This Optical Illusion Has People Divided As Everyone Is Seeing A Different Number

An optical illusion involving numbers is the latest craze surfacing across social media — and it's getting lots of reactions because everyone is seeing a different number.

Remember the dress that was either blue and black, or gold and white, which divided people in 2015? Well, another illusion is back and this time you'll really need to concentrate.

The image, which shows black lines rotating around in the shape of a circle, also has numbers hidden within the background.

A Twitter use named Benonwine captioned the post with a simple message: "Do you see a number? If so, what number?"

On initial glance, I saw "4528" and thought "well, that's easy," but then I saw people suggesting there were other numbers.

In the hundreds of replies to the post, some people say they can only see the number "528," while others are confused because they have other variations of numbers.

Many people are mistaking the "4" for a "1" and others guessed "15823" for their answer.

What Is The Correct Answer?

If you really concentrate, you can see the number "3" in the far left and then numbers "3" and "9" in the far right — so the correct answer is the seven-digit combination 3452839.

What Is The Science Behind It?

Optical illusions, such as this one, require something called contrast sensitivity.

According to ScienceDirect, this is the ability to detect subtle differences in shading and patterns, such as objects or details (numbers in this example) from their background.

Contrast sensitivity deteriorates with age and with health conditions such as cataracts.