[nattmat]

The brain fills in what it expects in your peripheral vision. For example, you can see colors in your peripheral vision, but it is only an illusion made in the brain.

[PavlikPaja]

I'm pretty sure I can actually see in my peripheral vision, only not as clearly. Including colors, I have tested that before.

[nattmat]

You can see in your peripheral vision, but not clearly, and not colors. This is because the cones in the eye are all in the center, and they are responsible for most of your daytime vision. Around the cones are rods, they are used for night vision and motion detection. The colors you see in your peripheral vision are not real, but an illusion made by the brain.

This Ted gives some good examples https://www.ted.com/talks/anil_seth_how_your_brain_hallucina...