Snakes have proven to drive early attentional capture due to their evolutionary importance, as reflected by the early posterior negativity (EPN). The EPN snake effect might be partly driven by the proximity of the animal. In this study, by employing full-body (medium shot) and head-focused (close-up) pictures, we investigated whether the relative nearness (proximity) of the animal on the picture affects the snake EPN effect. We presented thirty participants with medium shot and close-up snake, spider and bird pictures in a rapid serial presentation paradigm at a presentation rate of three frames per second. We extracted the mean EPN activity from the 225–330 ms time frame after stimulus onset at the parietal–occipital cluster (PO3, O1, Oz, O2, PO4). The results indicate enhanced EPN for snake pictures as compared to spider and bird pictures. In addition, medium-shot snake pictures elicited higher EPN amplitudes than close-up snake pictures, suggesting that the EPN is higher when local, high spatial frequency attributes are visible. Spatial frequency analysis of the stimuli indicated that medium-shot snake pictures possess more power in the high spatial frequency bands, compared to medium-shot spider and bird pictures.

事实证明，蛇由于其进化的重要性而引起了早期注意力的捕获，正如早期后负性（EPN）所反映的那样。EPN蛇效应可能部分是由于动物的接近所致。在这项研究中，通过使用全身（中景）和头部聚焦（特写）图片，我们研究了图片上动物的相对接近度（接近度）是否会影响蛇的EPN效果。我们以每秒三帧的显示速率，以快速的连续显示范例向30位参与者提供了中景和近摄的蛇，蜘蛛和鸟的照片。我们在顶枕骨簇（PO3，O1，Oz，O2，O2，PO4）开始刺激后，从225–330 ms时间范围内提取了平均EPN活性。结果表明，与蜘蛛和鸟类图片相比，蛇图片的EPN增强。此外，中景蛇照片比特写蛇照片引起的EPN幅度更高，这表明当局部，高空间频率属性可见时，EPN更高。刺激的空间频率分析表明，与中等拍摄的蜘蛛和鸟类照片相比，中等拍摄的蛇图像在高空间频段具有更大的功率。