Event-Related Brain Potential Investigation of Preparation for Speech Production in Late Bilinguals

Guillaume Thierry,Yan Jing Wu

doi:10.3389/fpsyg.2011.00114

Abstract

It has been debated how bilinguals select the intended language and prevent interference from the unintended language when speaking. Here, we studied the nature of the mental representations accessed by late fluent bilinguals during a rhyming judgment task relying on covert speech production. We recorded event-related brain potentials in Chinese–English bilinguals and monolingual speakers of English while they indicated whether the names of pictures presented on a screen rhymed. Whether bilingual participants focussed on rhyming selectively in English or Chinese, we found a significant priming effect of language-specific sound repetition. Surprisingly, however, sound repetitions in Chinese elicited significant priming effects even when the rhyming task was performed in English. This cross-language priming effect was delayed by ∼200 ms as compared to the within-language effect and was asymmetric, since there was no priming effect of sound repetitions in English when participants were asked to make rhyming judgments in Chinese. These results demonstrate that second language production hinders, but does not seal off, activation of the first language, whereas native language production appears immune to competition from the second language.

Highlights

Speaking is the process of transforming thoughts into speech
Post hoc analysis (LSD) showed that this difference was driven by faster reaction times for target pictures names that rhymed with prime pictures names in English as compared to all other conditions (Figure 2, all Ps < 0.05)
In the Chinese–English bilinguals, rhyming in English reduced reaction times (F3,42 = 3.08, P < 0.001) and increased error rates (F3,42 = 4.7, P < 0.001) as compared to semantically related and unrelated picture pairs, but no significant reaction time difference was found between pairs of picture names that rhymed in English and those that rhymed in Chinese (P > 0.1)

Summary

Introduction

Speaking is the process of transforming thoughts into speech. Current psycholinguistic models posit that speech production involves multiple stages of information processing including, conceptualization, retrieval of lexical representations, and the motor preparation for articulation (Dell, 1986; Levelt, 1989, 1999; Caramazza, 1997). An additional task is to select words from the appropriate (i.e., intended) language to speak. Experimental psychology and electrophysiological research have made the case that when they speak in one language, information in the other language is being activated. We first review previous attempts to reveal the nature of the cognitive and brain mechanisms that control bilingual language production, with a focus on methodology. We argue that the tasks and measurements used in these studies do not allow teasing apart the interplay of the first and second language; instead, they often mix the effects derived from activations of both languages during speech preparation. We introduce an alternative paradigm, which provides insights into first and second language activation, respectively, when bilinguals make covert spoken word production

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