Should I stay or should I switch? A cost–benefit analysis of voluntary language switching in young and aging bilinguals.

Bilinguals spontaneously switch languages in conversation even though laboratory studies reveal robust cued language switching costs. The authors investigated how voluntary-switching costs might differ when switches are voluntary. Younger (Experiments 1-2) and older (Experiment 3) Spanish-English bilinguals named pictures in 3 conditions: (a) dominant-language only, (b) nondominant-language only, and (c) using "whatever language comes to mind" (in Experiment 2, "using each language about half the time"). Most bilinguals, particularly balanced bilinguals, voluntarily mixed languages even though switching was costly. Unlike with cued switching, voluntary switching sometimes facilitated responses, switch costs were not greater for the dominant language, and age effects on language mixing and switching were limited. This suggests that the freedom to mix languages voluntarily allows unbalanced and older bilinguals to function more like balanced and younger bilinguals. Voluntary switch costs reveal an expanded role for inhibitory control in bilingual language production and imply a mandatory separation by language in bilingual lexical selection.