A person with dyslexia has difficulty reading printed words and understanding their meaning. "Acquired dyslexia" is caused when a person who could previously read and write has an accident which affects part of their brain.
Studies done on dyslexic patients have confirmed the two-pathway model of reading described above (see, for example, G. Hinton et al).
Some dyslexic patients have damage to the part of their brain that analyses the sound of letters in a word, but they retain some ability to extract meaning from the appearance of the whole word. Such patients may read the word 'yacht' for example, and translate it as 'boat'. They retain some capacity to read using the “whole word” pathway, even though the part of their brain which could break up a word into sounds has been badly damaged. This type of dyslexia is sometimes called "deep dyslexia".
Other patients retain some ability to break up a word into its sounds, but
lose the facility of getting the meaning from the appearance of the whole word.
Such patients would read 'yacht', for example, as 'yachet'. These patients have
lost the ability to get the meaning of a word without breaking it up into the
sounds of the letters. But they retain some capacity for reading via the
“sound-of-the-letters” pathway. This type of dyslexia is sometimes called
"surface dyslexia".
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