Hollow-Face Illusion

The Hollow-Face Illusion is an optical illusion where the perception of a concave object appears as a normal convex object. This usually pertains to masks and faces, but the effect can also be seen with other kinds of subjects. The human brain sees the shadows and the form and because all the massive amounts of data that we have previously acquired say that the form should be convex, we perceive it as such. It's best documented against human faces, and the more human a concave shape appears, the most likely it is to be perceived as convex. Other familiar concave objects will also appears as convex. We "know" that the object should appear a certain way, and this trumps the actual information that we are receiving. 

Examples in the World

Interesting real-world examples I found. It was pretty hard to find ones that weren't just masks, but I was pleasantly surprised to see that the hollow-face illusion works in a wide variety of mediums and shapes. It's truly mind-boggling that although I know all these are concave, I can only really perceive the shell as convex.

Examples in Media/Art

Reflection

The hollow-face illusion is quite interesting. When I was looking for pictures to decorate this project, it was actually quite difficult to tell if the picture was concave or convex if there weren't other visual cues in the image. I'm not a sculptor myself, so the hollow-face illusion isn't particularly useful in what I do, but the idea of our brain tricking us and having us perceive something different than from reality is very present in media, particularly in more representative works, since idea is to get the viewer to see something that might not actually be there.