We often take it for granted that how we see other people’s faces matches up with what they really look like, but for a small group of people with a rare neurological disorder, their perceptions are distorted. Known as prosopometamorphopsia (PMO), for the first time, researchers have now been able to visualize how people with the condition see faces.
PMO is thought to be a particularly rare condition; only around 75 on it have been published and as a result, it’s not especially well understood. However, it’s known that those with this condition perceive facial features as distorted, though how these distortions manifest – such as differences in shape, , and position of features – can vary from person to person.
Visualizing exactly what people with PMO see can be difficult, as lead author Antônio Mello explained in a . “In other studies of the condition, patients with PMO are unable to assess how accurately a visualization of their distortions represents what they see because the visualization itself also depicts a face, so the patients will perceive distortions on it too.”
But the team at Dartmouth College came across a unique case of a 58-year-old male who only saw faces as distorted in person, seeing them normally via a photo shown on screen or paper.
Because this patient could see both distorted and real faces, it presented the researchers with an opportunity to accurately visualize what he was seeing. To do this, they took a photo of a person’s face and then, with the real person in the room, showed the photo to the patient on a computer screen and asked him to compare the differences in real-time.
This allowed the team to edit the photo on the screen to match up with the distortions that the patient was perceiving on the in-person face – and it’s not hard to see why he had been describing people’s faces as “”.
The researchers hope that their findings will help clinicians become more aware of PMO and gain a better understanding of what their patients are experiencing. In turn, this could help to reduce under or misdiagnoses. It’s often misunderstood as psychiatric, rather than – for this patient, he might’ve seen people looking like demons, but this wasn’t accompanied by any delusional beliefs, like thinking they actually were demons.
“We’ve heard from multiple people with PMO that they have been diagnosed by psychiatrists as having schizophrenia and put on anti-psychotics, when their condition is a problem with the visual system,” said senior author Brad Duchaine.
“And it’s not uncommon for people who have PMO to not tell others about their problem with face perception because they fear others will think the distortions are a sign of a psychiatric disorder,” said Duchaine. “It’s a problem that people often don’t understand.”
The study is published in .