Date of Award

2025

Document Type

Thesis

Degree Name

MS in Neuroscience

Department

Communication Sciences and Disorders

First Advisor

Yan H Yu

Second Advisor

Tyreek Jackson

Third Advisor

Monica Wagner

Abstract

The development of lexical tone processing in children is shaped by both language experience and acoustic salience. While mismatch responses (MMRs) and late negativity (LN) components of event-related potentials (ERPs) have revealed early sensitivity to lexical tone in monolingual children, the timeline for achieving adult-like neural responses—particularly for acoustically distinct versus subtle tone contrasts— remains unclear. Moreover, little is known about how bilingual language experience, especially with tonal versus non-tonal home languages, modulates this neural processing. This study employed a passive multi-oddball paradigm using Mandarin Tone 3 (low dipping) as the standard, and Tone 1 (high level) and Tone 2 (rising) as deviants, to examine ERP responses in bilingual Mandarin-English, bilingual Spanish-English, and monolingual English-speaking children aged 5 to 10. Between 100–300 ms, bilingual Mandarin-English children exhibited significantly larger mismatch negativity (MMN) amplitudes at frontal and midline sites (F3, Fz, C3, Cz), indicating enhanced early auditory discrimination shaped by tonal language exposure. Between 300–500 ms, LN responses emerged for both Tone 1 and Tone 2 in the bilingual Mandarin-English group, most robustly at F3 and Fz, while the English and Spanish groups showed LN primarily to the more acoustically salient Tone 1. In contrast, the Spanish-English group exhibited a robust LN response F4 and C3 for Tone 1, suggesting differential engagement of attentional or cognitive mechanisms across groups. Together, these findings highlight both a bilingual language effect and a home language effect, highlighting how early language exposure differentially shapes the neurophysiological mechanisms underlying lexical tone processing during childhood.

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