Contribution of Eye Movements to Primary-School Children's Silent Reading Speed: Evidence from Ex-Gaussian Analysis

Reading speed, a core indicator of reading performance, requires efficient oculomotor behavior. While well-documented in adults, the contribution of eye movements to children's silent reading speed and grade-related changes remain underspecified. Furthermore, the distributional properties of fixation durations have rarely been examined in children. This study investigates how changes in eye-movement parameters associate with individual differences in children's silent reading speed. The eye movements of 194 typically developing Greek-speaking students (Grades 3-6) were recorded during silent reading of short passages. An Ex-Gaussian distributional analysis was applied to fixation durations, alongside traditional measures of mean fixation number, fixation duration, and saccade amplitude. Language and cognitive abilities were also evaluated. Silent reading speed increased with grade, driven by fewer and shorter fixations, and longer saccades. After accounting for age, vocabulary and cognitive measures, eye-movement parameters increased the explained variance in silent reading speed to 80% (adjusted R² = 0.800) in the full sample (N = 194). The Ex-Gaussian parameter τ was an independent predictor, distinct from mean fixation duration. Finally, age significantly moderated the association between forward fixations and silent reading speed. These findings indicate that oculomotor behavior is independently linked to children's silent reading speed across primary school years, as captured both by conventional and distributional oculomotor parameters.