Beyond Stimulus Onset: Ongoing Fixations Within an Object Do Not Re-evoke Category Representations During Free-Viewing

Abstract

Human visual perception in natural conditions involves multiple fixations within single objects. While traditional studies focus on transient neural responses to initial stimuli, this study investigates how object-category representations evolve across sequential fixations on an object. Using electroencephalography (EEG) and eye-tracking, we analyzed fixation-related potentials (FRPs) and applied multivariate pattern analysis (MVPA) to decode neural representations of faces and watches during prolonged viewing. Results revealed robust category-selective responses, including the N170 component, at stimulus onset, with sustained representations persisting throughout object presentation. Temporal signal deconvolution showed that subsequent fixations did not re-evoke the N170 but elicited transient occipital responses, likely reflecting low-level category differences. These findings underscore the dynamic interplay between transient and sustained neural processes during naturalistic vision and highlight the importance of disentangling overlapping neural signals during free viewing.