Fixation-related Potentials Reveal Preserved Extrafoveal Semantic Processing In Healthy Older Adults

Objects violating contextual expectations (e.g., finding a fork in a bathroom) are known to capture early attention and trigger a fronto-central N400 response, reflecting the cognitive effort to solve their semantic mismatch within the scene. Yet, the extent to which high-level semantic information is accessed from extrafoveal vision and whether this processing is spared by ageing remains unclear. This question was addressed by co-registering eye-tracking (1000 Hz) and EEG (64 electrodes, 512 Hz) in younger (N = 22) and healthy older adults (N = 20) as they freely viewed real-world indoor scenes in preparation for a change detection task. Each scene included a target object that was either semantically consistent (e.g., toilet paper) or inconsistent (e.g., tennis ball) with the embedding context (e.g., bathroom). We applied a regression-based linear deconvolution to model how semantic consistency modulates fixation-related potentials (FRPs). This analysis specifically examined semantic processing during the preceding fixation (t–1, i.e., parafoveal), the target fixation (t, i.e., foveal), and all non-target fixations, as well as scene-onset ERPs, while controlling for overlapping EEG activity across consecutive fixations. Both age groups displayed earlier and longer first fixations on semantically inconsistent objects, replicating prior findings that contextual violations are attentionally prioritized and require greater cognitive effort to be integrated within the scene. Crucially, EEG data revealed that both younger and older adults exhibited a larger frontocentral N400 response to inconsistent versus consistent objects, beginning during the preceding fixation and extending through the target fixation. This suggests that semantic information is detected extrafoveally, and its inconsistency is resolved once the object is foveated. The only age-related difference, independent of object semantics, was a significantly reduced neural response, widely distributed along the scalp, at scene onset in older compared to younger adults, which may point at a reduced efficiency in extracting the scene gist due to ageing. Together, these findings provide robust behavioural and neural evidence that healthy older adults retain the ability to access high-level semantic information from extrafoveal vision, countering the hypothesis that extrafoveal semantic processing deteriorates with age.