【Lena Paul - The Next Morning】

There's a new optical illusion on Lena Paul - The Next Morningthe block, and it's a good one.

Take a look at the image above. Take as much time as you want. It looks as though there's one, maybe two dots at the intersections of the diagonal gray lines, but the dots are constantly moving, right?

The dots are not moving: it's a static image and there is a total of 12 dots in the picture (the illusion is more apparent in the full version of the image, below).

There are twelve black dots at the intersections in this image. Your brain won’t let you see them all at once. pic.twitter.com/ig6P980LOT

— Will Kerslake (@wkerslake) September 11, 2016

We've seen our fair share of optical illusions -- even variations on the one above -- but rarely is one so undefeatable as this. It's nearly impossible to see more than maybe three dots at once, even when you've convinced your brain there are 12 dots.

Shared on Twitter on Sunday by game developer Will Kerslake, the image took over the top of Reddit on Monday, with more than 8,200 upvotes and 2,600 comments at the time of writing.

So what's happening here? One Redditor has an idea: a scientific paper from October 2000 called Variations on the Hermann Grid: An Extinction Illusiontalks about a similar set of optical illusions.

The paper's abstract explains the phenomenon thusly: "When the white disks in a scintillating grid are reduced in size, and outlined in black, they tend to disappear. One sees only a few of them at a time, in clusters which move erratically on the page. Where they are not seen, the grey alleys seem to be continuous, generating grey crossings that are not actually present."

As for why this happens, the paper does not give a definitive answer, but it appears the illusion is related to a phenomenon called "crowding" or "the inability to recognize objects in clutter," as well as some deficiencies in how human memory works as you fix your eyes on a subject i.e., "people do not combine information from multiple fixations in a fully integrated and detailed representation." For details, read the paper here.

Kerslake later shared another paper, from 1999, which also focuses on this type of optical illusion -- and has images of some other similarly great illusions. Read it here.