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Poster C49, Thursday, November 9, 10:00 – 11:15 am, Harborview and Loch Raven Ballrooms

Orthographic influences on Chinese spoken language in the brain: task-dependent effects as revealed by event-related fMRI

Pei-Chun Chao1, Wei-Fan Chen2, Jie-Li Tsai3, Chia-Ying Lee1,2;1National Yang-Ming University, Taiwan, 2Academia Sinica, Taiwan, 3National Chengchi University, Taiwan

The orthographic consistency effect on spoken word recognition is a well-established phenomenon to support that reading experience shapes the speech processing. However, it is still unclear whether this effect was resulted from the orthographic co-activation located in temporo-occipital visual cortex or the phonological restructuring located within the speech network. In Chinese, over 80% of Mandarin syllables can be mapped onto more than one character. Given the pervasive homophony of Chinese, one might expect a greater impact from orthography during speech in Chinese than that in the alphabetic writing system. Two types of orthographic effect have been demonstrated in Chinese spoken word recognition with ERP (Chen et al., 2016). One is the orthographic consistency (whether a set of homophones can be divided into subgroups based on their phonetic radicals) and the other one is the homophone density (the number of characters sharing exactly the same pronunciation). This study aims to examine these two orthographic effects on Chinese spoken language under semantic category and rhyming judgment tasks with event-related fMRI in order to explore the neural mechanisms underlying the orthographic effects and whether they are task-dependent. The monosyllabic Chinese spoken words used in the two tasks were sub-divided into three phonology-to-orthography mapping conditions based on their orthographic consistency (OC) and homophone density (HD) (1) low HD/ high OC; (2) high HD/ high OC; (3) high HD/ low OC. Twenty-four participants perform the Go/no go semantic categorization task with 108 critical stimuli for no-go trials and 60 animal names for go-trials. Additionally, twenty-eight participants perform rhyming judgment task with 90 critical stimuli paired with a rhymed or non-rhymed probe. In the semantic task, the brain activation for orthographic consistency effects were only localized to left inferior frontal gyrus (IFG), superior temporal gyrus (STG), and supramarginal gyrus for phonological and semantic processing, supporting the phonological restructuring view. Moreover, the homophone density effects occurred not only in the left IFG, insula, and STG for phonological processing, left posterior temporal-parietal regions for lexical/semantic processing, but also in left fusiform and lingual gyrus for orthographic processing, supporting the orthographic on-line activation view. These findings suggest that the two perspectives are not mutually exclusive. However, in the rhyming task, only orthographic consistency effects occurred within anterior perisylvian speech network were found. These results suggested that orthographic influences on speech may be task-dependent and imply that orthographic consistency and homophone density involve different mechanisms during Chinese spoken word recognition.

Topic Area: Meaning: Lexical Semantics

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