The internet is full of little tests and quizzes you can perform quickly to determine if you have what it takes to solve the puzzle. Many of them are quite difficult or are based on the subject’s previous knowledge, but one test is causing concern for a totally different reason.

The test is a vision test designed to determine how well you can see. The test is a simple image with static like what you might to find on a television screen when there’s no signal, only the static is a deep red.

Vaguely hidden beneath the red static is a number, but it is hard to read through the static clearly. It is as if the number is meant to be obscured to the critical point where only those with the absolute best vision can see it clearly.

There is only a single question associated with the quiz, and it is one that even gives the subject a clear guess at the number in the middle of the static. The question is whether the number is 571 or 574. Right away your eyes will fill in the 5 and the 7 in their rightful place, but you’ll notice that almost no matter how hard you try, the last number will remain a mystery. It almost appears equally as a 4 and a 1, but that is impossible.

The static is merely obscuring the area that makes up the difference in the physical shape of the 4 and the 1, but it is actually just a 1.