Welcome to The Face Podcast. I'm your host, Masoud Saman. On this show, we explore the human face, not just as anatomy, but as identity, memory, and social meaning. The face is how we know each other. It's how we navigate society, and are recognized today. I wanna talk about something that most of us take completely for granted. granted. The effortless ability to recognize thousands of faces across a lifetime. By adulthood, the average person can recognize at least 5,000 faces.
Some estimates suggest even more, and yet none of us were born with that ability fully formed. So it's something that develops slowly over years. What makes faces so special that the brain seems to carve out distinct real estate for it? It? Why does the ability mature over such a prolonged trajectory even into adulthood? And what happens when it fails to explore these questions and more? I'm speaking with Marlene Behrmann. Berman.
Marlene is a cognitive neuroscientist and a professor of ophthalmology and psychology at the University of Pittsburgh. Her research has been foundational in understanding how faces are represented in the brain, how face recognition develops Why faces occupy such a privileged place.
In the human mind, in the human brain, and how this skill unfolds across developments and what its breakdown reveals about the architecture of visual cognition, because sometimes we learn more about something's working when we study its failures. Marlene, welcome. Thank you so much. You make it all sounds so exciting. It gets me fired up all over again. That's wonderful. I'm so happy that you're here. I'm so excited that you accepted my invitation. Let's start from the beginning.
How did you get into this amazingly interesting field of study? Like many people I know, I was not born to study? face recognition. In fact, I discovered it in a very circuitous trajectory. I'd initially been trained as a clinical speech pathologist and audiologist, and I worked with individuals who had communication deficits. I was especially interested in the fact that after stroke or tumors, seemed to have lost the ability to communicate a deficit known as aphasia.
And what struck me most about this is I would go and see one patient who had damage, say to area X of the brain and their language impairment, had very particular properties. And then I went to see another patient. Who also had damage to the same area, and that patient showed the same breakdown of their behavior. occurred to me that there are clear rules in the brain that govern complex behavior after damage. Behavior breaks down in these very organized and predictable ways.
So how did I get into faces? I want you to understand these rules. So I went back to do a PhD and acquire the skills to conduct research. And in the course of my graduate training, I was required to do a small side project. And I studied some patients who had lost the ability to recognize faces after brain damage. And this was. Amazing. There were so many questions. they recognize animal faces, cartoon faces?
Some of the patients don't recognize themselves in photographs or even their own family members. And so this started me down this path of trying to understand the way the brain processes faces, here I am today to talk about it with you. That's fascinating. So you had a complete 180 of your career. You were boots on the ground, clinical field, diagnosis and treatment, and then you decided to study the cause. the cause? Yep. Exactly.
It is very fascinating what you're telling me because prior to my, my, facial plastic surgery days, I was an An otolaryngologist. an otolaryngologist of course, we worked very closely with. Speech pathologist yes pathologists.
I was a cancer surgeon, head and neck cancer surgeon, so I did a lot of laryngectomies, partial laryngectomies we worked very closely and yes, I also find these topics very fascinating and without having known that about you, and perhaps you didn't know that about me, Yeah. we came to this conversation about faces.
Why are faces in your opinion, so important for us humans, I think it's pretty obvious to everybody that recognizing faces so crucial in, and this is so in every day of our lives, we use faces to identify friends. We also use faces to identify foes. And so in some sense it's critical for survival and obviously it's really important for social interactions. But is that something that we see across the species?
Do we see that with other species who have preferential processing for faces like we do? it's a great question. And actually a number of years ago, I set out specifically to address this question and did a cross species, a a phylogenetic comparison of face recognition abilities. I'll actually tell you that I don't think that the human brain or other species, brains have carved out a very selective area that. Only is able to perform face recognition. So we can come to that a bit later.
But suffice it to say that many other species use faces. Of course, other primates use faces in the way that humans use faces, but even. Chicks are born and they imprint on their parents' face. They the template of their parents' face, like in, in a newborn state. That's how important face recognition is for maternal bonding in that case. But Yeah. faces are important. And And we see that with infants. My own children.
I I they weren't so good at recognizing my face, but maybe about it took about a week. I had to smile big and make my eyes big and, and do certain things to trigger the activity perhaps of this center of recognition that after about a week, they knew when it was me versus somebody completely. Different. And they would smile in, in response. Sometimes it wasn't my face, it was the light behind my head or something like this.
And this kind of sounds like a skill, it sounds like it's something that we develop over time. It's not something that we're just born with and we we possess, and it's something perhaps that needs to be to be practiced. And what skill does one need to be able to recognize faces? So well? We talked about 5,000 distinct faces. What, What going on? How are we doing that? there? Yeah. There's no question.
I think there's consensus in the field that it takes years for humans to develop this kind of expertise in recognizing faces. We are efficient, we are. It's done rapidly effortlessly. and one of the big challenges is that in the grand scheme of different things we can see in the world, faces are all remarkably similar to each other. We've all got two eyes above a nose that's above a mouth, and so it's a challenge for the visual system.
Sometimes I think about face recognition as like a stress test. the visual system you have to make fine grained discriminations between individual faces. So it might be easy to discriminate between you and I now because I have glasses, which is just, so obvious and right upfront, dare I say. but really the ability to recognize faces is not very sophisticated at birth. So yes, infants are able to recognize.
about faces, and particularly something about their parents' faces because they see them the most, almost like the chicks imprint, babies imprint on their parents' faces. And they only, we know that they can't even see very well soon after birth. And so they only have a very rough schematic of what your face looks like. And then, as you pointed out, over decades. The system becomes increasingly sophisticated and better configured. Okay. That that, that makes sense.
That explains why I have to do these exaggerated things and show teeth and make my eyes big for, to elicit some sort of a reaction from a newborn. But what is the consequence of losing the ability to recognize faces? I'm sure if this is a skill, then perhaps. There was a possibility of losing it. it. So this is probably the scenario that kind of got me excited about studying faces is that I had this opportunity to study individuals, adults who were.
Perfectly normal in face recognition and after some kind of brain damage lost that ability almost overnight. It's extremely dramatic, and really quite hard to understand. They can see just fine. It's not like they've gone blind. They can probably even say that it's a face. They just don't know whose face it is. So this is the disorder that we refer to as prosopagnosia from the Greek meaning. Without knowledge of the face.
And what's been, what was interesting for me, what sort of caught me initially was that I didn't need to run sophisticated experiments. I didn't need to like brush up on my statistical knowledge. I just had to show these patients some pictures of their family members even. they were unable to recognize them or even photographs of themselves that they failed to recognize unless they remembered the context in which the photograph was taken. And they told really amazing stories like this.
One very astute young man told me that he would go to the grocery store with his mother and she would go down one aisle and he would go down the other aisle. And if they met up at the end of the isles, he wouldn't recognize her unless he remembered. That, for example, she was wearing a red sweater that day. So it's That's fascinating. impairment and even reflecting on it, there's something very surreal or disorienting in not being able to remember even your own family members.
Recognizing faces, it just sounds like the most basic, even though it's very complex from a neurocognitive and processing standpoint, but it sounds like how we navigate the world. And losing that ability can have enormous consequences and quality of life and how we function. do these people then clinging onto other visual cues. cues? Yes. No question about it, but also other cues like auditory cues.
So the same young man would say as soon as his mother started speaking, it was so obvious to him that was his mother. Or other cues like hairstyle, one of the patients told me that but she and her husband were professors and they went to some convocation ceremony and they said they were going to go and put on their professorial robes and they'll meet back at this pillar.
So she comes in her robes and she's standing there waiting and he is there as well, but she can't recognize him because he has changed his clothing. My goodness. It is dramatic. And how common is this? What is the incidence and prevalence of this? So this form of prosopagnosia that we've been discussing this acquired form so that it was normal and then something happened and they lost the ability they acquired. The prosopagnosia is extremely rare.
There are, however, there is, however, a second group of Prosopagnosia patients whom we've come to recognize in about the last decade who seem to be unable to recognize faces. But that's always been the case. Like they just never learned to recognize faces. So I refer to this as congenital 'cause they always say it's like lifelong. Yep. people call it developmental, In my mind, they failed to master the skill of decoding the complex arrangement of the features of the face.
It may be a little bit like, some kids struggle to learn to read, have developmental dyslexia. This may be the right hemisphere equivalent where they fail to acquire the mastery. Of recognizing faces, and that is not so uncommon. Several studies have suggested that this occurs in about two out of a hundred individuals, 2% of the population. But do you, are you suggesting that this is some sort of a skill acquisition failure versus anatomic or functional organic issue with the brain? the brain?
Yes. It's a great question. There's a lot of debate on this particular topic. Will tell you because I can. Quote, my own work here is that I am definitely of the view that there's some structural anomaly that is preventing the recognition of faces, and in fact, in a study that we did a few years ago. We mapped out the circuit that the information has to flow in the brain in order to recognize faces.
There's a whole little set of regions that all get activated together to ensure face recognition, and we showed that in these individuals. Who failed to acquire face recognition. There was like a break in the circuit. The white matter tracks between the two main nodes of the circuit were compromised. And I'm assuming this is a functional MRI study. It was a functional MRI study, and Was like a structural diffusion tensor imaging study. Let's see.
add that these individuals the more congenital version it appears to run in families. Which again suggests that there is some genetic specification for the wiring of the circuit and transmitted through the genome is some architectural failure do we possess the ability to modify the mapping we have of that face? Yeah. This it's.
It's such an important question because faces never remain the same from even, my face today and my face tomorrow will look slightly different for a whole host of possible reasons. Like I didn't sleep that well, and now my eyes are weary. What's really interesting here is that our ability to recognize faces is so robust, and this Of the challenge in understanding this, is that we can, we inva to these changes. So even if I haven't seen somebody for 15 years and they've aged 15 years.
recognize them really well. Somebody's hair might have gone white. You still recognize them, although hair's sort of something of a different category. But, maybe somebody has a beard and then, they shave the beard. You can still recognize them. we can, of course, I can recognize you if you turn your head so I don't have a full frontal image of you. No problem. I know exactly who I'm looking at. there's something phenomenally resilient about this capacity.
And that makes it all the more dramatic. When somebody can't recognize a face, One of the most common concerns patients have when they come to see me is that they wish after their aesthetic or even reconstructive surgery to remain looking like themselves. Yeah, Of course, it's a bit of a dichotomy because we're going to make some changes, yet maintaining that sense of self. And I think that kind of plays into this.
And in certain patients we trigger a very prolonged time to reconcile that change Yeah. bring it back into that sense of self. And sometimes I tell my patients, you get a haircut and you, I know you mentioned the hair is a little bit different and I want to explore that, but you get a haircut, it takes you a week to get used to it. it. And so it's quite fascinating. Yeah. I think we do, we have a very strong sense of our own face. We've learned it over time.
We've lived with this face over time and changes in, in really any aspect of the face. You have your teeth redone or whatever. It is really shift. I am, I can even imagine. Sort of patients having a crisis because there is this disjunct between their deep conceptual sense of what their face is like and also how society perceives them Yeah. that they changed face after various manipulations.
And the time it takes for a patient to feel normal about what they had done on average is two months, but it's longer in older patients and shorter in younger patients. Yeah. I think it all is our clinical correlate of this processing system. This is exactly what we're talking about. When I tell a patient, look, it's the first six to eight weeks, you're not gonna necessarily recognize yourself or the way you see yourself.
It's complex facial procedures like rhinoplasty I think they show that the brain's visual and self-referential system can gradually remap a kind of a new facial configuration itself. Yeah. So I'm pretty sure that's what happens because it's really one face, or two faces. You had one face and you've now got a slightly different face. So it's really just that particular face that now needs to be updated in your self-referential system. It also.
Reminds me that I wanted to tell you how difficult it is to try and train individuals who are proso agnostic to learn to recognize faces. So most of the sort of attempts to remedy or rehabilitate the prosopagnosia has been done in adults, and I now, I think, have an understanding that it's as hard to learn to recognize faces in adulthood as it is to acquire a second language. It's really difficult. It's a little bit like not being able to teach an old dog new tricks.
Yeah, the dog, the harder it they're harder. Yeah. Yeah. And so this is of course very frustrating for people who are impaired at face recognition. It's also very difficult for me because I wanna be able to intervene and really train this, Yeah. to be able to do this. . Individuals with congenital prosopagnosia, that's one category and. and.
It makes me actually think of congenital deafness versus those who lose their hearing later on in life or later on, or proso, noia that happens later in life. That's right. What is the psychology or psychological impact to that sense of self, to that sense of navigating the world yeah. I have. I cannot think of a single study that has probed kind of phenomenological very well. something very obvious. I think we should. Really understand what their subjective experience is really like.
Um, there are, however, a number of elaborated case studies in the literature, including the one where as Oliver Sachs the neurologist wrote The man who mistook his wife for a hat, he thought his wife's face was a hat and he tried to put it on his head, of. It turns out that's not actually how this disorder works at all. The patients almost always say it's a face. They don't mistake it for a head. They just say, I just don't know whose face it is.
And they sort of, that's the struggle for them is they might even sack and see two eyes and nose and a mouth. I just still can't get Um, so one of the individuals in the literature, in this elaborate, um, case study, lament, his ability to be the same person that he previously and of, who he was, um, that it had limited him as an individual moving forward. I can imagine.
I mean, this is fundamental to us as humans to be able to recognize at a minimum, but each other and everybody else in our society. Yeah. we kind of touched the incidents. Do we have, uh, specific numbers? several studies, maybe three, let's say were done in, one was done in Germany, for example, the incoming class of medical students. Or completed a questionnaire about whether they can recognize faces or have have ever experienced some difficulty.
Another one I think was done in India and another one, um, was done to. I think they're Australian. The, the authors, um, and all of them kind of on this magic number of about two or in the at large. That's large rare. Yeah. So, you know, when I teach, uh, an auditorium of students, chances are there is somebody in that auditorium unable to recognize Oh I imagine that it'd be an extremely rare condition, 2% is not Right. But these are all of the congenital or developmental form. Mm-hmm.
The acquired form. they must be, they're not even a hundred patients reported in the literature. And to your knowledge, are there corollaries of other pathological states, whether it be medical or psychiatric that, or even traumatic, that perhaps have triggered or exacerbated the condition? Um, I mean, definitely patients it's, even if they've had it their whole lives, um, it, it makes not all, but some patients report that it has limited their Um, be social.
One individual told us that she was agoraphobic, like she had sort of fear of going because she was so anxious that she would see somebody that she didn't recognize she'd offend them. I Okay. know one of uh, one individual with the same congenital version who, who is interestingly a vision scientist himself, he can't recognize people and he's got this technique. goes to conferences and the first thing he does when he sees or talks to somebody, if she said, I just need to tell you.
I am not going to be able to recognize your face, so I'm not being um, a social or a snob. You just need to know this is a, I have this failure, and just sort of is completely transparent about it, um, right up front. Well, I bet after saying that nobody forgets Yeah, for sure.
but more into the reverse of I guess I want to explore whether or not you have noticed associated with this condition, meaning, I don't know uh, psychiatric, uh, are these patients being recognized or, um, um, diagnosed as issues? treat it for psychiatric problems. Um. I think probably not than in the population at large, maybe a little bit more because there is associated with it for some Okay? Of course.
in the congenital individuals where there seems to be this failure in wiring up the system. There are some associated deficits, like some of the. Patients or individuals have difficulty do um, navigating, like finding their way around town, for example. Um, so there are some kind of comorbidities. Some of them definitely have difficulties reading. Reading is kind of some some of the same computational requirements as faces. There are a small number of items like the alphabet.
You have to together to make a bigger thing, just like we have eyes and nose and a mouth that you have to put together to make it into a whole face. there are developmental comorbidities. Um, and these have been well reported, but much less psychiatric than I think you might have imagined. Yeah. Yeah. interesting psychiatric d you know, disorders that has a face component like syndrome Reduplicate These are very esoteric.
Um, and you know, there's like a single case in in the literature where, um. Somebody, thinks that the, the, the, well-known face is actually calls them by a different name, all different kinds of historical and past experiences to them. sort of like the loss between the face and the memory of who that person is. So there are some of these, um, more, more psychiatric disorders.
There is sometimes a phenomenon in the human brain, Where an input is perceived as threatening, useless, or even painful, and we decide to ignore that input. Yeah. Is there a possibility that these patients acquired the skill of facial recognition, but the input was distorted or somehow not serving them, and they decided I, I'm gonna put the skill aside, Um, meaning there is a cognitive, repressive, uh, not necessarily a a neurological.
I see it in the sense that patients come in for a say, and I ask them to describe their current nose, and they cannot. Interesting. em too much pain, too much. Something they don't like and they cannot tell me if the cannot tell me how big the hump is, and it's as if it's ignored. It's as if they look at themselves and they don't see it. Yeah. It's interesting. yeah, it's a kind of like selective blindness.
These are very, very I mean to, first of all, you're dealing with a. Quite a. rare condition and very difficult to set, set up the that give you the information to really look at every detail. Right. it does mean somebody like me is not going to be out of work anytime soon. And there are going to be people coming who also will be able to tackle some of these questions. And that's how science works. I mean, we are all standing on the shoulders of giants.
We add another link to the chain and hopefully it's a meaningful one and, and, and we move forward. Marlene, when you're looking at these patients, you're looking at the studies. you're in, you have your scientist hat on, Mm-hmm. but sometimes you perhaps take it off and you say, wow, what, what in the hell Yeah, has that happened to you? And what was it about Gimme, Gimme, an Okay, an example. So, um.
I have an individual with acquired was about just be in the, summer before he was due to start college. Yeah. Um, he had trained as a paramedic and worked in an ambulance, and the ambulance screeching out one night and they had an accident and he suffered. A traumatic brain injury and became prosopagnosia. He had some other, he broke some bones. Those all seem to heal. He has this, he's now close to 50. He still is prosopagnosia.
Now, one of the odd things about this um, is that his family owns a photographic store and he works in the photographic store job. Is to check the photographs once they come off the printer. And so I said, I asked him, how is it possible that you can be doing this job? And his answer was very uh, instructive. He said it's easier for him to do it because he doesn't recognize the face. He's only looking blemishes or imperfections in the picture.
And he's really good at picking out these small little things because he can basically ignore the face. So that is like. That's That's fascinating. That's amazing to take advantage of the deficit and put it Yeah. Marlene, what haven't I asked you? asked you? Has to do with artificial intelligence. Yeah. So. These AI models are supposed to be really good at face recognition. I mean, you can even use your face a, password, uh, at the bank you know, at the ATM, et cetera. Mm-hmm. But in fact.
AI models are nowhere as good as humans are faces, for example, they fail. If you have changed your face in any very obvious way, they would not do so well with your patients after rhinoplasty or some other kind of reconstruction. And so there's There's something really sophisticated and. Almost natural about the way the human brain can compute this kind of information and it's not easily captured in an artificial neural network.
One of the common almost jokes that patients tell me after surgery is that their phone doesn't unlock anymore and they have to redo their face, uh, or face id, and that's exactly that. Well, we know the brain is plastic. We, we know that there is, um, hardwired system can keep up with a system that can self-regulate and and remap. and And go that the human brain can, uh, and so that's good. That's good. We, we will all have jobs still. We'll have jobs.
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