will kerslake

Your brain literally won't let you win against this optical illusion:

There are 12 black dots in the picture, but I'd bet good money that you'll never be able to see all of them at once. If I squint, I can get four, and only four.

The illusion started taking over the internet after game developer Will Kerslake shared it via Twitter, but the picture itself originally came from the Facebook page of Akiyoshi Kitaoka, a psychology professor in Kyoto, Japan. It appears to be a variation of Ninio's extinction illusion, which is a grid illusion that scientists use to explain a big scientific concept.

Why you can't see all 12 dots? Basically, we can blame evolution.

The back of our eyes are full of light-sensing nerve cells, all crowded together, waiting for stimulation. You might think that when something interesting happens, they'd all start shouting and firing off signals — a furious rush of noise. But that's not what happens.

Instead, excited nerve cells actually kind of "shush" their neighbor cells, a phenomenon called lateral inhibition. They do this because it helps the message get through — if only a few people are shouting, the signal is clearer.

The end result is that our visual contrast goes up, but at the cost of muting whatever we're not looking at.

Meanwhile, our brain tries to be helpful by filling in that incomplete information with whatever it guesses is there. And since most of this picture is grey lines, our brain just leaves out the black dots.

So you're not going crazy, I promise. There really are 12 dots, but our eyes and brains do weird stuff sometimes to help us focus and survive. And as for what it means if you can see more dots than someone else? Well, the science doesn't really tell us much. Maybe you just have a different level of lateral inhibition than them, or maybe your brain is better at filling in the gaps.

Little mind games like this remind us of the limits of our brains.

We often assume seeing is believing, but optical illusions help show that's not true. Scientists are now using optical illusions to study how we perceive the world, why we react to certain things, and why we make quick assumptions. Optical illusions can teach us about bigger subjects like schizophrenia or even racism!

And, if nothing else, they're kind of trippy and fun.