This optical illusion started out as a fun pastime, but it could actually be useful when driving in the rain.
It was posted by a user named Benonwine on X, and people can scarcely believe their eyes.
The image seems like many other optical illusions: a black and white circle with zig-zagging stripes and – if you look closely – numbers inside.
However, the line spacing and random direction of the lines make it difficult – if not impossible – to see what some or all of the numbers are.
But it could be higher stakes than weighing in on the color of a dress or whether a line of cars is the same size.
In fact, using contrast sensitivity, which according to the National Institutes of Health, is “the ability to perceive sharp and clear outlines of small objects”.
It’s also defined as the ability to identify small tweaks in shading and patterns – exactly what this optical illusion needs your eyes to do.
There are some real-life scenarios where your level of contrast sensitivity could be an issue.
Things that indicate a lack of contrast sensitivity include being unable to read when paper and text are a similar color.
Tripping over curbs or steps can be a common side effect too.
Perhaps the most important: people with reduced visual contrast sensitivity are advised to avoid driving during low light, fog, glare or rain.
Vision is important when it comes to getting behind the wheel safely as glow-in-the-dark road lines in Australia are demonstrating.
And with one social media user revealing the impact of collisions even at low speeds – road safety seems more important than ever before.
And, like with any optical illusion, people were quick to stake their claim of what they believed the number on the post to be.
“45,283 … and what’s the catch? Should I book an appointment with my GP,” one social-media user said.
“I can see 45,283, since looking at the other replies … others are seeing two other numbers. I can see there are numbers there but can’t make them out,” a second said.
“3,452,839, but to be honest the first 3 is a bit of a guess. Can’t get a fix on it. Easier to see if you jiggle the image up and down, but I don’t know why,” a third said.
Others admitted they were relying on their prescription glasses to see the number.
In case you’re wondering, the entire number is 3,452,839.
Saw something else? It could be time to book in with your optometrist.