Dyslexic here. Dyslexia is not a single condition. The only way we define dyslexia is difficulty reading caused by the way the brain processes text so not something like poor eyesight or low intelligence. Therefore by definition this is not what a large percentage of dyslexics experience because there is no common experience. Maybe this is how some dyslexics experience reading, but I am not one of them and I don't think I have ever actually heard another dyslexic describe literally seeing letters changing as they look at them. It is often more that things seem to change when you aren't looking.
For me personally, I have no problem with letters. A "b" is never a "d" or whatever stereotypical explanations you might hear about dyslexia. My problem is with entire words. I will often substitute one word for another while reading (and writing). I can go back and might still read that incorrect word. But I don't think I ever really "see" that incorrect word. It is more that my brain is lazy and isn't actually reading, it is just assuming what is supposed to be there and that assumption is occasionally wrong.
I have dyslexia and find this simulation pretty accurate. Obviously it's just a simulation though. When I read, letters aren't literally jittering around the page, but I do have to do a lot of "double-takes": looking back at words and thinking hard to decode them.
As a kid, reading aloud in class was always nerve wracking because of this. The game was to do these double-takes so quickly that nobody could tell you were doing all of this extra work. Often you read ahead of what you're saying so that you can double-take before saying the word.
> As a kid, reading aloud in class was always nerve wracking because of this.
Yup, reading out loud was the absolute worst. I have different issues though, and because of my reading's tight associations with speech(1), I couldn't even read ahead. I think my "only-when-read-out-loud" stutter comes from the social anxiety I developed here.
(1) i.e. To read words with my eyes, I have to mentally speak them to myself.
> It is more that my brain is lazy and isn't actually reading, it is just assuming what is supposed to be there and that assumption is occasionally wrong.
It's not just your brain. It's how vision works in general. Everyone has physical blind spot (where the optic nerve attackhes to the retina) but no one can see it except if they carefully hunt hor it. Everyone can see high resolution only in a tiny area at the center of the visual field, and imagines the rest.
With dyslexia (and various physical vision problems), you're collecting even less input (due to misprocessing at some "lower layers"), so your higher-level recognition/comprehension brain has to fill in more missing deails, and so has a higher error rate.
I think our brains just picks all the letters in a word, mixes them up together into something like "e:a:l:p = 1:1:1:2", adds context and does a lookup into a dictionary of such "letters mix" -> meaning pairs. If this is correct, dyslexia is when the brain can't quickly estimate the "amount" of each letter in a word, and the incorrect proportions result into an incorrect lookup.
That analogy is close but doesn't quite match my experience because there doesn't have to be much overlap in letters in a word. I went back and reread a few of my most recent HN comments looking for an example (my condition impacts both reading and writing). There are some easy to understand mistakes like replacing "went" with "want". However I also used "because" in place of "beyond" in one comment. Those two words start with the same two letters, but they are completely different after that and are relatively distinct visually.
An algorithmic analogy I would use would be fuzzy matching. Most people's brains are set to look for exact matches (or fuzzy matching with a super high match criteria). When one part of their brain needs access to a word, the other part of their brain will supply the exact match. My brain is using fuzzy matching with the confidence level set mistakenly low. When part of my brain needs a word, the first match returned is occasionally a false positive match. The rest of my brain just accepts it and continues onto the next requested word. The match quality isn't a traditionally fuzzy matching algorithm like Levenshtein distance. It is heavily weighted to both the start of the word and the expectedness of the word in the given context. The latter makes it very difficult for me to immediately notice my own written mistakes since I am already primed to expect what I intended to write and not necessarily what I actually wrote.
Your second paragraph seems quite insightful. I will occasionally write out the wrong word, only to re-read the incorrect word as the word I intended to write, totally missing my mistake. As you describe, I think most often it relates to the 'fuzzy matching' of the first few bits of a word, my brain auto-completes the action of selecting the wrong letters for the word as the intended word.
I seem to be able to break the spell in a number of ways. When I'm re-reading a final draft of something (say an important email) I will try to eliminate context and deliberately read each word individually. Another way to break this spell is to read a document much later in time. Sometimes the pattern matching self-corrects later, or seemingly I have forgotten the verbatim phrasing of the idea that I previously wrote, and so upon reading I pick up the mistake.
I read thousands of words per day, probably write well into the hundreds. Fortunately, the amount of errors for me is very low, but if this were to happen with increased frequency, reading and writing would be quite stressful.
Yep, trying to give myself extra time to forget the exact intent of the writing and revisiting it later was my primary approach through school. However the absolute lifesaver since then has been text-to-speech software. Listening to my writing being read back to me makes it absolutely obvious when I used an incorrect word.
I have the word thing too. But my brain tends to pull words from adjacent lines. I never thought that I had it writing, but I do remember writing two words in the wrong order earlier today.
For me personally, I have no problem with letters. A "b" is never a "d" or whatever stereotypical explanations you might hear about dyslexia. My problem is with entire words. I will often substitute one word for another while reading (and writing). I can go back and might still read that incorrect word. But I don't think I ever really "see" that incorrect word. It is more that my brain is lazy and isn't actually reading, it is just assuming what is supposed to be there and that assumption is occasionally wrong.