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Manfred MacKeben; Enhancement of peripheral letter recognition by modifying typographic features. Journal of Vision 2001;1(3):100. doi: 10.1167/1.3.100.
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Purpose: To design a simple experimental strategy that can improve peripheral letter recognition by modifying typographic features based on psychophysics. Background: People with dense central scotomas can learn to read again by using a preferred retinal locus (“eccentric viewing”). It is assumed that peripheral letter recognition is one of the elements necessary for reading with eccentric viewing. Methods: The experimental design combines psychophysical testing, data analysis by confusion matrices, letter modification of most frequently confused letter pairs by font design software, and psychophysical re-testing. Six observers were in their twenties or in their fifties. Letters of the Sloan set in a common sans serif typeface were displayed tachistoscopically at an eccentricity of 8 degrees. Results: Most frequently confused letter pairs vary between Ss. These Ss most frequently confused either or both of the pairs H-N and D-O. Two features were modified: The cross bar of the “H” was doubled in width, and serifs were added to “D”. Mean recognition over the whole set improved significantly from 68.8% ░ 9.4 SD to 87.5 ░ 6.3 SD (p < 0.001). The mean d-prime for the modified letters rose significantly (* = 1.095 for “D”, p = 0.033; * = 0.921 for “H”, p = 0.039). The absolute amount of improvement can be explained by secondary interactions between the modified letters and others that are less frequently confused. Conclusion: These findings demonstrate that the combination of psychophysics and goal-directed modification of few typographic features in a given set is a viable experimental strategy. It is proposed that research aiming to improve conditions for eccentric viewing should include optimizing typographic design characteristics (see MacKeben, Vis.Impairment Res. 2/2, 95–103, 2000).
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