Reading ahead: Localized neural signatures of parafoveal word processing and skipping decisions

Visual reading proceeds fixation-by-fixation, with individual words recognized and integrated into evolving conceptual representations within only hundreds of milliseconds. This relies, in part, on interactions between cognitive and oculomotor systems, such that linguistic properties of words influence eye movements and fixation durations. When and where do these influences arise in the neural processing of an incoming word? To answer this, we combined magnetoencephalography (MEG) with eye-tracking in a natural story-reading paradigm. We replicated past findings that word frequency and predictability have additive influences on fixation durations. Next, we identified putative generators of these influences in localized brain activity time-locked to fixation onsets. Both properties independently influenced neural responses in left occipitotemporal and ventral temporal areas, at latencies early enough to influence subsequent saccade planning. These effects began in posterior areas (the left lingual gyrus, lateral occipital cortex) during parafoveal word processing, and shifted more anteriorly (the inferior temporal and parahippocampal gyri) when the word was fixated in foveal vision. Evidence for parallel processing of both parafoveal and foveal words was observed in the left posterior fusiform, which housed near-simultaneous effects of both the fixated and upcoming words frequency and surprisal. We also found that parafoveal processing in this region, together with the left middle temporal gyrus, distinguished whether an upcoming word was skipped or fixated. These results suggest that during natural visual reading, word recognition and integration begin parafoveally, underpinned by a left-lateralized occipitotemporal system, where word processing rapidly exerts downstream influences on eye movement decisions.