Many parents and some teachers worry that early bilingual immersion could have a negative impact on school performance. However, this notion has been widely disproved by all the recent research on the topic, including a University of Liège study by Martine Poncelet and Anne-Catherine Nicolay from the Department of Psychology: Cognition and Behaviour. Better still: early exposure to a second language appears to improve cognitive abilities, at least during the first few years of school. 

There is no universal agreement on the definition of bilingualism. In fact, there are even two opposing views.  The first and most rigorous definition insists that in order to considered bilingual, a subject must master each of the two languages as well as a monolingual native speaker.  "However, people who speak two languages usually tend to use them in different situations - one with family and the other professionally, for example. This means that the vocabulary they use is not the same for each language," explains Professor Martine Poncelet, head of the Neuropsychology of Language and Learning Unit within the University of Liège's Department of Psychology: Cognition and Behaviour. A university researcher who is a native French speaker may actually feel more comfortable presenting their work in English. The same thing happens with children who speak one language at school and another at home.  

The other extreme is to regard anyone who knows several words in another language as bilingual. Today the definition most widely accepted by specialists is more balanced: bilingualism is characterised by fluency in both languages, without requiring the subject to use both languages equally well in all contexts. 

In truth, there are a number of levels and types of bilingualism. An important distinction relates to the age at which the second language is introduced. As such, "early or simultaneous bilingualism" refers to children who learn both languages at the same time, or at least before the age of 3.  This is the case when their parents are from different countries and each speaks their own native language. This is also typical of families who live abroad, where the children are rapidly immersed in the language of the host country.  "Sequential bilingualism" refers to children who learn a second language after the age of 3. If the second language is not acquired until after the age of 10, it's referred to as "late sequential bilingualism".

A dramatic reversal

Until the early 1960s, bilingualism was generally perceived as being detrimental to mental functioning. In fact, the earliest research on the links between bilingualism and cognition provided evidence in support of this negative perception. Researchers showed that the IQ of bilinguals was significantly lower than that of monolinguals, among other things. But there were significant flaws in their methodology. "When this research was examined more closely, it became clear that they compared individuals from very different socio-cultural backgrounds, and the bilinguals were generally immigrants who were disadvantaged because of their origins," says Martine Poncelet. “Furthermore, the Intelligence quotient (IQ) tests were administered in the majority language, which the immigrants may not have spoken as well as their native language. And lastly, those tests also had strong cultural biases.”