The relationship between executive control and working memory predicts that bilingual advantages
are expected in more complex and executive-loaded working memory tasks. Indeed, Morales and
colleagues (2013) found working memory advantages for 5- and 7-year-old bilingual children in the
Frogs Matrices task. In this task, children needed to remember the location of a frog in a pond, represented
by a 3 3 matrix. Multiple locations were shown either simultaneously or sequentially. The
bilingual advantage was especially prominent in the executive-loaded sequential condition that
required recalling both the locations of the frog and the order of the locations, in line with the hypothesized
effect. However, Engel de Abreu (2011) failed to find bilingual visuospatial working memory
advantages, even though the tasks used in her study and those used by Morales and colleagues
(2013) were highly similar and children with the same ages and SES backgrounds were investigated
in the two studies.
For the current study, we investigated both visuospatial and verbal working memory using tasks
with different levels of executive control, that is, storage-only tasks and tasks that require both storage
and processing of information. Although most research on bilinguals’ advantages includes mediumand
high-SES children who are highly proficient in their two languages, the current study was
concerned with bilingual children from low-SES families who are less proficient in Dutch as a second
language than monolingual Dutch controls. The next sections address these two factors—linguistic
proficiency and SES—in turn.