When faces turn into nightmares

If you’ve seen portraits painted by Pablo Picasso or Francis Bacon, you might not be surprised to learn that both men might suffer from a disorder that affects the perception of faces.

Prosopometamorphopsia (PMO) is a condition in which faces appear distorted, and sometimes even demonic. In most cases, these distortions change the appearance of images of faces, as well as those seen in person. This makes it difficult for patients to assess the accuracy of illustrations depicting what they see, because the illustration itself will appear distorted.

However, a case described in a recent study has given researchers new insight into PMO. Unlike most other cases, the 58-year-old man (referred to as VS) perceived images of faces without distortion. Unfortunately, when he saw people in person over the past 31 months, every face seemed tense and “demonic.”

Not to be confused with prosopagnosia (poor recognition of faces but without visual distortions), PMO is considered extremely rare and people with it perceive faces as drooping, stretched, displaced, or smaller or larger than normal. . These distortions can apply to the entire face, to just one side, or even limited to specific features like the nose and mouth.

What are the causes of prosopometamorphopsia?

Unlike prosopagnosia, which can be either acquired (through an injury for example) or developmental (present from birth), PMO appears to be only the result of the former. A 2021 study by researchers in the Netherlands looked at 81 cases of PMO. Causes included cerebral infarction (disruption of blood flow to part of the brain), hemorrhagic stroke (bleeding in the brain), surgical complications, head trauma and brain tumor. However, in 24% of cases, there appeared to be no structural abnormalities in the brain. Instead, PMO was associated with other diagnoses like epilepsy, migraine, and schizophrenia.

It is reassuring that in the majority of cases, people with PMO appear to recover from their condition. This may be a complete or partial cure, sometimes resulting from treatments that address the underlying cause (such as anti-epileptic medications for epilepsy or surgery to remove a brain tumor). However, some people seem to recover without any intervention. Recovery time varies from a few hours to several years, but the typical recovery period often extends from a few days to several weeks.

Is facial recognition affected?

Despite the fact that people with PMO sometimes experience profound facial distortions, their ability to recognize faces rarely appears to be affected. However, patients may simply rely on other cues to aid recognition, such as the person’s voice or clothing. For some people, the distortions only appear after a few seconds or minutes after seeing a person’s face, giving them time to identify the person first. The researchers also attempted to model how PMO-type distortions might affect facial recognition. They found that the distance between the viewer and the face played an important role in how accurately the faces were recognized by the participants.

A recent study by researchers in New Hampshire, USA, focused on the case of a man known as VS. He had damage to his hippocampus (a region of the brain primarily associated with memory) but no other notable medical problems.

Even though VS viewed people’s faces as stretched and with deep grooves (appearing in his words as “demonic”), facial images were unaffected for him. The researchers presented VS with faces in person and the same faces on a computer screen. Then the researchers used image-editing software to edit each photo to match VS’s descriptions, listening to his comments in real time.

This was the first time researchers were able to create photorealistic visualizations of these types of distortions, providing a representation of how people with PMO may see those around them.

VS’s distortions also seemed to be affected by color. So the researchers studied what happened when VS looked at faces through colored plastic filters. They found that green filters decreased and red filters intensified the distortions compared to the no-filter baseline. These results showed that color filters worn in glasses could reduce facial distortions in PMO and that color could affect how we perceive facial shape in general.

What can we learn?

As researchers continue to learn more about PMO, it is likely that more information will be revealed about how the processes in the general population experience it. Among the many questions that remain unanswered, some concern how and where faces are represented in the human brain. We also still have much to learn about the specific nature of PMO distortions, what they can tell us, and why they seem to resolve themselves in some cases but not in others. For now, PMO is both a fascinating and worrying condition, one that could potentially teach us a lot about human face perception.

Since PMO is so rare and we still have so much to learn about it, consider contacting me (the author of this article) if you think you may be suffering from it. Remember, those who work in the Prime Minister’s Office don’t really think the world is distorted, but rather realize that their view is different in some way.When faces turn into nightmaresWhen faces turn into nightmares

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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