Seeing faces in inanimate objects isn't anything new, and the word pareidolia has been in use since the 1860s. An Instagram account called @things.faces documents some of the best. Our brains are highly tuned to see faces, and in 2014, a team of researchers from Canada and China dug into the neural mechanisms behind the phenomenon. Their paper, published in the journal Cortex, is titled "Seeing Jesus in toast: Neural and behavioral correlates of face pareidolia." It won an Ig Nobel Prize.
"Individuals often report seeing a face in the clouds, Jesus in toast, or the Virgin Mary in a tortilla," the researchers report. After observing the brain activity of individuals viewing face-like images, the paper implicates the right fusiform face area (rFFA).
The FFA was known for its role in seeing faces, but it hadn't been linked to illusory faces until this research. It's a small area of the brain that is part of the visual system, and based on fMRI imaging, it was active in people who made out faces from noisy images. It probably lights up in people who spot Jesus in their toast, too.
This tendency to detect faces in ambiguous visual information is perhaps highly adaptive given the supreme importance of faces in our social life and the high cost resulting from failure to detect a true face.Liu et. al