Learning a second language can be very hard and time consuming but learning native languages as a kid is very easy and usually comes naturally as the kid develops. Kids raised in a two-language home develop both languages as they grow and end up bilingual. Being bilingual is a privilege but usually comes at a cost such as later development of speech, language, and reading (Preston et al.,2010), but according to research the advantages of being bilingual are more than its disadvantages.
Most of the disadvantages that are developed early on in childhood are the building blocks for the advantages later on, because it forces the brain to develop more sophisticated processes during development (Mohr et al., 2016). The bilingual advantage has been debated on for a long time now and researchers have found out that the bilingual advantage is packed by structural and functional evidence, that shows what happens in the brain of a bilingual individual and how it functions compared to a monolingual individual’s brain.
First, compared to monolingual individual, bilinguals have some advantages. Some of these advantages are better working memory, flexibility in handling situations, and better inhibitory and attentional abilities. They also tend to be more field independent and more sensitive to input cues, which helps them succeed in learning and school (Mohr et al., 2016). According to research the improved cognitive abilities is known as the bilingual advantage, that advantage leads bilinguals to have better executive function, such as a more sophisticated processing and better decision making skills (Mohr et al., 2016).
Also, they tend to be better with recalling events with greater accuracy than monolinguals, which shows signs of possibly better long-term memory (Barac et., 2014). Moreover, bilinguals tend to be better at tasks that require shifting their attention to come to a conclusion. For example, if their in a group setting and everyone around them is talking but they need to finish an assignment, they tend to do better shifting their attention from the conversations around them to the assignment they are working on.
Even though the advantages outweigh the disadvantages in this case, the disadvantages do still occur. Some of these disadvantages are as mentioned previously delay in the development of speech, language and reading (Preston et al., 2010). Also, bilingual infants tend to have a limited vocabulary, and later development of grammar in both languages because the brain is trying to sort out more linguistic information than a normal monolingual infant (Mohr et al., 2016). Researches came up with a study where they tested 174 students whom parents specified if their children were “early”, “on time”, or “late” speakers.
The students went through standardized testing, IQ testing and underwent fMRI scans while going through a “match the picture to the word” test. Based on the fMRI scans and the testing, the late speakers showed the lowest rates of performance, which did show the disadvantages to late language development that usually accompanies bilingual children (Preston., et al. 2010).
Secondly, researches have been trying to find what goes on in the brain of bilingual individuals and if being bilingual has any visible affects on the brain that can justify the advantages they show. The bilingual advantage has been and still is a topic for debate to many researchers, but a lot of research has showed significant differences in the brains of the bilingual individuals compared to monolingual individuals. Behavioral studies have shown that bilingual individuals are better at executive functioning and have high levels of cognitive functions and that is due to structural, functional and connectivity differences in the brain (Wong., et al. 2015).
Structural differences between bilinguals and monolinguals are mostly in the frontal parietal brain areas. That was shown using voxel-based morphometry (VBM). The VBM is “a technique using MRI that allows investigation of focal differences in brain anatomy, using the statistical approach of parametric mapping. In this technique, volume of the whole brain, or its subparts, is measured by drawing regions of interest (ROIs) on images from the scan and calculating the volume enclosed” (Science direct).
The VBM scan showed greater grey area density in the inferior parietal cortex in the bilinguals brain compared to monolinguals, but this was also very dependent on when the individual learned the second language exactly and how proficient they were at both languages; the grey matter density was more in individuals who were early bilinguals than late bilinguals and was more in individuals with a higher L2 proficiency (Wong., et al. 2015). The frontal parietal lobe is in charge of language processing, and that’s why increase in the grey matter only occurred when the individual was an early bilingual or had a high L2 proficiency.
Also, MRI scan were done on bilinguals according to the same study. “MRI (Magnetic resonance imaging) scan uses a strong magnetic field and radio waves to create detailed images of the organs and tissues within the body” (Medical news today). The MRI scans also showed greater grey matter, but in the inferior parietal lobe, which is the reason behind why bilinguals show better attention span and cognitive control (Wong., et al. 2015).
Using VBM, researchers found structural differences in the basal ganglia; such as the grey matter volume in the left caudate nucleus was higher in bilinguals than monolinguals that area is where cognitive control is. (Wong., et al. 2015). Functional activation in the left caudate increased when the individuals were switching between languages compared to when they were not switching. Also, according to the same research, bilinguals usually experienced increased grey matter in the left caudate nucleus, when learning L2 vocabulary. (Hosoda,, et al. 2013). The increased grey matter is what causes the increase in executive functions and behaviors in bilingual individuals.
Another form of imaging that was used is fNIRS (functional near-infrared spectroscopy), which is “a specialized research imaging technique that uses near-infrared light to examine the function of the living brain” (NIRS). This form of scan was used by researches and helped determine that bilinguals activated both the dorsolateral prefrontal cortex and the inferior frontal cortex in judgment more than monolinguals did (Kovelman., et al. 2008). According to the research that was done by Wong., et al, “ Since, previous research has linked the dorsolateral prefrontal cortex with working memory, the researchers took this to mean that the ability to process more than one language might have led to functional changes in the brain regions that support working memory associated with the language processing”.
Later research by Jasinika and petitto, found that “bilinguals activated both the normal left hemisphere regions, such as the L inferior frontal gyrus, superior temporal gyrus, as well as the domain-general cognitive areas, such as the dorsolateral prefrontal cortex and restrolateral prefrontal cortex”. The restrolateral prefrontal cortex is what controls the planning, reasoning and integrating, while the dorsolateral prefrontal cortex is what controls the working memory (Wong., et al. 2015).
The researchers came to the conclusion that, when bilinguals go through the processes of selecting between languages and interpreting them, that’s when the connection between the prefrontal cortical activation increases, which is what causes bilinguals to have better executive functions, better working memory and better reasoning and planning skills. This is because the increased connection that is happening is between the key brain regions in executive functions and working memory.
Lastly, structural connectivity in the bilingual brain is different than the monolingual brains. Research done by Grady used DTI scans to determine the structural connectivity in the bilingual brain. “DTI scan is an MRI-based neuroimaging technique which makes it possible to estimate the location, orientation, and anisotropy of the brain’s white matter tracts” (Imagilys). “The DTI scan showed stronger connectivity in the frontoparietal control compared to monolinguals when they are at rest” (Wong., et al. 2015). This includes both the dorsolateral and inferior frontal regions, which are in charge in the executive functioning and cognitive control and that’s why bilinguals show better performance at both due to the stronger connectivity (Wong., et al 2015).
Based on the research above, being bilingual or being raised in a bilingual house does have its pros and cons. Some of the pros are increased executive functioning, greater working memory, better planning, reasoning and integrating skills, while some of the cons are later development of speech and cognitive abilities. Other cons are infants having fewer vocabularies in both languages and some grammatical errors in both languages and that is due to the brain trying to sort out between the two languages. Again, the cons that happen in early childhood are what lead to the pros in adulthood. Also, bilinguals have structural, functional and connectivity differences, that monolinguals does not have.
The differences in the brains do depend as mentioned above on the proficiency of the second language and when it was learned. Research has been going on for years now trying to find out the structural and functional evidence behind the bilingual advantage and good evidence have been found but the research keeps going to further develop the understanding of the bilingual brain and it’s advantages.