Neural oscillations reflect meaning identification for novel words in context.

Jacob Pohaku Momsen,Alyson D Abel

doi:10.1162/nol_a_00052

Abstract

During language processing, people make rapid use of contextual information to promote comprehension of upcoming words. When new words are learned implicitly, information contained in the surrounding context can provide constraints on their possible meaning. In the current study, EEG was recorded as participants listened to a series of three sentences, each containing an identical target pseudoword, with the aim of using contextual information in the surrounding language to identify a meaning representation for the novel word. In half of trials, sentences were semantically coherent so that participants could develop a single representation for the novel word that fit all contexts. Other trials contained unrelated sentence contexts so that meaning associations were not possible. We observed greater theta band enhancement over the left-hemisphere across central and posterior electrodes in response to pseudowords processed across semantically related compared to unrelated contexts. Additionally, relative alpha and beta band suppression was increased prior to pseudoword onset in trials where contextual information more readily promoted pseudoword-meaning associations. Under the hypothesis that theta enhancement indexes processing demands during lexical access, the current study provides evidence for selective online memory retrieval to novel words learned implicitly in a spoken context.

Highlights

The ability to learn new words and develop an extensive lexicon is a well-studied phenomenon of cognition
The current study set out to explore oscillatory neural dynamics that support implicit word learning from speech
Our data revealed that pseudowords eliciting a meaning representation were associated with greater theta power enhancement across trials relative to pseudowords presented in contexts where meaning was not activated

Summary

Introduction

The ability to learn new words and develop an extensive lexicon is a well-studied phenomenon of cognition. Word learning can be achieved in a number of different ways—via explicit instruction or alternatively through implicit means. If exposed to the unfamiliar word shap in the following sentence, “The boy held the shap tightly as he fell asleep,” interpretations would be constrained to potential meanings that are plausibly related to other familiar words in the sentence (e.g., “pillow”, “blanket”). While there is evidence that people can become sensitive to the meaning of a new word after being exposed to it context only once, long-lasting memory for new words becomes robust after multiple exposures (Horst, 2013). Learning words from context is often studied using written language (Nagy et al, 1987; 1985) but, importantly, many new words are learned by hearing them used in everyday speech (Carey & Bartlett, 1978; Jenkins et al, 1984; Saffran et al, 1997; McLeod & McDade, 2011)

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