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S. Chung, B.S. Tjan; Spatial–Frequency Properties of Reading in Central and Peripheral Vision . Invest. Ophthalmol. Vis. Sci. 2005;46(13):2329.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Little is known about the spatial–frequency properties of reading. The purpose of this study was to examine the spatial–frequency properties of reading, and in particular, whether these properties are similar between central and peripheral vision. Methods: Four observers with normal vision read aloud single sentences (∼11 words in length) presented on a computer monitor, one word at a time, using rapid serial visual presentation (RSVP). Text was rendered in Times–Roman font, with the letters digitally filtered with a set of 8 raised cosine log filters. The peak object frequency of these filters (bandwidth = 1 octave) ranged from 0.88 to 10 c/letter. Testings were conducted at the fovea and 10° in the inferior visual field. We first determined the critical print size (CPS) for each observer by measuring reading speed (based on RSVP exposure duration yielding 80% correct) for 5 print sizes of unfiltered text. We then determined reading speeds for filtered text of a range of spatial frequencies, for print sizes ranging from 1.2x to 16x CPS at the fovea, and up to 4x CPS at 10° eccentricity. Results: At both the fovea and 10° eccentricity, reading speed improved with the peak object frequency of the filtered text up to 1.77 c/letter, and then reached the maximum reading speed. There was a fall–off of reading speed at high frequencies for the smaller letter sizes such that plots of reading speed vs. object frequency exhibited spatial–tuning functions. For larger letter sizes, reading speed stayed at the maximum reading speed for at least up to 10 c/letter. The maximum reading speeds, at a given eccentricity, were similar across the range of print sizes tested. Conclusions: Reading speed shows similar dependence on the peak object frequency of the filtered text at the fovea and 10° eccentricity. Further, the scaling of the reading speed vs. object frequency functions is similar at the two eccentricities. These findings suggest that the spatial–frequency tuning for reading in central and peripheral vision is remarkably similar.
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