Previewing a face in the periphery reduces the fN170: Combined EEG and eye-tracking suggests two stages of trans-saccadic predictive processes

Abstract

The world appears stable despite saccadic eye-movements. One possible explanation for this phenomenon is that the visual system predicts upcoming input across saccadic eye-movements, based on peripheral preview of the saccadic target. We tested this idea using concurrent electroencephalography (EEG) and eye-tracking. Participants made cued saccades to peripheral upright or inverted face stimuli that could change (invalid preview) or keep their orientation (valid preview) across the saccade. Experiment 1 demonstrated better discrimination performance and a reduced fixation-locked N170 (fN170) with valid than with invalid preview demonstrating integration of pre- and post-saccadic information. Moreover, the early fixation-locked EEG showed a preview face inversion effect suggesting that we perceive pre-saccadic input up to about 170 ms post fixation-onset, at least for face orientation. Experiment 2 replicated Experiment 1 and manipulated the proportion of valid and invalid trials (mostly valid versus mostly invalid, 66.6% to 33.3%) to test whether the preview effect reflected active expectations. A whole-scalp Bayes factor analysis provided evidence for no influence of proportion on the fN170 preview effect. Instead, before the saccade the preview face orientation effect declined earlier in the mostly invalid than in the mostly valid block suggesting some form of pre-saccadic expectations. We conclude that visual stability is achieved by two trans-saccadic integration processes: pre-saccadic prediction, reflected in the pre-saccadic proportion modulation, and early post-saccadic change-detection reflected in the fN170 preview effect.