Things changed in 1962, when Canadian researchers Elisabeth Peal and Wallace Lambert brought attention to the methodological errors of previous studies and provided convincing data showing that bilinguals were not actually inferior to monolinguals in a number of cognitive aspects. At the same time, psychologists became more interested in bilingualism and ways to evaluate bilinguals, particularly in their native language. The results of this research seemed to demonstrate that there was no disadvantage to speaking two languages.

In the 1980s and 90s, another Canadian researcher, Ellen Bialystok of York University in Toronto conducted research (1&2) on different aspects of cognitive development showing that, on average, bilingual children had superior abilities, mainly in terms of attentional and executive functions (these allow us to inhibit irrelevant information, plan out our actions, develop strategies, etc.). "Ellen Bialystok subsequently conducted further studies which showed that these advantages extended to adults, including the elderly," explains Martine Poncelet. “Better still: bilingualism may delay the onset of Alzheimer's. Why? Because when someone speaks two languages, they will have more extensively developed executive and attentional functions throughout their life, building what is referred to as a "cognitive reserve". 

However, we still don't fully understand the mechanisms that provide bilinguals with a cognitive advantage. According to the ULg researcher, it is thought that speaking two languages requires people to constantly inhibit the other language, and that it takes enormous mental flexibility to switch from one language to another. As a result, inhibition skills and mental flexibility are stronger, and Ellen Bialystok's research shows that bilinguals are markedly superior to monolinguals in these two areas.

The success of immersion

In the 1960s, English-speaking Canadians recognized the need for their children to be fully bilingual. At that time, Wallace Lambert initiated the first experiment in early bilingual immersion education. The formula is simple: teaching is conducted part of the time in the native language (currently 25 or 50% of the time depending on the school) and the rest of the time in a second language (75 or 50% of the time). As part of this approach, the language is not taught as a foreign language, but rather is used to teach other subjects. 

Several criteria must be met. First of all, an early start: in the Wallonia-Brussels Federation, Léonie de Waha school in Liège welcomed its first bilingual class in 1989, which began in the 3rd year of pre-school. Secondly, the teacher should be a native speaker. However, this requirement is not always met given the lack of applicants - teachers of or recent graduates in German philology are sometimes hired. In French-speaking Belgium, there is a shortage of Anglo-Saxon teachers, which explains why only 20% of language immersion classes are in English, as compared to 80% in Dutch - even though a significant number of parents would like their children to learn English. 

Currently, at least 160 primary schools and 100 secondary schools offer bilingual immersion programs in the Wallonia-Brussels Federation. "The main objective is for students completing their 6th year of primary school to have the same skill level in all subjects as their monolingual counterparts, all while having acquired a thorough knowledge of Dutch or English," says Martine Poncelet.

(1)  Claudia Dreifus, The bilingual advantage - A conversation with Ellen Bialystok, in The New York Times, May 30th 2011. Read the article
(2) Elen Bialystok, L'acquisition d'une deuxième langue, le bilinguisme pendant la petite enfance et leur impacrt sur le développement cognitif précoce, York University, 15 mars 2006. Read the article