Local syntactic coherence interpretation. Evidence from a visual world study.

Local syntactic coherence interpretation. Evidence from a visual world study. Lars Konieczny (lars@cognition.uni-freiburg.de) Daniel Muller (daniel@cognition.uni-freiburg.de) Wibke Hachmann (wibke@cognition.uni-freiburg.de) Sarah Schwarzkopf (sarah.schwarzkopf@cognition.uni-freiburg.de) Sascha Wolfer (sascha@cognition.uni-freiburg.de) Center for Cognitive Science, University of Freiburg, Friedrichstr. 50 D-79098 Freiburg i. Br. , Germany Abstract This paper addresses the question whether locally coherent word sequences in spoken sentences interfere with the global interpretation. We present a visual world experiment where three depicted events were presented simultaneously while a sentence was spoken. The results suggest that local syntactic coherences are not only processed at a syntactic level, but they are interpreted on-line. Keywords: local coherence; sentence processing; parsing complexity; visual world, dynamical systems; simple recurrent networks. Introduction Sentences sometimes contain sequences that form partial or even whole sentences on their own when viewed in isolation. For example, the sentence i. The coach smiled at the player tossed a Frisbee by the opposing team. contains the grammatically correct main clause the player tossed a Frisbee. Similar constructions exist in German: ii. Die Tatsache, dass die Astronautin uberrascht den Auserirdischen entdeckte, erregte Aufsehen. The fact, that the astronaut [fem] surprisedly/surprises the alien discovered, caused a sensation. “The fact that the astronaut suprisedly discovered the alien, caused a sensation. ” Sentence (ii) contains the well-formed main clause die Astronautin uberrascht den Auserirdischen. (The astronaut surprises the alien.). In both cases the meaning of the embedded clause diverges from the global content of the sentence and should not be considered a possible interpretation because it is ruled out by the context of the preceding words. Do locally well-formed sequences, or local syntactic coherences (LSCs) nevertheless affect human sentence processing? This question has attracted a growing amount of attention recently because a measurable influence of LSCs would challenge the global consistency assumption (GCA) underlying most current theories of language processing: syntactic integrations of incoming material are always consistent with the preceding input. In recent years, several researchers reported evidence that LSCs indeed influence sentence processing and have to be considered a potential source of linguistic complexity. Tabor, Galantucci and Richardson (2004) found higher reading times in sentences like (i) on the morphologically ambiguous (past participle or a past tensed main verb) tossed than in the control conditions where the LSC was destroyed either by replacing tossed with the unambiguous thrown and/or by using the unreduced relative clause (…the player (who was) tossed/thrown…). Further evidence was provided by Konieczny (2005) from an online anomaly detection experiment, showing that the detection of errors took longer when they were locally coherent. Blicknell, Demberg and Levy (2008) report local coherence effects (local coherence effects) in an analysis of the Dundee Corpus of eyetracking data from reading of newspaper texts, and Cai, Pickering and Sturt (2008) report similar results from a self-paced-reading study. The human sentence processing mechanism (HSPM) is generally conceived of as an incremental parser whose strategy combines top-down strategies with a varying degree of bottom-up processing, depending on the particular model. Common to virtually all models, and naturally emerging from this view, is that sentence processing is maximally integrated at any given point in time, i.e. that each new word is integrated into a partial parse representation that includes all words of the sentence processed so far. Such an algorithm is parsimonious because only potentially viable structures are computed so that no memory and processing energy is wasted for unnecessary computations. Various complexity metrics based on this idea have since been proposed with considerable success in accounting for processing difficulties (e.g. Gibson 1998; Hawkins 1994). However, local coherence effects pose problems for these accounts because for LSCs to have an effect, the parser would have to compute a virtually infinite amount of analyses which could have been ruled out if the sentence context had been considered right away. Attempts to explain local coherence effects Several attempts have been made to explain local coherence effects. Tabor, Galantucci and Richardson (2004) interpret the effects as an interference of local and global analysis, based on a self-organized parser (SOPARSE, Tabor & Hutchins, 2004; see also Vosse & Kempen, 2000): Local lexical fragments – sometimes spanning several words –