If your eyes follow the movement of the rotating pink dot, you will only see one color, pink.
If you stare at the black + in the center, the moving dot turns to green.
Now, concentrate on the black + in the center of the picture. After a short period of time, all the pink dots will slowly disappear, and you will only see a green dot rotating if you’re lucky!
Blink, and all the pink dots suddenly re-appear again!
It’s amazing the way our eyes and brain work. There really is no green dot, and the pink ones really don’t disappear.
This might be proof enough, that we don’t always see what we think we see, and in more sense than one!
I have whole books of these optical illusions. They’re neat stuff. I wish I could find a complete explanation for how each of them work, though. Its easy to say “that’s the way the brain works,” but that’s hardly an explanation for why different colour tricks work, different black & white tricks work, or some of the incredible 3D tricks.
While most humans have three kinds of visual cone cells, it’s been known for some time that some men have only two. We call them “color blind”, although that’s not a completely accurate term.
But did you know that some women have four kinds? This means that those women can probably perceive color distinctions that are as incomprehensible to us “normal” folks as the red-green distinction is to men with red-green color blindness. And some shrimp have eleven kinds. Humans must really be color-blind compared to them.
There are a number of different kinds of optical illusions, many of which provide clues about the way vision works.
One of my favorites is the way a dot changing position on a computer screen appears to be moving from one place to another. I once wrote a program that drew a one-inch black dot, then erased it and drew it again somewhere else. It had a slider that could adjust the distance between the two positions. Even though I knew that it wasn’t moving on screen between those two positions, I could still see it moving.
Also, did you know that we total about 60-to-90 minutes a day during which we see nothing, yet we never notice it?
Another way to state your point is that what we see is not exactly what is.
