Phonological Cascade in Speech Production

描述(由申请人提供)：这项研究考察了言语产生中不同的语音过程相互作用的程度。语音产生理论通常假设语音处理的两个不同阶段。首先，词汇语音过程从长期记忆中提取词形的粗粒度表示。然后，语音过程产生更细粒度的音系结构。尽管理论上同意存在两个这样的过程阶段，但它们在相互作用的程度上存在分歧。这里提出的实验测试了一个关于这些阶段相互作用的具体假设：音位级联假说。这一假设认为，尽管存在进程之间的交互，但它是受限制的。级联激活通过允许源自词汇语音处理的效果(例如，诸如词频的词级变量)来影响语音处理来支持交互。交互作用受到从语音到词汇音系过程的反馈障碍的严重限制。这种对交互的限制防止了源自语音处理的效果(例如，诸如发音相似性之类的细粒度结构的效果)直接影响词汇语音处理。两个系列的实验验证了这一假设。第一项研究考察了后天缺陷个体在词汇、语音或语音加工方面的表现。第二项研究考察了神经学完好的参与者在实验中诱发的言语错误。音系级联假说预测，在词汇语音过程中产生的言语错误(无论是实验上的还是通过神经损伤产生的)应该对词级变量(如词频)表现出敏感，但由于缺乏反馈，不受语音结构的细粒度方面(如发音相似性)的影响。相反，由于级联效应，语音加工过程中产生的语音错误应该对这两种变量都很敏感。 项目叙述：通过解决如何处理单词的声音结构以支持语音产生这一相对未被探索的问题，这里提出的实验将为更丰富、更详细的语言产生理论提供基础。此外，增加我们对失语症成人语言处理系统如何崩溃的理解，可能有助于开发更精细的治疗获得性言语产生障碍的方法。

DESCRIPTION (provided by applicant): This research examines the degree to which different phonological processes in speech production interact with one another. Theories of speech production typically assume two distinct stages of phonological processing. First, lexical phonological processes retrieve coarse-grained representations of word form from long term memory. Phonetic processes then generate more fine-grained aspects of phonological structures. Although theories agree that two such processing stages are present, they disagree on the degree to which they interact with one another. The experiments proposed here test one specific proposal for the interaction of these stages: the phonological cascade hypothesis. This hypothesis proposes that although interaction between processes is present, it is restricted. Cascading activation supports interaction by allowing effects that originate within lexical phonological processing (e.g., word-level variables such as word frequency) to influence phonetic processing. Interaction is crucially limited by blocking feedback from phonetic to lexical phonological processes. This restriction on interaction prevents effects originating within phonetic processing (e.g., effects of fine-grained structure such as articulatory similarity) from directly influencing lexical phonological processing. Two series of experiments test this hypothesis. The first examines the performance of individuals with acquired deficits to lexical phonological or phonetic processing. The second examines experimentally induced speech errors in neurologically intact participants. The phonological cascade hypothesis predicts that speech errors generated within lexical phonological processes (either experimentally or via neurological damage) should show sensitivity to word-level variables (e.g., word frequency) but, due to the lack of feedback, be uninfluenced by fine-grained aspects of phonological structure (e.g., articulatory similarity). In contrast, due to cascade, speech errors generated during phonetic processing should be sensitive to both types of variables. Project Narrative: By addressing a relatively unexplored issue in how the sound structure of words is processed to support the production of speech, the experiments proposed here will provide the basis for richer, more detailed theories of language production. Furthermore, increasing our understanding of how the adult language processing system breaks down in aphasia may assist the development of more refined therapies for acquired speech production impairments.