Read but not write "idea": evidence for a third reading mechanism.

Most information processing accounts of reading incorporate either two or three mechanisms by which oral reading may be accomplished. The existence of a "third" mechanism by which words may be read lexically but without semantic mediation remains controversial. We report data from a patient (W.T.) with an infarction involving Wernicke's area who was unable to write, repeat, or comprehend words of low imageability yet read these and other words reliably; the patient could not, however, read nonwords. As the patient was unable to read on the basis of sublexical print-to-sound correspondences and, at least for words of low image-ability, was unable to read by means of a semantically mediated process, the data from this patient are most readily accommodated by models of reading incorporating three mechanisms.