“As vertebrates, mammals have this nonconscious visual system, but they have also incorporated vision into the neocortex. No other animals have a neocortex. This somewhat slower, conscious visual system allows mammals to become cognizant of objects for what they really are. The first neocortical stop is the primary visual area, which is particularly sensitive to edges and lines of different orientations.”
https://aeon.co/ideas/how-seeing-snakes-in-the-grass-helped-primates-to-evolve