Endogenous sources of variation in language acquisition

Abstract

A fundamental question in the study of human language acquisition centers around apportioning explanatory force between the experience of the learner and the core knowledge that allows learners to represent that experience. We provide a previously unidentified kind of data identifying children's contribution to language acquisition. We identify one aspect of grammar that varies unpredictably across a population of speakers of what is ostensibly a single language. We further demonstrate that the grammatical knowledge of parents and their children is independent. The combination of unpredictable variation and parent-child independence suggests that the relevant structural feature is supplied by each learner independent of experience with the language. This structural feature is abstract because it controls variation in more than one construction. The particular case we examine is the position of the verb in the clause structure of Korean. Because Korean is a head-final language, evidence for the syntactic position of the verb is both rare and indirect. We show that (i) Korean speakers exhibit substantial variability regarding this aspect of the grammar, (ii) this variability is attested between speakers but not within a speaker, (iii) this variability controls interpretation in two surface constructions, and (iv) it is independent in parents and children. According to our findings, when the exposure language is compatible with multiple grammars, learners acquire a single systematic grammar. Our observation that children and their parents vary independently suggests that the choice of grammar is driven in part by a process operating internal to individual learners.syntax | language acquisition | learning | verb raising | quantifier scope T he tension between nature and nurture permeates the study of learning in humans and animals. In the domain of human language, this tension has proven especially difficult to resolve because all human language learners are awash in linguistic data. When children learn a particular feature of their language, did the data of experience allow for the construction of knowledge through general cognitive mechanisms of categorization and generalization, or did that experience play more of a triggering role, facilitating the expression of abstract core knowledge in a way that is consistent with the speech of the ambient community? In other areas of biology, this kind of tension is often resolved experimentally through selective rearing (1-3). Restricting the exposure of the learning organism to only a subset of the data that a normally developing organism receives allows us to identify the role of data in typical development. Such experiments are unethical to conduct with human children, but nature may sometimes provide them by accident. One commonly discussed case concerns the language acquisition profiles of children who are not exposed to a natural language, due to a combination of biological and sociological factors, as in the case of deaf children without access to a signing communit...

Infant Statistical Learning

“…Children receive restricted input both quantitatively (in terms of the number of utterances they are exposed to) and qualitatively (in terms of how well the data point to the structures to be acquired). More than 50 years later, debates over the innateness of specific linguistic devices still turn on arguments based on poverty of the stimulus (for a current discussion, see Han et al 2016, Piantadosi & Kidd 2016). Developmental arguments that hinge on the input extend far beyond the problem of language acquisition.…”

“…Statistical learning accounts are not sophisticated enough to be able to account for many detailed aspects of language acquisition, especially some of the more complex linguistic structures that do not appear to be transparently mirrored in the input (e.g., Han et al 2016). However, both experimental tasks and computational models have suggested specific ways in which constraints on statistical learning might have influenced the structure of natural languages (e.g., Christiansen & Chater 2008, Saffran 2001b, Smith et al 2017).…”

The scope of children’s scope: Representation, parsing and learning

“…Moreover, this variability was not simply due to the difficulty of computing interpretations; when the universal was in subject position, all speakers allowed only the interpretation where the universal takes wide scope. Finally Han, Musolino and Lidz (2016) found that speakers were consistent in their judgments across multiple testing sessions, and that they were consistent in their scope assignments for both kinds of negation in Korean. This pattern supports the view that each speaker controls only one grammar, with the variability in scope judgments following from which grammar that is.…”

“…To explore this possibility further, Han, Musolino and Lidz (2016) tested a group of children with their parents. They found again that roughly half of both populations allowed the universal to scope over negation.…”

Social Network Limits Language Complexity

“…Each learner must observe the linguistic behavior of others, and use their endogenous abilities to discover a grammar that accounts for this input (Han et al, 2016). These abilities interject a bias towards certain analyses, and so subtle changes in the input can lead to novel patterns different from those used by the previous generation (Grünwald, 2007;Langley and Stromsten, 2000;Senghas and Coppola, 2001).…”