The impact of bilingualism on executive function in adolescents

In early childhood and older adulthood, bilinguals generally demonstrate better performance on executive function tasks than their monolingual counterparts, but in the young adult population, these differences are infrequently observed. However, few studies have examined these effects in the adolescent population, so the trajectory of these changes is unclear. The objective of the study was to compare performance on a modified flanker task for monolingual and bilingual adolescents, a time when the executive functions are still developing.

The flanker task was adapted by including a rule-switching component and contained three blocks: (1) rule; (2) flanker; and (3) mixed. In the rule block, a single red or blue arrow (indicated by light grey or medium grey in Figure 1) denoted a response rule; for example, a blue arrow signaled pressing the button indicating the direction the arrow was pointing but a red arrow signaled pressing the button indicating the opposite direction. The flanker block was a standard flanker task consisting of congruent and incongruent trials. The mixed block manipulated both congruency and rule conditions.

Mean reaction times and accuracy from 33 monolingual and 32 bilingual adolescents were analyzed using a repeated-measures analysis of variance with language group as the between-subjects variable and congruency and/or rule-type as the within-subjects variable depending on the block.

Bilingual adolescents outperformed monolingual adolescents but only on the block that was most similar to the standard flanker task. The blocks with the rule-switching component yielded equivalent performance.

Unlike previous studies, the current study adapted a simple executive control task to require greater attentional resources by manipulating task demands.

Our findings add to the growing body of literature examining bilingualism and executive control in the adolescent population and fill in the gap in our understanding of the lifespan trajectory of these effects.