The Role of Lexical Acquisition in Simultaneous Bilingualism

This thesis addresses a central issue within the field of Bilingual First Language Acquisition (BFLA) by exploring the extent to which the two languages can affect each other during development. The aim of this work is twofold. Firstly, it proposes a particular formalisation of the acquisition process which is based on a set of assumptions that are mostly drawn from standard linguistic theory. It then argues for a theory of the acquisition of lexical properties that is based on the interaction between two higher level systems. The first of these is a system dedicated to organising the developing lexicon into paradigms while the second is an informationally monotonic updating system whose role is to add newly acquired lexical information to those items that are not yet fully developed.
It is then argued that this model can accommodate transfer effects as an inevitable consequence of BFLA. Given that the lexicon of a bilingual child is larger than that of monolinguals, the updating mechanism has a wider field of application and therefore - besides over-generalisation - transfer effects will also obtain. An important consequence of this claim is that the only difference between a monolingual and a bilingual child lies in the domain within which the updating mechanism applies. The fact that language production in bilingual children differs from that of monolinguals does not force the postulation of special bilingual strategies but can be accounted for by appealing to the very two aspects that monolinguals and bilinguals do not have in common, namely the input and the number of developing lexical sets.
A substantial part of the thesis is dedicated to evaluating the empirical coverage of this model. This involves discussion of data from case-studies as well as experimental work both old and new.