Lower Task-Estimated Visual Working Memory Capacity in Adults with Epilepsy: A Cross-Sectional Quantitative Assessment Using Eye Tracking

Background/Objectives: Cognitive dysfunction is clinically relevant in epilepsy, and objective task-based measures could complement neuropsychological assessment, but visual working memory across graded loads and task-embedded gaze remain incompletely characterized. We quantified task-estimated capacity and performance using gaze-triggered change localization. Methods: We analyzed data from 222 adults with epilepsy, including focal and generalized epilepsy, and 133 healthy controls. Participants identified the changed item in a test array by sustained gaze; set size (2–7) followed a staircase procedure. Outcomes were three task-performance measures, two capacity-related measures, and eight eye-movement measures. Repeated-measure outcomes were analyzed with mixed-effect models and the capacity-related measures by ordinary least squares, with Benjamini–Hochberg correction. Results: Adults with epilepsy had lower mean set size and K at set size 4 (K4), lower accuracy, longer response time, and greater final gaze-to-target distance than controls (all q < 0.05; absolute Cohen’s d, 0.20–0.45). K4 was 2.66 versus 3.03 items. Differences persisted after adjustment for educational attainment and were directionally similar in focal and generalized epilepsy. No interaction between group and set size survived correction for task performance; group differences did not vary detectably across the observed load range. No eye-movement group difference survived correction. Conclusions: In a relatively large adult cohort, task-estimated visual working memory capacity and task performance were lower in epilepsy, without broad corrected group differences in the selected array-level eye-movement measures. By combining graded load with gaze-based response registration, the study characterizes the magnitude, load dependence, timing, and spatial precision of visual working memory performance differences within a single task.