It's called the "hollow face illusion," and it works because your brain assumes that anything resembling a face is convex, rather than concave. Even though the eye to your right is technically farther away from you, your brain believes that because the image is a face, it must actually be closer.

I Love Optical Illusions, But This Was SHOCKING. I’m Still Not Sure What Happened… | Distractify Saturday, January 18, 2014 @ 12:34pm