This study investigated the possibility that lifelong bilingualism may lead to enhanced efficiency in the ability to shift between mental sets. We compared the performance of monolingual and fluent bilingual college students in a task-switching paradigm. Bilinguals incurred reduced switching costs in the task-switching paradigm when compared with monolinguals, suggesting that lifelong experience in switching between languages may contribute to increased efficiency in the ability to shift flexibly between mental sets. On the other hand, bilinguals did not differ from monolinguals in the differential cost of performing mixed-task as opposed to single-task blocks. Together, these results indicate that bilingual advantages in executive function most likely extend beyond inhibition of competing responses, and encompass flexible mental shifting as well.

Bilingual advantages in executive control tasks are well documented, but it is not yet clear what degree or type of bilingualism leads to these advantages. To investigate this issue, we compared the performance of two bilingual groups and monolingual speakers in task-switching and language-switching paradigms. Spanish–English bilinguals, who reported switching between languages frequently in daily life, exhibited smaller task-switching costs than monolinguals after controlling for between-group differences in speed and parent education level. By contrast, Mandarin–English bilinguals, who reported switching languages less frequently than Spanish–English bilinguals, did not exhibit a task-switching advantage relative to monolinguals. Comparing the two bilingual groups in language-switching, Spanish–English bilinguals exhibited smaller costs than Mandarin–English bilinguals, even after matching for fluency in the non-dominant language. These results demonstrate an explicit link between language-switching and bilingual advantages in task-switching, while also illustrating some limitations on bilingual advantages. (JINS, 2011, 17, 682–691)

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 practised either a language or a non-linguistic colour/shape switching task and were tested one week later on both tasks. The colour/shape task produced significant immediate improvement with training, which was maintained one 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 one week, and there was also transfer facilitation from prior practice with the colour/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.

This study investigated reciprocal influences between the first and second languages of bilingual speakers. Participants were monolingual English speakers and bilingual speakers of English and Hebrew who learned Hebrew either as a first language or as a second language. Participants rated the semantic similarity of English word pairs that either shared a Hebrew translation or did not, and that varied in their baseline relatedness in English. Shared-translation pairs (e.g., tool and dish are both translated as “kli” in Hebrew) were rated as more similar in meaning than different-translation pairs by both bilingual groups, but not by the monolinguals. Knowledge of Hebrew influenced the way bilinguals processed words in English not only when Hebrew was the native language but also when it was learned as a second language later in life. These findings provide evidence for bidirectional transfer, and emphasise the dynamic nature of the bilingual lexicon.

Valian (2014) suggests that the messy state of the literature examining the effects of bilingualism on executive functioning (EF) stems from lack of clarity in how EFs are defined and measured, and from lack of control over other factors that can modulate EF. We argue that the lack of clarity in how bilingualism is defined and measured is no less problematic. We focus our commentary on two related issues.