| Dyslexia is a complicated process that involves many | | | | symbols. Support for this claim comes from |
| different procedures and cognitive faculties. Before | | | | demonstrating that presenting words in an unfamiliar |
| people are discussing the specific syndromes of | | | | form for example, by alternating the case of the |
| acquired dyslexia, the processes mediating word | | | | letters or introducing spaces between words would |
| recognition and pronunciation are briefly reviewed. The | | | | not mat substantially influences reading speed or |
| visual system efficiently processes a complicated | | | | accuracy. These data argue for a stage of letter |
| stimulus that is, at least for like alphabet based on | | | | identification in which the graphic form is transformed |
| languages, is composed of smaller meaningful unit | | | | into a string of alphabetic characters that are |
| letters. In part the number of words, there is often a | | | | sometimes called "abstract letter identities." |
| considerable visual similarity between words. In addition, | | | | The word identification requires not only that the |
| the position of letters within the letter string is also | | | | constituent letters be identified but also that the letter |
| critical to word identification. The light of theses factors, | | | | sequence be processed. There are mechanisms by |
| it is perhaps not surprising that reading places a | | | | which the position of letters within the stimulus is |
| substantial burden on the visual system and those | | | | determined and maintained is not clear, but a number |
| disorders of visual processing or visual attention may | | | | accounts have been proposed. One possibility is that |
| substantially disrupt reading. | | | | each letter is linked to a position in a world "frame" or |
| The fact that normal readers are so adept at word | | | | envelope. It should be noted that under normal |
| recognition has led some investigators to suggest that | | | | circumstances letters are not processed in a strictly |
| words are not processed as a series of distinct letters | | | | serial fashion, but may be analyzed by the visual |
| but rather as a single entity in a "process akin" to the | | | | system in parallel. Disorders of reading resulting from |
| recognition of objects. At least for normal readers | | | | impairment in the processing of the visual stimulus or |
| under standard conditions, it seems that this does not | | | | the failure of this visual information to access stored |
| appear to be the case. Rather, normal reading appears | | | | knowledge appropriate to a letter string are designated |
| to require the identification of letters as alphabetic | | | | "peripheral dyslexics" and are discussed in the future. |