We know that our minds can imagine faces wherever there is a touch of two eyes and a nose – from cloud formations to car helmets to sockets – and this is technically known as face pareidolia. A new study gives us insight into what is actually going on in the brain when this happens.
Researchers wanted to know if the brain treats these imagined faces in the same way as real human faces – and it turns out that there are some similarities in how we perceive and interpret them.
The study suggests that fake faces found through pareidolia are assessed in the same way a real face would be. Somehow, the same neural circuitry is involved in figuring out what a face is doing, even though we know that what we are looking at in a tree stump or a TV remote control is not a real face.
“We know that these objects are not really faces, but the perception of a face still lingers,”
“We end up with something strange: a parallel experience that it is both a convincing face and an object. Two things at once. The first impression of a face does not give way to the second perception of an object.”
Alais and his colleagues asked 17 volunteers to look at a series of dozens of illusory and human faces, repeated several times, and then assess the emotional strength of each through the same computer software.
The researchers found that the participants in the study mostly agreed with the expressions that the pareidolia faces showed, and that bias crept in based on the expression from the previous face – something we also do with human faces. This also happened when real and illusory faces were mixed together.
In other words, a series of happy faces makes us more likely to see the next one so happy too. That this bias was observed in both real and illusory faces suggests that the brain treats them in a similar way and uses similar neural networks.
“Pareidolia faces are not discarded as false detections, but undergo facial expression analysis in the same way as real faces,” says Alais.
“We need to read the identity of the face and distinguish its expression. Are they a friend or an enemy? Are they happy, sad, angry, painful?”
Researchers point to the importance of facial expressions as social communication as the reason why our brains constantly recognize faces and evaluate their expressions.
It helps us decide what kind of situation we are in and what to do next, which is why our brains have learned to do it so quickly and with so little information (just a touch of two eyes and a nose, maybe).
Previous research on facial pareidolia shows certain prejudices that may affect our brains when it comes to human faces may also apply to imagined faces – backing up this idea that a face does not have to be real for higher level sensory mechanisms in visual processing to be activated.
Considering that pareidolia faces can be so varied and subtle – of all shapes and sizes and materials, unlike human faces – the brain does an impressive job of processing these visual cues so quickly. When it comes to faces, it seems that the brain risks a few false positives if it means quick assessment of faces and their expressions.
“When objects look convincingly face-like, it’s more than an interpretation: they really run your brain’s face recognition network,” says Alais.
“And that scowl, or smile; it’s your brain’s facial expression system at work. For the brain, fake or real, faces are all treated the same way.”
The research has been published in Procedures of the Royal Society B.