Mind & Body

This Optical Illusion Makes Even Movie Stars Look Creepy

Do celebrities look like freaky aliens? Your gut reaction is probably "no," or "what?" And you're right that they don't — usually. But it depends how you look at them. It turns out that if you see a bunch of portraits of different people in quick succession, their faces start to look like caricatures, or E.T., or both. This happens even when each portrait, viewed on its own, looks extremely beautiful. This effect has so far been easier to name than to explain — experts call it the flashed face distortion effect, or the alien faces illusion.

Here's the Illusion

The video above comes from British science presenter Steve Mould who demonstrates the effect with the face of some of his favorite YouTubers. YouTube is full of videos that showcase the alien faces illusion — which is fitting. Some hypothesize the illusion exists because technology exposes us to new stimuli, like slideshows, that can be confusing for our bodies to digest; our eyes and brains evolved for real life, not for YouTube. (No offense, YouTube.)

Still, not every hyperspeed slideshow of faces will create this particular illusion. The portraits need to all show people facing forward, looking straight into the camera, and they all need to be "eye-aligned" (e.g., any two portraits, side-by-side, should have their eyes at the same level). That's pretty much it! The effect was discovered by an undergraduate student, Sean Murphy, when he was scanning a gallery of faces that met these specifications.

There are some ways to magnify the distortion, though. It's more pronounced when you don't look at the faces directly but instead stare at the space in between two side-by-side, rapidly changing faces. And a given face will be most warped by the effect when it's noticeably different from the other faces in their slideshow. For instance, someone with a large forehead, presented alongside people with average foreheads, will look profoundly deformed.

This phenomenon became a viral sensation via a video called "Pretty girls turn ugly," but this illusion isn't just for "pretty girls." The illusion will distort anyone's face, regardless of gender or attractiveness.

Why Do the Faces Look So Creepy?

No one knows, exactly, but that's typical for illusions. Usually, they're described first; later (sometimes much later), they're explained by science. This illusion was only discovered in 2012 when it took second place at the Best Illusion of the Year contest, and we're still in the early stages of figuring it out. There are some hypotheses, though.

One hypothesis is that we, Homo sapiens, didn't evolve to look at flashed face sequences — only the slow-moving faces we typically see in real life. Because of this, we see each new face in a flashed face sequence not as a new person, but as a horrific new facial expression. No facial expression should change a face that much, so the sequence starts to look creepy, even when no individual image does.

It's just a hypothesis, but it's true that our facial recognition abilities are easily disrupted. Often, we'll look at an upside-down face whose eyes and mouth are right-side-up and think, "That looks normal." (Really — it's called the Thatcher Effect.) Faces moving or positioned in ways we're not used to generally throw us for a loop.

However, according to another hypothesis, the speedy slideshow format is the root of the illusion, not our glitchy brains. A flashed face sequence allows us to easily and unconsciously compare a lot of different faces on a lot of different dimensions. Differences in bone structure, shape and size of features, proportions — normally subtle, or just not at the forefront of the viewer's mind — become hyper-visible and cartoonish when you see so many faces in quick succession.

Get stories like this one in your inbox or your headphones: sign up for our daily email and subscribe to the Curiosity Daily podcast.

Love how your eyes can play tricks on your mind? You should check out "The Ultimate Book of Optical Illusions" by Al Seckel. We handpick reading recommendations we think you may like. If you choose to make a purchase, Curiosity will get a share of the sale.

Related Video: One More Optical Illusion to Try

Written by Mae Rice July 12, 2018

Curiosity uses cookies to improve site performance, for analytics and for advertising. By continuing to use our site, you accept our use of cookies, our Privacy Policy and Terms of Use.