Written by Robin Kramer, University of Lincoln
LINCOLN, UK, March 31 (The Conversation) If you’ve ever seen portraits painted by Pablo Picasso or Francis Bacon, you’ll know that both suffered from disorders that affected the way their faces were seen. You may not be surprised to hear that this is a possibility.
Prosopagnosia (PMO) is a condition in which faces appear distorted and sometimes demonic. In most cases, these distortions change not only the image of your face, but also the way it looks in real life. This makes it difficult to assess the accuracy of the illustration in depicting what the patient is seeing, as the illustration itself appears distorted.
However, cases reported in recent studies have given researchers new insights into PMO. Unlike most other cases, a 58-year-old man (referred to as VS) perceived an undistorted facial image. Unfortunately, for the past 31 months, when he looked at people in person, every face seemed stretched and “demonic” to him.
Not to be confused with prosopagnosia (low ability to recognize faces but no visual distortions), PMO is thought to be extremely rare, and people with PMO experience a droopy face. perceived as stretched, stretched, out of place, or smaller or larger than normal. These distortions may be applied to the entire face, to only one side, or to specific areas such as the nose or mouth.
What is the cause of myopic metamorphopia?
In contrast to prosopagnosia, which can be either acquired (e.g. due to injury) or developmental (present from birth), PMO appears to occur only as a result of the former. A 2021 study by Dutch researchers looked at 81 cases of PMO. Causes include cerebral infarction (impaired blood flow to part of the brain), hemorrhagic stroke (bleeding into the brain), surgical complications, head trauma, and brain tumors. However, in 24% of cases, no structural abnormalities were found in the brain. Instead, PMO was associated with other diagnoses such as epilepsy, migraine, and schizophrenia.
Reassuringly, in most cases, people with PMO seem to get better. This may be complete or partial recovery, and may be the result of treatment that addresses the underlying cause (such as antiepileptic drugs for epilepsy or surgery to remove a brain tumor). However, some people seem to recover without any intervention. Recovery time can vary from hours to years, but the typical recovery period is often days to weeks.
Does it affect facial recognition?
Despite the fact that people with PMO sometimes experience severe facial distortions, their ability to recognize faces rarely seems to be affected. However, patients may simply rely on other cues to aid recognition, such as a person’s voice or clothing. For some people, the distortion only appears seconds or minutes after seeing a person’s face, giving them time to identify the person first. Researchers also tried to model how distortions like PMO affect facial recognition. They found that the distance between the observer and the face played an important role in how accurately participants recognized the face.
A recent study by researchers in New Hampshire, US, focused on a case in a man known as VS. He had lesions in the hippocampus (an area of the brain primarily associated with memory) but had no other notable medical problems.
Although VS saw people’s faces as elongated and with deep grooves (making them look, in his words, “diabolical”), the image of the face did not affect him. The researchers presented his VS with a face on a computer screen that was identical to the face he faced face-to-face. The researchers then used image editing software to modify each photo to match VS’s description while listening to VS’s real-time feedback.
This is the first time researchers have been able to create a photorealistic visualization of this type of distortion, allowing them to depict how people with PMO view those around them.
VS distortions also appear to be affected by color, so the researchers investigated what happens when VS views faces through colored plastic filters. They found that the green filter decreased and the red filter increased distortion compared to the unfiltered baseline. These results showed that the color filter attached to the glasses could reduce facial distortion in his PMO, and that its color could affect the recognition of facial shape in general.
What can we learn?
As researchers continue to accumulate knowledge about PMOs, more insights into how the public faces the process are likely to emerge. Among the many unanswered questions are some about how and where faces are represented in the human brain. I also discuss the specific nature of PMO distortions, what they tell us, and why distortions seem to resolve themselves in some cases but not in others. We still have much to learn. For now, PMO is a fascinating and alarming symptom that can potentially tell us a lot about human facial recognition.
Given that PMO is extremely rare and there is still a lot to learn about it, if you think you may be suffering from PMO, consider contacting me (the author of this article) please. Remember, people with PMOs don’t actually think the world is distorted, but rather that their visions are different in some way. (conversation)
