2011 — 2012 |
Lew-Williams, Casey |
F32Activity Code Description: To provide postdoctoral research training to individuals to broaden their scientific background and extend their potential for research in specified health-related areas. |
Infant Statistical Learning in Natural Language Acquisition @ University of Wisconsin-Madison
DESCRIPTION (provided by applicant): Infants are adept at tracking statistical regularities to segment words in continuous speech. Researchers have documented infants'learning abilities using highly simplified artificial languages as speech input. However, natural language is replete with variability. Infants listening to speech encounter different speakers, different word lengths, and numerous other dimensions of complexity. The proposed experiments will use speech that captures key aspects of the natural variation observed in infants'language environments to test whether infants use statistical learning mechanisms in identifying word boundaries. This research will provide a rigorous test of whether statistical learning is in fact linked to early language acquisition. Specific Aim 1 is to examine how infants segment words given variability in utterance types-specifically, the presence of both continuous speech and isolated words. A preliminary study showed that isolated words enhance infants'attention to statistical regularities in fluent, natural speech. Experiment 1 will test the hypothesis that hearing words in isolation helps infants discover other words in continuous speech. Experiment 2 will explore word segmentation given variation in voices, testing whether isolated words enhance statistical learning when speech comes from multiple talkers. Specific Aim 2 is to investigate how variability in language experience influences infants'subsequent detection of statistical regularities in fluent speech. In Experiment 3, infants will first receive brief laboratory exposure to novel isolated words. This pre-familiarization is expected to constrain infants'abilities to establish word boundaries in continuous speech. Experiment 4 will test whether cross-linguistic differences in the proportion of multisyllabic words in infant-directed speech shape infants'word segmentation abilities. Spanish-learning infants, who hear far more multisyllabic words than English-learning infants over the first year, are expected to show greater facility in segmenting trisyllabic words from continuous speech than English-learning infants. The results will assess the degree to which previous learning leads to expectations that facilitate processing future speech, or whether infants'computational abilities operate continuously at each moment in time. The outcomes of these studies will inform future research exploring statistical learning abilities in young children with emergent language impairments. PUBLIC HEALTH RELEVANCE: The goal of this research is to understand how typically developing infants discover structure in the complex speech they hear from caregivers. Future studies will use these tasks to assess language learning in children exhibiting difficulties with language (e.g., children at risk for specific language impairment, children with emergent autism spectrum disorder, or deaf children with cochlear implants). The eventual goals are to investigate whether the mechanisms responsible for learning are compromised in these clinical populations, and to develop more appropriate tools for early diagnosis and intervention.
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0.951 |
2015 — 2016 |
Lew-Williams, Casey |
R03Activity Code Description: To provide research support specifically limited in time and amount for studies in categorical program areas. Small grants provide flexibility for initiating studies which are generally for preliminary short-term projects and are non-renewable. |
Bilingual Infants' and Toddlers' Processing of Mixed Language
? DESCRIPTION: Many children both in the United States and around the world grow up bilingual, and as a consequence face substantial challenges in language learning. Contrary to popular belief, only a tiny minority of these bilingual children grow up in a strict one-person/one language environment. Instead, most bilingual children regularly hear two different languages from the same person, within the same conversation, and often within the same sentence (i.e., mixed-language sentences such as Look at the perro!). While considerable progress has been made in uncovering how young bilinguals process single-language input, very little is known about how they process mixed-language input. The proposed international project leverages the natural complexity observed in bilingual children's language environments, and provides a rigorous test of whether language mixing impacts processing and learning. Specific Aim 1 is to investigate whether bilingual infants differentiate between speech from a single language vs. a mix of two languages. Based on two preliminary studies, Specific Aim 2 is to investigate whether language mixing influences the speed of real-time language processing in bilingual toddlers. Specific Aim 3 is to investigate whether the hypothesized processing cost of language mixing has consequences for recognizing and learning words that occur after a language switch. Previous research has shown that bilingual infants can discriminate between individual sounds as well as full sentences in their two languages, and studies with bilingual adults have shown robustly that language mixing disrupts language processing. Given these findings, we predict that bilingual infants will successfully discriminate between single-language and mixed-language speech (Experiments 1a and 1b), and will show a processing cost of language mixing that delays word recognition (Experiments 2a and 2b) and impairs the comprehension of familiar words and the learning of novel words that occur downstream (Experiments 3a and 3b). The proposed experiments will be conducted simultaneously in two bilingual communities: Spanish/English bilingual children will be tested in Chicago, IL, U.S.A., and French/English bilingual children will be tested in Montr¿al, Qu¿bec, Canada. This approach enables an examination of differences between two communities to address how individual-level factors including socioeconomic status and household use of mixed language affect bilingual infants' and toddlers' processing of mixed language. The results will illuminate how bilingual infants and toddlers navigate the complexities of mixed-language input, which presents an important real-world challenge for language development. The outcomes of this research will inform a significant health concern about the consequences of different types of early bilingual experience, and address parents' questions about how to best support dual- language development in bilingual infants and toddlers.
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1 |
2019 — 2021 |
Byers-Heinlein, Krista (co-PI) [⬀] Lew-Williams, Casey |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Navigating Two Languages: Effects of Everyday Language Switching On Bilingual Infants and Toddlers
PROJECT SUMMARY Many infants in the United States and around the world grow up in bilingual environments, and their experience is defined by caregivers' dynamic switching between two languages. Contrary to popular belief, only a tiny minority of bilingual children grow up in a strict ?one-person-one-language? environment. Instead, most bilingual children regularly hear two languages from the same person, within the same conversation, and often within the same sentence (e.g., ?Look at the perro!?). Little is known about how young bilinguals learn through the inherent alternations between languages. Our primary goal is to understand how bilingual infants and toddlers learn two languages in the context of everyday switching across sentences, conversations, and people. Based on findings from our previous NICHD-funded R03 1, we will test the overarching hypothesis that language switching in bilingual environments is a key contributor to bilingual infants' language learning and language outcomes. The proposed international, cross-lab project will test the same Spanish-English and French-English bilingual children at 12, 24, and 36 months of age, using complementary behavioral, household, and longitudinal measures of young bilinguals' learning from language switches. Aim 1 will use eye-tracking and pupillometry experiments to investigate how bilingual infants and toddlers process and learn from language switching across sentences (Exps. 1-2), conversations (Exps. 3-4), and people (Exps. 5-6). Aim 2 (Exp. 7) will use multi-day recordings of household language to investigate whether and how language switching at home shapes early language processing and contributes uniquely to language and cognitive outcomes. The proposed experiments will be conducted simultaneously with two distinct bilingual populations: Spanish-English bilinguals in New Jersey, and French-English bilinguals in Montréal. Based on intersecting sociolinguistic, demographic, and experiential differences between these communities, this approach will address the crucial puzzle of generalizability in bilingualism research, i.e., whether findings are specific to one population or whether they warrant generalized conclusions. In summary, the proposed studies will illuminate an important, real-life challenge for language development: how bilingual infants and toddlers process familiar words and learn new words from the complexities of dual-language input, both from moment to moment and in aggregate. Findings will enable us to (a) generate a novel and comprehensive theoretical model of the emergence of bilingualism in infants and toddlers, and (b) create and disseminate evidence-based guidelines for fostering early bilingualism. Bilingual parents almost invariably assume that some bilingual environments are better than others, and ? like educators, pediatricians, and speech-language pathologists ? they strive to optimize children's dual-language learning and minimize the risk of language delays. Our complementary measures of the dynamics of bilingual input and learning may lead to better ways of supporting infants' and toddlers' pathways to bilingual proficiency.
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1 |