Fast Mapping of Novel Word Forms Traced Neurophysiologically

Yury Shtyrov

doi:10.3389/fpsyg.2011.00340

Abstract

Human capacity to quickly learn new words, critical for our ability to communicate using language, is well-known from behavioral studies and observations, but its neural underpinnings remain unclear. In this study, we have used event-related potentials to record brain activity to novel spoken word forms as they are being learnt by the human nervous system through passive auditory exposure. We found that the brain response dynamics change dramatically within the short (20 min) exposure session: as the subjects become familiarized with the novel word forms, the early (∼100 ms) fronto-central activity they elicit increases in magnitude and becomes similar to that of known real words. At the same time, acoustically similar real words used as control stimuli show a relatively stable response throughout the recording session; these differences between the stimulus groups are confirmed using both factorial and linear regression analyses. Furthermore, acoustically matched novel non-speech stimuli do not demonstrate similar response increase, suggesting neural specificity of this rapid learning phenomenon to linguistic stimuli. Left-lateralized perisylvian cortical networks appear to be underlying such fast mapping of novel word forms unto the brain’s mental lexicon.

Highlights

As a communication tool, human language is far more complex than any signaling system developed by other animal species
We investigated online neural correlates of novel word form learning using a small acoustically matched group of known words and novel spoken word forms which were presented, at a natural speech rate, to experimental participants in a passive auditory exposure together with acoustically matched novel non-speech stimuli, whilst online measures of the participants’ brain activity were taken using multi-channel electroencephalographic recordings
Given previous behavioral linguistic research indicating that word learning reaches a plateau at ∼150 repetitions in a short behavioral exposure (Pittman, 2008), we presented our experimental subjects with the novel spoken pseudo-words, control words, and signal-correlated noise (SCN) stimuli 160 times per each stimulus in a passive listening task lasting approximately 20 min

Summary

Introduction

Human language is far more complex than any signaling system developed by other animal species. Amongst the many features making human language unique is the impressive size of our vocabularies, which reach into tens of thousands of words (Corballis, 2009). To acquire this knowledge, humans learn new words with high speed and efficiency – as children acquiring their native tongue and as adults mastering a new one. Humans learn new words with high speed and efficiency – as children acquiring their native tongue and as adults mastering a new one This capacity for rapid learning of language, known as “fast mapping,” has been demonstrated in numerous behavioral studies and observations (Carey and Bartlett, 1978; Dollaghan, 1985) which have indicated immediate behavioral effects of fast word learning present even before the nervous system has had a chance of consolidating the new information. Much experimentation has been done on longer-term effects of learning revealing neural correlates of days and weeks of practice or at least an overnight consolidation (see Davis and Gaskell, 2009, for a review), whereas the rapid aspect of word learning has remained a difficult task for neurobiological studies

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