Bilingualism: An Overview

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Hola! Bonjour! Hello! Shalom! It’s likely you’ve heard some of these greetings even though not all of them are from your native language. Maybe you even speak more than one of the languages from which these greetings are. This is in large part due to our increasingly globalized world, as over 60 percent of the world speaks at least two languages. Bilingualism, or the ability to speak two languages, can provide much insight into the human mind and our language processing system. What is the relationship between bilingualism and cognition, if there is any at all? Are bilinguals advantaged or disadvantaged when it comes to performing cognitive tasks? Are the brains of bilinguals different compared to monolingual individuals? How does language acquisition for bilingual individuals compare to that of monolingual individuals? Join me in the quest for the answers to these questions!

Bilingual Diversity — a caveat

No two bilingual individuals are the same — even if they both speak the same two languages. There are varying levels of bilingualism, and one’s bilingualism tends to change over time as one is exposed to different environments in which his or her languages are used (or not used).

Some bilinguals get exposed to two languages from birth and navigate their entire lives using both languages. Others learn their second language after childhood. Within both categories, the use of both languages vary. Some early bilinguals are more balanced when it comes to how much they use both languages; however, there are others who tend to use one language much more than the other (Kroll et al 2015). For some people, they are exposed to two languages growing up, yet they do not practice speaking one of the languages from a young age, so they end up being able to understand both languages but unable to speak and/or read and write one of the languages (I’m one of those people, unfortunately).

A lot of the research I’ll be presenting does not distinguish among the different kinds of bilinguals. However, not all bilinguals are the same — I’d like to make that clear!

Language Activation

Is only one language activated at a time for bilinguals (language selective access) or are both languages activated even if only one language is being spoken at a time around bilinguals (language nonselective access)? Several studies have been done on this topic of language activation in bilingual individuals. One of these extensive studies was done by Dijkstra, Grainger, and van Heaven on Dutch-English bilinguals using cognates and interlingual homographs. Cognates are words with similar form and meaning across two languages (e.g. “absence” in French and English) and interlingual homographs are words with similar form but different meanings across two languages (e.g. “coin” which means a piece of money in English but a corner in French).

In the experiment, the bilinguals were presented with English words that were similar to Dutch words with respect to their phonology, orthography, and/or semantics. The participants were presented with a checkerboard, followed by a target English word. Then, another checkerboard was presented followed by the target English word. This continued for increasing amounts of time showing the English word and decreasing amounts of time showing the checkerboards until the participant pressed a button to indicate that he or she had identified the target word. The participant would then have to type the target word in a dialogue box, then the next trial would begin (Dijkstra, Grainger, & Van Heuven, 1999).

In a second similar experiment, the bilinguals were presented with letter strings, and they were tasked with deciding whether the strings were English words.

The results of both experiments show that there was a significant difference in the reaction times between cognates and interlingual homographs compared to the control words. Cognates led to faster reaction times compared to reaction times to the control words, while interlingual homographs led to slower reaction times compared to the reaction times to the control words. These findings demonstrate that the language selective access view is incorrect, because that theory would predict that there would be no differences in reaction times. The second experiment was also conducted on American English monolinguals, and there were no differences in their reaction times between the test words and the control words, demonstrating that the effects of the first two experiments were in fact due to their bilingualism (Dijkstra, Grainger, & Van Heuven, 1999).

These findings show that both languages are activated in bilinguals when it comes to reading; however, there are other studies which demonstrate that both languages are activated when it comes to listening comprehension (Marian and Spivey (2003) and speaking. When it comes to speaking, bilinguals often inhibit the language not in use (Green, 1998).

Overall, these studies and others show that both languages are activated in a bilingual brain, even though the bilingual may have to suppress the language not in use when it comes to speaking.

Bilingualism and Cognition

How in the world are people able to handle having two languages in their brain at one time? I can barely handle just one! You’re probably thinking that the fact that both languages are activated in the mind of a bilingual at the same time makes life more confusing for them. Before recent research on bilingualism, a lot of linguists, psychologists, and neuroscientists would have agreed with you. Are bilinguals at a disadvantage because they have two languages in their heads and have to decide when to use which one? Studies say no. In fact, many studies show that bilingualism is actually advantageous — bilingual brains are often better at performing cognitive tasks such as the Stroop task. Do it yourself using the video linked below and see how you perform!

The Stroop task is an example of conflict management, as the colors and the words are conflicting. The cognitive system has to focus on the color while ignoring the word; this ability is called inhibitory control. Bilingual individuals are usually better at these kinds of tasks than monolingual people, likely because they have to exert some kind of inhibitory control over the language they are not speaking/reading/listening to at a certain time (Marian and Shook, 2012). Additionally, bilingual people are also better than monolinguals at switching between two tasks. For example, when asked to switch from categorizing objects by color to categorizing them by shape, bilinguals were much quicker to do so than monolingual people (Marian and Shook, 2012).

There is evidence to show that bilingualism also protects older adults from age-related decline and diseases that come with aging such as Alzheimer’s. Craik, Bialystok, and Freedman conducted a study on 211 patients diagnosed with Alzheimer disease (Craik et al 2010). 102 of the patients were bilingual, and 109 of the patients were monolingual. The researchers found that the bilingual patients were diagnosed with Alzheimer’s 4 years later than their monolingual counterparts and had reported their onset of symptoms 5.1 years later than their monolingual counterparts. The monolingual patients had on average more formal education, but there was no difference in cognitive and occupational level between the two groups. Immigration status was also controlled. Their findings show that bilingualism, while not a perfect shield against aging, can help to delay the onset of Alzheimer’s disease. Good news for my bilingual Nigerian parents!

The benefits of bilingualism are not only seen in older people — studies have shown that young children, even as early as 7 months of age experience cognitive benefits as a result of being exposed to bilingual input. Kovàcs and Mehler did an experiment on 7 month infants raised in monolingual and bilingual environments. The researchers taught the children that whenever they heard a certain sound, a puppet would appear on one side of a screen. Then, halfway through the study, the puppet started to appear on the other side of the screen. To get a reward, the children had to adjust to the rule that they had just learned (that the puppet would appear on that specific side of the screen). The bilingual infants were much more successful in learning the new rule (that the puppet would appear on the side of the screen that they were not used to) compared to the monolingual babies (Kovàcs and Mehler 2009).

So, there is mounting evidence that being bilingual may not be as detrimental as we might think. Even though bilingual individuals may have various social and psychological hurdles that they have to face such as cultural identity issues, not all is hopeless for them — they seem to have cognitive benefits that monolinguals do not have.

Bilingualism and the Brain

What about the brain? If you’ve taken a psychology or neuroscience course, you’ve likely learned that a lot of what we do and how we think can be traced to the actual structure of our brains. I know what you’re thinking already: Bilinguals seem to have some protection from Alzheimer’s and also are better at cognitive tasks…you don’t mean to tell me that their brains are different too?

Well actually, they are! Or at least that’s what studies suggest (it’s important to take all studies and their findings with a grain of salt!).

Studies have shown that bilingualism correlates with a higher volume of gray matter in the left inferior parietal cortex (Mechelli et al 2004, Olulade et al 2015).

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The image above is adapted from the Olulade et al 2015’s study. The red areas are where the gray matter volumes were greater in one group compared to the other. The bilingual participants had more gray matter volume in total compared to those who spoke only English.

In addition to having more gray matter, bilinguals also seem to demonstrate more activation in the dorsolateral prefrontal cortex when alternating between their two languages (Hernandez et al 2000). This region of the brain is associated with cognitive skills such as attention and inhibition (Bialystok et al 2012). Bilinguals have also been shown to have a larger neural response compared to monolinguals when they are played simple speech sounds in the presence of background noise, meaning that their blood flow, which is an indicator of neuronal activity, is greater in the brain stem in response to the speech sounds compared to monolinguals. These findings suggest that bilinguals are better at encoding the fundamental frequency of sounds, which is a feature of sounds that is closely related to pitch perception (Krizman et al 2012).

Further Questions and Concluding Thoughts

In recent years, there has been a lot of studying done on bilinguals and much has been discovered. However, as research usually does, it’s left us (or me at least) with more questions than answers. A lot of studies have shown that bilinguals have improved executive function in performing cognitive tasks and also a delay in the onset of Alzheimer’s along with differences in their brains; however, do these findings extend to trilinguals and quadrilinguals and so on? Is it that the more languages you speak the more cognitive advantages you have, or is there an upper limit on our cognitive capabilities and once that point is reached, multilingualism is detrimental? What about passive/receptive bilinguals (those who can understand two languages but only speak one language)? Do they behave closer to bilinguals or to monolinguals in these same studies? Do they have more protection against Alzheimer’s than monolinguals? Are their brains different from both monolinguals and bilinguals?

We have a long way to go in terms of fully understanding bilinguals (can we ever fully understand anything, though?). But that work is necessary, for as I said in the introduction, so many people around the world are bilingual or multilingual. And in a world where some languages are seen as inherently “better” than others and some bilingual parents are not teaching their children their native languages because they don’t want to “confuse” them or they don’t think their language is “civilized,” maybe the research coming out about the benefits of bilingualism will convince parents to teach their kids their native language and save the world’s dying languages.


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