Luo Lin, Luk Gigi, Bialystok Ellen
Department of Psychology, York University, Toronto, ON, Canada M3J 1P3.
Cognition. 2010 Jan;114(1):29-41. doi: 10.1016/j.cognition.2009.08.014. Epub 2009 Sep 29.
We use a time-course analysis to examine the roles of vocabulary size and executive control in bilinguals' verbal fluency performance. Two groups of bilinguals and a group of monolingual adults were tested in English with verbal fluency subtests from the Delis-Kaplan Executive Function System. The two bilingual groups were equivalent in their self-rated English proficiency but differed in levels of receptive and expressive vocabulary. We hypothesized that the difference between the two bilingual groups in vocabulary and between the monolingual and bilingual groups in executive control would lead to differences in performance on the category and letter fluency tests and dissociate the roles of vocabulary knowledge and executive control in verbal production. Bilinguals and monolinguals performed equivalently in category fluency, but the high-vocabulary bilingual group outperformed both monolinguals and low-vocabulary bilinguals in letter fluency. An analysis of the retrieval time-course functions in letter fluency showed dissociable effects of resources available at the initiation of the trial, considered to reflect vocabulary size, and ability to monitor and retrieve new items using a novel phonemic-based word searching strategy, considered to reflect executive control. The difference in slope of the best-fitting curves reflected enhanced executive control for both bilingual groups compared to monolinguals, whereas the difference in the starting point of the logarithmic functions reflected higher levels of vocabulary for high-vocabulary bilinguals and monolinguals compared to low-vocabulary bilinguals. The results are discussed in terms of the contributions of linguistic resources and executive control to verbal performance.
我们采用时程分析来考察词汇量和执行控制在双语者言语流畅性表现中的作用。两组双语者和一组单语成年人接受了来自德利斯 - 卡普兰执行功能系统的英语言语流畅性子测试。这两组双语者在自评英语水平上相当，但在接受性和表达性词汇水平上存在差异。我们假设，两组双语者在词汇方面的差异以及单语者和双语者在执行控制方面的差异，会导致在类别流畅性和字母流畅性测试中的表现不同，并区分词汇知识和执行控制在言语产出中的作用。双语者和单语者在类别流畅性方面表现相当，但高词汇量双语组在字母流畅性方面的表现优于单语者和低词汇量双语者。对字母流畅性中检索时程函数的分析表明，试验开始时可用资源的可分离效应（被认为反映词汇量），以及使用基于音素的新颖单词搜索策略监测和检索新项目的能力（被认为反映执行控制）。与单语者相比，两组双语者拟合曲线斜率的差异反映了执行控制的增强，而对数函数起点的差异反映了高词汇量双语者和单语者相比低词汇量双语者具有更高的词汇水平。我们从语言资源和执行控制对言语表现的贡献方面对结果进行了讨论。
