Snakes were probably one of the earliest predators of primates, and snake images produce specific behavioral and electrophysiological reactions in humans. Pictures of snakes evoke enhanced activity over the occipital cortex, indexed by the "early posterior negativity" (EPN), as compared with pictures of other dangerous or non-dangerous animals. The present study investigated the possibility that the response to snake images is independent from visual awareness. The observers watched images of threatening and non-threatening animals presented in random order during rapid serial visual presentation. Four different masking conditions were used to manipulate awareness of the images. Electrophysiological results showed that the EPN was larger for snake images than for the other images employed in the unmasked condition. However, the difference disappeared when awareness of the stimuli decreased. Behavioral results on the effects of awareness did not show any advantage for snake images.

中文翻译：

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谁害怕隐形蛇？主观视觉意识调节后脑活动以应对具有进化威胁的刺激

蛇可能是灵长类动物最早的捕食者之一，蛇的图像会在人类身上产生特定的行为和电生理反应。与其他危险或非危险动物的图片相比，蛇的图片唤起了枕叶皮层活动增强，由“早期后部负性”（EPN）索引。本研究调查了对蛇图像的反应独立于视觉意识的可能性。在快速连续视觉呈现期间，观察者观看以随机顺序呈现的威胁性和非威胁性动物的图像。四种不同的掩蔽条件用于操纵图像的意识。电生理结果表明，蛇图像的 EPN 比在未屏蔽条件下使用的其他图像更大。然而，当对刺激的意识降低时，这种差异就消失了。对意识影响的行为结果没有显示蛇图像的任何优势。