Many studies have shown that bilingual children outperform monolinguals on tasks testing executive functioning, but other studies have not revealed any effect of bilingualism. In this study we compared three groups of bilingual children in the Netherlands, aged 6–7 years, with a monolingual control group. We were specifically interested in testing whether the bilingual cognitive advantage is modulated by the sociolinguistic context of language use. All three bilingual groups were exposed to a minority language besides the nation’s dominant language (Dutch). Two bilingual groups were exposed to a regional language (Frisian, Limburgish), and a third bilingual group was exposed to a migrant language (Polish). All children participated in two working memory tasks (verbal, visuospatial) and two attention tasks (selective attention, interference suppression). Bilingual children outperformed monolinguals on selective attention. The cognitive effect of bilingualism was most clearly present in the Frisian-Dutch group and in a subgroup of migrant children who were relatively proficient in Polish. The effect was less robust in the Limburgish-Dutch sample. Investigation of the response patterns of the flanker test, testing interference suppression, suggested that bilingual children more often show an effect of response competition than the monolingual children, demonstrating that bilingual children attend to different aspects of the task than monolingual children. No bilingualism effects emerged for verbal and visuospatial working memory.

We investigate how the rewards of individual tasks dictate a priori how easy it is to interleave two discrete tasks efficiently, and whether people then interleave efficiently. Previous research found that people vary in their ability to interleave efficiently. Less attention has been given to whether it was realistic to expect efficient interleaving, given the reward rate of each of the involved tasks. Using a simulation model, we demonstrate how the rewards of individual tasks lead to different dual-task interleaving scenarios. We identify three unique dual-task scenarios. In easy scenarios, many strategies for time division between tasks can achieve optimal performance. This gives great opportunity to optimize performance, but also leads to variation in the applied strategies due to a lack of pressure to settle on a small set of optimal strategies. In difficult scenarios, the optimal strategy is hard to identify, therefore giving little opportunity to optimize. Finally, constrained scenarios have a well-defined prediction of the optimal strategy. It gives a narrow prediction, which limits the options to achieve optimal scores, yet given the structure people are able to optimize their strategies. These scenarios are therefore best to test people’s general capability of optimizing interleaving. We report three empirical studies that test these hypotheses. In each study, participants interleave between two identical discrete tasks, that differ only in the underlying reward functions and the combined result (easy, difficult, or constrained scenario). Empirical results match the theoretical pattern as predicted by simulation models. Implications for theory and practice are discussed.

No abstract