Right visual field advantage in parafoveal processing: evidence from eye-fixation-related potentials

Readers acquire information outside the current eye fixation. Previous research indicates that having only the fixated word available slows reading, but when the next word is visible, reading is almost as fast as when the whole line is seen. Parafoveal-on-foveal effects are interpreted to reflect that the characteristics of a parafoveal word can influence fixation on a current word. Prior studies also show that words presented to the right visual field (RVF) are processed faster and more accurately than words in the left visual field (LVF). This asymmetry results either from an attentional bias, reading direction, or the cerebral asymmetry of language processing. We used eye-fixation-related potentials (EFRP), a technique that combines eye-tracking and electroencephalography, to investigate visual field differences in parafoveal-on-foveal effects. After a central fixation, a prime word appeared in the middle of the screen together with a parafoveal target that was presented either to the LVF or to the RVF. Both hemifield presentations included three semantic conditions: the words were either semantically associated, non-associated, or the target was a non-word. The participants began reading from the prime and then made a saccade towards the target, subsequently they judged the semantic association. Between 200 and 280ms from the fixation onset, an occipital P2 EFRP-component differentiated between parafoveal word and non-word stimuli when the parafoveal word appeared in the RVF. The results suggest that the extraction of parafoveal information is affected by attention, which is oriented as a function of reading direction.