Introduction

One of the more important questions in the study of bilingualism is: to what extent are the bilinguals' two languages functionally independent and to what extent do they constitute a single functional system?

Evidence of interaction between systems, namely from language mixing or code mixing, provides an important source of data on bilingual language processing. While such data can come from normal bilinguals as well as bilingual aphasics, language mixing in bilingual aphasia is presumed to offer a direct window on the mechanism of interaction between language systems and is therefore more valuable in modeling the neurolinguistic organization of two language systems with respect to one another.

In this chapter I will outline a neurolinguistic model of language processing in the bilingual and then propose to account for language mixing in terms of the framework of this model. According to this framework, both languages are activated when a bilingual prepares to speak and the two language systems interact via links between corresponding stages along a processing continuum. The different manifestations of language mixing reflect the interaction of language systems at different levels of language processing.

I will begin by reviewing the examples of language mixing in aphasia that have been reported in the literature. I will then discuss the relationship between language mixing in aphasia and language mixing in normals. In the final part of the chapter I will outline the model and show how various forms of language mixing may arise in terms of this model.