Skip to main content

Verified by Psychology Today

Understanding the Bilingual Brain

The neural bases of bilingualism

Post written by François Grosjean.

University of Houston professor, Arturo Hernandez, works on the underpinnings of bilingual language processing as well as second language acquisition in children and adults. He grew up speaking English and Spanish and acquired two other languages as an adult. A year ago, he published an important book, The Bilingual Brain, and he has very kindly accepted to answer a few questions about his work and his book.

There are many publications out now on the bilingual brain but the results are often opaque for the lay person. What are the latest notable findings in your field?

I think there are some interesting findings with regard to neuroanatomical differences and bilingualism. To me the notion that differences in language experience can lead to clear neuroanatomical differences is the most exciting finding to emerge in recent years.

You propose in your book that the bilingual's languages peacefully co-exist in the brain and share resources but they can also compete for these resources. Can you tell us more about this?

Let me give you two examples. I NEVER have problems differentiating between the words "effect" and "affect" but I have noticed that monolingual English speakers can confuse these two words. I attribute this to the fact that each of those words have Spanish cognates with very distinct pronunciations. In this way, Spanish helps my English. But the languages can also compete. Many years ago, a Spanish-speaking friend of mine told the waitress at a restaurant to be careful because he was vicious. The waitress was frightened. I had to remind my friend that “vicioso” means addict or having an addictive personality and that "vicious" means something else in English. Both words come from "vice" but they have a very different meaning in each language. This is the competing part.

According to you, stress may lead to the apparent loss of one language (in terms of it being forgotten), but not of the other. What can you tell us about this?

I don’t really make a strong link between memory and language in my writing but as I think more and more about this it becomes clear that one exists. Our memory is set up to remember what we need when we need it. In this sense, our languages are set up to be remembered when we need them. We could also think about language dominance within this perspective. If one language is more dominant it could be less susceptible to stress. It simply has stronger interconnections with our knowledge. So it takes a much bigger punch to knock it out. A less dominant language will have weaker interconnections and so take much less to show a loss.

Why are some languages privileged in the bilingual brain and not others?

I think two factors play a role. When you learn it and how well you speak it are the two main factors which are also known as age of acquisition and proficiency.

How do modern neural theories explain that a bilingual can speak just one language at one moment in time and speak two languages together in the form of "mixed speech" at another?

Language mixing is an interesting phenomenon. One metaphor is that there is a “language switch” that exists somewhere. Studies suggest that areas in the prefrontal cortex, the parietal lobe and/or the basal ganglia are involved. The problem is that individuals can engage in mixed speech with little apparent cost in some situations. To me the main issue has to do with external cues that might be serving to trigger each language. It reminds me a lot of your own monolingual and bilingual mode studies from many years ago. My guess is that the brain can readily adapt to these different cues and then load up the appropriate responses. This might require the prefrontal cortex which is involved in flexibility. But it could also be fairly automatic and hence rely on the basal ganglia as well.

It would appear that neuropsycholinguistics has moved away from where languages are stored in the brain (recall the hemispheric localization debates) to how they are processed? Is this due in part to recent development in imaging techniques?

I think the entire field of cognitive neuroscience has started to take a much more systems-oriented approach (i.e. how such things as the brain, the mind and other aspects of the human body interact). The days of thinking about one brain area as containing a representation are long gone.

You are a strong defender of merging the "older" mind sciences and the "newer" brain sciences. How can the two contribute on an equal footing to our understanding of language acquisition and language processing?

To me they are really the same thing. I think studying the brain has transformed how I think about language. Mind sciences are traditionally based on thinking about the mind as a computer. The information processing approach has yielded a rich data set. But the problem is that we are not computers. Liz Bates of the University of California at San Diego used to say that connectionist networks are not humans. They need to get a life. We are not just minds or brains operating in the world. Our brains are connected to the body and as such we function as an organism. I really believe that thinking about the mind as emerging from the brain and body makes more sense.

Where do you see the bilingual brain sciences going in the next few years?

I think the bilingual brain sciences need to come full circle and start to address the fundamental questions that were laid out in the late 19th century and early 20th century. How do age of acquisition, language proficiency and language control help to shape the bilingual brain. Rather than thinking about areas of the brain, we could start to think about cognition as a series of brain states that come and go like waves near the shore.

Photo of the profile of a head from Shutterstock.


Hernandez, Arturo E. (2013). The Bilingual Brain. New York: Oxford University Press.

"Life as a bilingual" posts by content area.

François Grosjean's website.

More from Francois Grosjean Ph.D.
More from Psychology Today
More from Francois Grosjean Ph.D.
More from Psychology Today