Speaker 1: Brains love to look at faces, But why and what
Speaker 1: is face blindness? And what is a super recognizer? Why
Speaker 1: does your electrical plug sometimes look to you like a
Speaker 1: little face? Did aliens plant a signal for us on Mars?
Speaker 1: Or are we looking at a quirk of our own brains?
Speaker 1: What does any of this have to do with the
Speaker 1: neurologist Oliver Sachs and his inability to recognize most of
Speaker 1: the people in his life, or looking at a magazine
Speaker 1: upside down? Or what the mistakes in computerized face recognition technology?
Speaker 1: Tell us Welcome to Inner Cosmos with me David Eagleman.
Speaker 1: I'm a neuroscientist and an author at Stanford, and in
Speaker 1: these episodes we dive deeply into our three pound universe
Speaker 1: to understand some of the most surprising aspects of our lives.
Speaker 1: Today's episode is about faces. Now, let's say I posed
Speaker 1: the question to you, how does the brain recognize faces?
Speaker 1: You may reasonably think, why is that even a question?
Speaker 1: Recognizing people's faces isn't really that hard, But think about
Speaker 1: how similar faces are to one another. They're insanely similar.
Speaker 1: You have two eyes, nose, mouth, chin, ears, everyone's face
Speaker 1: looks pretty much the same people's faces are pretty much
Speaker 1: very tiny variations on a theme. The only reason you
Speaker 1: are able to distinguish faces, literally thousands of faces from
Speaker 1: one another, is because your brain devotes an enormous amount
Speaker 1: of circuitry to it. It puts so much effort in
Speaker 1: that it feels effortless to you. And we have all
Speaker 1: this circuitry because face recognition is extremely salient. It's how
Speaker 1: we recognize this package of identity from this other. Oh
Speaker 1: that's my mother, that's my neighbor, that's my wife. There's
Speaker 1: Tom Cruise and his face is similar but different from
Speaker 1: Dwayne Johnson, and that's different from Joe Biden. It's massively
Speaker 1: important for us as a social species to keep track
Speaker 1: of identities. Your brain wants to know who it is
Speaker 1: and everything that entails, like is that a friend or
Speaker 1: an enemy? What are the risks and opportunities here? And
Speaker 1: the answer to that is massively different. If you're looking
Speaker 1: at the face of Ted Bundy versus your best pal,
Speaker 1: and keep in mind that to a space alien and
Speaker 1: these faces would be essentially indistinguishable. Now, when you're trying
Speaker 1: to distinguish faces, there are lots of other cues like
Speaker 1: hairline and hairstyle and height, and details of their skin
Speaker 1: from color to smoothness, and even cues like how they
Speaker 1: walk and their clothing choice. And context also plays a
Speaker 1: large role. You've probably experienced some time when you saw
Speaker 1: somebody you know well, like a neighbor or a colleague,
Speaker 1: but it's in an unfamiliar setting and you struggle to
Speaker 1: recognize them immediately. Why does that happen Because our brains
Speaker 1: use contextual cues when identifying people, So our brains rely
Speaker 1: not just on facial features, but also on surrounding context
Speaker 1: of all sorts to identify people. But despite all these
Speaker 1: other cues that we use, just note that facial recognition
Speaker 1: is possible even over zoom, where many of those other
Speaker 1: cues are gone. And even if you've got a bunch
Speaker 1: of movie stars to put on wigs and change their
Speaker 1: hairlines and so on, you'd still be pretty good at
Speaker 1: distinguishing them just based on the details of the face itself.
Speaker 1: And I think there are at least two ways to
Speaker 1: appreciate how hard a challenge face recognition is to the brain.
Speaker 1: The first is to understand how difficult it is to
Speaker 1: get computers to recognize and distinguish human faces. Now you
Speaker 1: might think, aren't we pretty good at this with modern technology. Yes,
Speaker 1: but this has been a sixty year slog by very
Speaker 1: smart people in the computer science world. Starting in the
Speaker 1: nineteen sixties, people realized that face recognition was a really
Speaker 1: hard problem, and they've been climbing that hill ever since.
Speaker 1: So the way that researchers have gotten face recognition to
Speaker 1: work on computers nowadays is by busting the problem up
Speaker 1: into different computational stages. So first, you have algorithms just
Speaker 1: for detecting a face, like is there a face out there?
Speaker 1: Then you have a second step where you segment this
Speaker 1: face from the background and figure out how the face
Speaker 1: is aligned to tell you about the size of the
Speaker 1: face and the illumination on the face and even the
Speaker 1: pose of the face. Then you have a third step
Speaker 1: where you extract the facial features, like here's the length
Speaker 1: of the nose and the distance between the eyes, and
Speaker 1: the shape of the mouth and the position of the ears.
Speaker 1: All these things you pinpoint and you measure them, and
Speaker 1: then in the fourth step, you match those numbers against
Speaker 1: a database of faces to see if you can identify
Speaker 1: this one. So this is a really complicated algorithm and
Speaker 1: it's instructive to see how computer get things wrong. I
Speaker 1: saw a great photograph where it's a family sitting on
Speaker 1: their porch at Halloween, and the computer has identified each
Speaker 1: of their faces and put a little label next to it,
Speaker 1: like Henry and John and Sarah, and then it identifies
Speaker 1: another face and says unknown person. But that face is
Speaker 1: the Jack O lantern, the pumpkin that's sitting there on
Speaker 1: the porch. Now, a human observer would never make that
Speaker 1: kind of mistake. But this goes to show that it's
Speaker 1: a very computationally challenging problem. So some version of this
Speaker 1: very complicated algorithm, probably not exactly the same, but equally complex.
Speaker 1: This is what your brain is doing under the hood
Speaker 1: when you just glanced at some billboard and you think, oh,
Speaker 1: that's Paul Giamati. I love that guy. And we'll come
Speaker 1: back to what the brain is doing in just a moment,
Speaker 1: but I just want to say for now that quite
Speaker 1: often we find that the tasks that seem most effortless
Speaker 1: to us are the things underpinned by the most brain circuitry.
Speaker 1: And I want to look at a second way to
Speaker 1: appreciate how hard a challenge face recognition is for the brain.
Speaker 1: Just look at a bunch of Golden Retriever faces. If
Speaker 1: you were in a situation where you were hanging out
Speaker 1: with hundreds or thousands of Golden Retriever dogs, do they
Speaker 1: really look that different to you? Or consider horse faces
Speaker 1: or squirrel faces or cowfaces. Obviously we can imagine some
Speaker 1: faces at the extreme that look a little bit different,
Speaker 1: But in general, if I dropped you into the middle
Speaker 1: of a giant ranch and you looked at thousands of cows,
Speaker 1: you'd say, okay, well, each face has two eyes and
Speaker 1: a snout and a mouth, and there's just not that
Speaker 1: much difference from one face to another. You wouldn't meet
Speaker 1: recognized if one of those cows had been in a
Speaker 1: movie like oh, that's that famous cow, or if one
Speaker 1: of those cows was wanted by the legal system, like
Speaker 1: wait a minute, I recognize that cow from the poster
Speaker 1: of the post office. And of course, if one of
Speaker 1: these cows was looking at you and a bunch of
Speaker 1: other humans, she would feel exactly the same way. There's
Speaker 1: not that much difference between human faces. Now side note,
Speaker 1: which we'll return to. If you were the rancher, you
Speaker 1: could get better at distinguishing cow faces. This is because
Speaker 1: of brain plasticity and because distinguishing the cows is salient
Speaker 1: to your rancher brain. But for now, what I want
Speaker 1: to surface is just how similar faces are before you
Speaker 1: get good at them from experience. Faces are unbelievably similar.
Speaker 1: And one expression of this difficulty in distinguishing faces comes
Speaker 1: from a psychological effe fact called the other race effect,
Speaker 1: and this refers to the tendency of people to have
Speaker 1: more difficulty recognizing faces that belong to races that are
Speaker 1: not their own race. This phenomenon is also known as
Speaker 1: the cross race effect or the own race bias, and
Speaker 1: it's been widely studied and you see it across all cultures.
Speaker 1: Now people sometimes hear this and they take this as
Speaker 1: evidence for racism. It's not racism in the sense of
Speaker 1: you treating your own group better and other groups more poorly. Instead,
Speaker 1: the other race effect simply results from the fact that
Speaker 1: your brain gets trained up on the faces around you,
Speaker 1: and you are better at recognizing those faces than other faces.
Speaker 1: So if you grew up in Cambodia, you will be
Speaker 1: excellent and distinguishing Cambodian faces, and maybe not so great
Speaker 1: at distinguishing Norwegian faces. If you grew up in Norway,
Speaker 1: you're excellent and distinguishing Norwegian f but not so great
Speaker 1: at distinguishing Zimbabwean faces. And if you grew up in Zimbabwe,
Speaker 1: you're not so good at Intuit Eskimo faces and so on.
Speaker 1: So your brain becomes attuned to the type of faces
Speaker 1: that you see most often, and this heightened sensitivity makes
Speaker 1: us better at distinguishing among those familiar faces. As a
Speaker 1: side note, can you mitigate the other race effect? Sure,
Speaker 1: it's just about exposure. You can improve the ability to
Speaker 1: recognize other race faces through training and exposure. Now, Hollywood
Speaker 1: has been on the forefront of this for a long time,
Speaker 1: making sure that there's a mixture that we all get
Speaker 1: exposed to different sorts of faces, and that's presumably very useful.
Speaker 1: It could be noted that Hollywood has tended to be
Speaker 1: mostly in love with white faces and black faces, and
Speaker 1: that leaves a lot of people out of the mix.
Speaker 1: So we the viewing audience don't necessarily get much better
Speaker 1: at Cambodian face or Norwegian faces, or Inuit Eskimo faces
Speaker 1: or whatever. But it's a start to training our brains
Speaker 1: on a broader diet of faces. So the other race
Speaker 1: effect underscores how our brains can get tuned to the
Speaker 1: social world around us, and it highlights our natural tendency
Speaker 1: to recognize familiar faces more easily. Okay, so where are
Speaker 1: we so far. It's really hard to distinguish faces unless
Speaker 1: your brain has had lots and lots of practice at it.
Speaker 1: But again it seems effortless to us now. Even though
Speaker 1: we're not always great at distinguishing faces from one another,
Speaker 1: unless we've had lots of practice, we are highly programmed
Speaker 1: to identify that there is a face there and to
Speaker 1: zoom in on it. Why because faces carry so much
Speaker 1: information for us, And this is why you sometimes look
Speaker 1: at the electrical plug in your wall and you see
Speaker 1: a little face, or you see a pattern of burn
Speaker 1: marks on a piece of toast and you think, oh,
Speaker 1: that looks just like a face, or you look at
Speaker 1: the surface of the moon and you think, oh, there's
Speaker 1: a man there looking at me. In science, this is
Speaker 1: called paradolia. Paradolia refers to our tendency to perceive specific
Speaker 1: and often meaningful images in random patterns, and the most
Speaker 1: common usage of this word is in the case of
Speaker 1: perceiving the pattern of a face in random unrelated objects.
Speaker 1: And we've all been there where your brain says, oh,
Speaker 1: that looks like a face when you're looking at a
Speaker 1: cloud or a rock formation, or some arrangement of fruits
Speaker 1: on a table. And I don't know if you've ever
Speaker 1: seen this image from the surface of Mars. I'll put
Speaker 1: it on the show. But on the bumpy landscape of Mars,
Speaker 1: there are some bumps that happen to fall into the
Speaker 1: pattern that look like two y's and a nose and
Speaker 1: a mouth. And many people go nuts about this image
Speaker 1: because they suggest that it's a sculpture of a human
Speaker 1: face planted there by aliens. But probably not. This is
Speaker 1: merely our brains experiencing garden variety paradolia. We assign patterns
Speaker 1: to random inputs, and in particular, we love to see faces. Okay,
Speaker 1: but why does this happen to us so commonly. Well,
Speaker 1: it's because we are hardwired to see faces everywhere, and
Speaker 1: the reason is that faces are crucial for social interaction.
Speaker 1: Seeing a face tells us about a person's identity, their
Speaker 1: emotional state, whether they're a friend or a foe. This
Speaker 1: ability helped our ancestors to survive by recognize is saying oh,
Speaker 1: that's a tribe member. Oh, that's a potential threat. In fact,
Speaker 1: even newborn babies prefer to look at faces. They look
Speaker 1: at face like stimuli more than other stimuli. So take
Speaker 1: two little circles and a little square beneath that, and
Speaker 1: a little rectangle underneath that, they'll stare at that as
Speaker 1: opposed to the same shapes in a different configuration. And
Speaker 1: this underscores that brains are primed to focus on faces.
Speaker 1: Paridolia is just an extension of this bias to recognize faces.
Speaker 1: It's our brain's way of staying vigilant because in the wild,
Speaker 1: it is safer to mistakenly see a face where there
Speaker 1: isn't one than to miss a real face. So this
Speaker 1: hypersensitivity to faces means the difference between life and death
Speaker 1: in some situations, like spotting a lurking predator or an
Speaker 1: aggressive intruder. By the way, I'll just mention that paradolia
Speaker 1: is something that artists have always exploited. They turn random
Speaker 1: patterns or abstract shapes into recognizable faces. Just as one example,
Speaker 1: one of my favorite artists, Salvador Dhli. He very often
Speaker 1: takes advantage of paradolia to create double images that play
Speaker 1: with the viewer's perception. You can see this as a
Speaker 1: rock formation or as a face. So paradolia highlights how
Speaker 1: our brains are constantly trying to make sense of the
Speaker 1: world around us, even when there isn't anything immediately recognizable.
Speaker 1: And I want to give just one other angle on
Speaker 1: paradolia here. If you're a regular listener to this podcast,
Speaker 1: you know that I often talk about how the brain's
Speaker 1: main job is to build an internal model of the
Speaker 1: outside world, and our model influences our perception. So whatever
Speaker 1: you specialize in, you'll see lots of that world. We're
Speaker 1: all specialists at faces, and we often see those where
Speaker 1: there isn't actually one, but it generalizes beyond that. So
Speaker 1: for me personally, when I look around the world, I
Speaker 1: tend to impose shapes that look like brains. I think, oh,
Speaker 1: there's a brain, or there's a midsadgital section, or there's
Speaker 1: a cerebellum. My friends who are pilots tend to see
Speaker 1: airplane shapes and runways. My collogist friends see mushroom shapes,
Speaker 1: my dermatologists friends see melanomas, and so on. Whatever you
Speaker 1: specialize in makes you an expert in detecting that in
Speaker 1: the world, and you impose that interpretation on lots of things.
Speaker 1: It's paridolia writ large. Okay, so back to faces in particular.
Speaker 1: Now we're ready to turn to how the brain does
Speaker 1: its magic with face recognition. One of the key areas
Speaker 1: in our brain that does this is in the temporal lobe.
Speaker 1: It's a little region called the fusiform face area or
Speaker 1: FFA fusiform face area. Now, we can see in brain
Speaker 1: imaging that this area is particularly sensitive to faces. But
Speaker 1: what's interesting is it's not just any part of the
Speaker 1: face that gets attention from the FFA, it's the holistic
Speaker 1: view of the face. So the FFA responds strongly to
Speaker 1: the overall configuration of a face rather than individual features.
Speaker 1: So that allows us to quickly recognize faces and familiar faces,
Speaker 1: even if we only get a quick glimpse of them.
Speaker 1: When you look at these brain imaging studies, for example,
Speaker 1: with fMRI, you find that this fusiform face area responds
Speaker 1: more to familiar faces than to unfamiliar faces. And given
Speaker 1: what we saw a moment ago with the other race effect,
Speaker 1: the FFA is more active when you're viewing faces of
Speaker 1: your own race compared to faces of other races. So again,
Speaker 1: just like recognizing the distinction between different cows if you're
Speaker 1: the rancher, or distinguishing faces that you grew up with
Speaker 1: as opposed to other cultures that you rarely see. Your
Speaker 1: visual system is specialized to efficiently process faces that you
Speaker 1: see a lot more. Now back to this issue about
Speaker 1: recognizing the face holistically rather than detail by detail. This
Speaker 1: is what underlies the phenomenon that's called the inversion effect,
Speaker 1: which is when you see a face that is upside down,
Speaker 1: it's really hard to recognize. So try this. Just open
Speaker 1: a magazine upside down and flip through the pages and
Speaker 1: see if you can recognize the people in it. And
Speaker 1: then when you flip it right side up, it's a
Speaker 1: whole different experience. And this is because this part of
Speaker 1: the brain FFA is super specialized on faces, and it's
Speaker 1: always seen faces in a particular way, and it's recognizing
Speaker 1: the whole big picture with two eyes above the nose,
Speaker 1: above the mouth, and if you throw a ranch in that,
Speaker 1: it doesn't function so well. The key thing is that
Speaker 1: this inversion effect is much stronger for faces than for
Speaker 1: other objects, which highlights this very specialized nature of face processing. Now,
Speaker 1: what's wild is that this part of the brain is
Speaker 1: trying to see faces everywhere, as we saw in paridolia.
Speaker 1: And so if someone puts an electrode into this part
Speaker 1: of your brain, then you might look at, let's say,
Speaker 1: a soccer ball, and when the electrode turns on and
Speaker 1: stimulates this area with electricity, the hexagons of the soccer
Speaker 1: ball seem to you to become the eyes and the
Speaker 1: mouth of a face. So activity in this part of
Speaker 1: the brain is always working over time to detect faces
Speaker 1: in the world, and sometimes it does this by imposing
Speaker 1: the interpretation onto the canvas of the world. Now, consistent
Speaker 1: with what I mentioned before, the FFA isn't specialized just
Speaker 1: for faces. It also plays a role in recognizing other
Speaker 1: things that we're highly familiar with, like cars for car enthusiasts,
Speaker 1: or birds for bird watchers. So that tells us slightly
Speaker 1: more generally that this part of the brain specializes in
Speaker 1: recognizing very detailed things that are relevant and that we
Speaker 1: have a lot of experience seeing. So back to faces,
Speaker 1: the FFA, it's not just that it's sensitive to faces.
Speaker 1: It's actually critical if you want to see a face.
Speaker 1: If you get damaged to the FFA or to its connections,
Speaker 1: then you become unable to recognize faces. And will return
Speaker 1: to that in a moment, but first I just want
Speaker 1: to make one more thing clear. Like almost everything in
Speaker 1: the brain, it's not just one area that's involved. Face
Speaker 1: recognition uses a broader, specialized network. Beyond the FFA, you
Speaker 1: have other areas involved, like the occipital face area and
Speaker 1: the superior temporal sulcus. Don't worry about the details, but
Speaker 1: the thing I want to surface here is that some
Speaker 1: areas are more focused on the detailed features of the
Speaker 1: face and others are sensitive to facial expressions and movements.
Speaker 1: And the key is that together these areas form a
Speaker 1: larger network that allows us to recognize faces and interpret
Speaker 1: their expressions well. Your brain's also doing a lot of
Speaker 1: work to gauge a person's emotions and then navigating social
Speaker 1: interactions by carefully watching the reactions of someone's facial expressions.
Speaker 1: We humans are super specialists at this because our well
Speaker 1: being generally depends on our ability to recognize and understand
Speaker 1: the people around us. And just to give you a
Speaker 1: sense of how all these networks interact, there are studies
Speaker 1: showing that you're interpretation of facial expressions is influenced by
Speaker 1: the broader context. So just as an example, in one study,
Speaker 1: you're shown faces with neutral expressions, but you're given different
Speaker 1: contextual information about the person. So if you're told the
Speaker 1: person is happy, you perceive the neutral face as slightly smiling,
Speaker 1: and if you're told this person is sad, you perceive
Speaker 1: that same face as slightly frowning. So, in other words,
Speaker 1: your brain combines the facial information with the context of
Speaker 1: the larger situation whenever you're interpreting emotions and for that matter, intentions.
Speaker 1: So putting together the giant networks in the brain involved
Speaker 1: in identifying and interpreting faces, the thing that becomes clear
Speaker 1: is that we are massively finely tuned to process faces
Speaker 1: in a way that benefits are social interactions and are survival. Now,
Speaker 1: if you've been listening to other episodes of this podcast,
Speaker 1: you'll know that I'm obsessed by the differences in the
Speaker 1: internal life from person to person, from head to head.
Speaker 1: And one place this really comes up is with individual
Speaker 1: variability in face recognition. So, while most people are fairly
Speaker 1: good at recognizing faces, there's a shocking amount of variation
Speaker 1: in this ability. Some people are exceptionally good at it,
Speaker 1: and other people struggle. And this brings us to the
Speaker 1: concepts of super recognizers on the one hand, and face
Speaker 1: blindness on the other hand. So let's start with the
Speaker 1: super recognizers. These are people who have an extraordinary ability
Speaker 1: to recognize faces. They can remember and identify faces even
Speaker 1: after just brief encounters or after long periods of time.
Speaker 1: Super recognizers are terrific at picking out their acquaintances and
Speaker 1: really large crowds, and they sometimes end up getting employed
Speaker 1: in security or law enforcement to identify perpetrators. Like they'll
Speaker 1: be hired to watch the video of let's say a
Speaker 1: subway entrance and you'll see thousands of people flowing in
Speaker 1: and out, and they'll just stare at the feed for
Speaker 1: hours or days, and then they'll say, oh, there's the guy. Now.
Speaker 1: On the other end of the spectrum, we have what's
Speaker 1: known as face blindness, and this is known as prosopagnosia.
Speaker 1: This word comes from the Greek pro sopon meaning face,
Speaker 1: and agnosia meaning lack of knowledge. So people with prosopagnosia
Speaker 1: have a very hard time recognizing faces, even faces of
Speaker 1: close family and friends. Now, by the way, this isn't
Speaker 1: all or none. The condition ranges from mild to severe,
Speaker 1: like difficulty recognizing familiar faces to an inability to distinguish
Speaker 1: any faces at all. And at that far end of
Speaker 1: the spectrum, just imagine not being able to recognize your
Speaker 1: own spouse or child if you see them out of context.
Speaker 1: And this is the reality for many people with prosopagnosia. Now,
Speaker 1: how does prosopagnosia happen? Usually you're born with it. This
Speaker 1: is called congenital prosopagnosia, just meaning it's present from birth.
Speaker 1: In rarer cases, you can have acquired prosopagnosia, which just
Speaker 1: means that you get it because of a brain injury
Speaker 1: later in life, like a stroke or a traumatic brain injury.
Speaker 1: And in these acquired cases, people notice the sudden change
Speaker 1: in their ability to recognize faces, which is obviously distressing
Speaker 1: and isolating. But what's fascinating is that people born with
Speaker 1: this usually don't realize they have it because they've never
Speaker 1: known anything different, and so they just get along by
Speaker 1: using other cues like people's voices or their clothing or
Speaker 1: the way they walk, and this is how they recognize people.
Speaker 1: One example of a person who had prosopagnosia was the
Speaker 1: neurologist Oliver Sacks, and he wrote an article in The
Speaker 1: New Yorker in twenty ten on this. He talked about
Speaker 1: his personal lifelong struggle with face blindness, but he never
Speaker 1: realized there was something unusual about this until his middle age.
Speaker 1: He'd always just been really bad with recognizing faces, but
Speaker 1: that was just the way it was. But he went
Speaker 1: to visit an older brother in Australia and they got
Speaker 1: to talking and he realized that his brother had the
Speaker 1: same problems with faces that he did, and it dawned
Speaker 1: on him that this was something beyond normal variation, and
Speaker 1: that they both had this trait of face blindness, and
Speaker 1: he guessed that there was probably some distinctive genetic basis
Speaker 1: to it. And very informally, I've noticed among people that
Speaker 1: I know that those with prosopagnosia often don't enjoy movies
Speaker 1: as much as other people, because in order to follow
Speaker 1: a plot, especially if it's switching between an A story
Speaker 1: and a B story and a C story, in order
Speaker 1: to follow that plot, you really need to get it
Speaker 1: when this actor comes into the scene who you haven't
Speaker 1: seen for fifteen minutes and who's now wearing different clothes,
Speaker 1: but this is just a continuation of his plot, and
Speaker 1: everyone else in the audience recognizes him and immediately remembers
Speaker 1: what was going on with him in the last act.
Speaker 1: But just try to imagine how difficult it makes things
Speaker 1: to follow along if you don't immediately recognize the person.
Speaker 1: And by the way, if you don't have prosopagnosia, you
Speaker 1: might be thinking what would that be like? How could
Speaker 1: you not recognize a person? A common analogy is to
Speaker 1: think about what it's like to walk through a forest
Speaker 1: and just imagine if you had to remember and distinguish
Speaker 1: every tree that you see. Imagine you had to have
Speaker 1: a name for every tree, and you were quizzed on
Speaker 1: it later. That sounds impossible to most of us, but
Speaker 1: this is what daily life is like for the person
Speaker 1: with face blindness. There wandering through a forest of people,
Speaker 1: all of whom look essentially indistinguish. Now, I just want
Speaker 1: to note beyond issues of following movie plots, prosopagnosia can
Speaker 1: have pretty significant social effects like anxiety and embarrassment and
Speaker 1: frustration because of and inability to recognize other people, And
Speaker 1: for children with face blindness, social development can be tough
Speaker 1: because you need to recognize your peers and your teacher,
Speaker 1: and occasionally kids will get misdiagnosed with other learning or
Speaker 1: behavioral disorders, which complicates things for them and an adults,
Speaker 1: face blindness can lead to social isolation or in difficulties
Speaker 1: in forming and maintaining relationships. So super recognizers and people
Speaker 1: with prosopagnosia they represent extreme ends of the face recognition spectrum.
Speaker 1: Most people fall somewhere in between, but with varying degrees
Speaker 1: of ability and understanding the spectrum in face recognition. This
Speaker 1: is how we can get insight into the differences between
Speaker 1: people's realities. Okay, now I just want to say lest
Speaker 1: you think that these issues about recognizing faces just show
Speaker 1: up in podcasts, In fact, they show up in courtrooms
Speaker 1: all the time, most notably in the very stormy world
Speaker 1: of eyewitness identification. If you check out my episode nineteen,
Speaker 1: I talked all about the difficulties of eyewitness identification, which
Speaker 1: is generally very difficult because of fundamental flaws in memory.
Speaker 1: But there are other challenges to this as well, and
Speaker 1: the main one of interest here is when people are
Speaker 1: asked to reproduce faces, as in who did you see
Speaker 1: at the scene of the crime. So what police did
Speaker 1: for centuries was to have a trained artist who sketches
Speaker 1: what you describe. But of course it's really hard to
Speaker 1: describe a face, and so by the late nineteen fifties,
Speaker 1: the Los Angeles Police Department introduced a new way of
Speaker 1: doing this where you line up individual strips for the eyes,
Speaker 1: the eyebrows, the nose, the mouths, and so on. So
Speaker 1: instead of me asking you, hey, can you describe that
Speaker 1: guy's face? Instead, you now get a bunch of possible
Speaker 1: eyes and possible noses and mouths and ears and chins,
Speaker 1: and you try to reconstruct it that way. And this
Speaker 1: ended up spreading from Los Angeles to Scotland Yard by
Speaker 1: the nineteen sixties, and they had some successes, and eventually
Speaker 1: this became a computerized system where people can piece this
Speaker 1: together on a computer, and so this was considered a
Speaker 1: real success about how you can use things beyond just
Speaker 1: unreliable verbal descriptions to identify perpetrators. But when researchers subjected
Speaker 1: this to more careful study, it turned out that this
Speaker 1: approach of piecing faces together this is pretty imperfect, and
Speaker 1: the fundamental problem is that the composite is built from
Speaker 1: pieces and parts, like the guy's eyes look like that,
Speaker 1: and his mouth looks like that, his nose like that,
Speaker 1: and so on. But that's not the way the human
Speaker 1: visual system works. It recognizes faces based on the whole picture,
Speaker 1: the gestalt, where the whole is perceived as more than
Speaker 1: the sum of the parts. And so it turns out
Speaker 1: that reconstructing a face from pieces and parts is not
Speaker 1: really so easy. I'll also mention another face recognition issue
Speaker 1: which shows up in courts all the time, and that's
Speaker 1: the other race effect which I mentioned earlier. People are
Speaker 1: more likely to misidentify individuals of other races, for example,
Speaker 1: a Hispanic person identifying a Japanese person and so on.
Speaker 1: This is not racism, it's just neuroscience. Your brain comes
Speaker 1: to represent what you see around you, and so in
Speaker 1: many ways, the legal system has to chew on the
Speaker 1: issue of how brain recognized faces and wear brains don't
Speaker 1: do it so well. Okay, So moving beyond courts into
Speaker 1: the broader society, we're now entering a brave new world
Speaker 1: of face recognition technology. There was a big moment in
Speaker 1: twenty eighteen in China where new face recognition technology picked
Speaker 1: out a person that the authorities wanted out of a
Speaker 1: crowd of sixty thousand people at a concert, and apparently
Speaker 1: when they came up and grabbed the guy, he was
Speaker 1: infinitely surprised because he assumed that being in a giant
Speaker 1: crowd made him safe, that no one would ever be
Speaker 1: able to spot him, and he was of course right
Speaker 1: that no one could, but the computer did. Now, this
Speaker 1: was an example where face recognition technology performed at a
Speaker 1: superhuman level, but note that the technology often messes up
Speaker 1: and also does something that's very human paradolia. We always
Speaker 1: see algorithms mistakenly idea identifying faces where there aren't any,
Speaker 1: which mimics the same tendencies that we have as humans.
Speaker 1: For example, remember the jack O lantern that I mentioned
Speaker 1: earlier that the Facebook algorithm mistakenly identified as a human face.
Speaker 1: Computers tend to impose patterns as much as we do.
Speaker 1: And I just want to say that even though we're
Speaker 1: often worried about new technologies and its face recognition abilities,
Speaker 1: what's also going to grow out of this are increasingly
Speaker 1: sophisticated assist of devices. You have AI driven tools that
Speaker 1: are going to offer real time face recognition support which
Speaker 1: is going to allow you to recognize your friend when
Speaker 1: you see him totally out of context. But more importantly,
Speaker 1: this has the potential to enhance the quality of life
Speaker 1: for people with prosopagnosia. So let's wrap up. Face recognition
Speaker 1: is a remarkably computationally intensive thing that we do, and
Speaker 1: even though it seems effortless, we have these massive, specialized
Speaker 1: neural networks that underpin our ability to do this. This
Speaker 1: ability highlights the very special role that faces play in
Speaker 1: our social lives and in our interactions, and it's so
Speaker 1: important that we all experience things like paradolia, where we
Speaker 1: impose an interpretation of faces on other patterns all around us,
Speaker 1: and this underscores our brain's need to make sense of
Speaker 1: the world, to impose order on chaos, and to connect
Speaker 1: what we see with what we know. And finally, we
Speaker 1: saw that skill in face recognition varies widely from person
Speaker 1: to person. We can measure this from brain imaging in
Speaker 1: people's performances, and we find a spectrum from super recognizers
Speaker 1: to those who are face blind. And understanding how different
Speaker 1: reality can be on the inside is critical for living
Speaker 1: in a society and understanding one another as it stands now,
Speaker 1: most people on the planet are unaware of this spectrum.
Speaker 1: They've never heard of something like prosapagnosia, and as a result,
Speaker 1: they don't recognize it in themselves or in a loved one.
Speaker 1: So this is one of the things we gain from
Speaker 1: a deeper understanding of the brain, a broader empathy that
Speaker 1: allows societies to interact more richly. So the next time
Speaker 1: you see a newborn baby, lock onto its mother's face
Speaker 1: and track the face and study it, just remember that
Speaker 1: you're not just seeing something cute, you are catching insight
Speaker 1: into deep circuitry of the inner cosmos. Go to Eagleman
Speaker 1: dot com slash podcast for more information and to find
Speaker 1: further reading. Send me an email at podcasts at egleman
Speaker 1: dot com with questions or discussion, and check out and
Speaker 1: subscribe to Inner Cosmos on YouTube for video of each
Speaker 1: episode and to leave comments. Until next time. I'm David Eagleman,
Speaker 1: and this is Inner Cosmos.