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的信息传递的重要性。这就产生了对高效、有效的成人语言学习新方法的需求。这种需求是真实存在的；世界上以英语为第二语言的人比以英语为母语的人多。双语能力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，因此开发下一代促进双语能力的方法可能会产生更广泛的影响。这一努力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，大脑对母语的语音“承诺”。这支持高效的本地语音处理，但同时也增加了学习使用不同声音系统的新语言的成本。人们一直认为，成年人的大脑无法通过训练来学习非母语语音。这一共识来自于几十年来为训练成年人提高非母语语言感知而设计有效学习方案的尝试。简单地总结一下这些文献，即使经过几周的广泛训练，学习效果也不大。此外，学习不能很好地推广到不熟悉的声音实例或新的声音。在Lori Holt博士的指导下，刘先生将针对这个问题寻找一个有希望的新方法。该团队之前的研究得出了一个违反直觉的发现，即把注意力从语言学习任务上转移开来，比传统的做出公开判断和获得明确反馈的方法能带来更有效的学习效果。当训练“隐藏”在其他引人入胜的任务中时，检查成人的学习情况是一种新颖且可能更有效的方法，可以教授成年人新的语言声音。刘先生的论文项目建立在这个隐式训练任务中的概念验证证据之上。本研究将考察以改善语音表征为目标的延长（1周）内隐知觉训练是否会影响潜在的神经表征（通过脑电生理反应评估），并在课堂学习后转化为词汇学习的改善。平行研究将调查优化稳健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局限性和语言学习的本质。它还将为有效和引人入胜的下一代教育工具的开发提供信息。

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.