Increases in attentional demands are associated with language group differences in working memory performance.

One approach to resolving the controversy over whether bilingualism affects executive function (EF) performance has been to identify the specific tasks and populations that might show these effects. The assumption is that the effect of bilingualism reliably occurs with some tasks and populations but not others and that identifying those conditions will settle outstanding contradictions. However, it is now clear that experiments using the same task (e.g., flanker, Simon, etc.) and apparently the same populations (monolingual or bilingual participants) still lead to different outcomes. Therefore, something in addition to these factors must determine performance. The present study tested the hypothesis that changes in demands for attentional control within a task is associated with performance differences for groups with different attentional resources, in this case, monolingual and bilingual participants. Sixty-four young adults who were classified as monolingual or bilingual based on a detailed questionnaire completed four increasingly difficult conditions of an n-back task while EEG was recorded. Behavioral results showed greater declines with increasing difficulty for monolinguals than bilinguals, and electrophysiological results revealed more effortful processing by monolinguals across all conditions. Our interpretation is that demands for attentional control by the task in conjunction with assessments of attentional resources in individuals or groups determines performance on executive function tasks. These results lead to a re-examination of how executive function is conceptualized and the role of bilingualism in performance on these tasks.