The elusive link between language control and executive control: A case of limited transfer.

We investigated the relationship between language control and executive control by testing three groups of bilinguals (104 participants) and 54 monolinguals in a training and transfer paradigm. Participants practiced either a language or a non-linguistic color/shape switching task and were tested one week later on both tasks. The color-shape task produced significant immediate improvement with training, which was maintained a week later, but exhibited no cross-task transfer effects. In the dominant-language, training effects did not persist after one week, and there were no transfer effects. In the non-dominant language there were significant training effects that lasted a week, and there was also transfer facilitation from prior practice with the color/shape task, which was limited to a reduction in mixing costs. Despite limited transfer, there were significant correlations between tasks in mixing costs for bilinguals, in switching costs for monolinguals, and in intrusion errors for all participants. Finally, the pattern of costs observed for the two tasks exhibited both similarities and differences across participants. These results imply a limited but significant role for executive control in bilingual language control, possibly playing a stronger role in facilitating non-dominant language production and in supporting the ability to monitor response outcomes to avoid errors.