In the past two years, the internet has given us The Dress, a photo of a mysterious missing leg, and this disorienting floor design.
If you're still hungry for more, INSIDER rounded up a mix of classic optical illusions, baffling viral photos, and mind-boggling designs that'll leave your head spinning and illustrate how our brains process and interpret color, peripheral vision, size, and more.
One quick note: We've included explanations for many of the images, so scroll down slowly if you don't want to spoil the illusion.
Although you may see a bunch of swirling circles, this image is actually completely still.
The image above was inspired by the famous illusion "Rotating Snakes," created by Japanese psychologist and professor Akiyoshi Kitaoka in 2003.
Both are examples of a peripheral drift illusion, in which we perceive still images as moving ones. Interestingly enough, when you stare at one part of the photo without moving or blinking your eyes, that part stops "swirling" (while the circles in your peripheral vision continue to "move").
You can read about the science behind this phenomenon on Business Insider.
Is this cat going up or down the stairs?
This innocent photo of a cat went viral back in 2015 as people wondered whether the animal was going up or down the flight of stairs.
Internet users used everything from architecture to biology to defend their answers to the hotly debated question. INSIDER's Megan Willett, for example, broke down why the cat is "definitely" going down the stairs — and after reading her explanation on Business Insider, I'm convinced.
This photo of two people hugging confused the internet last year.
The post went viral after Reddit user Blood_Reaper shared it online, along with the caption, "This hurts my brain...."
People couldn't figure out who was initiating the hug, as the man in the photo appears to have two pairs of legs.
See the rest of the story at Business Insider