Hull Rachel, Vaid Jyotsna
Department of Psychology, Texas A&M University, College Station, TX 77843-4235, USA.
Neuropsychologia. 2007 May 15;45(9):1987-2008. doi: 10.1016/j.neuropsychologia.2007.03.002. Epub 2007 Mar 7.
Two meta-analyses of 66 behavioral studies examined variables influencing functional cerebral lateralization of each language of brain-intact bilingual adults. Functional lateralization was found to be primarily influenced by age of onset of bilingualism: bilinguals who acquired both languages by 6 years of age showed bilateral hemispheric involvement for both languages, whereas those who acquired their second language after age 6 showed left hemisphere dominance for both languages. Moreover, among late bilinguals, left hemisphere involvement was found to be greater for those less proficient in their second language, those whose second language was English, and for studies involving dichotic listening paradigms; early bilinguals instead showed bilateral involvement in every condition. Implications of the observed differences in lateralization between early and late bilinguals are explored for existing theories of bilingualism and for neurocognitive models of brain functional organization of language.
两项对66项行为研究的荟萃分析，考察了影响大脑健全的双语成年人每种语言功能性脑侧化的变量。研究发现，功能性脑侧化主要受双语习得年龄的影响：6岁前习得两种语言的双语者，两种语言均表现为双侧半球参与；而6岁后习得第二语言的双语者，两种语言均表现为左半球优势。此外，在晚双语者中，发现第二语言熟练度较低者、第二语言为英语者以及采用双耳分听范式的研究中，左半球参与程度更高；而早双语者在每种情况下均表现为双侧参与。针对现有的双语理论以及语言脑功能组织的神经认知模型，探讨了早双语者和晚双语者在侧化方面观察到的差异的意义。
