Doctoral Dissertation Research on the Role of Domain-General Executive Functions in Language Production: Resolving conflict in lexical selection

理解说话者是如何在很少有意识的努力下成功地说出流利的语言的，这不仅对我们理解人类的语言能力至关重要，而且还能让我们深入了解大脑受伤是如何导致不同模式的语言能力丧失的。演讲是一项令人印象深刻的精神壮举。例如，即使是认知完整的个体有时也会说错词（例如，将一夫一妻制说成单调）。大多数时候，演讲者是如何设法避免这些困难的呢？在先前研究的基础上，该项目提出，说话者通过利用被称为执行功能的一般心理过程，有效地管理说话的复杂性。这使得说话者能够“集中”精神处理，使他们能够有效地检索他们想说的话。本项目通过研究言语产生效率与(i)执行功能的个体差异和（ii）在其他认知任务中使用执行功能的近期经验之间的关系来验证这一假设。更好地理解一般心理过程和特定语言心理过程之间的联系，可能有助于专业人士在治疗和教育环境中利用这些联系。例如，最近关于双语的研究表明，经常经历困难的语言处理——例如：当双语在多种语言之间交替使用时，可能会改善一般认知控制并延缓痴呆症的发作。因此，确定哪些一般过程与语言产生有关，可能有助于开发针对这些过程的认知控制训练——这可能用于帮助语言产生缺陷的个体。本研究将专门研究一般认知控制的特定部分如何在语音生成过程中对单词检索做出贡献。先前的研究表明，在单词检索过程中，多个表征之间存在竞争（例如，在看到CAT的图片时，CAT， RAT和DOG都会出现在脑海中）。这个项目将研究被称为执行功能的一般控制过程是否有助于解决这种竞争。具体来说，它将研究支持冲突解决的两种执行功能：反应抑制（抑制对刺激的自动反应）和干扰解决（在多种选择可用时防止错误反应）。两项研究中的第一项将测试说话者是否？在强竞争环境下，个体的反应抑制能力和干扰分辨能力差异影响了他们的图片命名表现。如果目标执行功能帮助说话者解决竞争性单词级表征之间的冲突，那么具有较高控制能力的说话者在存在竞争的情况下命名图片的困难应该更少。重要的是，几个行为任务将用于评估每个执行功能，确保执行功能的措施不反映任务特定的影响。第二，平行研究将使用负迁移的过程来检验目标执行功能和词语检索之间的因果关系。三个小组中的每一个都将接受非语言任务的强化练习，旨在“耗尽”特定的执行功能。如果目标控制过程（例如，反应抑制）参与了单词提取过程中的冲突解决，那么就会发生负迁移，这样，练习了该过程的说话者在练习后比练习前更难以命名图片。

Understanding how speakers succeed in producing fluent speech with little conscious effort is critical not only to our understanding of the human capacity for language, it also provides insight into how injury to the brain can result in different patterns of loss to that capacity. Producing speech is an impressive mental feat. For example, even cognitively intact individuals sometimes slip up and say the wrong word (e.g., monotony instead of monogamy). How is it that most of the time speakers manage to avoid such difficulties? Building on previous work, this project proposes that speakers efficiently manage the complexity of speaking by drawing on general mental processes called executive functions. These allow speakers to "focus" mental processing, allowing them to efficiently retrieve the words they wish to speak. This project tests this hypothesis by examining how the efficiency of producing speech is related to (i) individual differences in executive functions and (ii) recent experience using executive functions in other cognitive tasks. Gaining a better understanding of the links between general and language specific mental processes may help professionals capitalize on those links in therapeutic and educational settings. For instance, recent research on bilingualism suggests that regular experience with difficult language processing--e.g., when a bilingual alternates between multiple languages may improve general cognitive control and delay the onset of dementia. Identifying which general processes are involved in speech production may therefore allow the development of cognitive control training that targets those processes--which may be used to help individuals with deficits to language production.This research will specifically examine how particular parts of general cognitive control contribute to word retrieval during speech production. Previous work has shown that there is competition among multiple representations during word retrieval (e.g., upon seeing a picture of a CAT, the words CAT, RAT, and DOG all come to mind). This project will examine whether general control processes known as executive functions help resolve such competition. Specifically, it will investigate two executive functions that support conflict resolution: response inhibition (suppression of an automatic response to a stimulus) and interference resolution (prevention of an incorrect response when multiple options are available). The first of two studies will test whether speakers? individual differences in response inhibition and interference resolution abilities influence their picture naming performance in the context of strong competition. If the target executive functions help speakers resolve conflict among competing word-level representations, then speakers with higher control abilities should show have less trouble naming pictures in the presence of competition. Importantly, several behavioral tasks will be used to evaluate each executive function, ensuring that the executive function measures do not reflect task-specific effects. The second, parallel study will examine the causality of the relationship between the target executive functions and word retrieval using a procedure known as negative transfer. Each of three groups will receive intensive practice in non-linguistic tasks intended to 'exhaust' a specific executive function. If the target control process (e.g., response inhibition) is involved in conflict resolution during word retrieval, then negative transfer should occur, such that speakers who practiced that process have more trouble naming pictures after practice than before it.