Neural mechanisms for phonological alternation with high and low productivity - a case study on tone sandhi

在当今世界上使用的大约7000种语言中，保守估计约有一半是声调的，因为音调本身的使用可能会改变一个词的意思。这份名单包括在美国经济和国家安全中发挥关键作用的语言，如汉语和越南语，以及许多美洲原住民语言，如纳瓦霍语和切诺基语。更好地了解这些语言的语言特性是提高与这些语言的使用者的交流效率和为母语为英语的人开发更好的学习材料的有意义的第一步。这个项目研究了两种中国语言——普通话和台湾语的语调模式，使用最先进的神经语言学技术来阐明带有音调的单词是如何在说话者的大脑中表现出来的。它有助于方法论的创新，将允许生产加工的音调的不同阶段被跟踪的神经测量。此外，该项目涉及美国的一个研究机构与香港和台湾两个著名的神经语言学实验室之间的国际合作。建立的联系将为美国和国际学生提供教育机会。这个项目的重点是音调的变化模式，即音调在不同的语境中采取不同的音系形式，也被称为“变调”。行为学研究表明，变调模式以不同的方式延伸到新词中，也就是说，根据模式的音系性质，变调模式具有不同的生产力。这表明，不同的机制可能涉及到这种类型的音位交替的加工。本研究使用事件相关电位（ERPs）来检视国语与台湾语若干变调模式在语音产生过程中的编码时序。我们假设，非生产性发音模式主要由词汇机制提供服务，该机制在词汇检索的较早时间窗口（大约在产生后150-225毫秒）中参与神经活动，而生产性发音模式主要由计算机制提供服务，该机制在较晚的语音编码时间窗口（400-600毫秒）中参与神经活动。词汇机制的神经活动对词汇频率敏感，而计算机制的神经活动对词汇频率不敏感。这个项目将是第一个研究与产生性和非产生性音位交替相关的假定计算和词汇机制的神经活动。加深对语音交替的神经编码的理解将为语音产生的理论模型和语音能力的形式模型提供信息。这个项目的发现也可以与形态学分解的问题联系起来，如规律性和语义透明度，以实现对语言生产力的神经基础的更全面的理解。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Of the 7,000 or so languages spoken in the world today, a conservative estimate of around half of them are tonal, in that the use of pitch itself may change the meaning of a word. This list includes languages that play key roles in the economy and national security of the US such as Chinese and Vietnamese as well as many Native American languages such as Navajo and Cherokee. A better understanding of the linguistic properties of these languages is a meaningful first step in increasing the communication efficiency with speakers of these languages and the development of better learning materials for these languages for native speakers of English. This project investigates the linguistic patterns of tone in two Chinese languages--Mandarin and Taiwanese--using state-of-the-art neurolinguistic techniques to shed light on how words with tones are represented in the speakers' brains. It contributes methodological innovations that will allow the different stages of the production processing of tone to be tracked by neurological measures. Moreover, this project involves international collaboration between a US institution and two prominent neurolinguistic laboratories in Hong Kong and Taiwan. The established connections will provide educational opportunities for students both in the US and internationally. This project focuses on tonal alternation patterns whereby a tone takes different phonological forms in different contexts, also known as "tone sandhi." Behavioral studies have shown that tone sandhi patterns extend to novel words in different ways, i.e., have different productivity, depending on the phonological nature of the pattern. This suggests that different mechanisms may be involved in the processing of this type of phonological alternation. This project uses event-related potentials (ERPs) to examine the time-course of the encoding of a number of tone sandhi patterns in Mandarin and Taiwanese in speech production. It is hypothesized that unproductive sandhi patterns are primarily subserved by a lexical mechanism that engages neural activities in an earlier time window of lexical retrieval (approximately 150-225 ms after the initiation of production), while productive sandhi patterns are primarily subserved by a computation mechanism that engages neural activities in a later time-window of phonological encoding (400-600 ms). It is also hypothesized that the neural activities of the lexical mechanism are sensitive to lexical frequency, while those of the computation mechanism are less so. This project will be the first to investigate the neural activities underlying the putative computation vs. lexical mechanisms associated with productive and unproductive phonological alternations. The increased understanding of the neural encoding of phonological alternation will inform both the theoretical models of speech production and formal models of phonological competence. Findings of this project can also be linked to issues of morphological decompositionality such as regularity and semantic transparency to achieve a fuller understanding of the neural bases of linguistic productivity.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.