Co-registration of EEG and eye-tracking in reading research: Results from preview benefit and naturalistic reading studies

EEG and eye-tracking research on reading have long seemed methodologically incompatible because of the artefacts that eye movements cause in the EEG. This has resulted in the adoption of single word reading paradigms or unnatural word-by-word presentations of sentences to study processes underlying reading with EEG. Recent methodological advances allow for the co-registration of EEG and eye-tracking data and for artifact correction in the EEG. I will present a series of co-registration studies in Chinese that demonstrate the feasibility of the method and highlight its use to address questions beyond what has been possible with traditional EEG studies. We first looked at parafoveal preview effects in fixation-related potentials (FRP) in a series of studies and found these effects showed a consistent reduction of the N1/N250 negativity after preview of the same character compared to a different one across experiments. The preview effects in the FRPs were also similar to foveal repetition effects in a masked priming study suggesting facilitation of visual-orthographic processing. Moreover, the preview effects were modulated by the experience with the reading direction. In another study, we presented text in a more naturalistic sentence-by-sentence way and used a regression approach to analyze word characteristics. In particular, we were interested in the effects of the orthographic prediction error (a pixel-by-pixel deviance from the visual average across all words), word frequency, and context-based surprisal (derived from a Large Language Model). Results showed oPE effects at around 150 ms, word frequency effects at around 200 ms, and context effects at around 400 ms. Moreover, context-based characteristics constrained oPE effects, which is in agreement with a hierarchical predictive coding model of neural processing during naturalistic reading. Overall, the studies suggest that co-registration of EEG and eye-tracking is feasible to conduct experiments with time-sensitive boundary paradigms and naturalistic reading opening the way to a better integration of the fields of EEG and eye-tracking in research of reading.