Pictures, images, and pure alexia: A case study

A patient with pure alexia was presented with a series of tachistoscopic tests involving words, letters, pictures, and lines. Low level perceptual processing remained intact. A major deficit was revealed in the speed of identifying orthographic material. This deficit extended to the identification of pictures presented at tachistoscopic durations, although no disturbance in the visual identification of pictures or objects was observed in real time. There were frequent reports of visual imagery associated with the perception of written material. These images cannot account for the patient's partial recovery of reading functions; instead, it appears that the abnormal characteristics of the patient's reading arise because, after a visual stimulus is perceived, an abnormally long period of time is required before the patient can identify the stimulus. It is suggested that pure alexia is the behavioral manifestation of a deficit in speed of visual identification which is not specific to orthographic material.