Bilingualism is an issue that was close to my heart even before I decided to become a speech-language pathologist, so naturally I have had many questions over the years. I’ve tried to answer my own personal and professional questions in the best way that I know how: read the research. In this blog I will try to share what I’ve learned with you, from the perspective of a practicing speech therapist as well as that of a person with an interest in bilingual child-rearing.

As a professional, I often meet parents with the same question: should I speak only one language to my child? If the child seems to have difficulties with language, is it harmful to use two languages around him or her? It used to be that professionals would say parents should stick to one language in cases where language impairment was diagnosed or suspected. These days most professionals no longer hold that opinion, and the change has been brought about by a good deal of research into both typical bilingual language development and into language impairment. So what do we know?

Bilingual and monolingual kids have similar vocabulary sizes when you count both languages. In terms of the number of words a child knows, he or she may look delayed in one language, or even in both, but when you count all the words they know in both languages, their total vocabulary size is similar to monolingual children (Core et al., 2013; Poulin et al., 2013). Bilingual children might have a smaller “conceptual” vocabulary, though – that is, they might know two words that mean “table,” but they know the names of fewer objects/concepts overall when compared to monolinguals (Core et al., 2013). Mind you, this is typical for bilingual children, and it’s not an impairment: bilingual kids simply develop differently than monolingual kids.

Bilingual language learning can look like language impairment. This is especially true when a child is evaluated in one language only. They might seem to have a reduced vocabulary size (as discussed above), and they might also be behind monolingual children with respect to learning the grammar of a language. In fact, in the early years, children with language impairments and typically-developing bilingual children may look just the same when you catalogue the grammar that they use correctly, such as the –ing in “running,” the –ed in “jumped,” or grammatical function words such as “is” and “are” (Kohnert, 2010). But, on the other hand…

Exposure to two languages is not harmful to children with language impairment. For a speech therapist, this is *the* question. You have to have an answer for it. Research has shown that monolingual and bilingual children with a known language impairment perform with similar accuracy on diagnostic language tasks (Paradis, 2005). In some instances, bilingual children with language impairment have even been shown to perform better than monolingual children with language impairment. Other benefits of bilingualism have also been suggested, such as better executive functioning, leading to better attention skills (Poulin-Dubois et al., 2011).

So where does that leave us? We can now say that 1) raising a child with two languages does not cause language impairment and 2) a child with a language impairment is not harmed by exposure to two languages, but 3) typically developing bilingual children may appear to develop more slowly than typically developing monolingual children. In reality, perhaps they are just developing differently: grammar in two languages, vocabulary in two languages. Still, this last point makes it hard to diagnose language impairment in bilinguals. Assessment in both of the child’s languages is best, but not always possible, especially for languages that are less common. As a parent, you can help the diagnostic process along by providing an accurate estimate for the child’s total vocabulary size in both languages. Core et al. (2013) suggest this as a valuable piece of information when evaluating bilingual children.

This blog has taken as an assumption that the bilingual child is learning both languages simultaneously, but there are other ways of raising kids with two languages. Some might learn a different way, such as learning only one language, the language of the home, until entering a daycare or preschool.

That brings me to the other question that speech therapists always hear, and the question that has generated volumes and volumes of research in the field of second language studies: what is the best way to raise a bilingual child? “One parent/one language” has been a standard recommendation for decades, but research has shown that this approach is not the end-all-be-all of bilingual child-rearing tactics. To put it simply, no one method has been shown to be 100% effective or better than others. I tend to recommend a consistency approach. Whatever you do, do it consistently. And make sure both languages are necessary for the child – if he or she can get away with speaking only one, there’s a higher risk of losing the other. One parent/one language can work, as can one language for home and one language for outside the home.

Hopefully this has been as informative for you as it has been for me. The take-home message is that two languages can work! Language impairment exists, but bilingual parents should neither feel at fault for exposing their child to two languages, nor give up on teaching their child both. And if there are questions, seek a professional. That’s what we’re here for!

References

Core, C., Hoff, E., Rumiche, R., & Señor, M. (2013). Total and conceptual vocabulary in Spanish-English bilinguals from 22 to 30 months: Implications for assessment. Journal of Speech, Language, and Hearing Research, 56, 1637-1649.

Kohnert, K. (2010). Bilingual children with primary language impairment: Issues, evidence and implications for clinical actions. Journal of Communication Disorders, 43, 456-473.

Paradis, J. (2005). Domain-general versus domain-specific accounts of specific language impairment: Evidence from bilingual children’s acquisition of object pronouns. Language Acquisition, 13(1), 33-62.

Paradis, J. (2010). The interface between bilingual development and specific language impairment.Applied Psycholinguistics, 31, 227-252.

Poulin-Dubois, D., Blaye, A., Coutya, J., & Bialystok, E. (2011). The effects of bilingualism on toddlers’ executive functioning. Journal of Experimental Child Psychology, 108, 567-579.

Poulin-Dubois, D., Bialystok, E., Blaye, A., Polonia, A., & Yott, J. (2013). Lexical access and vocabulary development in very young bilinguals. International Journal of Bilingualism, 17(1), 57-70.