Assessing Proactive Language Control: Does Predictability of Language Sequences Benefit Language Switching?

Multilinguals often switch between the languages they speak. One open question is to what extent they can use anticipatory-or proactive-language control to reduce interference from non-target languages during language switching. In three experiments, unbalanced German-English bilinguals (N₁ = 24; N₂ = 35; N₃ = 37) named pictures in their L1 or L2 in mixed blocks. In all but the penultimate block, the language sequence in which pictures were named was predictable (e.g., L1, L1, L2, L2, etc.), thus allowing participants to prepare for upcoming trials. Performance in the non-predictable block was compared to average performance in predictable sequence blocks right before and after, thus controlling for practice effects. We predicted that language switching would be facilitated during predictable language trials, indicative of proactive language control. However, for Experiments 1-2, there was no evidence for a predictability benefit across both experiments. When the number of items that had to be switched between was reduced to two (Experiment 3), a limited repetition-specific predictability effect emerged. These findings suggest that people do not use preparatory processes endogenously on the basis of regularities in the language sequence to reduce interference during language switching, unless the specific item that needs to be produced can be anticipated.