Social Interaction Affects Neural Outcomes of Sign Language Learning As a Foreign Language in Adults.

Noriaki Yusa,Motoaki Sugiura,Masatoshi Koizumi,Jungho Kim,Ryuta Kawashima

doi:10.3389/fnhum.2017.00115

Abstract

Children naturally acquire a language in social contexts where they interact with their caregivers. Indeed, research shows that social interaction facilitates lexical and phonological development at the early stages of child language acquisition. It is not clear, however, whether the relationship between social interaction and learning applies to adult second language acquisition of syntactic rules. Does learning second language syntactic rules through social interactions with a native speaker or without such interactions impact behavior and the brain? The current study aims to answer this question. Adult Japanese participants learned a new foreign language, Japanese sign language (JSL), either through a native deaf signer or via DVDs. Neural correlates of acquiring new linguistic knowledge were investigated using functional magnetic resonance imaging (fMRI). The participants in each group were indistinguishable in terms of their behavioral data after the instruction. The fMRI data, however, revealed significant differences in the neural activities between two groups. Significant activations in the left inferior frontal gyrus (IFG) were found for the participants who learned JSL through interactions with the native signer. In contrast, no cortical activation change in the left IFG was found for the group who experienced the same visual input for the same duration via the DVD presentation. Given that the left IFG is involved in the syntactic processing of language, spoken or signed, learning through social interactions resulted in an fMRI signature typical of native speakers: activation of the left IFG. Thus, broadly speaking, availability of communicative interaction is necessary for second language acquisition and this results in observed changes in the brain.

Highlights

It is a trivial fact that all normal children effortlessly acquire a particular language used around them
By examining the acquisition of Japanese sign language (JSL) under two different social learning conditions, that learning through interaction with a deaf signer resulted in a stronger activation of the left inferior frontal gyrus (IFG) than learning through identical input via DVD presentations, though behavioral data did not show distinct differences
The current study investigated effects of social interaction on the acquisition of syntax in adult second language learners

Summary

Introduction

It is a trivial fact that all normal children effortlessly acquire a particular language used around them. Less trivial is the fact that children do so through social interactions: children cannot acquire a language from linguistic input such as TV, or computer presentations (Sachs et al, 1981; Baker, 2001; Kuhl et al, 2003). Infants less than 6 months old of age can discriminate various speech contrasts in the world that do not exist in their mother tongues (Eimas et al, 1971; Werker and Tees, 1984), but they lose the discriminating ability between 6 and 12 months of age (Werker and Tees, 1984) During this period, they grow into “native listeners” from “universal listeners.”. The result clearly indicates that phonetic learning is not triggered by simple exposure to linguistic input, but that infants must be exposed to a language in socially interactive situations to develop speech perception (Kuhl, 2007). TV programs or DVDs cannot be substitutes for human instruction in the early periods of phonetic learning

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