Man sees cat features in human faces after brain surgery

Karl, a 28-year-old man living in the northeastern United States, experiences a rare visual phenomenon in which features of his grey tabby cat, Luna, appear superimposed on the faces of people he encounters. This condition, documented in a report published in the journal Cortex, involves a form of palinopsia that leads to face distortions known as prosopometamorphopsia, or PMO.

Karl’s symptoms began two years ago following a surgical procedure in which part of his right temporal lobe was removed. The surgery was necessary to treat an arteriovenous malformation, a tangled mass of blood vessels between arteries and veins that can lead to a brain bleed if left untreated.

In the mornings, Karl’s cat is often the first face he sees. On some days, this initial exposure to Luna’s face triggers a persistent visual effect where he sees the cat’s almond-shaped eye sockets, enlarged pupils, and stripes on the human faces he encounters later in the day. This transfer of features occurs whether he is interacting with people in person or viewing them online. Conversely, if Karl sees a human face at the start of his day instead of his cat, he may perceive that person’s pupils and eye shape on other people’s faces, and even on his own cat’s face.

Lead author Brad Duchaine, a professor and chair of psychological and brain sciences at Dartmouth College, notes that this case demonstrates that individual features can be pulled from memory and influence ongoing perception. Duchaine’s lab studies PMO and has heard from more than 250 people who experience face distortions. He points out that some of these individuals have been misdiagnosed with psychiatric problems and placed on antipsychotics, when in fact they are experiencing visual processing issues rather than mental health disorders.

Duchaine was reminded of a 1986 study published in Cortex that reported on a woman who, after a stroke, saw a poodle on a passenger’s lap and subsequently perceived the poodle’s face on every passenger on the bus. While both cases involve the transfer of facial features, Karl’s experience differs in that only components of faces are transferred rather than an entire face.

To illustrate visually what Karl was experiencing, Duchaine prepared a line-drawn sketch and fed it into a large language model to make the image more photo-realistic. He then shared the image with Karl, and the two went back and forth modifying a set of images that are included in the report. Duchaine explains that AI provides researchers with the ability to generate more accurate visualizations of what people are experiencing when they have distorted visual perceptions. This collaborative process allows the patient to take part in creating the visualizations, which can help researchers better understand and potentially control the condition.

The use of AI in this context is also helpful for patients who want to convey to their healthcare professionals, friends, and family what faces look like to them.

Antônio Mello, a PhD student in the Department of Psychological and Brain Sciences, and Jennifer Nosker, a neuropsychologist at Brigham and Women’s Hospital, also contributed to the study.

Subject of Research: After brain surgery, man sees cat's eyes in human faces

Article Title: After brain surgery, man sees cat's eyes in human faces

Article References: After brain surgery, man sees cat's eyes in human faces. Original publication (Bibliographic details unavailable.)

Image Credits: AI Generated

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Keywords: brain, surgery, sees, cat's, eyes, human, faces, scientific research