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.

Analyzing combined eye-tracking/EEG experiments with (non)linear deconvolution models

“…In other words, while ERP researcher have traditionally presented isolated objects during steady fixation, visual objects are typically primed and/or predicted during natural vision based on a coarse extrafoveal preview of the object. Indeed, a similar preview effect, as shown here for words, was recently reported for the N170 component of previewed human faces (Buonocore, Dimigen, & Melcher, 2020;de Lissa et al, 2019;Huber-Huber et al, 2018). This indicates that the attenuation of the late N1 and N170 components by preview may be a characteristic feature of visual object recognition under real-world conditions.…”

“…The first reason is of methodological nature and directly linked to the problems of overlap and covariates: The baseline for the FRP is often biased because of differences in the duration of the preceding fixation, differences in the size of the preceding saccade, or a different overlap with the stimulus-onset ERP. Several workarounds have been proposed to deal with this problem, such as placing the baseline before trial onset (Dimigen et al, 2011;Nikolaev et al, 2016) before an earlier fixation (Coco et al, 2018;Degno et al, 2018, Huber-Huber et al, 2018, or in the first few milliseconds after fixation onset ( However, a second reason why the baseline should still be chosen carefully are effects of preprocessing. Because viewers obtain some information about soon-to-be fixated items in parafoveal and peripheral vision (Baccino & Manunta, 2005;Buonocore et al, 2020;Coco et al, 2018;de Lissa et al, 2019), EEG effects may in some cases already begin before an object is foveated (e.g.…”

Perceptual continuity across saccades

“…Evidence from experiments with human subjects point in the same direction, although the effects are only observed after saccade offset (but this could be due to methodological constraints). Multiple fMRI studies (Dunkley et al, 2016;Fairhall et al, 2017;Merriam et al, 2003;Zimmermann, Weidner, et al, 2016) and EEG studies (Edwards et al, 2018;Huber-Huber, Buonocore, Hickey, & Melcher, 2018) showed that a visual stimulus before a saccade affects the processing of a stimulus at the same spatiotopic location after the saccade, corroborating observations from human psychophysics. Although these studies do show clear post-saccadic effects of a pre-saccadic stimulus, it remains unclear when these effects arise in the human visual system.…”