Which face is normal?

A woman's face printed onto a round steel disc, sits on an exhibition table

When a face is turned upside down (inverted), we seem to lose the ability to judge even the simple things such as facial expressions.

How it works

Digitally altered photos of faces are printed upside down on discs. Look at each inverted face, then turn the discs around to see the face in their normal upright position.

Things to try or ask around the exhibit

Why was it so hard to judge whether a smiling mouth had been turned into a pout when the face was inverted?

Background

  • Scientists are unsure why these strange faces look so normal when they’re upside down (or inverted). When faces are the right way up, we ‘understand’ faces as a whole based on their internal components. This is called judging the face holistically.
  • When you look at an inverted face, you seem to lose the ability to process it holistically. Instead, you analyse individual features (eyes, nose and a mouth), which makes it harder to detect that something is wrong with the inverted face.
  • This is often called The Thatcher Illusion or Effect, because a photo of former British Prime Minister Margaret Thatcher was manipulated by Peter Thompson of the University of York in England.