Bilingualism: Cross-linguistic Issues in Dyslexia

Research suggests that more cases of dyslexia are diagnosed in populations that speak languages with highly opaque writing systems, such as the United States, the United Kingdom, or France, and fewer cases of dyslexia are diagnosed in populations that speak language with transparent writing systems, such as Italy, Spain, or Mexico. This disparity can be explained by the differences in how dyslexic people and non-dyslexic people read and by the many irregular combinations of letters in opaque orthographies that require memorization. Discussing these topics paves the way to considering issues of bilingualism and second language learning as they are related to dyslexia. _____________________________________________________________________________________ Introduction Dyslexia is a learning disability that is often misunderstood. The popular perception of what dyslexia is or feels like is not in line with the reality of dyslexia. Dyslexia becomes an even more complex issue when multiple languages – and with them, multiple writing systems – are brought into play. My goal in this paper is to explore what dyslexia is, why dyslexia is different in various languages, how issues of multiple orthographies change dyslexia, the challenges faced by dyslexics who want to learn a second language, and the unique issues surrounding bilingualism in dyslexia. Throughout this exploration, it is inevitable to discover again and again that the unique characteristics of different writing systems are extremely influential in how dyslexia is manifested and even defined. What is Dyslexia? First, it would be valuable to give some background on what dyslexia is and what causes it. Most of the research done on dyslexia has been written in and about English speakers, partly because a large breadth of scholarly work is done in English and partly because English speakers, as a group, have a high prevalence of dyslexia as compared to speakers of other languages. As a result of this ample amount of work done on dyslexia in English speakers and because this paper is in English, I will talk about dyslexia in English speakers in this section. Dyslexia is defined as “unexpectedly low reading ability in people who have adequate intelligence, typical schooling, and sufficient sociocultural opportunities,” (Siok, Zhendong, Jin, Perfetti, and Tan, 2008, pg. 5561). Basically, dyslexia is only diagnosed after exhausting all other possible reasons for low reading levels. Although the definition of dyslexia essentially labels it as a catch-all for poor readers, dyslexia is a specific impairment in reading and writing with its own unique characteristics. Most dyslexics struggle with issues of phonemic/phonological awareness. Far from the popular image of letters swirling around a page, impossible to catch and thus impossible to decipher, dyslexics actually have difficulty aurally distinguishing the phoneme [b] from [p] or [m] from [n] and so forth with other sounds that share multiple features. They also have issues in recognizing what a phoneme is. Dehaene (2009) gives the example of asking a child how many sounds they hear in the word “rich” and then asking how many they hear in the word “pitch.” For “rich,” most children will say three (r-i-ch), but for “pitch,” they will say L. Dulude / IUJCS 7 (2012) 23 four (p-i-t-ch) despite the fact that “rich” and “pitch” are minimal pairs and sound the same except for the first phoneme. This confusion results from having learned that [tʃ] can be notated as “ch,” but not yet realizing that it can also be written “tch,” so the children trick themselves into believing that they also hear a [t] in “pitch” as a result of a lack of understanding of grapheme to phoneme conversion. An adult with no language impairment would likely tell you that she hears three sounds for both “rich” and “pitch” because she has higher phonemic awareness than a child just learning to read. Dyslexics have trouble with these kinds of phonemic awareness tasks, generally answering in agreement with the child, and that difficulty is a defining characteristic of their condition. Neurologically, Dehaene tells us, when dyslexics read, the left middle temporal gyrus is activated less than it would be in the brain of a non-dyslexic reader. To compensate for the lowperforming left middle temporal gyrus, dyslexics overuse the left inferior frontal cortex (which contains Broca’s area). However, it does not seem to help them decode writing. Upon further examination, researchers have determined that dyslexics have more gray matter in the left middle temporal gyrus than have non-dyslexics. Unfortunately, this larger mass of gray matter seems to actually decrease productivity in the region because it is very unorganized and contains ectopias (misplaced neurons). The quantity of misplaced gray matter correlates positively with the severity of the reading impairment, which seems to go along with the idea that more gray matter in the left middle temporal gyrus decreases reading skill or productivity (2009). These ectopias in the left middle temporal gyrus led researchers to the genetic causes of dyslexia, which include abnormal neuronal migration. During pregnancy, neurons migrate from the ventricles to where they are supposed to end up in the cortex. Ectopias are formed when the neurons go too far and “crash” land. Essentially, the excess unorganized gray matter around the left middle temporal gyrus in the brains of dyslexics is formed by neurons that were not told how to migrate correctly. Neuronal migration is dictated by some sections of DNA. Of the four genes that have been isolated and connected with dyslexia, three of them are involved in neuronal migration. If any of those three genes do not give the correct information and the neurons do not migrate how and where they are supposed to migrate, excess gray matter is formed around the left middle temporal gyrus while the child is still in the womb, later causing dyslexia (Dehaene, 2009). There is more than one type of reading impairment, so it is important for anyone who is studying dyslexia to understand what other types of impairment there are, especially in terms of understanding when dyslexia is involved and when the impairment is something else. When I mention dyslexia in this paper, I am talking about developmental dyslexia, which is genetically transferred in the way that I have described above and present from birth. However, there are also many types of acquired dyslexia that usually result from brain lesions, either in the posterior region of the dominant hemisphere for language (usually the left) or in the dominant perisylvian region, meaning the area around the sylvian fissure (Coslett, 2000):