We examine whether early acquisition of a second language (L2) leads to native-like neural processing of phonemic contrasts that are absent in the L1. Four groups (adult and child monolingual speakers of English; adult and child early bilingual speakers of English and Spanish, exposed to both languages before 5 years of age) participated in a study comparing the English /ɪ/ - /ε/ contrast. Neural measures of automatic change detection (Mismatch Negativity, MMN) and attention (Processing Negativity, PN and Late Negativity, LN) were measured by varying whether participants tracked the stimulus stream or not. We observed no effect of bilingualism on the MMN, but adult bilinguals differed significantly from adult monolinguals on neural indices of attention. The child bilinguals were indistinguishable from their monolingual peers. This suggest that learning a L2 before five years of age leads to native-like phoneme discrimination, but bilinguals develop increased attentional sensitivity to speech sounds.

BackgroundLateral temporal neural measures (Na and T-complex Ta and Tb) of the auditory evoked potential (AEP) index maturation of auditory/speech processing. These measures are also sensitive to language experience in adults. This paper examined neural responses to a vowel sound at temporal electrodes in four- to five-year-old Spanish-English bilinguals and English monolinguals and in five- to six-year-old Turkish-German bilinguals and German monolinguals. The goal was to determine whether obligatory AEPs at temporal electrode sites were modulated by language experience. Language experience was defined in terms of monolingual versus bilingual status as well as the amount and quality of the bilingual language experience.MethodAEPs were recorded at left and right temporal electrode sites to a 250-ms vowel [Ɛ] from 20 monolingual (American)-English and 18 Spanish-English children from New York City, and from 11 Turkish-German and 13 monolingual German children from Ulm, Germany. Language background information and standardized verbal and non-verbal test scores were obtained for the children.ResultsThe results revealed differences in temporal AEPs (Na and Ta of the T-complex) between monolingual and bilingual children. Specifically, bilingual children showed smaller and/or later peak amplitudes than the monolingual groups. Ta-amplitude distinguished monolingual and bilingual children best at right electrode sites for both the German and American groups. Amount of experience and type of experience with the target language (English and German) influenced processing.ConclusionsThe finding of reduced amplitudes at the Ta latency for bilingual compared to monolingual children indicates that language specific experience, and not simply maturational factors, influences development of the neural processes underlying the Ta AEP, and suggests that lateral temporal cortex has an important role in language-specific speech perception development.

This study investigated the influence of first language (L1) phoneme features and phonetic salience on discrimination of second language (L2) American English (AE) vowels. On a perceptual task, L2 adult learners of English with Spanish, Japanese or Russian as an L1 showed poorer discrimination of the spectral-only difference between /æ:/ as the oddball (deviant) among frequent /ɑ:/ stimuli compared to AE controls. The Spanish listeners showed a significant difference from the controls for the spectral-temporal contrast between /ɑ:/ and /ʌ/ for both perception and the neural Mismatch Negativity (MMN), but only for deviant /ɑ:/ versus /ʌ/ (duration decrement). For deviant /ʌ/ versus /ɑ:/, and for deviant /æ:/ versus /ʌ/ or /ɑ:/, all participants showed equivalent MMN amplitude. The asymmetrical pattern for /ɑ:/ and /ʌ/ suggested that L2 phonetic detail was maintained only for the deviant. These findings indicated that discrimination was more strongly influenced by L1 phonology than phonetic salience.

Objectives: To examine maturation of neural discriminative responses to an English vowel contrast from infancy to 4 years of age and to determine how biological factors (age and sex) and an experiential factor (amount of Spanish versus English input) modulate neural discrimination of speech. Design: Event-related potential (ERP) mismatch responses (MMRs) were used as indices of discrimination of the American English vowels [ε] versus [I] in infants and children between 3 months and 47 months of age. A total of 168 longitudinal and cross-sectional data sets were collected from 98 children (Bilingual Spanish–English: 47 male and 31 female sessions; Monolingual English: 48 male and 42 female sessions). Language exposure and other language measures were collected. ERP responses were examined in an early time window (160 to 360 msec, early MMR [eMMR]) and late time window (400 to 600 msec, late MMR). Results: The eMMR became more negative with increasing age. Language experience and sex also influenced the amplitude of the eMMR. Specifically, bilingual children, especially bilingual females, showed more negative eMMR compared with monolingual children and with males. However, the subset of bilingual children with more exposure to English than Spanish compared with those with more exposure to Spanish than English (as reported by caretakers) showed similar amplitude of the eMMR to their monolingual peers. Age was the only factor that influenced the amplitude of the late MMR. More negative late MMR was observed in older children with no difference found between bilingual and monolingual groups. Conclusions: Consistent with previous studies, our findings revealed that biological factors (age and sex) and language experience modulated the amplitude of the eMMR in young children. The early negative MMR is likely to be the mismatch negativity found in older children and adults. In contrast, the late MMR amplitude was influenced only by age and may be equivalent to the Nc in infants and to the late negativity observed in some auditory passive oddball designs.

When originally published, the article by Datta et al, included a misspelling of the sixth author's name. The correct spelling is Marcin Wróblewski as is reflected in the corrected version of the online article.