Under naturalistic viewing conditions, humans conduct about three to four saccadic eye movements per second. These dynamics imply that in real life, humans rarely see something completely new; there is usually a preview of the upcoming foveal input from extrafoveal regions of the visual field. In line with results from the field of reading research, we have shown with EEG and eye-tracking coregistration that an extrafoveal preview also affects postsaccadic visual object processing and facilitates discrimination. Here, we ask whether this preview effect in the fixation-locked N170, and in manual responses to the postsaccadic target face (tilt discrimination), requires saccade execution. Participants performed a gaze-contingent experiment in which extrafoveal face images could change their orientation during a saccade directed to them. In a control block, participants maintained stable gaze throughout the experiment and the extrafoveal face reappeared foveally after a simulated saccade latency. Compared with this no-saccade condition, the neural and the behavioral preview effects were much larger in the saccade condition. We also found shorter first fixation durations after an invalid preview, which is in contrast to reading studies. We interpret the increased preview effect under saccade execution as the result of the additional sensorimotor processes that come with gaze behavior compared with visual perception under stable fixation. In addition, our findings call into question whether EEG studies with fixed gaze capture key properties and dynamics of active, natural vision.

在自然观看条件下，人类每秒进行大约三到四次眼球扫视运动。这些动态意味着在现实生活中，人类很少看到全新的东西；通常可以预览来自视野的中心凹外区域的即将到来的中心凹输入。与阅读研究领域的结果一致，我们通过脑电图和眼动追踪协同配准表明，中心凹外预览也会影响视觉对象处理后并促进辨别。在这里，我们询问注视锁定 N170 中的预览效果以及对扫视后目标面部（倾斜辨别）的手动响应是否需要扫视执行。参与者进行了一项注视相关实验，其中中央凹外的面部图像可以在针对他们的扫视过程中改变他们的方向。在控制区中，参与者在整个实验过程中保持稳定的注视，并且在模拟眼跳潜伏期后，中央凹外的面部重新出现在中央凹处。与无眼跳条件相比，眼跳条件下的神经和行为预览效应要大得多。我们还发现，无效预览后的首次注视持续时间较短，这与阅读研究形成鲜明对比。我们将扫视执行下增强的预览效果解释为与稳定注视下的视觉感知相比，凝视行为带来的额外感觉运动过程的结果。此外，我们的研究结果对固定凝视的脑电图研究是否捕捉到主动、自然视觉的关键特性和动态提出了质疑。