What's in a Face? Creepy Illusions of the Face

Sunday, July 10, 2011

So a friend, and Psychobabble regular, Matt, has recently co-authored a serendipitous little finding.

When two faces are presented side-by-side and flipped through in a series at high-speed they suddenly appear grotesque and disfigured.

Check it:

The tagline so frequently associated with this is 'pretty girls turn ugly'; it dominates the first page of google and has nearly 1.2 millions hits on youtube (an increase of 400,000 in 12 hours. That's fracking insane. [12/7/11]). See Matt's UQPsychblog post here, where he discusses the finding first-hand.

The effect was discovered when a member of their lab programming faces into a series and aligning the eyes. In spot-checking they flipped through the series at high speed to check that the faces were aligned as intended. Viola - ugliness.

Given the way the effect was discovered it's no surprise they have no sure clue as to the mechanism. They suggest, however:

"Relative encoding seems to drive the effect. That is, forcing the observer to encode each face in light of the others. By eye-aligning the faces, it becomes much easier to compare their shape and the relative location of their features, so the differences between them become more evident..."

Furthermore, the effect seems stimuli dependent. Individuals with prominant jaws, or foreheads, or eyes appear to become caricatures of themselves.

I can't help but wonder if the 'pretty girls turn ugly' angle has helped spread this video, but, upon my suggestion, he's looking at doing the same thing with celebrity faces. Though I know much less about the literature than he does, I wonder if the effect is so pronounced (perhaps even more jarring) on people we all generally agree are beautiful.

James, another Psychobabble regular, wrote a blog post some time ago on a different, but equally cool face illusion.

Can you spot what's wrong with this image?

Yes, yes. It's upside down... but if you look closely you'll notice the mouth - the smile - is actually the correct way up. It's an open, upward facing 'U'. Similarly, the eyes are as they would be if the face was correctly oriented - notice the eye-lashes?

James wrote an excellent exposition on the effect here. At this post is a cool .gif which rotates the face so you can observe the exact moment your perception switches for normal to illusion. Highly recommended.

Now if you just take a moment and consider what a face actually is - It's an accumulation of sense-organs, put up high on our bodies and directly wired to the brain. Everyone has a face, and everyone's face conforms to the same basic layout. It's been this way for a very long time - and after briefly thinking about it (happy to be proven wrong) - the same basic configuration is preserved across most mammalian species. Eyes above nose, above mouth; ears usually midpoint and above.

So we have faces, and eyes, and we're social animals. This has influence the way in which we process faces, 'cause we need to do it all the time. We process faces holistically. We don't interpret eyes+mouth+nose=face; we just see a face and recognize it as a result. I'm not sure if we do the same thing with expressions, but I suspect we do. It's this holistic process thingy that plays into these illusions (particularly the second, and I suspect the first). We see a face, then process the components contained within it. Oh look a face... it looks angry/happy/sexy; If it was the other way round it would be like, look a mouth and it's angry; look a nose, and it's crinkled; look - eyes, and the brow is furrowed.

Processing faces holistically is way more efficient, but it clearly leads to some very cool mistakes that involve us caricaturing faces beyond recognition and recognizing inverted faces a even though they are biologically impossible.

...and if you've read this far, and want to know a bit more about faces, only a few weeks ago we published a Psychobabble episode on Faces (live streaming available at the link), also available on itunes.

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