The consequences of early language experience and literacy for adult learning and brain structure

该奖项是美国国家科学基金会社会、行为和经济科学博士后研究奖学金（SPRF）计划的一部分。SPRF计划的目标是为学术界、工业界或私营部门和政府的科学事业准备有前途的早期职业博士级科学家。SPRF奖励包括在知名科学家的赞助下进行为期两年的培训，并鼓励博士后进行独立研究。美国国家科学基金会寻求促进科学界各阶层的科学家，包括那些未被充分代表的群体的科学家，参与其研究项目和活动；博士后阶段被认为是实现这一目标的一个重要的专业发展阶段。每个博士后必须解决各自学科领域的重要科学问题。在幼儿时期接触过两种语言的双语成年人，他们学习这两种语言的方式和成年后说、读两种语言的技能有很大的不同。尽管两种语言在美国的使用越来越多，但人们对早期双语经历的变化对成年说双语者的思想和大脑的影响知之甚少。在美国国家科学基金会（National Science Foundation）的支持下，PI Atagi将在加州大学河滨分校（University of California, Riverside）进行博士后研究。河滨分校是一所西班牙裔服务机构，代表了调查这一问题所需的语言经验的多样性。计划中的研究考察了具有广泛语言和读写技能的双语大学生，以了解童年的语言经历和读写能力如何塑造语言学习能力、认知和大脑结构。该项目探讨的问题是，童年学习两种语言阅读是否会对成年后的语言学习能力产生影响，以及是否会对已被证明受双语影响的大脑结构产生影响。在美国，越来越多以母语而非英语长大的传统人士使得理解这些早期经历的重要性成为促进更多不同学习者群体学术和经济成功的重中之重。计划中的研究还有助于培养多样化的语言和认知神经科学家群体，其中包括本科研究生，其中大多数人本身就是双语的。通过确定早期语言和识字经历不同的个体的大脑结构如何变化，该项目还将使我们了解大脑如何适应经验。成年人的大脑对新语言学习的适应能力远比我们之前认为的要强。对语言处理过程的研究表明，学习一门新语言，即使是成年人，也是一个动态的过程，它会改变母语的处理方式。然而，人们对早期语言体验对成人语言学习和认知的长期影响知之甚少，而对不同类型的双语语言体验（如两种语言的读写能力）如何影响成人的学习和认知则知之甚少。该研究利用认知神经科学方法来研究早期双语语言经历和读写能力如何影响成年后的语言学习、认知和大脑结构。本研究考察并比较了传统双语大学生与早期同步双语者和英语单语者。传统语言使用者是一个多元化的双语群体，他们成年后使用两种语言的技能各不相同。在该奖项的第一年，计划研究的重点是确定对成年后学习影响最大的语言和读写经验；因此，计划中的研究首先通过使用一系列语言、读写能力和认知测量以及新单词学习任务来检查早期语言和读写能力的行为后果。在该奖项的第二年，一组结构成像研究将检查从这些组中抽取的成人学习者，并确定最初发现的可复制性。这项研究的发现将开始确定早期双语经历的各个方面，这些方面可能会塑造思想和大脑。虽然已经发现双语能力与大脑的结构差异有关，特别是在皮质厚度方面，但双语能力的结构相关性尚不清楚。此外，通过考察读写能力（一种独特的语言体验，使学习者接触到比语言更多样化的单词和句子结构），本研究开始理清早期口语体验和读写能力对成年双语者的认知和神经影响。如果发现两种语言的读写能力在不同于说两种语言的方式上有利于语言学习和认知，这可能表明双语学生应该更好地支持两种语言的读写能力。

This award was provided as part of NSF's Social, Behavioral and Economic Sciences Postdoctoral Research Fellowships (SPRF) program. The goal of the SPRF program is to prepare promising, early career doctoral-level scientists for scientific careers in academia, industry or private sector, and government. SPRF awards involve two years of training under the sponsorship of established scientists and encourage Postdoctoral Fellows to perform independent research. NSF seeks to promote the participation of scientists from all segments of the scientific community, including those from underrepresented groups, in its research programs and activities; the postdoctoral period is considered to be an important level of professional development in attaining this goal. Each Postdoctoral Fellow must address important scientific questions that advance their respective disciplinary fields. Bilingual adults who were exposed to two languages in early childhood vary considerably in the ways in which they learned the two languages and the skill they have as adults to speak and read both languages. Despite the increasing presence of two languages in the US, there is little known about the consequences of variation in early bilingual experience for the minds and brains of adult speakers. With the support of the National Science Foundation, PI Atagi will conduct postdoctoral studies at the University of California, Riverside, a Hispanic Serving Institution that represents the diversity of language experience required to investigate this issue. The planned research examines bilingual college students with a wide range of language and literacy skills to understand how childhood language experiences and literacy shape language learning abilities, cognition, and brain structure. This project asks whether learning to read in both languages in childhood has consequences for later language learning abilities in adulthood and for the brain structures that have been shown to be affected by bilingualism. The growing number of heritage speakers in the US who grew up with a home language other than English makes understanding the significance of these early experiences a high priority for promoting the academic and economic success of a more diverse group of learners. The planned research also contributes to the training of a diverse group of language and cognitive neuroscientists by the inclusion of undergraduate research students, most of whom are themselves bilingual. By identifying how brain structure may vary for individuals who differ in their early language and literacy experiences, the project will also inform our understanding of how the brain adapts to experience.The adult brain is far more adaptive to new language learning than previously thought. Studies examining language processing show that learning a new language, even as an adult, is a dynamic process that changes the way the native language is processed. However, little is known about the long-term consequences of early language experiences for adult language learning and cognition, and even less is known about how different types of bilingual language experiences, such as literacy in two languages, affect adult learning and cognition. The proposed research exploits cognitive neuroscience methods to examine how early bilingual language experiences and literacy shape later adult language learning, cognition, and brain structure. This study examines and compares bilingual college students who are heritage speakers to early simultaneous bilinguals and English-monolinguals. Heritage speakers are a diverse group of bilinguals, who vary in the skill they have as adults to speak and read both languages. In the first year of the award, the planned research focuses on identifying the language and literacy experiences that have the greatest impact on later adult learning; thus, the planned research initially examines the behavioral consequences of early language and literacy by using a battery of language, literacy, and cognitive measures, as well as a new word learning task. In the second year of the award, a set of structural imaging studies will examine adult learners drawn from those groups and to determine the replicability of the initial findings. Findings from this research will begin to identify the aspects of early bilingual experience that may shape the mind and brain. Though bilingualism has been found to be associated with structural differences in the brain, particularly in cortical thickness, the structural correlates of bilingual literacy are yet unknown. Additionally, by examining literacy, a distinct type of language experience that exposes learners to more varied words and sentence structures than speech, this research begins to disentangle what cognitive and neural consequences early spoken language experience and literacy have for adult bilinguals. If literacy in two languages is found to benefit language learning and cognition in ways distinct from speaking two languages, it may suggest that literacy in both languages should be better supported in bilingual students.