Stare at the below image, what do you see?
If you see Albert Einstein, great. If you only see Marilyn Monroe, you might need glasses, or at least an eye test.
This optical illusion was created by MIT professor Aude Oliva. It's called a hybrid image, combining a blurry and clear picture.
Healthy eyes will see the lines on Einstein's face, while people without perfect vision will not be able to see past Monroe's blurry image.
"Depending on how well you're able to focus, or pick up contrast, your eye will only pick out details," a video revisiting the hybrid image from AsapScience notes.
"Up close, we're generally able to pick up fine details like Einstein's moustache and wrinkles. But as the distance increases, or if your vision is poor and creates a more blurred image in the first place, your ability to pick up details fades away."