Integration Costs on Auxiliaries? - a self-paced reading study using WebExp

Integration Costs on Auxiliaries? – a self-paced reading study using WebExp Vera Demberg (vera@coli.uni-saarland.de) Cluster of Excellence, Saarland University, Campus C7.4, 66123 Saarbr¨ucken, Germany Abstract In their evaluation of the integration cost component of Depen- dency Locality Theory on the Dundee Corpus, Demberg and Keller (2008) found no significant main effect of DLT integra- tion cost on reading times, but suggested that this might be due to auxiliaries incurring some of the full verb’s integration cost and thus facilitating processing of the verb. This hypothesis however, has to date not been tested. The present paper fills this gap by reporting an experiment on subject vs. object rel- ative clauses including auxiliaries, as well as by testing Dem- berg and Keller’s hypothesis directly on the Dundee Corpus. A further contribution of this paper is methodological: we replicate experimental results on the subject vs. object rela- tive clause assymmetry in a self-paced-reading experiment run remotely on the web using WebExp. Keywords: Dependency Locality Theory, Relative Clause, Auxiliary, WebExp, Dundee Corpus, Self-paced reading, Eye- tracking Introduction Dependency Locality Theory (DLT), proposed by (Gibson, 1998; Gibson & Pearlmutter, 2000) is a theory of sentence processing which has received quite a lot of attention in the field of psycholinguistics, and has been argued to explain a range of phenomena including including the SRC/ORC processing difficulty asymmetry, difficulty of centre embed- dings, cases of processing breakdown, filler-gap dependen- cies, heavy NP shift and extraposition. (Demberg & Keller, 2008) evaluated the integration cost component of DLT on an eye-tracked corpus of newspaper ar- ticles (Dundee Corpus; Kennedy and Pynte, 2005), and found that verbs which were preceded by nouns were read more slowly than verbs which were preceded by both auxiliaries and nouns. Demberg and Keller thus hypothesized that inte- gration costs might not be incurred at the main verb (as pre- dicted by DLT), but at the auxiliary, at which it should thus be possible to observe an integration cost effect. They did however not test whether such an integration cost effect could indeed be detected on the auxiliaries. This paper fills this gap through two studies that test Demberg and Keller’s hypothesis: a self-paced reading experiment of matched and controlled subject and object relative clauses containing auxiliaries, as well as a corpus study analysing the auxiliaries across various syntactic constructions in the Dundee Corpus for an integration cost effect. (IC) measures the distance between a head its dependent in terms of new discourse referents (DR) that occur inbetween them. Figure 1 shows the dependencies for a subject rela- tive clause (SRC) and an object relative clause (ORC). In the example, discourse referents are marked as either 0 (no new discourse referent) or 1 (new discourse referent). The depen- dency edge between reporter and the main clause verb ad- mitted is annotated with “+2” to express that two discourse referents occur between these words (namely, attacked and senator). The interesting case when comparing the subject and object relative clause is the embedded verb attacked: the integration cost is 1 in the SRC case (just the cost of con- structing the discourse referent), while the it is 3 in the case of the object relative clause. There is a cost of 1 for construct- ing the discourse referent, plus a cost of 2 for integrating the relative pronoun who at the trace *t*, at which point two dis- course referents (senator and attacked) intervene. There are also integrations of senator and attacked and the trace and at- tacked, but no new discourse referents occur between them, so these integrations are cost-free. SRC The reporter who *t* attacked the senator admitted the error. DR: 0 IC: 0 ORC The reporter who the senator attacked *t* admitted the error. DR: 0 IC: 0 Figure 1: Dependency Locality Theory Integration Cost. Auxiliaries in DLT Most previous experimental studies on locality effects do not contain auxiliaries. An exception is Experiment 4 from (Warren & Gibson, 2002), which compares self-paced read- ing times of an object relative clause with a full or pronominal embedded subject NP vs. a complementizer clause with full or pronominal subject NP, see example (1). a. Background and Related Work Dependency Locality Theory An important component for quantifying processing difficulty in DLT is the so-called “integration cost”. Integration cost b. Relative clause: The woman who you/the boy had accidentally pushed off the sidewalk got upset and decided to report the incident to the policeman standing nearby. Complement clause: The woman knew that you/the boy had accidentally pushed the girl