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Reddit user Heinderhead shared an image of a lost cat poster and the cat's head seems to follow as you walk by it.
We've all seen those paintings which appear to follow us as we walk around the room. They're always old, creepy and used in Scooby Doo episodes.
As Scooby Doo eventually tells us, it's either some creepy person hiding behind the painting, or it's just an optical illusion.
The image, which is supposedly in Russia, has inspired some great responses.
Before you go thinking the poster is haunted or actually one of those moving newspaper images from Hogwarts, let us clarify what's happening.
Thanks to science we know that this - a picture that has the appearance of eyes or a head following you - happens with anything resembling a face that's concave.
Similarly with those creepy paintings, the effect is created by receding the eyes below the surface of the painting.
The extra depth helps the edges of the eye sockets to hide the whites of the eyes on the side it's being viewed from.
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