Electrophysiological indices of vowel discrimination in late bilinguals

The purposes of the current study are: (1) To investigate discrimination of a vowel contrast not found in Spanish by late learners of English with Spanish as a first language; (2) to assess whether the use of natural consonant-vowel-consonant stimuli and multiple exemplars will show the same pattern of results as found in studies using synthetic stimuli; and (3) examine whether better speech perception as examined by the event-related potential, mismatch negativity (MMN) correlates with greater language usage as measured by a language background questionnaire. The results indicate that late-bilinguals are slower at discriminating the vowel contrast than the English monolinguals, as indexed by MMN. Monolingual English listeners showed significant MMN from 200 to 300 ms, whereas for late learners of English, the MMN was significant 50 ms later between 250 and 300 ms. Both groups showed excellent behavioral discrimination of the vowel contrast. Results also suggest that vowel category reshaping is less flexible in adult learners of a second language. The results will be discussed in relation to language usage.