Eyes of the Moon: after the operation, the man began to see faces differently

Carl, a 28-year-old resident of the United States, developed visual distortions after brain surgery. On some days, he saw the eyes of his cat on people's faces, and the eyes of a familiar person on the animal's face. About how Karl's perception of faces changed and why scientists recreated what they saw with the help of AI, see the Izvestia article.

Whose face did Carl see first

Carl often sees the Moon, his gray tabby cat, first thing in the morning. Sometimes during the day he begins to notice her features in people. He sees almond-shaped eye contours, large pupils and stripes around the eyes. This happens both in person and when a man looks at faces on the Internet.

If Carl sees a person's face first in the morning, he may see the same eye shape and pupil size in other people or in the Moon. In one of the described episodes, he recognized the eyes of a familiar woman in the eyes of a cat. Such distortions usually last for several hours, and sometimes persist all day.

According to Karl, a face with someone else's features looks whole at the same time. When the viewing angle or distance to the interlocutor changes, the shape and size of the transferred details change along with the rest of the face. A man can find out who the eyes belong to, even when he sees them in another person.

What happened after the operation

About two years earlier, Karl had had part of his right temporal lobe removed due to an arteriovenous malformation. This is the name of an abnormal connection of arteries and veins, which can lead to hemorrhage. Repeated visual distortions appeared after the operation.

Karl's case combines two phenomena. In palinopsia, the visual image persists or returns after the person stops looking at the object that caused it. Prosopometamorphopsy is called the distortion of faces. With this disorder, the size of the eyes, the position of the mouth, or the proportions of one half of the face may change. Karl's previously seen image manifested itself in the features of the face he was looking at at the moment.

The right temporal lobe is involved in processing faces, and perception itself depends on the work of several brain regions. In a review of 81 clinical cases published in Cortex in 2021, researchers found that different types of distortions are associated with damage to different parts of this network. For example, with distortions of both halves of the face, the damage more often affected the right occipital region or occipital areas on both sides.

Why did scientists remember the poodle on the bus

In 1986, Cortex published the story of a woman who, nine months after her stroke, saw a poodle on a passenger's lap on a bus. When she shifted her gaze, instead of the faces of all the passengers, she began to see the face of the same dog. The effect persisted for about half an hour after the woman got off the bus.

In that case, the whole face changed. Carl recognized individual details, especially the eye area. This observation suggested to the researchers that visual memory can store the features of a familiar face individually and use them when perceiving another face.

How the patient helped to recreate what he saw

In 2024, researchers from Duchaine's team described in The Lancet a 58-year-old patient whose faces were distorted in person, but looked familiar on the screen. The scientists showed him a photo of the man sitting in front of him, and changed the picture in the photo editor at his prompts. This way, the patient could immediately compare the result with what he saw.

In Karl's case, the starting point was his story and sketch. Two illustrations were made using ChatGPT 5.5. One showed the Moon with the eyes of a familiar woman, the other showed a human face with feline features. Carl clarified the details, and made some of the edits himself. The illustrations convey how he remembered these episodes.

According to him, the illustrations help to explain to doctors and relatives how a person sees others. More than 250 people have already contacted the scientist's laboratory, who noticed facial distortions. Duchane said that some of the complaints were considered a manifestation of a mental disorder and in some cases antipsychotics were prescribed. The team plans to continue working with Karl.