Bilingual experience shapes language processing: Evidence from codeswitching

- Codeswitchers process frequent codeswitches more easily than rare codeswitches.
- Non-codeswitchers show an ERP switch effect, regardless of the type of codeswitch.
- Codeswitching map task data mirrors naturalistic codeswitching regularities.
- Results support experienced-based models of processing.

We report three experiments on two groups of Spanish-English bilinguals who differed in codeswitching experience (codeswitchers and non-codeswitchers) to examine how different production choices predict comprehension difficulty. Experiment 1 examined the processing of gender congruent and gender incongruent determiner-noun switches in sentential contexts using event-related potentials. While codeswitchers demonstrated N400 sensitivity to congruency manipulations, non-codeswitchers showed a modulation of early frontal EEG activity to switching, regardless of switch type. Experiment 2 validated the translation-equivalent target words compared in Experiment 1. In Experiment 3, the bilinguals who participated in Experiment 1 completed a task that elicited naturally-produced codeswitched speech. Codeswitchers switched more often than non-codeswitchers, and their switches robustly reflected the conditions that were more easily processed in Experiment 1. Together, the results indicate the comprehension system becomes optimally attuned to variation in the input, and demonstrate that switching costs depend on the type of codeswitch and bilinguals' language experience.