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Bilingualism and Early Brain Development Bilingual Language Development & "The Bilingual Brain" Prevailing research on very young bilinguals had reported that young bilingual babies exhibited language delay and confusion relative to monolingual babies because they ostensibly had a single, fused representation of their two native languages, which they were only able to sort out over the first three years of life. By contrast, Petitto’s findings suggest that very young bilingual babies have highly For nearly a century, parents, educators, and scientists have been of two minds about the bilingual child. This phenomenon is so pervasive that Petitto and team have termed it "the bilingual paradox" (Petitto et al., 2001, Journal of Child Language). We freely marvel at the seemingly effortless ways that young children can acquire two or more languages simultaneously if exposed to them in early life. At the same time, we view early simultaneous bilingual exposure with suspicion, fearing that exposing a young child to two languages, too early, may cause language delay, and worse, language confusion. To better understand the impact that bilingual language exposure has on the brain's neural circuitry for language, the development of language, the development of reading, and the processing of language and reading, Petitto and her team of researchers have conducted two decades of studies on bilingual infants, children, adults. They have explored the ways that being exposed to two languages versus one language can change the human brain and impact its linguistic and other higher cognitive capacities. Petitto and her team have been particularly fascinated in understanding how the neural circuitry for language (and the processing of language) is impacted when the first systematic exposure to another language occurs at different ages of life (for example, bilingual language exposure from birth versus from ages 3, 5, and beyond). This is now known as the "Age of First Bilingual Language Exposure," or AoE. They have also been fascinated in uncovering how being exposed to two languages (rather than one) may lead to both cognitive and, crucially, language processing advantages. Petitto and team's research findings have revealed several key findings (see especially Petitto, 2009, Journal of Mind, Brain, and Education for a detailed review of the points below, as well as individual Petitto publications listed in this website): (i) Infants and young children who are exposed to two languages early in life achieve each and every language milestone on the same maturational timetable as one another without language delay or confusion (be it two spoken languages, for example, English & French, or, one spoken and one signed language, for example, English & ASL from birth). The key language production milestones common to a young bilingual's two languages at the same time involve, for example, the onset of Babbling and its developmental changes over time (around 6-12 months), "First-Word" (around 12 months), "First-Two-Words" (around 18 months), etc. Further, these overall bilingual milestones are on the identical maturational timetable as monolingual language production milestones. Said another way, early exposure to two languages simultaneously is not harmful to dual language mastery and may be optimal (Petitto et al., 2001, Journal of Child Language). (ii) Early schooling in two languages simultaneously affords young bilingual children a reading advantage and may also ameliorate the negative effect of low socioeconomic status on literacy. (Kovelman, Baker, & Petitto, 2008, Bilingualism: Language and Cognition). (iii) Using powerful brain imaging technology spanning young bilingual infants, children, and adults, Petitto and team found unequivocally that the age of first bilingual language exposure is a vital predictor of bilingual language and reading mastery, with early dual language exposure proving most optimal for achieving entirely comparable, and comparably high, language and reading success. (Petitto, 2009, Mind, Brain, and Education). (iv) Brain imaging studies of young infants being exposed to two languages from birth, and studies of children and adults with early bilingual language exposure, reveal that all use the same classic language brain tissue as observed in monolinguals. Here, the (early-exposed) bilinguals and monolinguals also recruit highly similar cognitive and Executive Function brain tissue. It is only with later bilingual language exposure do we observe key differences in the recruitment of higher cognitive/Executive Function neural tissue and networks. ( Kovelman, Baker & Petitto, 2008, Bilingual and Monolingual brains compared: An fMRI investigation of syntactic processing and a possible "neural signature" of bilingualism. Journal of Cognitive Neuroscience). Educational and scientific models that promote later bilingual language and reading instruction, or those that assert human brain development is unrelated to bilingual language mastery, are not supported by the present body of findings. Bilingualism and Sign Language: The Bimodal Bilingual In a fascinating instance of bilingualism, Petitto and colleagues also study individuals who are "bimodal" bilinguals. These are individuals who are being exposed to a signed language and a spoken language from birth. Petitto and colleagues tested two critical populations: (1) "bilingual" hearing infants who were being exposed to signed and spoken languages (i.e., one parent signs, one  parent speaks), and (2) "bilingual" hearing
infants who were being exposed to two distinct signed languages (ASL and LSQ; here, both parents only sign to their baby), and who were receiving no spoken language input whatsoever. Group 1 children achieved all linguistic milestones in both modalities at the same time, e.g., vocal and manual babbling, first words and first signs, first grammatical combinations of words and signs, respectively, and beyond. See Petitto et al., 2001, Journal of Child Language. Group 2 children also achieved each and every classic language milestones on the same timetable--but, here, this was occurring across their two signed languages (Petitto, 2005, The Cambridge Companion to Chomsky; Petitto et al., 2001, Nature). Further, the children in both groups (1 and 2) exhibited their semantic-conceptual milestones on the identical overall maturational timetable as seen in monolingual children (Holowka, Brosseau-Lapre, & Petitto, 2002, Language Learning), with their specific developmental patterns being identical to Petitto's important control groups, specifically, bilingual hearing babies exposed to two spoken languages (e.g., spoken French and spoken English). Significance 
distinct representations of their two native languages quite probably from birth. Crucially, Petitto has articulated, and for the first time, the typical language milestones that one can expect to observe in young bilingual babies and bilingual children, and has empirically shown that they are similar to monolingual milestones. |
