Bilingualism: A Three-Domain Meta-Analysis in Adulthood and Aging

The attached supplementary materials contain three related sets of data supporting the systematic review and meta-analysis: Appendix 2: Study characteristics and extracted variables This appendix provides a detailed study-level extraction table. For each included study, it records information such as the sample size and comparison groups, participants’ age, bilingual proficiency, duration and frequency of bilingual language use, languages spoken, tasks or measures employed, reported outcomes, and the domain in which a bilingual advantage, disadvantage, or null result was observed. The studies cover behavioral, lexical, executive-function, neuroimaging, cognitive-reserve, stroke, and dementia-related outcomes. Appendix 3: Effect-size data This appendix reports the quantitative data used in the meta-analysis. It identifies the primary outcome selected from each study, the type of effect-size calculation, the bilingual and monolingual sample sizes, and the estimated standardized effect, generally expressed as Hedges’ g. Positive values are coded as favoring bilinguals, whereas negative values indicate poorer bilingual performance. The table includes both advantages and disadvantages across outcomes such as working memory, conflict processing, picture naming, switching, metacognitive efficiency, and neural measures. Appendix 5: PRISMA 2020 checklist This appendix documents how the review addresses the PRISMA 2020 reporting requirements. For each checklist item, it provides the reporting status, supporting evidence or a precise manuscript reference, explanatory notes, and the relevant manuscript location. It covers areas including the review objectives, eligibility criteria, search strategy, screening process, data extraction, outcome definitions, risk-of-bias assessment, effect measures, and synthesis procedures.本随附补充材料包含三组相关数据集，用以支撑本次系统综述与元分析（meta-analysis）的实施： 附录2（Appendix 2）：研究特征与提取变量 本附录提供了一份详尽的研究层面提取表格。针对每一项纳入研究，该表格记录了样本量、对照组设置、受试者年龄、双语熟练度、双语使用时长与频率、所使用语言、采用的任务或测量手段、报告的研究结局，以及观察到双语优势、劣势或无显著效应的研究领域。纳入研究涵盖行为学、词汇学、执行功能、神经影像学、认知储备、脑卒中及痴呆相关的各类结局指标。 附录3（Appendix 3）：效应量数据 本附录呈现了元分析所用的量化数据，明确了从每项研究中选取的主要结局指标、效应量计算类型、双语组与单语组的样本量，以及经标准化后的估计效应值，通常以赫奇斯g值（Hedges' g）表示。效应值为正时代表双语群体表现更优，为负时则提示双语群体表现较差。该表格涵盖了工作记忆、冲突处理、图片命名、任务切换、元认知效率及神经测量等各类结局指标下的优势与劣势效应数据。 附录5（Appendix 5）：PRISMA 2020检查表（PRISMA 2020 checklist） 本附录记录了本次综述如何满足PRISMA 2020报告规范的要求。针对检查表中的每一项条目，本附录提供了报告状态、佐证材料或精准的手稿参考文献、解释性说明，以及相关手稿的具体位置。其涵盖内容包括综述目标、纳入排除标准、文献检索策略、筛选流程、数据提取、结局指标定义、偏倚风险评估、效应指标及合成方法。