Crowding, the phenomenon of impaired visual discrimination due to nearby objects, has been extensively studied and linked to cortical mechanisms. Traditionally, crowding has been studied extrafoveally; its underlying mechanisms in the central fovea, where acuity is highest, remain debated. While low-level oculomotor factors are not thought to play a role in crowding, this study shows that they are key factors in defining foveal crowding. Here, we investigate the influence of fixational behavior on foveal crowding and provide a comprehensive assessment of the magnitude and extent of this phenomenon (N = 13 human participants, four males). Leveraging on a unique blend of tools for high-precision eyetracking and retinal stabilization, we show that removing the retinal motion introduced by oculomotor behavior with retinal stabilization, diminishes the negative effects of crowding. Ultimately, these results indicate that ocular drift contributes to foveal crowding resulting in the same pooling region being stimulated both by the target and nearby objects over the course of time, not just in space. The temporal aspect of this phenomenon is peculiar to crowding at this scale and indicates that the mechanisms contributing to foveal and extrafoveal crowding differ.

拥挤，即由于附近物体导致视觉辨别能力受损的现象，已被广泛研究并与皮质机制有关。传统上，拥挤是中心外研究的;它在急性度最高的中央凹的潜在机制仍存在争议。虽然低水平动眼神经因素被认为在拥挤中不起作用，但这项研究表明它们是定义中心凹拥挤的关键因素。在这里，我们调查了注视行为对中心凹拥挤的影响，并对这种现象的幅度和程度进行了全面评估 （N = 13 名人类参与者，4 名男性）。利用用于高精度眼动追踪和视网膜稳定的独特工具组合，我们表明，通过视网膜稳定去除动眼神经行为引入的视网膜运动，可以减少拥挤的负面影响。最终，这些结果表明，眼漂移导致中央凹拥挤，导致同一聚集区域在一段时间内受到目标和附近物体的刺激，而不仅仅是在空间中。这种现象的时间方面是这种规模的拥挤所特有的，并表明导致中央凹和中心凹外拥挤的机制不同。