You may remember the blue and black dress versus white and gold dress debate, and you may also remember being incredibly irritated over what seemed to be an optical illusion. While a phenomenon known as color constancy ended up explaining this particular debate, some still argue over what two colors “The Dress” really is. Thankfully, AsapSCIENCE is here to explain the secret behind this new video and show how we can use it as a measure of our eyesight.

At the start of the video, you probably see a somewhat blurry image of Albert Einstein, but if you stand up and move away from your computer you’ll start to notice another famous face that is a little easier on the eyes: Marilyn Monroe. Don’t be alarmed or call in your friend for a second opinion. You just passed this eyesight test. What you’re seeing is a “hybrid image,” or a combination of two images.

The picture of Albert Einstein is easier to distinguish up close, but almost impossible to see from a distance because it consists of hard, detailed lines. The picture of Marilyn Monroe, on the other hand, is made up of soft outlines, meaning it is easy to see even from a distance. “Hybrid image” tests are used for research purposes by Dr. Aude Olivia from MIT to show the different levels our visual perception system can operate at.