence that com- prehenders resolve local structural ambiguity during incremen- tal sentence processing by combining expectations about up- coming discourse continuations with their knowledge of typi- cal relationships between event participants. We interpret these results as supporting an account in which comprehenders dy- namically integrate cues from an in-principle unbounded range of sources during language comprehension. Keywords: Syntactic ambiguity resolution; discourse process- ing; event knowledge. Introduction Psycholinguistic research shows that comprehenders rely on cues of many different types during language processing. We distinguish between two general explanations of the way that comprehenders store and use these cues. One possibil- ity is that comprehenders appeal to a broad set of knowledge sources including discourse pragmatics and real-world event knowledge, integrating cues from this arbitrarily large set of sources as they incrementally process a sentence (an ‘arbi- trary integration’ account). As Willits, Sussman, and Amato (2008) point out, however, another possibility is that com- prehenders merely appear to be integrating cues from many sources, but instead are making use of simpler and easier to calculate statistical contingencies (correlated with knowledge sources such as event knowledge and discourse pragmatics) such as cooccurrence patterns (a ‘simple statistics’ account). There is evidence from a variety of domains that compre- henders make use of both simple and more complex statisti- cal models of linguistic events. For example, eye movements during reading can be significantly predicted using very sim- ple probabilities such as the transitional probability from one word to the next (McDonald & Shillcock, 2003) as well as more complex probabilities such as the likelihood of a word given the preceding syntactic structure (Demberg & Keller, 2008). Also, the omission of optional material in language production (e.g., the rate of omission of optional that) has been found to vary with the predictability of the next word given the preceding syntactic context within the sentence (Levy & Jaeger, 2007). There is also evidence that online processing is sensitive to a broader set of knowledge sources including discourse prag- matics and real-world event knowledge. For example, Simner and Pickering (2005) show that expectations about upcom- ing discourse continuations are sensitive to the discourse’s causal structure. Comprehenders also appear to readily in- tegrate their real-world knowledge of typical events during processing. Priming studies have shown facilitation between verbs and their typical agents, patients, instruments, and lo- cations (e.g., arresting∼criminal or spoon∼stirred) within 250 ms (McRae, Hare, Elman, & Ferretti, 2005; Ferretti, Ku- tas, & McRae, 2007). Experiments using self-paced reading and event-related potentials have also shown that comprehen- ders’ use of event knowledge extends beyond single verb-to- participant dependencies and includes more complex knowl- edge about specific combinations of verbs, agents, patients, and instruments (Bicknell, Elman, Hare, & McRae, 2008; Matsuki, McRae, Tabaczynski, Elman, & Hare, 2008). To- gether, these studies suggest that comprehenders store a large body of knowledge about typical events and the relationships between event participants, and can deploy that knowledge rapidly during language comprehension. In a recent paper, however, Willits et al. (2008) present evi- dence that some of the results mentioned above as support for the use of real-world event knowledge can also be modeled using simple word co-occurrence patterns. Specifically, they show that in Ferretti et al.’s (2007) priming study, the proba- bility of the target occurring within 10 words of the prime in Wikipedia is higher in precisely those conditions that showed significant facilitation. Willits et al. argue that much of the evidence standardly taken to support the integration of a wide variety of knowledge sources can likewise be explained by simpler statistical models over linguistic events. To test whether the simple statistics account is sufficient, we will present data that seem to demand an account in which comprehenders dynamically combine cues from real-world knowledge and discourse pragmatics during incremental sen- tence comprehension. In order to distinguish these two ac- counts, we refine the design of one of the existing studies that could perhaps be reinterpreted in terms of simple statistics (Rohde, Levy, & Kehler, 2008). Rohde, Levy, & Kehler (2008) Rohde et al. (2008) used contexts in which the syntactic at- tachment site of a relative clause is temporarily ambiguous.