This study investigated the underlying nature of apraxia of speech (AOS) by testing two competing hypotheses. The Reduced Buffer Capacity Hypothesis argues that people with AOS can plan speech only one syllable at a time Rogers and Storkel [1999. Planning speech one syllable at a time: The reduced buffer capacity hypothesis in apraxia of speech. Aphasiology, 13(9-11), 793-805. https://doi.org/10.1080/026870399401885]. The Program Retrieval Deficit Hypothesis states that selecting a motor programme is difficult in face of competition from other simultaneously activated programmes Mailend and Maas [2013. Speech motor programming in apraxia of speech: Evidence from a delayed picture-word interference task. American Journal of Speech-Language Pathology, 22(2), S380-S396. https://doi.org/10.1044/1058-0360(2013/12-0101)]. Speakers with AOS and aphasia, aphasia without AOS, and unimpaired controls were asked to prepare and hold a two-word utterance until a go-signal prompted a spoken response. Phonetic similarity between target words was manipulated. Speakers with AOS had longer reaction times in conditions with two similar words compared to two identical words. The Control and the Aphasia group did not show this effect. These results suggest that speakers with AOS need additional processing time to retrieve target words when multiple motor programmes are simultaneously activated.

中文翻译：

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通过语音相似词的顺序产生检查言语失用症和失语症的言语运动规划困难

本研究通过测试两个相互竞争的假设来调查言语失用症 (AOS) 的潜在性质。缓冲容量减少假说认为，患有 AOS 的人一次只能计划一个音节 Rogers 和 Storkel [1999. 一次一个音节规划语音：语音失用中的缓冲容量减少假设。失语学，13（9-11），793-805。https://doi.org/10.1080/026870399401885]。程序检索缺陷假设指出，面对来自其他同时激活的程序 Mailend 和 Maas [2013] 的竞争，选择一个运动程序是困难的。言语失用症中的言语运动编程：来自延迟图片词干扰任务的证据。美国语言病理学杂志，22（2），S380-S396。https://doi.org/10.1044/1058-0360(2013/12-0101)]。患有 AOS 和失语症的演讲者，没有 AOS 的失语症和未受损的对照组被要求准备并保持一个两个词的话语，直到一个 go 信号提示一个口头反应。目标词之间的语音相似性被操纵。与两个相同单词相比，具有 AOS 的说话者在具有两个相似单词的条件下具有更长的反应时间。对照组和失语组没有表现出这种效果。这些结果表明，当同时激活多个运动程序时，具有 AOS 的说话者需要额外的处理时间来检索目标词。对照组和失语组没有表现出这种效果。这些结果表明，当同时激活多个运动程序时，具有 AOS 的说话者需要额外的处理时间来检索目标词。对照组和失语组没有表现出这种效果。这些结果表明，当同时激活多个运动程序时，具有 AOS 的说话者需要额外的处理时间来检索目标词。