The impact of central sparing on the word-length effect in hemianopia. Issue 7 (16th November 2016)

• Record Type: Journal Article
• Authors: Rubino, Cristina; Yeung, Shanna C.; Barton, Jason J. S.
• Is Part Of: Cognitive neuropsychology. Volume 33:Issue 7/8(2016)
• Page Start: 353
• Page End: 361
• Publication Date: 2016-11-16
• Subjects: Alexia -- font -- hemianopic dyslexia -- macular sparing -- reading; Neuropsychology -- Periodicals; 152
• DOI: 10.1080/02643294.2016.1232707
• Languages: English
• ISSNs: 0264-3294

Abstract

ABSTRACT: Studies suggest that a word-length effect of up to 160 ms/letter distinguishes hemianopic dyslexia from pure alexia. However, partial preservation of central vision is common in right hemianopia, but its effects on single-word reading are unknown. Eighteen healthy subjects read single words with a gaze-contingent right hemianopia simulation that varied the degree of central sparing. Mean reading onset time declined with small degrees of central sparing, but the word-length effect did not decrease until sparing exceeded 3.15°. We next evaluated the effects of font size. Effects of central sparing were constant when expressed in number of letters, with a decline in word-length effect beginning as sparing approached 4 letters. We conclude that the effects of central sparing on mean reading onset time and the word-length effect are distinct. We provide diagnostic word-length criteria for discriminating between pure alexia and hemianopic dyslexia with various degrees of central sparing.