This is called the Coffer illusion.
— Massimo (@Rainmaker1973) March 4, 2024
In this image there are 16 circles. Can you find them? pic.twitter.com/b0bOZkQDD5
Can you count how many circles are in this image? No? Can you see any circles at all? What seems to be a series of rectangular boxes does contain circles, but you have to look for them, because there are no curved lines in the image. Try concentrating on the vertical bars and ignore the horizontal bars for a minute. If that doesn't help, look at this visual aid at imgur. Still can't see them? That's okay, it doesn't mean that there's anything wrong with you.
The Coffer Illusion is not named after Dr. Coffer, but for the appearance of decorative panels in a door, called coffers. This illusion was created by Anthony Norcia, psychology professor at Stanford University. It was a finalist in the 2006 Illusion of the Year competition. While there are explanations for the visual perception involved, they all mostly boil down to the fact that we identify what we are looking at quickly, and once that identification is made, we have a hard time shifting our brains to see something different. -via Digg