Prosopometamorphopsia: what is this rare disorder that distorts the perception of faces? : Current Woman Le MAG

Have you ever heard of prosopagnosia, the disorder that Brad Pitt said he had? This term comes from the Greek words “prosopon”, which means “face”, and “gnôsis”, which means “recognition”. Prosopagnosia prevents those who suffer from it from recognizing faces. And this is not the only disorder impacting the way we see faces. Coming from the Greek words “prosopo” (“face”) and “metamorphopsia,” which refers to visual distortions, prosopometamorphopsia (PMO) is a disorder that distorts the perception of faces. In an article published in the scientific journal The Lancetresearchers from Dartmouth University (United States), were interested in this rare pathology.

What is prosopometamorphopsia?

Prosopometamorphopsia can take different forms, as Brad Duchaine, professor of psychological and brain sciences and principal investigator of the Social Perception Lab at Dartmouth, explains on his website dedicated to this disorder.

Visual distortion can thus affect the shape, size, color and position of facial features and can last for days, weeks or even years. It is stated that full-face prosopometamorphopsia (“full-face PMO”) and hemi-prosopometamorphopsia (“hemi-PMO”) are the two most common subtypes of this disorder.

While the causes of prosopometamorphopsia are unclear, Brad Duchaine explains on his site that abnormalities in the occipital and temporal lobes, the regions of the brain used to process faces, may come into play.

Prosopometamorphopsia: a visual distortion that distorts the perception of faces

As part of the work published in The Lancet, the researchers were interested in the specific case of a patient suffering from prosopometamorphopsia. It was a 58-year-old man who told scientists that the visual distortion he suffered gave people a face he described as “demonic”: their features were very stretched and they had deep furrows on their foreheads. , cheeks and chin. However, this disorder did not prevent him from recognizing people and did not impact his perception of faces in photos, nor that of the objects around him. Moreover, “the distortions were not accompanied by delusional beliefs about the identities of the people he encountered, such as his family or friends”can we read in the publication of The Lancet.

The researchers therefore tried to understand precisely what this patient saw on the faces of the people around him. To do this, a person stood in front of him, and while he looked at them, the researchers also showed him a photo of the same person’s face. The patient could thus comment on what he saw on the face of the person in front of him, while the researchers modified the photo of this person’s face using computer software by following his comments.

Better understand the prosopometamorphopsia to improve diagnosis

“Thanks to this process, we were able to visualize the patient’s perception of facial distortions in real time”, explained in a press release Antônio Mello, doctoral student in the department of psychological and brain sciences at Dartmouth who participated in the study. This is the first work to provide precise images of the visual distortions experienced by people with prosopometamorphopsia.

Researchers hope to raise awareness among the general public about this disorder, which is poorly understood and therefore poorly diagnosed. “Many people suffering from PMO have told us that psychiatrists have diagnosed them with schizophrenia and had put them on antipsychotics, even though it was a problem of the visual system”, said Brad Duchaine, lead author of the study, in a press release.

Sources:

• Visualizing facial distortions in prosopometamorphopsia – The Lancet, March 2024
• If faces look like demons, you could have this extraordinary condition – Dartmouth University (press release)
• Site of Brad Duchaine, professor of psychological and brain sciences and principal investigator of the Social Perception Lab at Dartmouth, dedicated to prosopometamorphopsia.