Code switching by bilinguals: Evidence against a third grammar

Bilingual code switching within sentences (as in “The towel roja was dirty”) is often observed in bilingual communities. The present study addressed two issues. First, what is the nature of the grammatical rules that underlie code switching? Second, how do bilingual speakers acquire such rules? We addressed the first issue by obtaining judgments of the grammaticality of four types of sentences containing code-switched words. Judgments of acceptability seemed to be based on two rules: (1) Code switching can occur only when the code-switched words are positioned in accord with the rules for which they are approriate lexical items; (2) code switching within word boundaries is considered ungrammatical. We addressed the second issue by exploring the effects of age and code switching experience on the grammatical judgments of bilingual children and adults. Extensive code-switching experience did not seem to be necessary for bilingual speakers to know the grammatical constraints of code switching. This suggests that the constraints of code switching are based on the integration of the grammars of the two code-switched languages rather than on the creation of a third grammar. There were developmental changes in the judgments made to the sentences. All aged subjects found sentences that violated the word-order rule (1 above) unacceptable. However, the youngest children (8- to 10-year-olds) found mixing within a word acceptable. This developmental change could be due to a change in the grammar of code switching, in the ability to make metalinguistic judgments, or in the child's general knowledge about the nature of languages.