The following should not be considered science fact, it is strictly my interpretation of the limited information available to me.
I have seen several ‘fit everyone into the mold’ reasons for what physically causes dyslexia. Most, unfortunately, start giving very ‘fuzzy’ answers when one starts asking questions relating to different levels of dyslexia other than the type that the explanation was designed around. Thus, I would like to give my conjecture on what causes dyslexia as a whole, not just for one group or one symptom.
In order to understand my reason for what causes dyslexia one must first understand two areas that at first glance seem to have nothing to do with each other.
Some time ago I saw a report on how we (everyone not just people with dyslexia) see the world (physically see) and how the mind filters and appends the images that we see.
The report went on to say that basically the image that we see is not truly a 'solid' image but rather a series of 'grids' put together by our mind.
Something like (though to be more accurate the 'grids' should be round):
To make life a little more complicated the report went on to say that not only is the image pieced together but we usually do not get all the pieces in one 'shot'. But rather several 'overlayed' images with each image looking something like:----------
While any individual image would might be unintelligible by itself, once our mind overlays what we do see and fills in what we expect to see in the blanks we then get the whole picture.
something like this:
A different report discussed which parts of the brain are active as we perform various tasks.
The report indicated that as we learn new tasks or do new things the cerebellum and areas around it are extremely active.
Then as we become familiar with the task the functions are 'transferred' to various other parts of the brain.
My conjecture is, suppose the problem that we (people with dyslexia) are experiencing is that the cerebellum (or some other part of the brain, that controls where information is to be processed) is 'working' slightly faster, or slightly slower, than the other sections of the brain.
The problem of interpreting images, remembering sequences, etc. could be that the mind is 'overwriting' (for lack of a better term) some of the information before the other sections of the brain can interpret and place the 'patches' of information in the proper order. Thus, making it very difficult for the mind to interpret an image.
For instance what do you see with the image below? Random blocks or a word? As you step away from the monitor does the image appear to change?
Obviously the image did not change. Yet what we see does. Totally based on how our mind puts patterns of information together.
(just for fun click here for a few more pictures that show how our minds put things together based on what we think we see rather than what might really be there.)
Carrying this one step further to explain the various forms of dyslexia, suppose rather than working at the same 'speed' several sections of our brain work at a slightly faster or slightly slower rate than the other sections. Thus, causing different effects/levels of dyslexia including the problems sometimes noticed in dyslexics with reading, writing, speech, hearing and memory.
Again, this is just a thought and should not be taken as science fact.