http://www.readinghorizons.com/blog/post/2010/10/04/What-Causes-Dyslexia-An-Overview-of-5-Theories.aspx
What Causes Dyslexia? An Overview of 5 Theories
As you may know, dyslexia is a learning disability that causes reading and language difficulties. These difficulties are the result of the dyslexic’s brain impaired ability to process graphic symbols (letters) in connection to their sounds (phonemes) in a given language.
Although many of the symptoms and outcomes of dyslexia have been discovered, it still remains unclear what causes dyslexia. However, there are several theories which help explain the origin of this condition. Most researchers believe dyslexia is caused by a combination of these theories, but the exact combination or specific cause is yet to be discovered.
1. Brain Development
Some researchers have found clusters of cells in the dyslexic brain that did not make it to the same location they are found in the non-dyslexic brain. In the non-dyslexic brain these cells are found primarily in the left side of the brain, the same area used dominantly for reading and language tasks, thus it is believed that these cell misplacements make it difficult for dyslexics to process language tasks.
2. Wiring of the Brain
In connection with the cell misplacement in the first theory, another theory is that dyslexia is caused by a unique wiring in the brain. Dyslexics have been found to have strong activity in the right side of their brain. Because of the strength of their right brain, they engage this area while performing language tasks. However, as mentioned before, language tasks are typically and most efficiently performed in the left side of the brain. Thus, the wiring of the dyslexic brain is often prescribed as the cause of dyslexia.
3. Genetic Inheritance
These differences in brain structure and development are often found to be generational. Not every child of someone with dyslexia is dyslexic, but it is common for a dyslexic to have a family history of the condition. Also, dyslexia has been found to correlate to left-handedness. Just because someone is left-handed does not mean they are dyslexic, but it has been found that about have of the family members of a dyslexic are commonly left handed.
4. Hearing Problems at a Young Age
Another theory is that dyslexia is caused by hearing problems while a child’s brain is still developing and learning language. Early colds and other infections can cause a child’s ears to get blocked on occasion and thus impair their hearing. By not having clear hearing, a child can have a difficulty learning the sounds of language (phonemic awareness). This early learning period of the sounds of language is very important for developing effective language skills in the future. This problem can be resolved if caught at an early stage. There are treatments available, the most common being a tiny tube that is inserted into the child’s ear to prevent it from getting blocked again.
5. Evolutionary Perspective
Lastly, there is a theory that dyslexia is a result of evolution. The theorists supporting this idea claim that reading is an unnatural act that was not required in the past, and has only been used in the recent past. Most societies have been reading for less than 100 years, and thus not all humans have evolved the ability.
Conclusion
Although the experts are still not exactly sure what the cause of dyslexia is, there is evermore research that is being conducted and the cause is still being sought after.
Let us know what theory you agree with. We would love to hear your thoughts!
I am sorry but I completely disagree with your first paragraph where you say the following:"As you may know, dyslexia is a learning disability that causes reading and language difficulties."
I teach dyslexic children and I believe that dyslexic children are just wired in a slightly different way, say, like a left hander. There was a time when left handers were treated as disabled.But today we know many left handers who are just as good if not better than right handers.
A dyslexic just learns in a different way than a non dyslexic. If they are taught in a way appropriate for them they learn just as fast as any other.(They are like left handers in a right handers world.)
I teach dyslexics 3 languages and they can read in 2 languages as fluently as any other kid can. These two languages use the same 26 alphabets as the English language.As such how can it be said that dyslexics have a reading and language problem, unless you take English as the only language in the world.But even English can be taught to them if taught in a proper manner.
To say that, "These difficulties are the result of dyslexics brain impaired ability to process graphic symbols (letters) in connection to their sounds (phonemes) in a given language." is also incorrect. All my students do not have a problem with grapheme and phoneme when it comes to Malay and Romanized Mandarin. They also do not have a problem with grapheme and phoneme when it comes to reading phonologically correct English words. Their minds shut down when the grapheme and phoneme do not make sense.If the different phonemes of the English alphabets are clearly explained to a dyslexic child he can and will read as fluently as any other kid. How many teachers actually teach a child that the letter 'a' consists of 6 phonemes (may be more) and that the grapheme 'e' represents at least 7 phonemes.This is why I have seen my dyslexic students giving a blank look when I teach them "A cat" after having taught them the words bat, cat, fat, hat, mat, pat, rat and sat which they learn with ease. (refer my lessons in my blog in March). They are puzzled with "A cat" because the phoneme of the "A" in A cat is different from the phoneme of 'a' in cat. The children however, can accept and understand and continue learning when I tell them that the letter 'a' has more than one phoneme unlike in Malay and Mandarin. The same goes for Finnish, Tamil and many other orthographically consistent languages.
Parents with dyslexic children are welcome to use my lessons in my blog to teach their dyslexic children. They have proven effective with my own students and many parents from many parts of the world have also written to say that they are grateful for the lessons.The lessons are all free of charge.
I believe that instead of wasting valuable resources in finding out what causes dyslexia (just like it would be a waste of time finding out why left handers use their left hand more efficiently)it would make more sense in finding out how to teach a dyslexic. Instead of fighting over a choice between "whole word" and phonics use both like I have used in my lessons. By using both anyone can learn to read simple sentences from the first lesson.
Thank you and kind regards,
Luqman Michel
http://www.parentingdyslexia.com
Although many of the symptoms and outcomes of dyslexia have been discovered, it still remains unclear what causes dyslexia. However, there are several theories which help explain the origin of this condition. Most researchers believe dyslexia is caused by a combination of these theories, but the exact combination or specific cause is yet to be discovered.
1. Brain Development
Some researchers have found clusters of cells in the dyslexic brain that did not make it to the same location they are found in the non-dyslexic brain. In the non-dyslexic brain these cells are found primarily in the left side of the brain, the same area used dominantly for reading and language tasks, thus it is believed that these cell misplacements make it difficult for dyslexics to process language tasks.
2. Wiring of the Brain
In connection with the cell misplacement in the first theory, another theory is that dyslexia is caused by a unique wiring in the brain. Dyslexics have been found to have strong activity in the right side of their brain. Because of the strength of their right brain, they engage this area while performing language tasks. However, as mentioned before, language tasks are typically and most efficiently performed in the left side of the brain. Thus, the wiring of the dyslexic brain is often prescribed as the cause of dyslexia.
3. Genetic Inheritance
These differences in brain structure and development are often found to be generational. Not every child of someone with dyslexia is dyslexic, but it is common for a dyslexic to have a family history of the condition. Also, dyslexia has been found to correlate to left-handedness. Just because someone is left-handed does not mean they are dyslexic, but it has been found that about have of the family members of a dyslexic are commonly left handed.
4. Hearing Problems at a Young Age
Another theory is that dyslexia is caused by hearing problems while a child’s brain is still developing and learning language. Early colds and other infections can cause a child’s ears to get blocked on occasion and thus impair their hearing. By not having clear hearing, a child can have a difficulty learning the sounds of language (phonemic awareness). This early learning period of the sounds of language is very important for developing effective language skills in the future. This problem can be resolved if caught at an early stage. There are treatments available, the most common being a tiny tube that is inserted into the child’s ear to prevent it from getting blocked again.
5. Evolutionary Perspective
Lastly, there is a theory that dyslexia is a result of evolution. The theorists supporting this idea claim that reading is an unnatural act that was not required in the past, and has only been used in the recent past. Most societies have been reading for less than 100 years, and thus not all humans have evolved the ability.
Conclusion
Although the experts are still not exactly sure what the cause of dyslexia is, there is evermore research that is being conducted and the cause is still being sought after.
Let us know what theory you agree with. We would love to hear your thoughts!
I am sorry but I completely disagree with your first paragraph where you say the following:"As you may know, dyslexia is a learning disability that causes reading and language difficulties."
I teach dyslexic children and I believe that dyslexic children are just wired in a slightly different way, say, like a left hander. There was a time when left handers were treated as disabled.But today we know many left handers who are just as good if not better than right handers.
A dyslexic just learns in a different way than a non dyslexic. If they are taught in a way appropriate for them they learn just as fast as any other.(They are like left handers in a right handers world.)
I teach dyslexics 3 languages and they can read in 2 languages as fluently as any other kid can. These two languages use the same 26 alphabets as the English language.As such how can it be said that dyslexics have a reading and language problem, unless you take English as the only language in the world.But even English can be taught to them if taught in a proper manner.
To say that, "These difficulties are the result of dyslexics brain impaired ability to process graphic symbols (letters) in connection to their sounds (phonemes) in a given language." is also incorrect. All my students do not have a problem with grapheme and phoneme when it comes to Malay and Romanized Mandarin. They also do not have a problem with grapheme and phoneme when it comes to reading phonologically correct English words. Their minds shut down when the grapheme and phoneme do not make sense.If the different phonemes of the English alphabets are clearly explained to a dyslexic child he can and will read as fluently as any other kid. How many teachers actually teach a child that the letter 'a' consists of 6 phonemes (may be more) and that the grapheme 'e' represents at least 7 phonemes.This is why I have seen my dyslexic students giving a blank look when I teach them "A cat" after having taught them the words bat, cat, fat, hat, mat, pat, rat and sat which they learn with ease. (refer my lessons in my blog in March). They are puzzled with "A cat" because the phoneme of the "A" in A cat is different from the phoneme of 'a' in cat. The children however, can accept and understand and continue learning when I tell them that the letter 'a' has more than one phoneme unlike in Malay and Mandarin. The same goes for Finnish, Tamil and many other orthographically consistent languages.
Parents with dyslexic children are welcome to use my lessons in my blog to teach their dyslexic children. They have proven effective with my own students and many parents from many parts of the world have also written to say that they are grateful for the lessons.The lessons are all free of charge.
I believe that instead of wasting valuable resources in finding out what causes dyslexia (just like it would be a waste of time finding out why left handers use their left hand more efficiently)it would make more sense in finding out how to teach a dyslexic. Instead of fighting over a choice between "whole word" and phonics use both like I have used in my lessons. By using both anyone can learn to read simple sentences from the first lesson.
Thank you and kind regards,
Luqman Michel
http://www.parentingdyslexia.com
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