The culprit in our seeing faces that aren’t technically there is called “face pareidolia,” according to a study published in the journal Cortex.
The simple way of explaining it is this: if one expects to see a face in something, the part of the brain that processes faces may be activating. More specifically, according to TIME it’s caused by the interaction of the brain’s frontal cortex, which manages expectations of what something should look like, and the posterior visual cortex, which processes images.
To arrive at this conclusion, researchers at the University of Toronto and several Chinese institutions recruited 20 Chinese men to look at images. The men were tracked with functional magnetic resonance imaging (fMRI), which tracked blood flow to the brain. This allowed the researchers to see when neurons in the brain fired up, indicating increased activity.
For the first round of testing, the men were shown a series of images, half of which showed male faces. One of the two faces was easy to spot, the other somewhat camouflaged. A week later, the participants had the same test, only with letters instead of faces. The final image in each sequence was just “visual noise,” or nothing discernible.
After these sequences, participants were shown another series of images consisting entirely of visual noise, but researchers told the participants that there were faces or letters.
As a result, participants reported seeing faces 34 percent of the time and letters 38 percent of the time even though there weren’t any, The researchers found out that the region of the brain that sees more activity is the fusiform face area, a small part of the brain behind the ear. It is responsible for recognizing faces, but also for discerning similar objects from one another.
The CBC reports that besides the fact that we see faces because we expect them, the reason some people see religious figures like Jesus or the Virgin Mary is because religious beliefs can strongly affect how one wants to perceive the world.
