Ever seen Elvis in a corn chip? How about a face in a building or a cloud? Spotting faces – even ones that don’t exist – is something your brain is very good at.

Seeing faces? Image credit Mk2010 via Wikimedia Commons

Do you see what I see?

One of my favourite Twitter accounts is Faces in Things. You’d be amazed where people have spied faces and other human and animal shapes.

You’ve probably heard about Jesus on a banana peel, the Man in the Moon and the face of Madonna on a toasted sandwich (which sold for US$28,000). We’ve seen capsicums that look like British politicians and a crab tainted with the face of Osama bin Laden.

Melbournians may know the Hume Highway rooster tree, now with its own Facebook page and song.

Since the 1700s, the surface of Mars has been a particularly rich source of these illusions. In 1976, people were captivated by images of a face on Mars, which turned out to be nothing more than a trick of light and shadows. Mars also boasts a smiley face in a crater, a lava flow that resembles Kermit the frog, the face of Mahatma Gandhi, a rat and Bigfoot.

Famous cases aside, people have spied faces in power points, trees, buildings, rocks and USB drives. If you tend to see faces everywhere, don’t worry. You’re not going crazy: our brains are exceptionally good at spotting faces.

It’s called pareidolia: the tendency to perceive a familiar pattern when one doesn’t exist.

Faces, faces everywhere

There are many different kinds of pareidolia, but seeing faces is the most common. Why are we so quick to see a face where there isn’t one? Simple – because we spend so much of our time looking at faces. And we’ve evolved to depend on our ability to recognise and extract information from these faces.

We’ve over-learned human faces so we see them where they aren’t – Professor Takeo Watanabe, Brown University

We are hard-wired to recognise faces: our social lives have long relied on us being able to spot a face from a distance or in low light. Not only that, it’s extremely useful to be able to deduce other things from a face: mood, age, gender and the direction a person is looking. Is this person a friend, or a threat? Even as very young babies, we prefer to look at faces over non-faces.

It turns out we have an entire brain area dedicated to recognising faces – the Fusiform Face Area (FFA). This area is active when we see a face, even in blind people.

Research shows this area of the brain lights up in the same way when we see an illusory face as when we see a real face. The FFA is active when a person reports seeing a face, even when there is absolutely no pattern (in a pure noise image).

True believers

Identifying patterns is nothing new – it’s the basis of the infamous Rorschach inkblot test. But some of us are more likely to see faces than others.

A Finnish study firstly asked volunteers whether they saw faces in dozens of objects and landscapes. The researchers then asked about the belief systems of the participants. Did each person believe in God? And how about the paranormal? Religious people and those who believed in the paranormal were much more likely to see faces than atheists and skeptics. ‘Believers’ were also more likely to see emotions in the illusory faces.

And if you’re thinking our ability to see faces in toast, tortillas and toilets is something that makes us uniquely human, think again.

Recent research shows rhesus monkeys see faces that aren’t there too. And it makes perfect sense – if a monkey thinks it sees a tiger when there’s no tiger around, it isn’t a big deal. But the consequences of not spotting a real tiger might not be so pretty. It’s not just humans who have evolved to be highly tuned to faces.

Now given I’m hard-wired to spot faces, excuse me while I waste a bit more time indulging my pareidolia.

Links and stuff

• TED talk: why people believe weird things
• SciShow video: Why people keep seeing crazy stuff on Mars
• What do you see in this inkblot? Take the test (Or you could take the spoof version of the test)
• These artists are mapping the earth….with facial recognition software