Facing facts

"I'm sorry, but I have no idea who you are."

I can't tell you how many times I've had to utter that sentence.  Regular readers of Skeptophilia know why; I have a peculiar disability called prosopagnosia, or "face blindness."  I have a nearly complete inability to recognize faces, even of people I've known for some time.

Well, that's not exactly true.  I recognize people differently than other people do.  I remember the people I know as lists of features.  I know my wife has curly brown hair and freckles and an infectious smile, but I honestly have no mental image of her.  I can't picture my own face, although -- like with my wife -- I could list some of my features.

That system doesn't have a high success rate, however, and a lot of the time I have no idea who the people around me are, especially in a place where there are few clues from context.  I have pretty serious social anxiety, and my condition makes it worse, having put me in the following actual situations:

• introducing myself twice to the same person at a party
• getting a big, enthusiastic hug and an "it's been so long!" from someone in our local gym, and never figuring out who I was talking to
• having two of my students switch seats and not realizing it for three weeks, until finally they 'fessed up
• going to see a movie, and not knowing until the credits rolled that the main characters were played by Kenneth Branagh, Penelope Cruz, Judi Dench, Derek Jacobi, Michelle Pfeiffer, Daisy Ridley, and Johnny Depp
• countless incidents of my fishing for clues ("so, how's your, um... spouse, parents, kids, pets, job..."), sometimes fruitlessly

My anxiety has made me really good at paying attention to, and recalling, other cues like voice, manner of dress, posture, walk, hair style, and so on.  But when one or more of those change -- such as with the student I had one year who cut her hair really short during the summer, and whom I didn't recognize when she showed up in one of my classes on the first day of school the following year -- it doesn't always work.

One up side to the whole thing is that I do get asked some funny questions.  One student asked me if when I looked at people, their faces were invisible.  Another asked me if when I look in the bathroom mirror in the morning, I don't know that's me.  (It's a pretty shrewd guess that it is me, since there's generally no one else in there at the time.)

But at least it's not as bad as the dumb questions that my former students who are identical triplets sometimes get.  One of them was once asked by a friend how she kept track of which triplet she was.

No, I'm not kidding.  Neither, apparently, was the person who asked the question.

[Image licensed under the Creative Commons Randallbritten, FaceMachine screenshots collage, CC BY-SA 3.0]

In any case, all of this comes up because of some research that came out in the journal Cortex that tried to parse what's happening (or what's not happening) in the brains of people like me.  Some level of prosopagnosia affects about one person in fifty; some of them lose their facial recognition ability because of a stroke or other damage to the fusiform gyrus, the part of the brain that seems to be a dedicated face-memory module.  Others, like me, were born this way.  Interestingly, a lot of people who have lifelong prosopagnosia take a while to figure it out; for years, I just thought I was unobservant, forgetful, or a little daft.  (All three of those might be true as well, of course.)  It was only after I had enough embarrassing incidents occur, and -- most importantly -- saw an eye-opening piece about face blindness by Leslie Stahl on 60 Minutes, that I realized what was going on.

In any case, the paper in Cortex looked at trying to figure out why people who are face-blind often do just fine on visual perception tests, then fail utterly when it comes to remembering photographs of faces.  The researchers specifically tried to parse whether the difference was coming from an inability to connect context cues to the face you're seeing (e.g., looking at someone and thinking, "She's the woman who was behind the counter at the library last week") versus simple familiarity (the more nebulous and context-free feeling of "I've seen that person before").  They showed each test subject (some of whom weren't face-blind) a series of 120 faces, then a second series of 60 faces where some of them were new and some of them were in the previous series.  The researchers were not only looking for whether the subjects could correctly pick out the old faces, but how confident they were in their answers -- the surmise being that low confidence on correct answers was an indicator of relying on familiarity rather than context memory.

The prosopagnosics in the test group not only were bad at identifying which faces were old and which ones they'd seen before; but their confidence was really low, even on the ones they got right.  Normally-sighted people showed a great deal more certainty in their answers.  What occurs to me, though, is that knowing they're face-blind would skew the results, in that we prosopagnosics are always doubtful we're recalling correctly.  So these data could be a result of living with the condition, not some kind of underlying mechanism at work.  I almost never greet someone first, because even if I think I might know them, I'm never certain.  A lot of people think I'm aloof because of this, but the reality is that I honestly don't know which of the people I'm seeing are friends and which are total strangers.

One thing about the researchers' conclusion does ring true, however.  The subconscious "feeling of familiarity" is definitely involved.  My experience of face blindness isn't that I feel like I'm surrounded by strangers; it's more that everyone looks vaguely familiar.  The problem is, that feeling is no stronger when I see a close friend than when I see someone I've never met before, so the intensity of that sense -- what apparently most people rely on -- doesn't help me.

So that's the view of the world through the eyes of someone who more often than not doesn't know who he's looking at.  Fortunately for me, (1) at this point in my life I'm unembarrassed by my condition, and (2) most of the people in my little village know I'm face-blind and will say, "Hi, Gordon, it's Steve..." when they walk up, and spare me the awkwardness of fishing for clues.  (Nota bene: This only works if it actually is Steve.  Otherwise it would be even more awkward.)  But hopefully some good will come from this research, because face blindness is kind of a pain in the ass.

"Our results underscore that prosopagnosia is a far more complex disorder that is driven by more than deficits in visual perception," said study first author Anna Stumps, a researcher in the Boston Attention Learning Laboratory at VA Boston.  "This finding can help inform the design of new training approaches for people with face blindness."

Which would be really, really nice.

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Face forward

Life with prosopagnosia is peculiar sometimes.

Better known as "face blindness," it's a partial or complete inability to recognize people's faces.  I'm not sure where I fall on the spectrum -- I'm certainly nowhere as bad as neuroscientist and author Oliver Sacks, who didn't recognize his own face in the mirror.  Me, I'm hampered by it, but have learned to compensate by being very sensitive to people's voices and how they move.  (I've noticed that I'm often more certain who someone is if I see them walking away than I am if they're standing right in front of me.)

Still, it results in some odd situations sometimes.  I volunteer once a week as a book sorter at our local Friends of the Library book sale, and there's this one guy named Rich who is absolutely a fixture -- he always seems to be there.  I've seen him and spoken with him at least a hundred times.  Well, a couple of weeks ago, I was working, and there was this guy who was behind the counter, messing with stuff.  I was about to ask who he was and what he was doing, when he said something, and I realized it was Rich -- who had shaved off his facial hair.

Until he opened his mouth, I honestly had no idea I'd ever seen him in my life.

Then, a couple of nights ago, my wife and I were watching the Doctor Who Christmas episode "Joy to the World," and afterward got to see a thirty-second teaser trailer for season two, which is being released next spring.  Well, in season one, there was this mysterious recurring character named Mrs. Flood (played by British actress Anita Dobson) whose role we have yet to figure out, and who has the Who fandom in quite the tizzy.  And in the trailer, there's a quick clip of an old woman in formal attire watching a theater performance through opera glasses, and until another fan said, "What did you think about the appearance of Mrs. Flood in the trailer?" I had no clue -- not the least suspicion -- that it was her.

So it's kind of inconvenient, sometimes.  When people post still shots from movies or television shows on social media, I usually not only don't know who the actors are, I have no idea what film it's from (unless there's an obvious clue from the setting).  And as I've related before, there are times when even my voice-recognition strategy hasn't worked, and I've had entire conversations with people and then left still not knowing who it was I'd been talking to.

The reason the topic comes up (again) is some research out of Toyohashi University of Technology that was the subject of a paper in the Journal of Vision last week.  The researchers were trying to figure out if humans have a better innate ability to filter out extraneous visual distractions when it comes to facial recognition than they do for recognizing other objects.  Using a technique called "continuous flash suppression" (CFS), they presented volunteers with fast-moving high-contrast images in one eye, and a target image in the other, then using an fMRI measured how long it took the brain's visual recognition centers to "break through" the distraction and recognize the target image.

If the target image was a face -- or "face-like" -- that breakthrough happened much faster than it did with any other sort of image.  And, interestingly, the breakthrough time was significantly slowed for faces that were upside-down.

We're wired, apparently, to recognize right-side-up human faces faster than just about anything else.

"Our study shows that even vague, face-like images can trigger subconscious processing in the brain, demonstrating how deeply rooted facial recognition is in our visual system," said Makoto Michael Martinsen, who co-authored the study.  "This ability likely evolved to help us prioritize faces, which are critical for social interaction, even when visual information is scarce...  [However] we didn’t consider factors like emotion or attractiveness, which can affect facial perception...  Despite this, our study highlights the brain’s incredible ability to extract important information from minimal cues, especially when it comes to faces.  It emphasizes the importance of facial features in both conscious and subconscious perception and raises interesting questions about how this mechanism evolved."

Naturally, I found myself wondering how face-blind people like myself would do in this task.  After all, it's not that we can't tell something is a face; it's that the visual information in a face doesn't trigger the same instantaneous recall it does in other people.  When I do recognize someone visually, it's more that I remember a list of their features -- he's the guy with square plastic frame glasses and curly gray hair, she's the woman with a round face and dark brown eyes who favors brightly-colored jewelry.  This, of course, only takes me so far.  When someone changes their appearance -- like Rich shaving off his beard and mustache -- it confounds me completely.

So I'm curious whether I'd be like the rest of the test subjects and have faster recognition times for faces than for non-face objects, or if perhaps my peculiar wiring means my brain weights all visual stimuli equally.  I'd be happy to volunteer to go to Japan to participate, if anyone wants to find out the answer badly enough to spot me for a plane ticket.

No?  Oh, well, perhaps that'll be the next phase of Martinsen et al.'s research.  I'm willing to wait.

Until then -- if I know you, and happen to run into you in the local café, keep in mind I may have no idea who you are.  It helps if you start the conversation with, "I'm _____" -- I'm not embarrassed by my odd neurological condition, and it's better than spending the day wondering who the person was who came up and gave me a hug and asked about my wife and kids and dogs and whatnot.

****************************************

Voices and faces

I've blogged before about my difficulties with prosopagnosia (better known as "face blindness").  My ability to recognize faces is damn near nonexistent; when I do recognize someone, it's either through context or because I remember a specific feature or features (she's the woman with the blonde hair, green eyes, and lots of freckles; he's the guy with curly gray hair and a little scar on the forehead; and so forth).  This, of course, backfires badly when someone changes their appearance.  It's why I have an extremely poor track record of recognizing actors in unexpected roles, where makeup and costumes can dramatically change what distinctive features they may have.  I was absolutely flattened when I found out that Jim the Vampire in What We Do In the Shadows was played by none other than Mark Hamill, and that Peter Davison -- the Fifth Doctor in Doctor Who, a show I'm absolutely obsessed with -- played the suave French teacher Mr. Clayton in Miranda.

When I figure it out, it's often because the actor has a distinctive voice that even being in a different character can't quite hide.  I know British actress Zoë Wanamaker from three very different roles -- Quidditch instructor Madam Hooch in Harry Potter, the scheming Lady Cassandra in Doctor Who, and hapless mystery writer Ariadne Oliver in Agatha Christie's Poirot.  But in each role, she keeps a very distinct clipped, staccato cadence in her voice that, for me, is instantly recognizable.

So I'm above average at voice recognition, whereas I can't form mental images of faces at all.  Hell, sitting here right now, I can't picture my own face.  I know I have sandy blond hair, gray eyes, black plastic-framed glasses, and a narrow face, but it doesn't come together into any sort of image.  If I see a photograph of myself in a group shot, I often have a hard time finding myself, unless (1) I know where I was standing, (2) I recognize the shirt I'm wearing, or (3) there aren't any other skinny blond guys with glasses in the photo.

As I've mentioned before, to anyone local who is reading this; if I've walked past you on the streets of the village with a blank look, and not said hi, please don't take it personally.  I had no idea who you were, or that I'd ever seen you before.  I have no problem if you say hi and mention your name; in fact, I really appreciate it.  It's much less awkward to have someone say, "Hi, Gordon, it's Bill" than to have me standing there trying frantically to search for clues so I can figure out who I'm talking to, or worse, ignoring someone I actually like.

[Image licensed under the Creative Commons mikemacmarketing, Facial Recognition22, CC BY 2.0]

The reason this topic comes up is because of a puzzling piece of research in the Journal of Neurophysiology this week, that looked at the brain firing patterns in people when they heard famous people speaking (they used the voices of Barack Obama, George W. Bush, and Bill Clinton).  The test subjects were epileptic -- such studies often use epileptic volunteers who already have electrodes implanted in their brains to monitor their seizures, and the same technology can be used to study their other brain responses -- but were not prosopagnosic. 

The reason I say the research was puzzling is they found that very same part of the brain that seems to be miswired in prosopagnosia, the fusiform gyrus of the basal temporal lobe, was extremely active during the volunteers' attempts to identify voices.  Put a different way, the face-responsive sites in the brain are also involved with vocal recognition.

How, then, does one of those responses go so badly wrong in people like me, and the other one is largely unimpaired?

The current research is preliminary; identifying the site in the brain where a response occurs is only the first step toward figuring out what exact pathway the firing sequence takes or how it's mediated.  The parts of the brain have a remarkable degree of functional overlap, and this is hardly the only example of two seemingly related abilities working in very different ways.  

In fact, I can think of another instance of this phenomenon from my own experience.  I have near-perfect recall for music; my wife calls it my "superpower."  I hear a melody a couple of times, and I pretty much have it for life, and if it's in the range of my instrument, I can play it for you.  My ability to remember text, though, is mediocre at best, the main reason I gave up on doing community theater -- memorizing lines was painfully difficult for me.  It's hard to imagine why two different examples of recall involving sound would be so dramatically different, but they are.

So here, there's obviously something going on in the fusiform gyrus in face-blind individuals that interferes with visual recognition and leaves vocal recognition largely unaffected.  It'd be interesting to look at the electrocorticography for prosopagnosic volunteers.  (To use the technique in the paper, though, they'd have to find face-blind people who were also epileptic and had surgical electrode implants, which would be a small subset of a small subset of a small subset of humanity.  Kind of limits the possibilities for volunteers.)

In any case, it's interesting research, and I'm curious to see where it will lead.  We're only at the beginning of understanding how our own brains work, and the next twenty years should see some significant strides toward the maxim engraved on the walls of the temple of the Oracle of Delphi -- γνῶθι σεαυτόν (know thyself).

****************************************

Facing facts

"I'm sorry, but I have no idea who you are."

I can't tell you how many times I've had to utter that sentence.  Regular readers of Skeptophilia know why; I have a peculiar disability called prosopagnosia, or "face blindness."  I have a nearly complete inability to recognize faces, even of people I've known for some time.

Well, that's not exactly true.  I recognize people differently than other people do.  I remember the people I know as lists of features.  I know my wife has curly brown hair and freckles and an infectious smile, but I honestly have no mental image of her.  I can't picture my own face, although -- like with my wife -- I could list some of my features.

That system doesn't have a high success rate, however, and a lot of the time I have no idea who the people around me are, especially in a place where there are few clues from context.  I have pretty serious social anxiety, and my condition makes it worse, having put me in the following actual situations:

• introducing myself twice to the same person at a party
• getting a big, enthusiastic hug and an "it's been so long!" from someone in our local gym, and never figuring out who I was talking to
• having two of my students switch seats and not realizing it for three weeks, until finally they 'fessed up
• going to see a movie, and not knowing until the credits rolled that the main characters were played by Kenneth Branagh, Penelope Cruz, Judi Dench, Derek Jacobi, Michelle Pfeiffer, Daisy Ridley, and Johnny Depp
• countless incidents of my fishing for clues ("so, how's your, um... spouse, parents, kids, pets, job..."), sometimes fruitlessly

My anxiety has made me really good at paying attention to, and recalling, other cues like voice, manner of dress, posture, walk, hair style, and so on.  But when one or more of those change -- such as with the student I had one year who cut her hair really short during the summer, and whom I didn't recognize when she showed up in one of my classes on the first day of school the following year -- it doesn't always work.

One up side to the whole thing is that I do get asked some funny questions.  One student asked me if when I looked at people, their faces were invisible.  Another asked me if when I look in the bathroom mirror in the morning, I don't know that's me.  (It's a pretty shrewd guess that it is me, since there's generally no one else in there at the time.)

But at least it's not as bad as the dumb questions that my former students who are identical triplets sometimes get.  One of them was once asked by a friend how she kept track of which triplet she was.

No, I'm not kidding.  Neither, apparently, was the person who asked the question.

[Image licensed under the Creative Commons Randallbritten, FaceMachine screenshots collage, CC BY-SA 3.0]

In any case, all of this comes up because of some research that came out in the journal Cortex last week that tried to parse what's happening (or what's not happening) in the brains of people like me.  Some level of prosopagnosia affects about one person in fifty; some of them lose their facial recognition ability because of a stroke or other damage to the fusiform gyrus, the part of the brain that seems to be a dedicated face-memory module.  Others, like me, were born this way.  Interestingly, a lot of people who have lifelong prosopagnosia take a while to figure it out; for years, I just thought I was unobservant, forgetful, or a little daft.  (All three of those might be true as well, of course.)  It was only after I had enough embarrassing incidents occur, and -- most importantly -- saw an eye-opening piece about face blindness by Leslie Stahl on 60 Minutes, that I realized what was going on.

In any case, last week's paper looked at trying to figure out why people who are face-blind often do just fine on visual perception tests, then fail utterly when it comes to remembering photographs of faces.  The researchers specifically tried to parse whether the difference was coming from an inability to connect context cues to the face you're seeing (e.g., looking at someone and thinking, "She's the woman who was behind the counter at the library last week") versus simple familiarity (the more nebulous and context-free feeling of "I've seen that person before").  They showed each test subject (some of whom weren't face-blind) a series of 120 faces, then a second series of 60 faces where some of them were new and some of them were in the previous series.  The researchers were not only looking for whether the subjects could correctly pick out the old faces, but how confident they were in their answers -- the surmise being that low confidence on correct answers was an indicator of relying on familiarity rather than context memory.

The prosopagnosics in the test group not only were bad at identifying which faces were old and which ones they'd seen before; but their confidence was really low, even on the ones they got right.  Normally-sighted people showed a great deal more certainty in their answers.  What occurs to me, though, is that knowing they're face-blind would skew the results, in that we prosopagnosics are always doubtful we're recalling correctly.  So these data could be a result of living with the condition, not some kind of underlying mechanism at work.  I almost never greet someone first, because even if I think I might know them, I'm never certain.  A lot of people think I'm aloof because of this, but the reality is that I honestly don't know which of the people I'm seeing are friends and which are total strangers.

One thing about the researchers' conclusion does ring true, however.  The subconscious "feeling of familiarity" is definitely involved.  My experience of face blindness isn't that I feel like I'm surrounded by strangers; it's more that everyone looks vaguely familiar.  The problem is, that feeling is no stronger when I see a close friend than when I see someone I've never met before, so the intensity of that sense -- what apparently most people rely on -- doesn't help me.

So that's the view of the world through the eyes of someone who more often than not doesn't know who he's looking at.  Fortunately for me, (1) at this point in my life I'm unembarrassed by my condition, and (2) most of the people in my little village know I'm face-blind and will say, "Hi, Gordon, it's Steve..." when they walk up, and spare me the awkwardness of fishing for clues.  (Nota bene: This only works if it actually is Steve.  Otherwise it would be even more awkward.)  But hopefully some good will come from this research, because face blindness is kind of a pain in the ass.

"Our results underscore that prosopagnosia is a far more complex disorder that is driven by more than deficits in visual perception," said study first author Anna Stumps, a researcher in the Boston Attention Learning Laboratory at VA Boston.  "This finding can help inform the design of new training approaches for people with face blindness."

Which would be really, really nice.

***********************************

This week's Skeptophilia book of the week is for anyone fascinated with astronomy and the possibility of extraterrestrial life: The Sirens of Mars: Searching for Life on Another World, by Sarah Stewart Johnson.

Johnson is a planetary scientist at Georgetown University, and is also a hell of a writer.  In this book, she describes her personal path to becoming a respected scientist, and the broader search for life on Mars -- starting with simulations in the most hostile environments on Earth, such as the dry valleys of central Antarctica and the salt flats of Australia, and eventually leading to analysis of data from the Mars rovers, looking for any trace of living things past or present.

It's a beautifully-told story, and the whole endeavor is tremendously exciting.  If, like me, you look up at the night sky with awe, and wonder if there's anyone up there looking back your way, then Johnson's book should be on your reading list.

[Note: if you purchase this book using the image/link below, part of the proceeds goes to support Skeptophilia!]

Face card

I ran into an article in the New York Times a couple of days ago that begins with the line, "The brain has an amazing capacity for recognizing faces."

This made me snort derisively, because as I've mentioned before, I have prosopagnosia -- face blindness.  I'm not completely face blind, as the eminent writer and neuroscientist Oliver Sacks was -- Sacks, after all, didn't even recognize his own face in a mirror.  I'm not quite that badly off, but even so, I don't have anywhere near instantaneous facial recognition.  I compensate by being good at remembering voices, and paying attention to things like gait and stance.  Beyond that, I tend to remember people as lists of features -- he's the guy with the scar through one eyebrow, she's the one with black hair and three piercings in her left ear.  But it's a front-of-the-brain, conscious cognitive thing, not quick and subconscious like it (apparently) is with most people.

And even that strategy can fail, if someone changes hair styles, gets new glasses, or begins to dress differently.  Then I have to rely on my other strategies, as I did a couple of days ago in our local pharmacy.  The check-out clerk smiled at me, and I said hi and greeted her by name.  She was a former student who had taken my neuroscience class a couple of years ago, and she grinned at me and said, "I thought you didn't recognize people's faces."

"I don't," I said.  "You're wearing a name tag."

[image courtesy of the Wikimedia Commons]

Despite my scornful snort at the first line of the article in the Times, I was pretty interested in its content, not least because it gives me an insight into my own peculiar inability.  The article describes the research of Le Chang and Doris Y. Tsao (published this week in Cell), of Caltech, who using fMRI monitoring of the brains of monkeys, have begun to elucidate how the brain processes faces.  Chang and Tsao write:

Primates recognize complex objects such as faces with remarkable speed and reliability.  Here, we reveal the brain’s code for facial identity.  Experiments in macaques demonstrate an extraordinarily simple transformation between faces and responses of cells in face patches.  By formatting faces as points in a high-dimensional linear space, we discovered that each face cell’s firing rate is proportional to the projection of an incoming face stimulus onto a single axis in this space, allowing a face cell ensemble to encode the location of any face in the space.  Using this code, we could precisely decode faces from neural population responses and predict neural firing rates to faces.  Furthermore, this code disavows the long-standing assumption that face cells encode specific facial identities, confirmed by engineering faces with drastically different appearance that elicited identical responses in single face cells.  Our work suggests that other objects could be encoded by analogous metric coordinate systems.

Put more simply, the brain seems to encode facial recognition in a fairly small number of cells -- possibly as few as 10,000 -- which fire in a distinctive pattern depending on the deviation of the face being observed, on various metrics, from an "average" or "baseline" face.  This creates what Chang and Tsao call a "face space" -- a mapping between facial features and a set of firing patterns in the facial recognition module in the brain.

Chang and Tsao got so good at discerning the "face space" in a monkey's brain that they could tell which face photograph a monkey was looking at simply by watching which neurons fired!

So what that means is that we don't have devoted neurons to particular faces; there is no "Jennifer Aniston cell," as the concept has often been called.  We simply respond to the dimensions and features of the face we're observing, and map that into "face space," and that allows us to uniquely identify a nearly infinite number of different faces.

Tsao suspects that there are other types of encoding in the brain that will turn out to work the same way.  "[There is in] neuroscience a sense of pessimism that the brain is similarly a black box," she said. "Our paper provides a counterexample.  We’re recording from neurons at the highest stage of the visual system and can see that there’s no black box.  My bet is that that will be true throughout the brain."

Which makes me wonder where this whole system is going wrong in my own brain.  I certainly see, and can recall, facial features; it is not (as I thought when I was younger) that I am simply inattentive or unobservant.  But somehow, even knowing features doesn't create any kind of recognizable image for me.  For people I know well, I could list off features -- round face, crooked nose, wavy brown hair, prominent chin -- but those don't come together in my brain into any sort of visual image.  The result is the odd situation that for people I know, I can often describe them, but I can't picture them at all.

So anyhow, if at some point I pass you on the street and don't say hi, or even make eye contact and have no reaction, I'm not being unfriendly, you haven't somehow pissed me off, and I'm not daydreaming.  I honestly don't know who you are.  It'd be nice if, like my former student, everyone went around wearing name tags, but failing that, I'll just have to keep muddling along in a sea of unfamiliar faces.