The Neuroscience of Reading – Part 2

The second day of Learning and the Brain’s “Neuroscience of Reading” summer institute was a continuation of great learning.  The majority of the lecture time was spent examining what’s going on in the brain of regular readers and those with reading disorders, specifically dyslexia.

What is Dyslexia?

Both Gabrieli and Christodoulou firmly established that there is very little agreement as to the diagnostic criteria for dyslexia.

  • The one dominant and widely accepted criteria is that there is a discrepancy between intellect and reading ability.
  • The other fairly readily (but not entirely consistently) agreed upon criteria is that of a limitation in phonological processing.
  • The often cited criteria of letter or word reversals is not inherent in dyslexia. Some readers with dyslexia will have reversals show up as a presenting issue, but many will not.  Word and letter reversals can also be present without having dyslexia.  It seems to be pretty much a non-issue in terms of diagnosis, although the explanation as to why such reversals happen is pretty interesting.

When considering the issue of diagnosis, it is worth noting that there is a high comorbidity between dyslexia and ADHD, although it seems that often the dyslexia component is present without diagnosis in many children with ADHD. There is a 25-40% comorbidity rate between ADHD and dyslexia.  It is easy to see that difficulty in reading could certainly cause a person to be/appear to be unfocused.

Why do children struggle with letter reversals?

Both Christodoulou and Gabrieli indicated that humans are programed to be able to identify any given object regardless of its orientation.  If any type of transformation is applied, confusion does not ensue.  For example, if you see a chair lying on its side, you still know it’s a chair.  If you see your cat lying in a new position, you still know it’s your cat.  Written letters and numbers seem to be the only exception to this rule.  They are the only instance when seeing it from a different perspective no longer renders it as that object.  Think of the letter ‘b’, which, under a variety of transformations, could be a ‘d’, a ‘p’ or a ‘q’.  So with that, we are to render the differences as significant, and yet we are expected to view any particular letter, written in any conceivable font, or handwriting, as the same.  It is on this premise that letter reversals occur.  Children must override the innate rule that teaches them that objects seen from different perspectives are still the same object, and teach themselves that letters and numbers are exceptions to this.

When breaking down the process of reading, it becomes apparent that it is an incredibly complex task on a neurological level.  Thus, it is of little surprise that there is capacity for brain processing issues in one or more areas of this process, which in turn may present as reading disabilities.  With any area of ability, there is possibility of disability.  The more complex the task, the more potential areas there are in the breakdown of employing that task.

What does our brain do when we read?

Reading is a complex task that requires employing various skills in tandem:

1. Auditory and visual neurological functions:

Gabrieli points out that we are designed as visual and auditory people.  There are large sections of our brains that are devoted to each of these tasks.  Reading, he notes, is something that was developed after the existence of humanity and is not a task for which we have an innate ability.  We have an innate ability to see and we have a visual processing area of the brain.  We have an innate ability to listen and we have an auditory processing area of the brain.  Likewise, we have an innate ability to speak.  What we don’t have, however, is an innate ability to read or a specific ‘reading’ part of the brain.  Reading involves many areas of our brain.

2. Orthography and phonology:

Orthography is the way that words look and phonology is how they sound.  In an ideal world, there would be one phoneme (sound) for every grapheme (letter symbol).  This would greatly simplify the reading process and would enable people to learn to read with much greater ease.  The problem, however, is the number of letters that have multiple sounds as well as the number of rule exceptions that exist.  There is no language that has a 1:1 ratio of graphemes to phonemes.  Italian has a 33:25 ratio, so it is quite close.  English, on the other hand, has a 1120:45 ratio.  It should come as no surprise, then, that Italian-speaking children, on average, learn to read in a year, whereas English-speaking children take three years to accomplish the same task.  Gabrieli spoke of a study that compared the ability of dyslexic readers and non-dyslexic readers to identify letters and sounds.  The study shows that regular readers very often activated the brain’s areas for processing of sound and letters simultaneously, but the brains of the readers with dyslexia very rarely activated both neural processing areas at the same time.  This is important to note because it makes a distinction between being developmentally behind in reading as opposed to having a brain that processes reading in an atypical manner.

Gabrieli explained another study that illustrated exactly this fact.  Children with dyslexia were compared with non-dyslexic readers who were a number of years younger but read at the same level.  The study quite clearly showed that the children with dyslexia were using a different processing method to accomplish the same reading as their ability-matched peers.

3. Listening comprehension and decoding

Christodoulou spoke of the “reading equation”.  She stated that reading comprehension = listening comprehension + decoding.  Both of these processes must be working at the same time as well.  The listening comprehension refers to being able to contextualize and make meaning of the words that are being decoded.  If you were given a sentence of nonsensical words, you would be able to decode them, but you would have no listening comprehension as to the meaning of those words, thus reading comprehension would be non-existent.  The opposite is also true, if a student can understand and make meaning of words but does not have the ability to decode, obviously they will not have reading comprehension either.  Perhaps here it is worth mentioning yet another study, which illustrated the fact that children with dyslexia use a far greater amount of their brain when they read than those without.  To accomplish the same task, they must work much harder.

Other complexities of reading:

Another interesting fact regarding the complexity of reading is that it requires the children to go backwards in a process with which they are very familiar.  A pre-reading child can converse about a great deal of topics.  They can speak of the chair in the room, and the word ‘chair’ has meaning.  There is nothing that they need to do to unleash that meaning.  When they begin to read, however, their ability to gain meaning from words is compounded by the addition of many extra steps.  They now must simultaneously employ all of reading skills that were previously mentioned, just to get meaning from the word ‘chair’.

I suppose that the strongest thing that was reiterated for me in this day’s session was that dyslexia does not simply mean that students are behind in their reading.  Rather, it means that their brain uses quite a different process to read than most.  It seems that there would likely be many families that would benefit from seeing some of the fMRI pictures which show this with great clarity.  Dyslexia is not related to intelligence.  Dyslexia is not related to effort (in fact, there is much evidence that readers with dyslexia exhibit far greater effort than the average reader).  Dyslexia is a term that is applied to brains that respond in a very unique way to print on a page.  As teachers, we’re not going to be able to change the way the dyslexic brain functions.  We can only hope to to intervene in meaningful ways to make the dyslexic child’s method of processing work for them in the best possible way.

Related Posts: 
The Neuroscience of Reading – Part 1
The Neuroscience of Reading – Part 3
Dear Friend with Dyslexia


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