How the Dominant Reading Direction Changes Parafoveal Processing: A Combined EEG/Eye-Tracking Study.

Reading directions vary across writing systems. Through long-term experience, readers adjust their visual systems to the dominant reading direction in their writing systems. However, little is known about the neural correlates underlying these adjustments because different writing systems do not just differ in reading direction, but also in visual and linguistic properties. Here, we took advantage of the fact that Chinese is read to different degrees in left-to-right or top-to-bottom directions in different regions. We investigated visual word processing in participants from Taiwan (both top-to-bottom and left-to-right directions) and from mainland China (only left-to-right direction). We used combined EEG/eye-tracking with a saccade-contingent parafoveal preview manipulation to investigate how the dominant reading direction shapes neural visual processing while participants read 5-word lists. Fixation-related potentials (FRPs) showed a reduced late N1 effect (preview positivity), but this effect was modulated by prior experience with a specific reading direction. Results replicated previous findings that valid previews facilitate visual word processing, as indicated by reduced FRP activation. Critically, the results provide the first neuroelectric evidence that this facilitation effect depends on experience with a given reading direction. The findings provide insight into how cultural experience shapes the way people process visual information and demonstrate how a person's everyday visual experience can influence how the brain processes parafoveal information.