Phonological Cascade in Speech Production

描述（由申请人提供）：本研究考察了语音产生中不同语音过程相互作用的程度。言语产生理论通常假设语音处理的两个不同阶段。首先，词汇语音过程从长时记忆中提取单词形式的粗粒度表征。语音过程然后产生语音结构的更细粒度的方面。尽管理论一致认为存在两个这样的处理阶段，但他们对它们相互作用的程度存在分歧。这里提出的实验测试一个具体的建议，这些阶段的相互作用：语音级联假说。这一假说提出，虽然过程之间的相互作用是存在的，但它是有限的。级联激活通过允许起源于词汇语音处理的效果来支持交互（例如，词级变量，如词频）来影响语音处理。语音到词汇的语音过程的反馈被阻断，从而限制了交互作用。对交互的这种限制防止了源自语音处理内的影响（例如，细粒度结构的影响，如发音相似性）直接影响词汇语音处理。两个系列的实验验证了这一假设。第一部分考察了词汇、语音或语音加工的后天缺陷个体的表现。第二个检查实验诱导的语音错误在神经系统完整的参与者。语音级联假说预测，在词汇语音过程中产生的言语错误（无论是实验还是通过神经损伤）应该对单词水平的变量（例如，词频），但是由于缺乏反馈，不受语音结构的细粒度方面的影响（例如，发音相似性）。相比之下，由于级联，语音处理过程中产生的语音错误应该是敏感的两种类型的变量。 项目叙述：通过解决一个相对未被探索的问题，即如何处理单词的声音结构来支持语音的产生，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，增加我们对成人语言处理系统如何在失语症中崩溃的理解，可能有助于开发更精细的后天言语产生障碍治疗方法。

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.