Why do we keep seeing faces in everyday objects?

Ever seen the Virgin Mary in a slice of toast? Probably not. But a few years ago, Diane Duyser from Chicago was so convinced she'd found a woman in a cheese toastie, a casino paid her $28,000 to buy the sandwich and display it for the world to see.  

It's a common occurrence, Jesus has been found on everything from toast, tacos, pancakes and bananas. And he's not the only one. Pareidolia, or seeing people in things has a long and rich history. Leonardo Di Vinci described seeing characters in stone walls, and the Bank of Canada had to remove banknotes from circulation in the 1950s after people said they saw a grinning devil in the Queen's hair.  

But what's going on? Is it divine intervention?  No, says Kang Lee, a researcher at the University of Toronto who studies this phenomenon.

I see faces 😲

In one of Lee’s studies, subjects were shown random grey patterns – similar to static on a TV. Given some subtle priming, they reported seeing a person about 34% of the time. Any contours that appeared in the images would have been extremely fuzzy – yet somehow, the brain was conjuring the illusion that a person was staring back. “It turns out it’s pretty easy to induce this phenomenon,” says Lee.

Although we tend to think that our eyes faithfully report whatever is in front of us, the retina records an imperfect and confusing image that needs to be tidied up by the brain. And Lee thinks this “top-down processing” by the brain is what leads to pareidolia.

One way the brain makes sense of the mess is by making predictions about what we will see, based on our past experience, and then subtly projecting those expectations onto what we see. That way, it can piece together a clearer picture, even if the scene is obscured by poor lighting or fog, say. But it also makes our vision more subjective than you might think – in a sense you really do see what you want to see.

In summary, your eyes are a pair of liars and aren't to be trusted.