Are all interferences bad? Bilingual advantages in working memory are modulated by varying demands for controlled processing

We investigated bilingual advantages in general control abilities using three complex-span tasks of working memory (WM). An operation-span task served as a baseline measure of WM capacity. Additionally, two modified versions of the Stroop-span task were designed to place varying attentional-control demands during memoranda encoding by asking participants either to read the to-be-remembered item aloud (lower cognitive control; i.e., Stroop-span task) or to name the font color of the to-be-remembered item while still encoding the word for later recall (greater cognitive control; i.e., attention-impeded Stroop-span task). Twenty-six Korean-English bilinguals and 25 English-native monolinguals were tested. We found that bilinguals outperformed monolinguals on the attention-impeded Stroop-span task, but on neither the operation-span nor the Stroop-span task. Our findings demonstrate that bilingualism provides advantages in controlled processing, an important component of WM and other executive functions, suggesting that the demand for controlled processing in WM tasks moderates bilingual effects on WM.