Chapter 1: What is the main topic discussed in this episode?
When your therapist won't take your calls anymore, there's always The Last Show with David Cooper. Have you ever heard of someone that sees all faces distorted? In some cases, faces look like demons. Well, it's a rare brain condition where if you have it, perfectly normal faces suddenly appear twisted, drooping, strange, even grotesque sometimes.
The people you see are real, but the distortion is happening entirely inside your own brain. Tonight, what that glitch reveals about how we actually see each other. We're going to discuss that with psychological and brain sciences professor at Dartmouth College, Brad Duchesne. Brad, welcome to the show. Thanks for having me, David.
This sounds totally wild to me and might to most people, the idea that you could look at a face and not see what everyone else is seeing. Tell me more about it.
Chapter 2: What is prosopometamorphopsia and how does it affect perception of faces?
How often does this happen? It's quite rare. And it is wild. I mean, I've been studying this condition for years, and yet I'm still amazed by the stories we hear from people. So these are individuals who, when they look at a face, they will see some aspect of that face distorted. And sometimes it's the feature's shape. Sometimes it's the position of the features on the face.
Other times it might be the texture of the face or even the color of the skin. To me, this sounds like someone is hallucinating, but the thing that struck me is that these people aren't hallucinating. This is just like a daily experience. The brain just seems to scramble the face. Why is the brain doing this? Why is our brain vulnerable to do something like this in rare cases?
Yeah, so we've got a network of what we call face-selective areas in the brain, and when there's a glitch within this network, then you can get face distortions. Faces seem to have their own dedicated circuitry in the brain. Is my understanding correct? There's a portion of our brain that is just dedicated to processing other people's faces. Tell me about it. Yeah, that's exactly right.
So if I were to put you into an fMRI scanner and we were measuring the activity in your brain, we showed you faces, we showed you objects, places, things like that, we would find something like 12 to 14 areas within your brain that show really strong responses to faces and little or no response to other categories.
And then people go in and will record from neurons within those areas and they find that the neurons within those patches respond to faces and faces only. And so this is a
network that's specialized for for processing faces and so we use this network to figure out who we're seeing around us how they're feeling what they're interested in terms of what they're attending and all the other information that we get from the face now at the risk of taking too far a tangent here is this why when i look at like an electrical plug i can see a smiling face or i look at like a coat hanger i seem to recognize smiley faces everywhere is that portion of my brain lighting up when i do that
That's exactly right. Yeah. So the face network is pretty liberal in what it'll allow into the system. So as long as there's some minimal configuration of stimuli that indicate that something's a face, what will turn on that network? Okay, back to the rare brain condition. Can you say the name of it for me? Because at the commercial break, I was trying to pronounce it and I definitely failed.
Sure. So it's prosopometamorphopsia. Prosopo meaning face and then metamorphopsia meaning distortion. And so it's face distortions is what we're talking about. And we always call it PMO because prosopometamorphopsia is such a mouthful. It certainly is. OK, PMO, what are some of the distortions that people report? I think the sensational headline is some people see a sort of demonized face.
But what would people with PMO report? What would be some examples? Sure. I mean, we could first we could lead off talking about the guy who was said to have demon face syndrome. So this is a gentleman that we work with. who lives in the US. And every single face that he sees in daily life, the features are stretched back. So the mouth is pulled back, the nose, the eyes, even the ears.
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Chapter 3: Why do some people perceive faces as distorted while others do not?
And this is what he sees on every single face that he encounters in daily life, whether it's, say, a frontal view of the face. If somebody turns their face in profile, he's still seeing those same distortions. Would that have any negative effects or is it just people would only realize it when they compare how they see faces to others and they would just live a normal life?
Well, so VS used to see faces. So we tend to use initials when we describe the people we work with. And VS used to see faces perfectly normally. Then one day he woke up and was seeing these faces. And he thought maybe he'd died and gone to hell. He didn't know what was going on with these people. scary looking faces that he was experiencing.
Now, what you mentioned probably is true for some people. There probably are some people out there who see face distortions their entire life. And so they just think that's how faces look. It's sort of like a synesthesia. That's when your senses blend and you see music and you hear colors and stuff.
And some people who have it don't even realize they have it until they get asked about their experience. Are there any other interesting patient examples other than VS? Sure, yeah. So one of the most interesting types of PMO is what's called hemipmo. And in hemipmo, it's just one half of the face that's distorted. And so we work with a South African man.
When he looks at a face, the right side, from his perspective, distorts so that he sees some discoloration on the side, the cheek goes out, the right eye shifts down and to the outside, and then there's slight pulling on the mouth and on the nose. And he'll see this on every face that he encounters, including his own face, of course, when he looks in the mirror.
That sounds so bizarrely specific. Just half a face, it's always the same half, I imagine. Does that tell us anything about how the brain constructs a face from, I don't know, pieces or parts or halves? No, it absolutely does. And it told us something that we didn't realize before.
So what it tells us is the two halves of the face, even though when we look at them, they feel like we're looking at this seamless representation, the two halves are actually represented separately from one another. And what we know is that actually what you're seeing on the right side of the face is processed in the left hemisphere. The left side is processed in the right hemisphere.
And only later are they brought together in the right hemisphere. When we look at our own faces in a mirror, it's like opposite of what everyone else sees. If you look at your face in a true mirror that shows you what other people would see, a lot of people like don't recognize themselves or there's this uncanny feeling.
Could this be the reason we're so used to processing our face in this opposite way? Well, yeah, we're used to that typical way that we see it in the mirror. And so I think it's not that people don't recognize themselves, but it's more that something looks off. You're like, that's me, but not quite me. Yeah, I'm used to the freckle on the other side kind of thing.
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Chapter 4: How does the brain's circuitry affect our perception of faces?
That definitely plays into the stereotype of demonizing things. Through red, it looks more kind of distorted versus green. That is fascinating, and I would love to know the reason why, but I guess that's for future research. Yeah, we're working on that.
Now, stepping back from this disorder, what does looking at a condition like this teach us about something most of us take for granted, this simple act of recognizing another human being's face? Yeah, so there are a number of theoretical questions that we can address with people with PMO. We mentioned earlier about this representation of the two halves of the face being separate.
That's something we learned from PMO. Another thing we're able to look at with PMO is the specificity of visual recognition. And so in some of the individuals we work with, for example, V.S., The only thing that he sees that's distorted is the face. And so that provides really good evidence that this face network we've talked about is specialized for processing faces and faces only.
And so we show people thousands of images and we see, do they see distortions to anything other than a face? And what we find in some individuals, it's really restricted just to faces. And that tells us something important about the organization of visual recognition that it's broken down by categories. Brad, this conversation has been so cool.
Thanks for illuminating, I don't know, the PMO, how we recognize faces, all of it. I appreciate you coming on the show. Okay, thanks for having me, David. Brad Duchesne is a psychological and brain sciences professor at Dartmouth College.
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