💬 “Our eyes are built for two perspectives. During the daytime we rely on our cone cells, which depend on lots of light and let us see details. At night the cone cells become useless and we depend on rod cells, which are much more sensitive. The rod cells in our eyes are connected together to detect stray light; as a result they don’t register fine details. If we want to see something in bright light, we focus the image on the center of our retina (the fovea), where the cone cells are tightly packed. To see something at night, we must look off to the side of it, because staring directly at it will focus the object on the useless cone cells in the fovea. The way we see in bright light differs from the way we see in shadows. Neither is the ‘‘right’’ way. We need both.” - Gary Klein (2009) Streetlights and Shadows. Searching for the Keys to Adaptive Decision-making. Cambridge, MA: MIT Press.

On reflection, more can be said along these lines. Another way of looking at this ‘double perspective’ of human vision is to note that it constantly depends on some kind of accommodation between our two eyes working simultaneously and in concert.

So although vision is actually several processes taking place at once, we insist on perceiving it as one unified process. We can’t help it. We’re made to synthesize. But that doesn’t mean it is one process.