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This study investigated how phonological saliency, deviance size, and maturation affect mismatch responses (MMRs) in early infancy. MMRs to Mandarin vowels and initial consonants were measured using a multi-deviant oddball paradigm in adults, newborns, and 6-month-olds. The vowel condition consisted of Mandarin syllable da as the standard, du as the large deviant and di as small deviant. As for initial consonant condition, we took syllable ba as standard, ga as large deviant, and ba as small deviant. While adults showed typical mismatch negativities (MMNs), newborns demonstrated broad positive MMRs (P-MMRs) to both initial consonants and vowels. For 6-month-olds, deviance size affected the polarity of MMRs to vowels. The large deviant du/da contrast elicited an adult-like MMN, while the small deviant di/da contrast elicited a P-MMR. Initial consonant changes elicited only P-MMRs, regardless of deviance size. In summary, MMRs to vowels switched from P-MMR at birth to MMN at 6 months. However, the polarity transition was not found for MMRs to initial consonants. The developmental trajectories of MMRs to vowels and initial consonants further support the phonological saliency hypothesis.

This study aimed to understand how reading ability shapes the lexicality effects on N400. Fifth-three typical developing children from 2nd to 6th grades were asked to perform the pronounceability judgment task on a set of Chinese real characters, pseudocharacters and noncharacters, as ERPs were recorded. The cluster-based permutation analysis revealed that children with low- to medium-reading ability showed greater negativity to noncharacters than to real characters and pseudocharacters in frontal sites from 300 to 450 ms, while children with high ability group showed a greater positivity to noncharacters than both real character and pseudocharacters at central to posterior sites. Furthermore, the linear mixed model (LMM) analysis was applied to investigate the relationship between lexicality effects on N400 and reading-related behavioral assessments on a set of standardized tests (including character recognition, vocabulary size, phonological awareness, and working memory). The results found that in children with lower reading ability, the N400 elicited by noncharacters becomes more negative in the frontal sites. For children with higher reading ability, the N400 elicited by noncharacters became more positive than that elicited by real characters or pseudocharacters in the posterior sites. These findings demonstrate the developmental changes in the lexicality effects on N400 as children become more advanced readers and suggest the lexicality effects on N400 can serve as neural markers for the evaluation of orthographic proficiency in reading development.

The present study investigates how age, phonological saliency, and deviance size affect the presence of mismatch negativity (MMN) and positive mismatch response (P-MMR). This work measured the auditory mismatch responses to Mandarin lexical tones, initial consonants, and vowels in 4- to 6-year-old preschoolers using the multiple-deviant oddball paradigm. The data showed the coexistence of MMN and P-MMR in the same age group when responding to the three types of syllabic features in Mandarin. The transition from a predominantly positive response to a predominantly negative response supported the multiple MMN mechanisms. Congruent with the phonological saliency hypothesis and the phonetic acquisition order of Mandarin in behavioral studies, for the compulsory elements of Mandarin syllables, lexical tones, and vowels, the larger deviants elicited adult-like MMNs, whereas the smaller deviants elicited P-MMRs. The optional elements of the Mandarin syllables, the initial consonant, only elicited P-MMR in preschoolers. These findings suggest that MMN and P-MMR index different functional characteristics and may provide information on when and how children's speech perception becomes automatic at different developmental stages.