Scientists have discovered why people with a rare visual syndrome see illusions more often than others

This phenomenon is called pareidolia, an illusion in which the brain recognises a face where none actually exists. For most people, this is a harmless perceptual effect.

However, a new study published in Perception has found: people with visual noise syndrome have these illusions much more often and more severely than others. This is reported by The Conversation.

What is visual noise syndrome?

It is a rare neurological disorder in which a person constantly sees flickering dots or "noise" throughout the entire field of vision - as if the TV screen is out of tune. These visual disturbances do not disappear even in complete darkness.

The cause of the syndrome is not fully understood, but evidence suggests that the visual cortex is overactive - the part of the brain that processes visual information. Due to increased neuronal activity, there is constant "visual noise" in perception.

Associated symptoms can include migraines, photosensitivity, afterimages and visual traces. All of this makes perceiving the world more stressful and tiring.

The course of the experiment

To find out how this affects perception, the researchers conducted an online experiment involving more than 250 people. Participants first completed a survey to determine if they had signs of visual noise syndrome. They then rated 320 images of everyday objects (e.g. tree trunks, teacups, building facades), giving a score from 0 to 100 - how clearly a face was seen in them.

As a result, 132 people showed signs of the syndrome, while 104 were part of an age-matched control group. The researchers also recorded the presence of migraine to analyse the impact of the combination of factors.

What the results showed

Participants with visual noise syndrome were significantly more likely and more likely to see faces where there were none than participants without it. The effect was particularly pronounced in those with both visual noise and migraine.

Although both groups generally agreed on which images most resembled faces, scores were significantly higher in the group with the syndrome. This suggests that their illusions were more pronounced.

The scientists explain this by saying that in visual noise syndrome, the brain is more likely to produce false "guesses" and the back-checking of such signals works worse - so even random patterns can seem meaningful.

Why migraine amplifies the effect

Visual noise syndrome is often combined with migraines, and both problems are related to neuronal hypersensitivity to visual stimuli. When the two overlap, the brain's susceptibility to illusory images becomes even greater.

This feature can help in diagnosis: a simple pareidolia test can be a tool to detect the syndrome, especially in children or people who have difficulty describing their sensations.

Why it's important

Pareidolia is not a disorder, but a reflection of how we are evolutionarily trained to recognise faces. However, in people with visual noise syndrome, this mechanism is overdeveloped - the brain sees faces literally everywhere.

The study shows that perception is not just a "mirror of reality" but a complex interpretation of signals by the brain. People with visual noise syndrome don't make up what they see - their neurons actually process visual information differently.

"By understanding why some people see too much, we will better understand how our vision works in general," emphasises study author Jessica Taubert.