Remember when they used to sell 'Magic Eye' pictures in the mall about 15 years ago? They're made by computers that create a stereogram image and if you look at it just right, you can see the illusion of an image with depth perception.
The band Young Rival made this video using the same method...
You know how a photographer will tell you that 'it's all about the lighting?' This video proves it to be true. Watch how his womans face changes with the different angles and color of lighting. Some of the angles actually make her appear to be older...
It doesn't matter how many times I watch this, it still gets me. This illusion is a prime example of your brain contradicting your eyes. Even after you know the answer to the illusion, your brain still reverts back to seeing what it wants to see...
If you think these two blocks are the same color, your eyes are playing a trick on you. Watch the video below and you'll see that these blocks are actually the same color.