Purpose: Evidence has indicated that the size of the visual span (the number of identifiable letters without movement of the eyes) and reading speed can be boosted through perceptual learning in alphabetic scripts. In this study, we investigated whether benefits of perceptual learning could be extended to visual-span size and sentence reading (all characters are presented at the same time) for Chinese characters and explored changes in sensory factors contributing to changes in visual-span size following training.
Methods: We randomly assigned 26 normally sighted subjects to either a control group (n = 13) or a training group (n = 13). Pre- and posttests were administered to evaluate visual-span profiles (VSPs) and reading speed. Training consisted of trigram (sequences of three characters) character-recognition trials over 4 consecutive days. VSPs are plots of recognition accuracy as a function of character position. Visual-span size was quantified as the area under VSPs in bits of information transmitted. A decomposition analysis of VSPs was used to quantify the effects of sensory factors (crowding and mislocation). We compared the size and sensory factors of visual span and reading speed following training.
Results: Following training, the visual-span size significantly increased by 11.7 bits, and reading speed increased by 50.8%. The decomposition analysis showed a significant reduction for crowding (-13.1 bits) but a minor increase in the magnitude of mislocation errors (1.46 bits) following training.
Conclusions: These results suggest that perceptual learning expands the visual-span size and further improves Chinese text sentence-reading speed, indicating that visual span may be a common sensory limitation on reading that can be overcome with practice.