Doctoral Dissertation Research: Investigating generalization, transfer, and representation resulting from non-native speech category training

全球化增加了跨越传统语言边界进行信息传递的重要性。这就产生了对既高效又有效的成人语言学习新方法的需求。这种需求是实实在在的；世界上以英语为第二语言的人比以英语为母语的人多。双语在增强认知能力和防止神经退行性衰退方面也具有竞争优势，因此开发下一代方法来促进双语可能会产生更广泛的影响。这项工作的一个重大挑战是教成年人一门新语言的发音。构成语言基石的语音在不同的语言中差别很大。长期的实验室研究表明，大脑会对母语的语音做出“承诺”。这支持高效的本地语音处理，但增加了学习使用不同声音系统的新语言的成本。在成人时期感知非母语语音是一种情况，人们认为成年人的大脑根本不能被训练来学习。这一共识源于几十年来人们试图设计有效的学习方法来训练成年人提高非母语言语感知能力。非常简要地总结这篇文献，即使在几周的课程中进行广泛的培训，学习收益也是有限的。此外，学习不能很好地概括陌生的声音或新的声音。在洛里·霍尔特博士的指导下，刘先生将针对这个问题提出一种有前途的新方法。该团队之前的研究发现，将注意力从语言学习任务上转移出来，比起做出公开判断和获得明确反馈的传统方法，可以带来更有效的学习收获。当训练隐藏在其他引人入胜的任务中时，检查成年人的学习是一种教成年人新语言声音的新颖且潜在更有效的方法。刘先生的论文项目建立在这项隐性培训任务中的概念验证证据之上。本研究将考察以改善语音声音表征为目标的延长(1周)的内隐知觉训练是否影响潜在的神经表征(通过电生理大脑反应来评估)，并转移到词汇学习的改善上，模拟课堂学习。平行研究将调查优化健全的成人学习和对新说话者和单词的概括的条件。本研究的结果将有助于理解成人知觉可塑性的限度和语言学习的本质。它还将为开发有效和吸引人的下一代教育工具提供信息。

Globalization has increased the importance of information transfer across traditional language boundaries. This has created a demand for new approaches to adult language learning that are both efficient and effective. This need is real; there are more second-language speakers of English in the world than native speakers. Bilingualism also confers a competitive advantage with respect to enhanced cognitive abilities and protection from neurodegenerative decline, so developing next-generation approaches to promoting bilingualism may have even broader impact. One of the significant challenges to this endeavor is teaching adults the sounds of a new language. The speech sounds that form the building blocks of language vary considerably across languages. A long history of laboratory research demonstrates that the brain "commits" to the speech sounds of the native language. This supports efficient native speech processing but confers a cost to learning a new language that uses a different sound system. Perceiving non-native speech sounds in adulthood is a case where it has been thought that the adult brain simply cannot be trained to learn. This consensus has arisen from decades of attempts to devise effective learning regimens for training adults to improve non-native speech perception. To summarize this literature very briefly, learning gains are modest even with extensive training over the course of weeks. Moreover, learning does not generalize well to unfamiliar instances of the sounds or to new voices.Under the direction of Dr. Lori Holt, Mr. Liu will target a promising new approach to this problem. Prior research from this team led to the counterintuitive finding that directing attention away from the task of language learning can lead to more efficient learning gains than the traditional approach of making overt judgments and getting explicit feedback. Examining adult learning when training is "hidden" in other engaging tasks is a novel and potentially more effective approach to teaching adults new language sounds. Mr. Liu's dissertation project builds on proof-of-concept evidence within this implicit training task. This study will examine whether extended (1-week) implicit perceptual training targeting improvement of speech sound representations impacts underlying neural representations (assessed via electrophysiological brain responses) and transfer to improvements in vocabulary-learning, modeled after classroom learning. Parallel studies will investigate conditions that optimize robust adult learning and generalization to new talkers and words. Results from this research will contribute to the understanding of the limits of adult perceptual plasticity and the nature of language learning. It also will inform the development of effective and engaging next-generation educational tools.