Abstract
Purpose :
Patients with central vision loss have to use their peripheral vision to read. For English text, visual span in both the temporal and spatial domains limits reading speed in peripheral vision. It is unknown whether the same is true for Chinese reading. Individual Chinese characters contain more information than individual English letters and can be sequenced horizontally or vertically. This study examined the relationship between visual span and reading of Chinese characters in normal central and peripheral vision.
Methods :
13 young Chinese native readers were recruited. Reading performance in terms of maximum reading speed (MRS) and critical print size (CPS) was examined using the rapid serial visual presentation paradigm at three visual field locations: central vision, 10o left and 10o below fixation. Temporal visual span was measured using trigram character-recognition as described by Cheong et al. (2007), with strings of three-randomly selected Chinese characters presented at a range of exposure durations. Spatial visual span was measured by presenting trigrams at different character position away from the fixation for 200ms. Visual span measurements were made for all three central (horizontal and vertical presentations), 10o left (vertical) and 10o lower (horizontal) visual field locations.
Results :
MRS was significantly faster and CPS smaller at central vision than left and inferior vision (p<0.001). No significant differences for MRS or CPS were observed between the two peripheral visual field locations. Temporal visual span in terms of temporal threshold (TTT) was significantly shorter in central vision than inferior or left visual field. Spatial visual span in terms of average recognition accuracy (ARC) at central 5-character positions was significantly higher for central vision than inferior or left visual field. No differences in visual span were found between inferior and left visual field. MRS was significantly correlated horizontal TTT and horizontal ARC for central and inferior vision (rs>-0.60) but not for the left visual field.
Conclusions :
Our results support the hypothesis that visual span contributes to reading performance for Chinese characters in central vision and in the inferior field. Surprisingly, this hypothesis does not apply when they read at 10o left visual field, suggesting that other factors might better explain the reduced reading performance at left visual field.
This is a 2021 ARVO Annual Meeting abstract.