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Steve Mansfield, Taylor West, Zierra Dean; Is the critical print size for reading linked to letter recognition?. Journal of Vision 2018;18(10):1163. doi: 10.1167/18.10.1163.
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© ARVO (1962-2015); The Authors (2016-present)
Rationale: The critical print size for reading is the smallest print size that can be read at the reader's maximum reading speed. We have explored whether the critical print size is related to the size at which letter recognition starts to become difficult. In a pilot study of recognition errors with blurred Times-Roman letters, we noted that some letters [d, f, g, j, k, m, p, q, v, w, and y] remain easy to identify at more severe levels of blur than others. We hypothesize that sentences containing more of these easy letters ought to have a smaller critical print size than sentences containing fewer easy letters. Method: We created two sets of computer-generated, 60-character, MNREAD sentences that contained either many (M=14.3, SD=0.81) or few (M=4.7, SD=0.56) easy letters. We used computer versions of the MNREAD chart with 12 print sizes spanning +0.8 to –0.3 logMAR to measure reading-speed versus print-size curves from 36 participants. Each participant read five versions of the chart for each sentence condition. Results: The critical print size (estimated from curve fits to the reading-speed versus print-size data) for sentences containing many easy letters was 0.034 logMAR (i.e., 8.1%) smaller than the critical print size for sentences containing few easy letters (95% CI [0.027, 0.040]). Conclusion: This finding is consistent with the critical print size being linked to letter recognition. We propose that, with large print, letter recognition is accurate and reading is fast. But as print size is reduced, letter recognition becomes error prone and the reader is required to infer the identity of words that contain misidentified letters — this produces slower reading speeds.
Meeting abstract presented at VSS 2018
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