Automatic Analogical Reasoning Underlies Structural Priming in Comprehension of Ambiguous Sentences

Automatic Analogical Reasoning Underlies Structural Priming in Comprehension of Ambiguous Sentences Vencislav Popov (vencislav.popov@gmail.com) Penka Hristova (phristova@cogs.nbu.bg) Department of Cognitive Science and Psychology, New Bulgarian University, 21 Montevideo Street Sofia 1618, Bulgaria Abstract The structure of previous sentences influences both production and comprehension of subsequent sentences, although there is less support for the latter. This effect, called structural priming, supposedly results from the repetition of syntactic structure, while evidence for the influence of thematic roles is controversial. We suggest that structural priming is achieved by automatic analogical mapping and transfer, which predicts that the thematic structure should be primed too. An experiment showed that the shared thematic structure is responsible for structural priming in comprehension of ambiguous sentences, rather than the syntactic structure. When participants read an unambiguous base sentence with an instrumental thematic role, they tended to interpret the corresponding role in the ambiguous prepositional phrase in the target as an instrument as well. This effect was present only when base and target sentences shared their whole thematic structure, not only the key role and in the absence of syntactic repetition. Keywords: structural priming, automatic analogy, thematic roles, ambiguous sentences, language comprehension Introduction Here we present an experiment with ambiguity. Now, the truth is that our study is about ambiguity, but can you really determine this from the previous sentence without doubt? No, it can also be easily interpreted to mean that our presentation will be ambiguous, and although no article would begin with such a confession, both interpretations are equally grammatical if not equally probable. Traditional theories of sentence comprehension propose that structural ambiguity is resolved by purely syntactic considerations (Frazier & Fodor, 1978; Pickering & Ferreira, 2008). But can syntactic parsing be affected by semantic factors as well? Sentences such as the one we began with contain a structural ambiguity called prepositional phrase attachment (PPA) ambiguity (Schutze & Gibson, 1999). In such sentences, a prepositional phrase (PP) can be attached either to the verb or to the immediately preceding noun. For example, in the sentence “The hunter watched the alpinist with binoculars. ” the PP can modify either the verb watched or the noun the alpinist. Whereas the hunter is watching the alpinist through binoculars in the verb-attachment condition, in the noun-attachment condition, the alpinist had the binoculars. This difference can be conceptualized in terms of thematic roles too. When the PP modifies the verb, it serves as an instrument of the action, and when the noun is modified, it serves as its attribute. Traditionally, the preferential parsing of one or the other alternative has been explained by the minimal attachment principle and by the late-closure strategy (Frazier & Fodor, 1978). According to the minimal attachment principle, the parser tries to construct the simplest possible syntactic structure, which happens when the PP is verb-attached. On the other hand, the late-closure strategy proposes that new lexical items are attached to the current constituent to reduce working memory load. In that case, the PP would be attached to the immediately preceding noun phrase. Recent research indicates that some extraneous factors can influence syntactic parsing as well. Branigan, Pickering, and McLean (2005) used the structural priming paradigm to show that the choice of analysis can be primed by a structurally similar sentence. They argued that it was the repetition of syntax across sentences which influenced interpretation. However, both the thematic 1 and the syntactic structures were shared in their stimuli, and it is not clear which was responsible for the effect. In fact, priming of thematic structure was shown by Goldwater, Tomlinson, Echols, & Love (2011), who suggested that analogical mapping and transfer underlie structural priming in production. We had two goals – to disentangle the effects of syntactic and thematic structure in comprehension-to-comprehension structural priming and to test the suggestion that analogical reasoning is responsible for the effects. First we turn to a discussion of relevant findings. Structural priming Structural priming 2 , the tendency for structural repetition across utterances, has been extensively used for studying processes both during sentence production (Bock, 1986; Bock & Loebell, 1990; Pickering & Branigan, 1998; Goldwater et al, 2011) and during comprehension (Branigan et al., 2005; Thothathiri & Snedeker, 2008; Boudewyn, Zirnstein, Swaab, & Traxler, 2013). Initial studies of structural priming in production showed that the effects cannot be explained by semantic or thematic factors (Bock, Loebell, & Morey, 1992; Bock & Loebell, 1990). Because of that, syntactic repetition has been used as an argument in favor of an abstract syntax (Bock & Loebell, 1990; Pickering & Ferreira, 2008). The organization of thematic roles in a sentences By “structural priming” we denote the effects of all structural repetitions. We will use the modifiers “syntactic” and “thematic” when we discuss priming of the specific structures.