Cheng, Y. 1 , Wu, H. 2, 3 , Tzeng, Y. 1 & Lee, C. 1, 4
1 Institute of Neuroscience, National Yang-Ming University, Taipei, Taiwan
2 Buddhist Tzu Chi General Hospital, Taipei Branch, Taipei, Taiwan
3 School of Medicine, Tzu Chi University, Hualien, Taiwan
4 The Institute of Linguistics, Academia Sinica, Taiwan
Mandarin Chinese is a tonal language with a relatively simple syllable structure, in which vowels and tones are compulsory units for a syllable whereas initial and final consonants are optional. According to the phonological saliency hypothesis, a vowel carries higher saliency than a consonant and thus vowels should be acquired earlier than initial consonants. Supporting evidence has shown that Mandarin-speaking children?s vowel production stabilized by 3-year-old but the initial consonant production did not until age 5 to 6. This study examined the phonological saliency hypothesis by measuring mismatch response (MMR) to Mandarin vowel and initial consonant changes in newborns and 6-month-olds with a multi-deviant oddball paradigm. For initial consonants, the small deviant ?da? (VOT=11 ms) and the large deviant ?ga? (VOT=23 ms) were compared with the standard ?ba? (VOT=10 ms). For vowels, the small deviant ?di? (front-high vowel) and the large deviant ?du? (back-high vowel) were compared with the standard ?da? (central-low vowel). Newborns revealed a broad positive mismatch response (P-MMR) to both initial consonants and vowels, but showed no difference between large and small deviants. For 6-month-olds, the polarity of MMR to vowels depends on the deviant size. The du/da contrast elicited an adult-like MMN in intervals of 172 to 234 ms after the stimulus onset but the di/du contrast only elicited a P-MMR in 268 to 440 ms. However, only P-MMRs were found for both large and small deviants of initial consonants in 6-month-olds. In summary, infants show an adult-like MMR to vowel change at as early as 6 months of age, but show no such a sign when responding to initial consonants yet. Our findings characterize the developmental trajectories of MMRs to vowels and initial consonants and support the phonological saliency hypothesis.