Function word substitutions

Pure alexia is also characterized by a length effect, in which words with more letters are read more slowly and are less likely to be read correctly than words with fewer letters (Table III). The length effect is likely a consequence of the explicit letter-by-letter reading strategy: The more letters that must be identified and named, the longer it must take to do so. There are no effects of concreteness, part-of-speech, regularity, or familiarity either when these patients are attempting to read words or when words are spelled aloud to them.

Patients with pure alexia usually have intact language, although there may be some degree of anomia (difficulty retrieving words), which may be particularly pronounced for colors (color anomia). They frequently have a visual field cut called a right homonymous hemianopia, in which the right side of visual space cannot be seen.

Both the retained ability to spell and write and the retained ability to recognize orally spelled words suggest that orthographic information about words remains intact in patients with pure alexia. Thus, it has been suggested that the disorder reflects a disconnection of visual information from intact language processing areas of the brain.

The anatomy of pure alexia is consistent with the notion of a disconnection between visual and language processing centers of the brain. Pure alexia typically results from a stroke within the distribution of the left posterior cerebral artery or from a tumor located in the posterior left hemisphere of the brain. In most cases, the left occipital lobe is damaged such that the primary

Table III

Central Alexias and Word Properties Affecting Reading

Table III

Central Alexias and Word Properties Affecting Reading


Word properties affecting reading

Pure alexia

Letter length

Surface alexia


Phonological alexia

Part of speech



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