The Bilingual Acquisition of English and Mandarin: Chinese Childr ...

1.4. Theoretical Issues in Bilingual First Language Acquisition

A major question in research on bilingual first language acquisition has been whether the young child initially forms one linguistic system (the unitary language system hypothesis in Genesee, 1989; also called the fusion system hypothesis in Meisel, 1989) that he or she then gradually differentiates into two separate linguistic systems, or whether the child actually forms two differentiated linguistic systems from the onset of morphosyntactic development (the separate development hypothesis for De Houwer, 1990; or the differentiation hypothesis in Meisel, 2001).

Although all researchers agree that mixing of the two languages occurs during bilingual development, opinions differ with regard to the explanations of this phenomenon. Studies that claim the validity of the unitary language system hypothesis posit that bilingual children start out with a single lexical system, which includes words from both languages, and apply the same syntactic rules at first, irrespective of language input and context. Different studies have defended this position with different arguments. Works by Volterra and Taeschner (1978) and Taeschner (1983) are representative of this position.

Researchers in favour of the separate development hypothesis maintain that children are able to differentiate from an early age between the two linguistic systems to which they are exposed (see reviews in De Houwer, 1990, 1995, 2005; Genesee, 2000, 2003; Lanza, 1997; Meisel, 1990, 2001).

However, recent research has moved on to investigate how the languages influence and interact with each other in acquisition and use. Questions have been raised about the effects of language interdependence, such as interference or transfer, and acceleration and delay (for reviews, see Genesee, 2000; Lanza, 2000; Meisel, 2001; Yip & Matthews, 2007; Zhu & Li, 2005). Researchers in this area claim that the early bilingual separation of the two languages does not mean that the developmental processes of the two languages are identical or that the child’s two developing languages cannot influence and interact with each other.