This optical illusion was originally tweeted by @benonwine, and many, many people commented with their answer; however, they had different answers.

Let’s look at the original tweet together. See what number you see, and we’ll walk through this optical illusion, the correct answer, and why it matters.

When we first looked at this image, we almost immediately saw the number 2. Then, we quickly realized that 2 wasn’t the only number in the picture. We mentally changed our answer to 528.

A lot of people answered 528, but there are actually more numbers in the picture. If that was your answer look again. Do you see any more numbers? Many people answered 45283, and some answered 15283. There is not a number 1 in this image, but the answer 45283 is not entirely correct either.

Look again. Do you see any other numbers?

The actual answer to this optical illusion is the number 3452839. We’re proud to say we got the correct answer, but not everyone did. Even after being told the correct answer, some people still can’t see all of the numbers.

What does this mean? Why can some people see more numbers in this optical illusion than others?

It all has to do with contrast sensitivity. This is not something that is measured on a standard eye test. If you think back to the last time you saw an eye doctor or took a vision test at the DMV, you probably remember that a vision test usually involves looking at black letters on a white background. Black and white are high contrast colors, so it is pretty easy to distinguish the two colors from each other.

Now, imagine taking a vision test where the letters are in one shade of gray and the background is in another shade of gray. This would be a lower contrast. The ability to distinguish shapes and colors when there is not a lot of contrast means you have a high level of contrast sensitivity. This ability is particularly important during certain situations like driving at night when it’s dark outside.

If you had trouble seeing all of the numbers in this optical illusion, you might want to contact your eye doctor to schedule a test for contrast sensitivity.

What number did you see when you looked at this optical illusion? Did you get the correct answer? If not, were you able to see all of the numbers after learning the correct answer, or were you still unable to see it? Do you have trouble distinguishing between shapes and colors at night or in low light situations?