Spatial-frequency and contrast properties of reading in central and peripheral vision.

In this study, we examined the effects of contrast and spatial frequency on reading speed and compared these effects between the normal fovea and periphery. We found that when text contrast was low, reading speed demonstrated spatial-frequency tuning properties, with a peak tuning frequency that partially scaled with print size. The spatial-frequency tuning disappeared when text contrast was 100%. The spatial-frequency tuning and scaling properties for reading were largely similar between the fovea and the periphery, and closely matched those for letter identification. Just as for the task of letter identification, we showed through an ideal-observer analysis that the spatial-frequency properties for reading could be primarily accounted for by the physical properties of the word stimuli combined with human observers' contrast sensitivity functions.