Somewhere in the northeastern United States, a 28-year-old man named Karl wakes each morning to the face of his grey tabby, Luna, and in the hours that follow he begins to find her features scattered across the faces of strangers and friends alike. Two years earlier, surgery to remove part of his right temporal lobe, a region central to recognizing faces, had altered the way his memory and perception now interact. His experience, documented in the journal Cortex by researchers at Dartmouth, reminds us how much of what we see is shaped by what we have already seen. It also opens a quiet questio
After Brain Surgery, One Man Sees His Cat's Eyes in Human Faces
A 28-year-old man lives with persistent face distortions after surgery to remove part of his brain, and some similarly affected people have been wrongly given antipsychotics.
Only components of faces are transferred rather than an entire face.
Mark
So what is actually happening to Karl each morning?
Mimi
Whatever face he sees first seems to lend its features to faces he sees afterward. If it's Luna, he sees her eye shape, pupils and stripes on people.
Mark
And it works in reverse?
Mimi
Yes. A person's pupils and eye shape can show up on other people and even on Luna.
Luke
Before we go further: this is one patient, correct? What can that carry?
Mimi
It's a single case report, so it shows something is possible, not how common it is. Duchaine's claim is that features can be pulled from memory and shape perception.
Mark
Why does the surgery matter here?
Mimi
Part of his right temporal lobe was removed two years ago, and that region is critical for face processing. The report ties his symptoms to that period.
Luke
Does it say the surgery caused it?
Mimi
The source gives the timing and the region's role. It doesn't spell out a proven mechanism, so I'd keep it at that.
Mark
What about the AI images?
Mimi
Duchaine sketched, an AI model made it photorealistic, and Karl helped refine it. Those images are in the report.
Luke
Worth noting they're Karl's reported experience rendered by a tool, not a direct picture of his perception.
Mimi
Fair. Still, the lab says it helps research and helps patients explain what they see.
Mark
And the antipsychotics?
Mimi
The lab says some of the 250-plus people it has heard from were told they had psychiatric problems and some were medicated, when it was a visual issue. That comes from Duchaine, not a tally of cases.
O Pulso
- A man's everyday view of faces has been quietly warped, with his cat's almond eyes, enlarged pupils, and stripes appearing on the people around him.
- The distortions began after surgery removed part of his brain's face-processing region, leaving him with a condition that echoes an older case from 1986.
- Dartmouth researchers are using AI-enhanced images, shaped together with Karl, to show exactly what he sees and to help doctors understand it.
- More than 250 people with similar face distortions have come forward, and some were wrongly treated with antipsychotics, a misstep the team hopes to correct.
Somewhere in the northeastern United States, a 28-year-old man named Karl wakes each morning to the face of his grey tabby, Luna, and in the hours that follow he begins to find her features scattered across the faces of strangers and friends alike. Two years earlier, surgery to remove part of his right temporal lobe, a region central to recognizing faces, had altered the way his memory and perception now interact. His experience, documented in the journal Cortex by researchers at Dartmouth, reminds us how much of what we see is shaped by what we have already seen. It also opens a quiet question about how far the mind can carry its past into the present.
Karl is 28 and lives in the northeastern United States with a grey tabby named Luna, whose face is usually the first he sees each morning. Later in the day, her features begin to appear on the people he meets, in person and online: almond-shaped eye sockets, enlarged pupils, stripes. Sometimes the effect runs the other way, and he sees a person's features on his cat.
The case, published in the journal Cortex, describes a form of palinopsia in which earlier visual impressions persist and distort what comes after. Karl's version affects faces, a condition called prosopometamorphopsia. It began two years ago, after surgeons removed part of his right temporal lobe to treat an arteriovenous malformation, a dangerous tangle of blood vessels that could cause a brain bleed. That region plays a critical role in recognizing faces.
Brad Duchaine, the report's lead author and head of the Social Perception Lab at Dartmouth, sees in Karl's case proof that individual features can be drawn from memory and imposed on what we perceive in the moment. To make Karl's experience visible, Duchaine turned a sketch into photorealistic images with a large language model, then refined them with Karl, one exchange at a time. He believes such images can help researchers study the problem, guide treatment, and help patients explain their experience to the people around them.
The lab has heard from more than 250 people with face distortions, and some were told they had a psychiatric illness when their condition was visual. The team plans to keep working with Karl.
Karl is 28 and lives in the northeastern United States. He has a grey tabby named Luna, and most mornings her face is the first one he sees. On some days after that, he starts to see her features on the people around him: almond-shaped eye sockets, enlarged pupils, stripes. They show up on faces he meets in person and on faces he sees online.
The effect also runs the other way. If the first face of his day is a person's rather than Luna's, he may see that person's pupils and eye shape on other people, and even on his cat.
The case is documented in a report in the journal Cortex. Karl has a form of palinopsia, in which something seen earlier persists or reappears in later perception. In his case it produces distortions of faces, a condition called prosopometamorphopsia, or PMO.
His recurrent palinopsia began two years ago. Part of his right temporal lobe had to be removed because of an arteriovenous malformation, a tangle of blood vessels linking arteries and veins that can cause a brain bleed if left untreated. The right temporal lobe plays a critical role in face processing.
Brad Duchaine, the report's lead author, is a professor and chair of psychological and brain sciences at Dartmouth and principal investigator of its Social Perception Lab. He says the case shows that individual features can be pulled from memory and influence what we perceive in the moment. It also echoes an older report. A 1986 study in Cortex described a woman on a bus who saw a poodle on a passenger's lap and then saw the poodle's face on every passenger. She had had a stroke nine months earlier. The difference with Karl is that only components of a face transfer, not an entire face.
To show what Karl sees, Duchaine made a line-drawn sketch and fed it into a large language model to make it more photorealistic. He shared the result with Karl, and the two went back and forth, modifying a set of images that appear in the report. Duchaine says AI lets researchers produce more accurate visualizations of distorted perception, and that knowing what a person experiences makes it easier to study the problem and look for ways to control it. Patients can also take part in making the images, and can use them to show doctors, friends and family what faces look like to them.
The research team plans to keep working with Karl.
Duchaine's lab studies PMO and has heard from more than 250 people who experience face distortions. Some of them, he says, were told they had a psychiatric problem and in some cases were put on antipsychotics, when what they had were visual problems. The lab maintains a PMO website with more information on face-processing distortions. Antônio Mello Guarini, a PhD student in the department, and Jennifer Nosker, a neuropsychologist at Brigham and Women's Hospital, also contributed to the study.
Citações Notáveis
AI provides researchers with the ability to generate more accurate visualizations of what people are experiencing when they have distorted visual perceptions.— Brad Duchaine, Dartmouth
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