Functional flexible adaptation of selective attention in bilingualism

We analysed performance on selective attention tasks in the context of very high processing loads, in order to establish how this finite capacity is affected by bilingualism and age. If bilingual modulation of selective attention reflects redistribution rather than enhancement, and the constant demands of bilingualism consume a portion of attentional capacity, very high attentional loads can be expected to tax bilinguals’ performance more than in monolingual controls. To test this, we designed an “extreme” dual attentional task with competing demands. Monolingual and bilingual participants performed an auditory dichotic listening task with varying levels of interference, while also detecting visual targets on the screen. The same task was performed by children and adults, to establish how this adaptation of selective attention in bilingualism might change with maturation. Results showed equivalent performance on accuracy of the dual attention task for monolinguals and bilinguals in both age groups. Reaction times from the visual task however revealed differences between groups, with bilingual children’s responses significantly slower relative to monolingual children in conditions of high processing load, whereas the bilingual and monolingual adults’ performance was equivalent. These results are indicative of distribution of the available capacity and task prioritisation in bilingual children relative to monolinguals, with these differences in performance receding by adulthood. This suggests that maturation of the selective attention system enables adaptation to the combined load of second language processing and competing task demands; resulting in flexibly adapted selective attention system capable of optimal processing even under very high processing loads.