The significance of visual information processing in reading: Insights from hemianopic dyslexia.

ABSTRACT

We present the first comprehensive review of research into hemianopic dyslexia since Mauthner's original description of 1881. We offer an explanation of the reading impairment in patients with unilateral homonymous visual field disorders and clarify its functional and anatomical bases. The major focus of our review is on visual information processing, visuospatial attention and eye-movement control during reading. An advanced understanding of the basis of hemianopic dyslexia and its rehabilitation also increases our knowledge about normal reading and its underlying neural mechanisms. By drawing together various sources of evidence we illustrate the significance of bottom-up and attentional top-down control of visual information processing and saccadic eye-movements in reading. Reading depends critically on the cortical-subcortical network subserving the integration of visual, attentional and oculomotor processes involved in text processing.