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Two Languages, More Potential?The effects of bilingualism on the brain, the mind and the body
Hwang Celine  |  celine9797@yonsei.ac.kr
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승인 2015.12.08  22:08:55
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IN THE past, there was a common perception that bilingualism was harmful to ones educational development. Past studies indicated that bilinguals had weaker verbal skills and knew fewer words of any semantic category in comparison to monolinguals. However, recent research has shed insight on the various benefits of bilingualism. The advantages of bilingualism are now thought to be significant enough to challenge past notions of bilingualism as a handicap.
 
The activity and structure of bilinguals brains
   By utilizing brain imaging techniques like functional magnetic resonance imaging (fMRI), researchers have observed which brain regions are active when bilinguals complete tasks that require them to switch between their two languages. In one study, when bilinguals switched between naming pictures in Spanish and English, activity was detected in their dorsolateral prefrontal cortex (DLPFC). More specifically, along the DLPFC, activity in the left inferior frontal gyrus (left-IFG) was found. Because the DLPFC is associated with cognitive skills like attention and inhibition, while the left-IFG is regarded as the language production center, bilingualism can lead to both cognitive and linguistic advantages.
   Additionally, bilingualism was linked to subcortical brain areas that have been associated with sensory processing. When researchers played speech sounds in the presence of background noise, bilingual listeners demonstrated a larger neural response than monolingual listeners. In other words, in response to the sound, bilinguals blood flow in the brain stem was greater than that of monolinguals. Such a response reveals that bilingualism is linked to advantages in auditory attention.
   Bilingualism not only affects activation in neural structures, but also impacts the brains structure. According to researchers from the Center for the Study of Learning at Georgetown University, bilinguals have more grey matter in their nervous system. Grey matter is the component of the central nervous system that includes neuron cells, synapses and other major components of the neural network. It is linked closely to systems that control memory, the senses, emotions, speech, decision making and self-control. Therefore, a larger amount of this grey matter may heighten ones ability to carry out functions related to such systems.
 
A boost in cognitive skills
   Bilingualisms effects on neural activity and the brains structure can explain its various tangible benefits. First of all, because bilingualism leads to improvements in cognitive and sensory processing, it can allow bilinguals to more efficiently process linguistic information. In a series of studies by Ellen Bialystok, York University Distinguished Research Professor, bilingual children outperformed monolinguals in tasks that required cognitive, linguistic abilities. In one study, Bialystok asked children the following sun-moon question created by Piaget: suppose everybody got together and decided to call the sun the moon and the moon the sun. What would be in the sky when we go to bed at night? What would the sky look like? In response, both fully and partially bilingual children significantly outscored monolingual children by answering the sun to the first question and dark to the second. Additionally, when Bialystok asked young children to count the number of words in a sentence, she found that bilingual children performed better than their monolingual counterparts. According to Bialystok, this result indicates bilinguals enhanced understanding of criteria that determine the identity of words and ability to pay attention to relevant units of speech.
   Furthermore, bilingualisms effects on the brain can explain bilinguals increased ability to manage conflicts.  Unlike monolinguals, bilinguals have to deal with conflicting information on a daily basis. When a bilingual person reads, hears or speaks one language, the other language that is not used still impacts their overall bilingual performance and often competes with the language in use. For instance, according to a 2007 study published in Proceedings of the National Academy of Science of the United States of America, when Chinese-English bilinguals judge how alike two English words are in meaning, they automatically consider whether the Chinese translations of those words are written similarly. Hence, bilingual individuals need to suppress one language so that they can effectively communicate in the other language.
   By constantly suppressing one language whenever they want to communicate in the other language, bilingual individuals are able to strengthen control over their cognition. As a result, they often perform better than monolinguals on tasks that require conflict management. For example, in a study published in Psychology and Aging, bilinguals were less influenced by the Simon effect, a phenomenon in which cognitive clashes cause a persons reaction time to slow down. To test this phenomenon, subjects were shown a computer that displayed either a red or blue square on either the left-hand or right-hand side of the screen. They were then instructed to press left on the keyboard if the square was blue, and right if the square was red. Bilinguals performed more rapidly on this test, demonstrating that they were less confused by the cognitive clash between the placement of the square and that of the key.
 
Postponement of cognitive damage
   Bilingualism has even been speculated to protect individuals from age-related decline. By providing a cognitive reserve which enables brain networks to efficiently enhance brain function when one ages, bilingualism delays the advancement of cognitive decline. In other words, while bilingualism cannot eliminate ones chances of being diagnosed with Alzheimers, it can slow down the effects of such diseases.
   In a 2010 study of over 200 bilingual and monolingual patients with Alzheimers disease, bilingual patients reported seeing initial symptoms of the disease around five years later than their monolingual counterparts. Computed topography (CT) brain scans of these patients revealed that among individuals who displayed the same symptoms of Alzheimers, bilinguals demonstrated more advanced brain deterioration than monolinguals. In other words, though the physical state of bilinguals brains would suggest that their symptoms would be worse than that of monolinguals, their symptoms were similar to those of monolinguals. From such results, researchers have reasoned that bilingualism protects older adults from Alzheimers disease by slowing down its effects on the brain.
   Researchers have offered several explanations for this protection. For instance, they have speculated that the areas of bilinguals brains that are associated with executive function and attention are more developed, since bilinguals exercise their executive control system more frequently. Furthermore, there is speculation that bilingual experience heightens the brains ability to find alternative networks for those that are damaged as a result of the aging process.
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   Though academics have not yet reached a consensus on the exact effects of bilingualism, recent research is focused on the possible advantages of bilingualism. While such research has linked bilingualism to linguistic and cognitive benefits, results have also demonstrated that bilingualism cannot drastically alter ones intelligence. Hence, monolinguals do not face major disadvantages in comparison to bilinguals. In fact, monolinguals can experience the aforementioned benefits of bilingualism even if they acquire second languages later on in their lives.   

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