Dimension-selective attention and second language acquisition

在全球化的世界里，越来越多的成年人移居到一个新的国家，并试图学习第二语言（L2）。不幸的是，许多第二语言学习者最终产生严重的口音讲话，并努力理解讲话。了解第二语言学习困难的来源可能会导致补救措施，旨在提高学习困难的学习者的第二语言技能。语言结构是由一组复杂的声音线索传达的，包括持续时间，幅度和频率的变化。能够更好地检测这些声学线索的人可能能够更快地吸收新语言的结构。然而，检测L2的声学线索可能是困难的，因为不同语言在声音模式如何传达语言结构方面存在差异。例如，在声调语言中，如普通话，音高是单词含义的重要线索，但在非声调语言中，如英语，它扮演着更次要的角色。因此，音高可能是普通话使用者的“注意力磁铁”：他们在学习感知英语语音时可能很难学会忽略音高并注意其他更相关的特征。在第二语言中，越能将注意力集中在单个声学维度上的个体，越能将注意力集中在提供最可靠信息的声学线索上。我们提出了一个假设，即与英语母语者相比，汉语母语者更难将注意力从音高转移到其他声学维度上。从而在英语语音感知和产生过程中过分重视音高。我们将使用EEG来检查当参与者被动地听复杂的音调流或被要求注意一个维度时，参与者的神经反应编码音高与音色变化的程度。我们还将研究神经夹带音高轮廓与幅度包络，而参与者听自然口语叙事。我们预测，普通话讲者将表现出更大的音高跟踪相比，母语为英语的人不仅在被动和自然的听力条件下，而且当被要求参加音色。此外，我们预测，普通话参与者谁能够更好地抵制出席音高，并成功地出席音色也将表现出更多的母语一样的英语演讲生产。最后，利用功能磁共振成像，我们将调查的神经网络的注意力的声学尺寸在言语知觉;我们预测说普通话的人在扫描仪中对语音进行分类将显示出前额叶皮层和听觉皮层中与音高感知相关的区域之间更强的联系。我们进一步建议训练说普通话的人抵抗注意力磁铁，在言语感知期间将注意力引导到其他有用的信息源。参与者将在几个月内完成九次训练，在训练中，他们将根据音高以外的各种线索对语音特征（如重音或词义）进行分类。一个控制组将完成一系列的词汇提高练习。我们预测，在接下来的几个月里，实验训练组将实现更接近母语的语音感知策略和更准确的发音。此外，我们预测，实验培训将提高参与者的能力，直接注意到语音中的声音尺寸，如使用EEG测量。这个项目将导致更好地理解为什么有些人比其他人更难学习第二语言。这可能会导致第二语言能力测试的发展，更准确地预测谁将最容易在成年后掌握一门新语言。此外，该项目还可能导致制定干预措施，旨在通过教学习者注意演讲的最相关方面来促进第二语言学习。

In a globalized world, a growing number of adults are moving to a new country and attempting to learn a second language (L2). Unfortunately, many L2 learners end up producing heavily accented speech and struggling to comprehend speech. Understanding the sources of L2 learning difficulties could lead to remedial approaches designed to boost L2 skills in struggling learners. Language structure is conveyed by a complex set of acoustic cues, including changes in duration, amplitude, and frequency. Individuals who are better able to detect these acoustic cues may be able to more rapidly absorb the structure of a new language. However, detecting the acoustic cues of an L2 can be difficult, due to differences across languages in how sound patterns convey language structure. For example, in tone languages such as Mandarin, pitch is a vital cue to the meaning of words, but it plays a more secondary role in non-tonal languages such as English. As a result, pitch may be an "attentional magnet" for Mandarin speakers: they may have difficulty learning to ignore pitch and attend to other, more relevant features when learning to perceive English speech. Individuals who are better able to direct their attention to individual acoustic dimensions may be better able to focus on the acoustic cues which provide the most reliable information in an L2.We propose to test the hypothesis that Mandarin speakers, compared to native English speakers, have difficulty directing attention away from pitch and towards other acoustic dimensions, and thus place undue importance on pitch during English speech perception and production. We will use EEG to examine the extent to which participants' neural responses encode changes in pitch versus timbre when participants listen passively to complex tone streams or are asked to attend to one dimension. We will also examine neural entrainment to pitch contour versus amplitude envelope while participants listen to naturalistic spoken narratives. We predict that Mandarin speakers will show greater pitch tracking compared to native English speakers not only in the passive and naturalistic listening conditions, but also when asked to attend to timbre. Moreover, we predict that Mandarin participants who are better able to resist attending to pitch and successfully attend to timbre will also demonstrate more native-like English speech production. Finally, using fMRI, we will investigate the neural networks underlying attention to acoustic dimensions during speech perception; we predict that Mandarin speakers categorizing speech in the scanner will show stronger connections between pre-frontal cortex and regions in auditory cortex linked to pitch perception.We further propose to train Mandarin speakers to resist the attentional magnet, directing attention towards other useful sources of information during speech perception. Participants will complete nine sessions of training over several months in which they will categorize speech features (such as stress or word meaning) on the basis of various cues besides pitch. A control group will complete a series of vocabulary boosting exercises. We predict that over the course of the following months, the experimental training group will achieve more native-like speech perception strategies and more accurate pronunciation. Furthermore, we predict that the experimental training will improve participants' ability to direct attention to sound dimensions in speech, as measured using EEG.This project will lead to a better understanding of why some people struggle to learn a second language more than others. This could lead to the development of second language aptitude tests which more accurately predict who will most readily acquire a new language in adulthood. Moreover, this project could also lead to the development of interventions designed to boost poor second language learning by teaching learners to attend to the most relevant aspects of speech.