But, their overall experience does not let them understand all that the author is telling them. They cannot look at the text and turn the print words into aural words in their mind quickly and easily like normal people do. In contrast, when the print is read for them orally they will understand fully what is written. And, they will do it instantaneously like normal persons read print visually. This rate of reading is what is required for the print language to be used as it was intended.
Dyslexic persons are of average to very superior mental ability.
Their problem varies in severity. In more severe cases a person can hardly read 2nd and 3rd grade words while in milder cases the person can read many words on their grade level but must devote so much energy to perform the visual decoding that they are unable to fully understand what the author is communicating. In these milder cases students will report that they cannot read fast enough to do all their work. It is true that they cannot keep up but equally important is that they are so involved with the visual decoding that they are only getting bits and pieces of the information that the author is providing. Bright dyslexic persons can take these bits and pieces and make statements and answer questions about the passage.