Bilingual Children Have Advantage in Working Memory

A post in this blog, "Mother Tongue Based - Multilingual Education : A Barrier to Cognitive Development?"
last year shared the results of a study in India that demonstrated better cognitive development among bilingual school children. The authors' explanation for their findings were as follows:
"...Getting education through English involves differential curricular pressure and cognitive demands on the part of the students. The student has to understand the instructions presented in English which is not his mother tongue, to develop linguistic competence in it and simultaneously master the course content. For Odia medium children the task is much simpler as they have to master the course content only using a language already acquired earlier at home. However, this tougher task demand at an early age helps in faster development of cognitive processes in the children being educated through English medium...."
This year, a recent paper has been published in the Journal of Experimental Child Psychology that examines the effect of bilingualism on working memory. The article, "Working memory development in monolingual and bilingual children", has the following abstract:
Two studies are reported comparing the performance of monolingual and bilingual children on tasks requiring different levels of working memory. In the first study, 56 5-year-olds performed a Simon-type task that manipulated working memory demands by comparing conditions based on two rules and four rules and manipulated conflict resolution demands by comparing conditions that included conflict with those that did not. Bilingual children responded faster than monolinguals on all conditions and bilinguals were more accurate than monolinguals in responding to incongruent trials, confirming an advantage in aspects of executive functioning. In the second study, 125 children 5- or 7-year-olds performed a visuospatial span task that manipulated other executive function components through simultaneous or sequential presentation of items. Bilinguals outperformed monolinguals overall, but again there were larger language group effects in conditions that included more demanding executive function requirements. Together, the studies show an advantage for bilingual children in working memory that is especially evident when the task contains additional executive function demands.
The children included in these studies have been carefully chosen so that the grouping between bilinguals and monolinguals does represent the only major difference between the students. Parents in both groups all have college education and the students all live in a somewhat homogeneous middle class neighborhood. In terms of English vocabulary, the monolingual children (those who speak English in both home and school) perform better. On "Pictures Task", an exercise that measures working memory and speed, bilinguals are significantly faster than the monolinguals although both groups have similar accuracy. A second study described in this paper makes use of a test similar to a Corsi block task:

An example of a Corsi block task
Downloaded from Gebhard Sammer, "Working memory load and EEG-dynamics as revealed by point correlation dimension analysis"
In this test, monolinguals do as well as bilinguals when the children are asked to recall only which blocks had a figure. However, when asked to provide the correct sequence, 5-year old bilinguals had a higher score (50% correct) than the 5-year old monolingual children (41% correct).

The paper then concludes with the following paragraph:
"The current studies fill an important gap in our understanding of the bilingual mind. Working memory is crucial to cognitive development, and its precocious development by bilingual children is important evidence for developmental effects of experience. The results also contribute to the growing literature on the effect of experience on cognitive outcomes. In this regard, bilingualism is particularly important because, unlike experiences such as musical training and video game playing, bilingual children are not typically preselected for talent or interest. The children in the current studies were bilingual because of a family history of immigration and not because of a talent for learning languages. This is powerful evidence for the role of experience in shaping the mind and directing the course of development."