Why cant we see/ focus on things in our peripheral vision?

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Why cant we see/ focus on things in our peripheral vision?

In: Biology

Because as a predator we focus on what’s in front of us, peripheral vision is only a ‘warning’ that something is moving next to us.

We do not have vision cones that cover our peripheral vision. And the vision rods which do cover it are spaced very far apart in that region of our retina. So we can not see color and we can not see clearly. The reason why this seams odd to you is that your brain fills in the missing information with things it remembers. So you do not notice that you are essentially blind in 95% of your vision field. But your vision is good enough to notice movement which makes your eyes move to that spot automatically and update your memory of it.

Imagine a circle with a ton of dots in it that are mostly scattered about but seem to have a higher concentration/density in one smaller, circular area. What you’re picturing is roughly what the retina is in the back of your eye [(this is a picture of the retina and that darker spot in the middle is the high-density area you’re picturing, called the fovea)](https://www.verywellhealth.com/thmb/fNyH-n-IjzI8ttY0—ypM_lGZw=/1500×0/filters:no_upscale():max_bytes(150000):strip_icc():format(webp)/GettyImages-308783-003-56acdcd85f9b58b7d00ac8e8.jpg). The high density area is where your pupil/lens focuses light and it’s the center of your vision, and this combination of high density/lens focus is what gives the center of vision its clarity. The further you get away from this area, the less focused things will be – this is your peripheral vision, and it’s the result of the opposite – less lens-focused light and less dense receptors.

Hypothetically if your lens were able to twist around inside your eye and take that focal point of light and move it around you might could better focus on the periphery, but it’s fixed in place so that doesn’t happen. Receptor type also plays a role, but that’s the ELI5 of it.