This study addressed how bilingual speakers switch between their first and second language when speaking. Event-related brain potentials (ERPs) and naming latencies were measured while unbalanced German (L1)-Dutch (L2) speakers performed a picture-naming task. Participants named pictures either in their L1 or in their L2 (blocked language conditions), or participants switched between their first and second language unpredictably (mixed language condition). Furthermore, form similarity between translation equivalents (cognate status) was manipulated. A cognate facilitation effect was found for L1 and L2 indicating phonological activation of the non-response language in blocked and mixed language conditions. The ERP data also revealed small but reliable effects of cognate status. IntroductionBilingual speakers show remarkable flexibility in their ability to control their language output. They can restrict their speech to one language only but also intentionally switch between languages in bilingual settings. The question arises how bilinguals select the intended language and what mechanisms they rely on when switching from one language to the other. Bilinguals vary in proficiency of their second language ranging from very high levels of proficiency (highly proficient bilinguals or balanced bilinguals) to low levels of proficiency (L2 learners and L2 attriters). Even highly proficient bilinguals usually have a dominant and a non-dominant language which is reflected, for instance, in faster picture-naming latencies for their first compared to their second language (e.g., Chen and Leung, 1989;Christoffels et al., 2006;Potter et al., 1984). However, under language switching conditions, this difference in naming latencies between L1 and L2 may disappear or even reverse, with shorter picture-naming latencies for the second than the first language (Costa and Santesteban, 2004;Costa et al., 2006;Meuter and Allport, 1999;Philipp et al., 2006; see also Kroll et al., 2006). Switching between languages may therefore profoundly affect production in the native tongue. In this study, we address intentional language switching and the impact of the bilingual switching context on distinguishing transient and sustained components of language control.

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Speakers use external auditory feedback to monitor their own speech. Feedback distortion has been found to increase activity in the superior temporal areas. Using fMRI, the present study investigates the neural correlates of processing verbal feedback without distortion. In a blocked design, the following conditions were presented: (1) overt picture-naming, (2) overt picture-naming while pink noise was presented to mask external feedback, (3) covert picture-naming, (4) listening to the picture names (previously recorded from participants' own voices), and (5) listening to pink noise. The results show that auditory feedback processing involves a network of different areas related to general performance monitoring and speech-motor control. These include the cingulate cortex and the bilateral insula, supplementary motor area, bilateral motor areas, cerebellum, thalamus and basal ganglia. Our findings suggest that the anterior cingulate cortex, which is often implicated in error-processing and conflict-monitoring, is also engaged in ongoing speech monitoring. Furthermore, in the superior temporal gyrus, we found a reduced response to speaking under normal feedback conditions. This finding is interpreted in the framework of a forward model according to which, during speech production, the sensory consequence of the speech-motor act is predicted to attenuate the sensitivity of the auditory cortex. Hum Brain Mapp 28: [868][869][870][871][872][873][874][875][876][877][878][879] 2007. V V C 2007 Wiley-Liss, Inc.