Whole-language and item-specific control in bilingual language production.

The current study investigated the scope of bilingual language control differentiating between whole-language control involving control of an entire lexicon specific to 1 language and lexical-level control involving only a restricted set of recently activated lexical representations. To this end, we tested 60 Dutch-English (Experiment 1) and 64 Chinese-English bilinguals (Experiment 2) on a verbal fluency task in which speakers produced members of letter (or phoneme for Chinese) categories first in 1 language and then members of either (a) the same categories or (b) different categories in their other language. Chinese-English bilinguals also named pictures in both languages. Both bilingual groups showed reduced dominant language fluency after producing exemplars from the same categories in the nondominant language, whereas nondominant language production was not influenced by prior production of words from the same categories in the other language. Chinese-English, but not Dutch-English, bilinguals exhibited similar testing order effects for different letter/phoneme categories. In addition, Chinese-English bilinguals who exhibited significant testing order effects in the repeated categories condition of the fluency task exhibited no such effects when naming repeated pictures after a language switch. These results imply multiple levels of inhibitory control in bilingual language production. Testing order effects in the verbal fluency task pinpoint a lexical locus of bilingual control, and the finding of interference effects for some bilinguals even when different categories are tested across languages further implies a whole-language control process, although the ability to exert such global inhibition may only develop for some types of bilinguals.