Snakes and spiders, two animals that the human brain seems primed to notice with alarm, capture attention even when their images are flashed so fast we have no conscious awareness of having seen them. The bottom-up circuits spot them more quickly than neutral objects, and send an alarm (flash those images by an expert on snakes or spiders and she will still have attention capture—but no alarm signal).
— Focus: The Hidden Driver of Excellence (Daniel Goleman), Loc. 495–8