Why do some people notice "faces" in clouds, trees, and building facades while others do not? An international team of scientists found that people with visual snow syndrome, a rare neurological disorder that causes constant "graining" in front of the eyes, experience such illusions significantly more often and more intensely. "The Conversation" reports on this discovery.
Visual snow syndrome manifests as constantly flashing dots that resemble static light on a TV screen. These points are preserved even in the dark. Patients also often complain of photophobia, "afterimages" and migraines.
The cause is thought to be overstimulation of the visual cortex, the part of the brain responsible for processing visual information. Neurons in this area are overactive, literally "overloading" perception with noise.
To understand how this affects perception, researchers invited more than 250 volunteers to take an online test. Participants were shown 320 images, ranging from tree bark to coffee cups, and asked to rate on a scale of 0 to 100 how clearly they saw the face in each image. One hundred and thirty-two people reported symptoms of visual snow, while 104 formed the control group. The researchers also noted which participants suffered from migraines.
The results were clear. people with visual snow were significantly more likely to "recognize" faces in all images. And participants with both the syndrome and migraine had the highest scores.
Seeing faces in random patterns is normal and is known as pareidolia. From an evolutionary perspective, the human brain is "programmed" to quickly recognize faces, an important social signal.
In people with visual snow, this ability seems to be extremely enhanced; the brain "connects the dots" where none exist. This confirms that the syndrome is not just a visual disorder, but a change in the activity of the entire perception system.
The authors believe that facial pattern recognition tests may be a suitable method for diagnosing visual snow syndrome. They are quick, simple and suitable even for children or patients who have difficulty describing their feelings.
Translation courtesy of Euromedia24.com
