Human beings differ in their ability to master the sounds of their second language (L2). Phonetic training studies have proposed that differences in phonetic learning stem from differences in psychoacoustic abilities rather than speech-specific capabilities. We aimed at finding the origin of individual differences in L2 phonetic acquisition in natural learning contexts. We consider two alternative explanations: a general psychoacoustic origin vs. a speech-specific one. For this purpose, event-related potentials (ERPs) were recorded from two groups of early, proficient Spanish-Catalan bilinguals who differed in their mastery of the Catalan (L2) phonetic contrast /e-/. Brain activity in response to acoustic change detection was recorded in three different conditions involving tones of different length (duration condition), frequency (frequency condition), and presentation order (pattern condition). In addition, neural correlates of speech change detection were also assessed for both native (/o/-/e/) and nonnative (/o/-/ö /) phonetic contrasts (speech condition). Participants' discrimination accuracy, reflected electrically as a mismatch negativity (MMN), was similar between the two groups of participants in the three acoustic conditions. Conversely, the MMN was reduced in poor perceivers (PP) when they were presented with speech sounds. Therefore, our results support a speech-specific origin of individual variability in L2 phonetic mastery. mismatch negativity ͉ event-related potentials ͉ bilingualism L earning a nonnative language sound system is notoriously difficult and often results in the foreign accent that characterizes nonnative speakers. This difficulty in learning a new speech sound system also has consequences for comprehension of the nonnative language. For example, most Japanese native speakers may consider that the English words /rock/ and /lock/ are the same word (1), because the Japanese speech-sound system does not distinguish between the phonemes /r/ and /l/. However, individuals differ significantly in the degree to which they master a nonnative phonetic code, and factors such as the age of acquisition, the amount of exposure, and motivational constraints have a crucial role in final phonetic attainment (2). Despite very early, extended exposure to a L2, many individuals continue to have considerable difficulties in the perception and production of some foreign sounds (3), whereas other nonnative speakers cannot be distinguished from native speakers (4). Discovering the origin of such individual differences is crucial for predicting success in L2 acquisition and for designing learning protocols that maximize the success of L2 learning. To advance in our knowledge of the origin of this individual is the goal of the present study. Specifically, we assess whether such individual differences stem from differences in domain-general psychoacoustic processes or, rather, from differences in specific speech perception abilities.One prolific line of research has explored the neural differences between ind...

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This study investigates the temporal dynamics of sign production and how particular aspects of the signed modality influence the early stages of lexical access. To that end, we explored the electrophysiological correlates associated to sign frequency and iconicity in a picture signing task in a group of bimodal bilinguals. Moreover, a subset of the same participants was tested in the same task but naming the pictures instead. Our results revealed that both frequency and iconicity influenced lexical access in sign production. At the ERP level, iconicity effects originated very early in the course of signing (while absent in the spoken modality), suggesting a stronger activation of the semantic properties for iconic signs. Moreover, frequency effects were modulated by iconicity, suggesting that lexical access in signed language is determined by the iconic properties of the signs. These results support the idea that lexical access is sensitive to the same phenomena in word and sign production, but its time-course is modulated by particular aspects of the modality in which a lexical item will be finally articulated.

We examined whether iconicity in American Sign Language (ASL) enhances translation performance for new learners and proficient signers. Fifteen hearing nonsigners and 15 proficient ASL-English bilinguals performed a translation recognition task and a production translation task. Nonsigners were taught 28 ASL verbs (14 iconic; 14 non-iconic) prior to performing these tasks. Only new learners benefited from sign iconicity, recognizing iconic translations faster and more accurately and exhibiting faster forward (English-ASL) and backward (ASL-English) translation times for iconic signs. In contrast, proficient ASL-English bilinguals exhibited slower recognition and translation times for iconic signs. We suggest iconicity aids memorization in the early stages of adult sign language learning, but for fluent L2 signers, iconicity interacts with other variables that slow translation (specifically, the iconic signs had more translation equivalents than the non-iconic signs). Iconicity may also have slowed translation performance by forcing conceptual mediation for iconic signs, which is slower than translating via direct lexical links.