The impact of language internal and external factors on community language acquisition by Japanese-Brazilian Portuguese bilingual children in Japan.

Abstract

This thesis explores the acquisition of Japanese word order variation and morphological marking of noun phrases with case and topic particles by two Japanese-Brazilian Portuguese (BP) bilingual children. There are more than 200,000 Japanese Brazilian immigrants living in Japan. Children born into such immigrant families are raised in BP as the heritage language at home and acquire Japanese as the dominant language in the community, specifically at the Japanese daycare centres where the Japanese-BP bilingual children spend most of the day while their parents are at work. Japanese word order variation and choice of case and topic particles relate not only syntax but also discourse-pragmatics and thus could be markers of proficiency that are important for understanding both acquisition and dominance in a bilingual child.

The study asked what differences there are between bilingual and monolingual acquisition, and tried to identify to what extent the following factors affect the Japanese-BP bilingual child's acquisition of Japanese word order and case and topic marking: 1) language dominance, defined here in terms of the difference in proficiency in the bilingual child’s two languages, 2) cross-linguistic influence, 3) quantity and quality of caregiver input at the daycare centre, and 4) parental expectations and attitudes towards bilingualism.

The study consisted of three components: longitudinal data collection, a picture selection experiment, and a parental questionnaire survey plus interviews. Three kinds of speech samples were collected: Japanese interaction between the target child and me, Japanese caregiver input at the daycare centre, and BP interaction between the target child and parents at home. The speech samples were analysed in two ways: firstly, Mean Length of Utterance (MLU) values and code-switching were checked as part of understanding the children’s overall language dominance; and secondly, the children’s production of Japanese word order and case and topic particles was examined and compared with caregiver input and with published data on monolingual Japanese acquisition. In the data elicitation experiment, the bilingual children and two monolingual control groups responded to a picture selection paradigm designed to assess comprehension of word order and case particles. The parental questionnaire survey and interviews were conducted in order to understand how parental attitudes and expectations for children’s language use are reflected in children’s language behaviour.

The results show no obvious differences in Japanese word order and case system acquisition between the two bilingual children, monolingual control groups in this study, or monolingual acquisition reported in previous studies. MLU turned out to be insufficient as an indicator of proficiency because the two languages are typological distinct and MLU is task and context dependent. The pattern of code switching in the language samples demonstrated that while the bilingual children never used BP in the Japanese monolingual environment of the daycare centre, they felt free to use the community language Japanese rather than the heritage language BP at home, depending on the topic and the person they talked to. Despite receiving a more limited amount of Japanese input than monolinguals, the bilingual children's performance in both production and perception of word order variation and case and topic particles is within the range of individual variation among Japanese monolinguals. Detailed examinations of two core linguistic structures produced by the bilingual children in this study, object right dislocation and the use of the existential verb aru in possessive constructions, revealed that most of the utterances were discourse appropriate. The source of particular forms in the speech of bilinguals appears to be complex. Neither cross-linguistic influence nor input alone can account for the results. The findings from the parental questionnaire indicated that, despite parents’ high expectations for and positive attitudes towards bilingual acquisition, parents’ heritage language use at home did not necessarily lead a child to use BP as much as their parents. It is speculated that this could be due to assimilative pressures faced by their children at school or lexical gaps. Further studies are necessary to determine how to support bilingual children’s use and development of Japanese at school and at the same time help their parents to support the use and development of heritage languages at home.