Optical illusions can be downright mind-boggling, right? Even when we’re convinced we’re seeing something clearly, our brains sometimes play tricks on us. There are plenty of famous optical illusions out there—like that spiral image that makes it look like Van Gogh’s “Starry Night” is moving, or the Ames window that seems to swing back and forth when it’s actually spinning in a full circle.

But sometimes, optical illusions pop up by pure accident. These unintentional illusions are even more fascinating because they’re not created by someone trying to mess with our minds. Nope, these illusions are all thanks to the way our brains interpret what we’re seeing.

Take this one, for example: A picture shared by the popular Massimo account on X (formerly Twitter) shows what seems to be a person and two dogs hanging out in the snow. But, the more you look at it, the more you realize—wait a minute—that’s not a person with two dogs.

Surprise! The image actually features three dogs. Can you spot the third one? Frustrated yet, trying to find that elusive third dog in the picture?

Here’s a clue: The third dog is a poodle, and it’s facing the camera. What you might’ve thought was a scarf or stole is actually the poodle’s head, and the “hat” on the “person” is the dog’s fluffy tail.

Be honest—did you catch that right away? Probably not. Even when you’re told that the “person” is actually a dog, your brain might still struggle to see it. If your brain is like most people’s, it probably saw a two-legged figure dressed in black, with a furry stole and hat. But nope, that figure is just a black poodle! It’s funny how our brains can be so sure of something and still get it totally wrong.

Once you finally see it, it’s obvious, but until someone points it out, your brain might be interpreting the image completely differently. One explanation is that the black fur blends with the shadows and curves, so our brains only pick up the outline—which, to our eyes, looks like a person facing away.

It’s been hilarious watching how people react to this optical illusion. To help you out, here’s an outline showing where the third dog is:

We love optical illusions because they’re a reminder that our minds aren’t perfect. Unlike a computer that just processes data and spits out a result, our brains interpret and make sense of what our senses pick up—and that’s been a crucial part of human evolution. But, as amazing as our brains are, they’re not flawless. Optical illusions are a fun way to play with our perception and remind us that we’re only human, after all.