Communicative biases shape structures of newly acquired languages

Communicative biases shape structures of newly acquired languages Maryia Fedzechkina (mashaf@bcs.rochester.edu), T. Florian Jaeger (fjaeger@bcs.rochester.edu) Department of Brain and Cognitive Sciences, University of Rochester Rochester, NY 14627 USA Elissa L. Newport (eln10@georgetown.edu) Department of Neurology, Georgetown University, Washington, DC 20007 USA Abstract across the world share many properties that facilitate such efficient information transfer (S.T. Piantadosi, H Tily, & E Gibson, 2011; S.T. Piantadosi, H. Tily, & E. Gibson, 2011; Qian & Jaeger, 2012). The study of language universals has primarily relied on typological and diachronic data, which has several major limitations. First, typological and diachronic studies suffer from data sparsity since only a small fraction of 6909 known languages (Lewis, 2009) have been sufficiently documented. This led some researchers to suggest that there is no evidence for language universals once common ancestry and geographical proximity between languages are taken into account (Dunn, Greenhill, Levinson, & Gray, 2011). Second, typological and diachronic studies do not provide an insight into the mechanism of how the hypothesized constraints come to shape language over time. The aim of this study is three-fold. First, we set out to provide direct behavioral evidence for the existence of cross-linguistic universals. Second, we investigate the cause of these universals. We ask, in particular, whether some typologically frequent phenomena can be explained by domain-general biases associated with considerations about human communication. Finally, we explore whether learning can provide a potential mechanism through which these biases come to shape language structures. We employ an artificial language learning paradigm, where learners are exposed to miniature languages designed to have certain properties of interest. This method has been used to study learning biases in adults and children (Culbertson, Smolensky, & Legendre, 2012; Hudson Kam & Newport, 2009) and has provided behavioral evidence for typological universals (Christiansen, 2000; Culbertson et al., 2012; Finley & Badecker, 2008; E. Newport & Aslin, 2004). Of particular interest is a recent study by Fedzechkina, Jaeger, and Newport (2012), who have used this paradigm to investigate the impact of learners’ communicative preferences on language structure and shown that language learners are biased towards efficient case systems. Here we focus on the correlation in a language between the flexibility of word order and the presence of a case system. It has long been observed that languages with rich case-marking typically allow more word order freedom than languages with no case-marking (Blake, 2001; Sapir, 1921). Languages like Russian or Latin, which allow sentential subjects and objects to be placed in a variety of positions Languages around the world share a number of commonalities known as language universals. We investigate whether the existence of some recurrent patterns can be explained by the learner’s preference to balance the amount of information provided by the cues to sentence meaning. In an artificial language learning paradigm, we expose learners to two languages with optional case-marking – one with fixed and one with flexible word order. We find that learners of the flexible word order language, where word order is uninformative of sentence meaning, use significantly more case-marking than the learners of the fixed word order language, where case is a redundant cue. The learning outcomes in our experiment parallel a variety of typological phenomena, providing support for the hypothesis that communicative biases can shape language structures. Keywords: Language acquisition; learning biases; language universals; efficient communication. Introduction In his seminal paper, the American linguist Joseph Greenberg (Greenberg, 1963) noticed that the vast majority of patterns that recur in apparently unrelated languages, also known as language universals, take the form of implicational statements: If a language has property A, then it will most likely have property B. Language universals point towards constraints on the space of structures possible in natural language since some of the theoretically possible feature combinations are cross-linguistically observed more frequently than others. The nature of these recurrent patterns has sparked a debate in the cognitive sciences: Are language universals due to constraints specific exclusively to language which are not shared by other aspects of human cognitive systems (Chomsky, 1965), or are they due to general cognitive constraints such as constraints on perception, memory and learning (Hawkins, 2004; E Newport, 1981; Slobin, 1973)? In this work, we explore the long-standing hypothesis that domain-general pressures associated with human communication can shape languages over time (Bates & MacWhinney, 1989; Slobin, 1977; Zipf, 1949). Support for this hypothesis comes from recent studies that apply mathematical theories of communication to the study of language structures. This work has found that speech has many properties that strike an efficient balance between successful and fast communication (Jaeger, 2010). Recent cross-linguistic studies have further found that languages