I have no idea what it's called, but the effect is real. It's not caused by the eye, however. It's caused by the brain. Basically, your brain has to deal with a lot of information at all times when you're conscious, far more than it can process at once. So it gets good at filtering out the unwanted details to free up brain power for processing and memory that's relevant. In this particular case, the brain refuses to see all of the various shades of light on the wall. However, you can train your brain to see it. You just have to spend a lot of time looking for subtle differences in tonality and tint in things, and eventually you'll retrain your brain to see these as important details that shouldn't be ignored. It's like how some baseball players have trained their brains to focus on ultra quick and ultra small visual changes so well, that they can read numbers and letters written on rotating baseball that wizzes past them at a speed of 100+ mph.
They taught us about this phenomenon while I was in art school. I still remember the moment a teacher showed this to me. I made a painting after a photograph I took and the teacher asked me why I painted this one shadow grey, and I told her because it was grey in the photo. She then took a piece of notebook paper and poked a hole through it with her pencil and placed it over the photo. Without the paper over it, the shadow looked grey. But with the paper blocking out the rest of the photo, it looked purple. Indeed, it was actually purple. My brain was just making it look gray when it was exposed to all of the other information contained in the photo. With everything else removed, my brain could finally concentrate, and see the color for what it really was. My paintings improved 10 fold in just a few seconds that day. It was one of the most profound breakthroughs I've experienced in my life.
Back when I was a musician, I had another similar experience when I started recording music, though it didn't occur as quickly. I never knew how much the sound of a room colors everything we hear, because our brains are so good at tuning that stuff out. But now that I've had so much experience focusing on that while recording, I can literally navigate a pitch black room just by clapping my hands (provided the room isn't full of sound absorbing material). A lot of blind people have been known to do the same thing. And the weird thing is, my actual hearing is terrible (from all of the years playing in rock bands). It's just that I've trained my brain really well with that stuff, so I can make more out of what I do hear, even if I hear less.
