Phonetic learning in adults with and without language impairment

 描述(由申请人提供)：尽管对特定语言障碍的病因进行了数十年的辩论，但缺陷的来源尚未确定。显著的症状包括较难获得低知觉突显的语法语素(Leonard，2014)，较差的言语工作记忆(Ellis-Weismer，1996)，较慢的语言处理(Friedrich，Weber，&Friederici，2004)，以及在噪音中识别语音的困难(Ziegler等，2005)。Joanisse和Sciedenberg(1998)假设，语音表征的不稳定会导致较差的言语工作记忆，进而导致语法习得的障碍。虽然这一框架解释了语音加工/知觉缺陷，但语音缺陷的起源仍然存在争议。一些人认为，较差的表征质量源于低级听觉加工的差异(McArthur&Bishop 2001，Wright等人)。1997)，而另一些人(如Ullman&Pierpont，2005)则提出了一种全局性的内隐学习缺陷。内隐学习缺陷更好地解释了在听觉/语言领域以外的绩效测量中观察到的差异(例如Lum，Conti-Ramsden，Morgan，&Ullman，2014)；然而，内隐学习缺陷如何与建立语音表征有关尚不清楚。我们的实验室已经开发了一种实验方案，在典型成年人的知觉训练之后，检查新的(非本地)语音的编码时间进程(Earle&Myers，在出版中，提交)。我们认为，训练后的睡眠在建立新的语音类别方面发挥着重要作用(参见Earle&Myers，2014)；因此，我们感兴趣的不仅是获得语音信息的初始阶段，而且是训练后最初24小时内该信息是如何编码的。在目前的方案中，我们将我们在语音学习方面的工作扩展到有语言障碍的个人，以便对语音缺陷做出记忆解释。我们将评估参与者在训练前、训练后立即和一段时间睡眠后感知非本地对比的能力。我们将进一步获得睡眠的基本测量，以确定睡眠持续时间的个体差异是否会影响相对于即刻后测的睡眠后表现。我们还打算收集对训练声音的敏感性的电生理测量，以确保组之间观察到的差异不依赖于元语言任务的表现。这项研究将加深我们对记忆编码过程如何影响语音学习的认识，并进一步揭示语言障碍个体在编码语音特征时的崩溃机制。这一描述可能会指导对SLI记忆缺陷的神经生物学基础的进一步研究，最终目标是确定适当的补救/干预措施。因此，我们项目中概述的研究旨在指出三个研究领域的潜在贡献：言语感知、记忆巩固和特定语言障碍。

 DESCRIPTION (provided by applicant): Despite decades of debate devoted to the etiology of Specific Language Impairment, the origin of deficit has yet to be identified. Hallmark symptoms include the relative difficulty to acquire grammatical morphemes of low perceptual salience (Leonard, 2014), poor verbal working memory (Ellis-Weismer, 1996), slowed language processing (Friedrich, Weber, & Friederici, 2004), and difficulty identifying speech in noise (Ziegler et al., 2005). Joanisse and Sciedenberg (1998) hypothesize that instability in phonological representations lead to poor verbal working memory, cascading to the impairment in the acquisition of grammar. While this framework accounts for speech processing/perceptual deficits, the origins of phonological deficit remain in debate. Some argue that poor representational quality arises from differences in low-level auditory processing (McArthur & Bishop 2001, Wright et al. 1997), while others (e.g. Ullman & Pierpont, 2005) propose a domain-general implicit learning deficit. A deficit in implicit learning better accounts for the differencs observed in performance measures outside the auditory/linguistic domain (e.g. Lum, Conti-Ramsden, Morgan, & Ullman, 2014); however, how a deficit in implicit learning relates to building phonological representations is not yet clear. Our lab has developed an experimental protocol that examines the time course of encoding of new (nonnative) speech sounds following perceptual training in typical adults (Earle & Myers, in press, submitted). We have argued that post-training sleep plays an important role in building new phonetic categories (see Earle & Myers, 2014, for review); thus, our interest has been not only in the initial phase of acquiring phonetic information, but in how that information is encoded during the initial 24 hours following training. In the current proposal, we extend our work on phonetic learning to individuals with language impairment in order to contribute a memory account of the phonological deficit. We will assess participants' ability to perceive a nonnative contrast before training, immediately aftr training, and after a period of sleep. We will further obtain a rudimentary measure of sleep to determine if individual differences in sleep duration affect post-sleep performance relative to immediate posttest. We also intend to gather electrophysiological measures of sensitivity to the trained sounds, to ensure that differences observed between groups are not dependent on metalinguistic task performance. The proposed research will advance our knowledge of how memory encoding processes contribute to speech sound learning, and further inform the mechanism of breakdown in encoding phonetic features in individuals with language impairment. This account may direct further research into the neurobiological underpinnings of the memory deficits in SLI, with the eventual goal of identifying an appropriate remediation/intervention. The studies outlined in our project aims therefore point to potential contributions to three areas of research: speech perception, memory consolidation, and Specific Language Impairment.