Deep dyslexia, imageability, and ease of predication.

A development of existing theories of deep dyslexia is outlined. It proposes that the effects of imageability upon the ease of reading of words by deep dyslexics occur as a result of variation in the ease with which individual words summon semantic predicates, on the basis of which reading responses can be made. Ease-of-predication scores are obtained for a corpus of nouns and found to be, as hypothesized, closely related to imageability scores. It is shown that the other major characteristics of deep dyslexia can also be accounted for by this proposed mechanism. These include the well-established effects of syntactic category (in particular, of the distinction between content and function words) upon reading. Further evidence is provided that this effect may be attributed to variation in ease of predication.