Chang, F.

Fitz, H.

English

MPG.PuRe

LEARNING STRUCTURE-DEPENDENT PROCESSING FROM COMBINATORIAL MEANINGHartmut Fitz (Max-Planck Institute for Psycholinguistics Nijmegen) & Franklin Chang (University ofLiverpool)hartmut.fitz@gmail.comKnowledge of language includes syntactic principles which appear unlearnable given the languageinput children receive in development. The structure dependence of auxiliary fronting in complexpolar questions is a paradigm case of such a principle (Chomsky, 1980).English complex questions are formed by fronting the main clause auxiliary (“Is the boy whois eating running?”, structure-dependent movement), not the embedded clause auxiliary (“Is theboy who eating is running?”, structure-independent movement). Since these questions are rare inchild-directed speech, it has been claimed that innate constraints are needed to remove structure-independent rules from the learner’s hypothesis space (Berwick et al., 2011). Here we test whetherstructured meaning can be an alternative to innate syntactic constraints.We adapted a connectionist model of language acquisition and sentence production (Chang,2009) that learns from exposure to meaning-form pairs. Crucially, we assume that learners mustbe able to infer non-linguistic meanings, e.g., that the above sentence describes the two eventsRUNNING(BOY) + EATING(BOY). The EATING message is given and the RUNNING message isnot known by the speaker (marked as a question). Over time, the model should learn to use thismessage structure to acquire the correct rule.Model input consisted of simple and complex declaratives and questions with copulas, modalauxiliaries, and progressive verbs. No complex questions with auxiliaries in both clauses occurredin training. After 500K learning episodes, the model produced a diverse set of such questionswith +95% accuracy from novel meanings. Model behavior was consistent with a range of findingsconcerning relative clause length, structure, and auxiliary type.Errors during development were similar to those found in children who would often repeat auxil-iaries (“*Is the boy that is nice is happy?” ) in elicited production (Crain and Nakayama, 1987) andoccasionally make embedded-auxiliary errors (“*Can boys that run can jump?” ) (Ambridge et al.,2008). The model suggests how children could eventually learn to retreat from these errors andcorpus evidence is provided to support this explanation.From simple questions the model learned that features in the message signalled auxiliary move-ment, and from complex declaratives that different parts of a sentence depended on different mes-sage components. By combining these regularities that are present in child-directed speech, it wasable to generalize auxiliary movement in a structure-dependent way. This is the first explicit compu-tational model that learns to use message structure for subject-auxiliary inversion in the productionof complex questions.ReferencesAmbridge, B., Rowland, C. E., and Pine, J. M. 2008. Is structure dependence an innate constraint? Newexperimental evidence from children’s complex-question production. Cognitive Science 32, 222–255.Berwick, R. C., Pietroski, P., Yankama, B., and Chomsky, N. 2011. Poverty of the stimulus revisited. CognitiveScience 35, 7, 1207–1242.Chang, F. 2009. Learning to order words: A connectionist model of heavy NP shift and accessibility effectsin Japanese and English. Journal of Memory and Language 61, 374–397.Chomsky, N. 1980. On cognitive structures and their development. In M. Piattelli-Palmarini (Ed.), Languageand Learning: The Debate between Jean Piaget and Noam Chomsky. London: Routledge and Kegan.Crain, S. and Nakayama, M. 1987. Structure dependence in grammar formation. Language 63, 3, 522–543.THURSDAY 16:4031

Learning structure-dependent processing from combinatorial meaning

http://hdl.handle.net/11858/00-001M-0000-0024-3107-E

Learning structure-dependent processing from combinatorial meaning

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