If you stay, it might be easier: Switch costs from comprehension to production in a joint switching task

Switching language is costly for bilingual speakers and listeners, suggesting that language control is effortful in both modalities. But are the mechanisms underlying language control similar across modalities? In this study, we attempted to answer this question by testing whether bilingual speakers incur a cost when switching to a different language than the one just used by their interlocutor. Pairs of unbalanced Dutch (L1)-English (L2) bilinguals took turns naming pictures in a pure Dutch, a pure English, and a mixed-language block. In the mixed block, one participant (Switching Participant) voluntarily switched between Dutch and English, whereas the other (Non-switching Participant) named all pictures in Dutch. Within the mixed block, the Non-switching participant took longer to name pictures when the Switching participant's response on the preceding trial had been in English rather than Dutch, and this local switch cost was larger the more the Non-switching participant was proficient in English. Additionally, there was strong cross-person, item-level interference: The Non-switching participant named pictures more slowly in Dutch if the Switching participant had previously named those same pictures in English rather than Dutch. These findings indicate that comprehension of utterances produced by another speaker in L2 makes subsequent production of L1 utterances more costly. We interpret this as evidence that language control mechanisms are shared between comprehension and production, and specifically that bottom-up factors have a considerable influence on language selection processes in both modalities.