The neural timecourse of American English vowel discrimination by Japanese, Russian and Spanish second-language learners of English

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 /AE:/ as the oddball (deviant) among frequent /alpha:/ stimuli compared to AE controls. The Spanish listeners showed a significant difference from the controls for the spectral-temporal contrast between /alpha:/ and /lambda/ for both perception and the neural Mismatch Negativity (MMN), but only for deviant /alpha:/ versus /lambda/ (duration decrement). For deviant /lambda/ versus /alpha:/, and for deviant /AE:/ versus /lambda/ or /alpha:/, all participants showed equivalent MMN amplitude. The asymmetrical pattern for /alpha:/ and /lambda/ 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.