"Pareidolia illustrates the interaction between the visual cortex and the frontal cortex of the human brain. It suggests that our brain is highly sensitive and expecting to encounter and process some special classes of objects in our environment because they are biological and socially important to our adaptions to the environment," professor Lee explained to us.

"For example, when you are walking in a dark street in the evening, your brain is on high alert to detect whether any threat will jump out any moment. In this case, you are more likely to have face or human pareidolia because it is important for you to err on the side of caution if you mistake a tree as a human being."

The professor pointed out that this is the reason why pareidolia often occurs in ambiguous situations. "However, for some people, their frontal cortex’s expectation for certain objects (e.g., faces) become so high that they see faces in many situations where no faces exist."

"Even in this kind of situation, it is normal. There is nothing wrong with these individuals," he stressed. "Pareidolia is different from paranoia or delusion or abnormal vision of individuals with psychosis. In fact, a recent study shows that those people with pareidolia tend to be more creative. Also, people who are religious may be able to see religious icons in non face objects as well."

Professor Lee highlighted that pareidolia as a phenomenon shows how powerfully our imaginations (which comes from our frontal cortex) can affect our perception (which takes place first in the visual cortex which is located in the occipital lobe in the back of our head).

He added that pareidolia also tells us that "what we see are not things over there in the world but actually the co-creation of what is out there physically and what is in our mind mentally through our expectations and imaginations."

"Pareidolia is a broader phenomenon as it extends to touch and sound and other sensory channels. For example, you sometimes sense your phone vibrating when it is not, it is a tactile form of pareidolia. When you hear voices in a noisy environment, it is an auditory form of pareidolia."

“If someone reports seeing Jesus in a piece of toast, you’d think they must be nuts,” professor Lee previously told BBC Future. “But it’s very pervasive. We are primed to see faces in every corner of the visual world.” According to him, our imaginations exert a very powerful influence over our perceptions.

(On a semi-related note, no wonder we keep bumping into things—we're too busy imagining what it’d be like to fly on the back of a fire-breathing dragon.)

According to Live Science, people who are religious or have very strong beliefs about the supernatural see faces in objects and landscapes more often. Cosmologist Carl Sagan thought that pareidolia is a survival mechanism that helps us recognize faces from a distance and determine whether we’re being approached by an ally or an enemy.

Meanwhile, legendary artist and inventor Leonardo da Vinci saw pareidolia as an artistic device: “If you look at any walls spotted with various stains or with a mixture of different kinds of stones, if you are about to invent some scene you will be able to see in it a resemblance to various different landscapes adorned with mountains, rivers, rocks, trees, plains, wide valleys, and various groups of hills.”

There’s also something called the electronic voice phenomenon, aka auditory pareidolia, where people hear hidden messages that were supposedly placed there on purpose by songwriters. And that… that’s given rise to plenty of conspiracy theories, like the one that began circulating in 1966 that musician Paul McCartney had supposedly died and been replaced by a lookalike. Conspiracy theorists looked for clues in The Beatles songs and album covers.