Tuesday, July 18, 2006

Mutants among us

Prosopagnosia, or face blindness, affects a surprisingly large fraction (few percent) of the population. Those who suffer from it have difficulty in distinguishing human faces, except by conscious effort (recalling particular features, or contextual clues). Preliminary evidence is that (a) we have a specialized module in our brains for face recognition and (b) there are one or more alleles (gene variants) which disable this function to various degrees.

How could these alleles survive selection? One would guess that face blindness is an evolutionary handicap, at least to some degree (although perhaps less so in small hunter gatherer groups, or in theoretical physics ;-). Is there a compensating advantage provided by the mutation?

It's fascinating to consider how many other strange cognitive mutations are present in our population at the percent (or fraction of percent level). Memory? Musical ability? Specialized mathematical ability (e.g., visualizing geometrical shapes, or a "feel" for magnitudes of quantities, or lightning calculation)?

I suspect we'll find more and more of these, and their associated alleles, as time goes by. See GNXP.com for more discussion and references.

It just occurred to me that there are likely dozens of readers of this blog who have prosopagnosia. Would anyone care to share their (anonymous) comments on how they adjust to the condition, and when they noticed having it?
NYTimes: Dr. Sellers, a professor of English at Hope College in Holland, Mich., has a disorder called prosopagnosia, or face blindness, and she has had it since birth. “I see faces that are human,” she said, “but they all look more or less the same. It’s like looking at a bunch of golden retrievers: some may seem a little older or smaller or bigger, but essentially they all look alike.”

Face blindness can be a rare result of a stroke or a brain injury, but a study published in the July issue of The American Journal of Medical Genetics Part A is the first report of the prevalence of a congenital or developmental form of the disorder.

The researchers say the phenomenon is much more common than previously believed: they found that 2.47 percent of 689 randomly selected students in Münster, Germany, had the disorder.

Dr. Thomas Grüter, a co-author of the paper, said there were reasons to believe that the condition was equally common in other populations. “First,” he said, “our population was not selected in terms of cognition deficits. And second, a study done by Harvard University with a different diagnostic approach yielded very similar figures.”

Dr. Grüter is himself prosopagnosic. His wife and co-author, Dr. Martina Grüter of the Institute for Human Genetics at the University of Münster, did not realize he was face blind until she had known him more than 20 years. The reason, she says, is he was so good at compensating for his deficits.

“How do you recognize a face?” she asked. “For most people, this is a silly question. You just do. But people who have prosopagnosia can tell you exactly why they recognize a person. Thomas consciously looks for the details that others notice unconsciously.”


Anonymous said...

I first noticed I had prosopagnosia during my first trip to China....

Just kidding!

Anonymous said...

This very curious, I was looking for something about mutants, since I discovered that I have "Espontanious Freezing" wich is a suden droop of my body temperature and some other "Anomalies" enough to make my life very unusual and then, there is this blog wich mentions something that drives me mad allmost every single day. people talks to me and greets me by my name and to me it seems that is the first time I see them in my life, usually I keep the conversation expecting them to betray themselves and give me a clue but many times after a conversation I wonder "Whom was that guy?" I live in Mexico City and once I had to give the information for a drawn sketch of a criminal and it was terrible, it seemed like looking for his face in the worst fog imaginable, and my wife just laughs beacouse I allways am asking her the name of the actors in the movie we are seeing, except for Tom Cruise, Al Paccino, Dustin Hoffman and Sharon Stone, they all get mixed in generic groups. kool right?

Steve Hsu said...

Thanks for that comment! Please tell us more if you have the chance someday to compare your situation to what is described by researchers who study this condition. If you google around you can probably find a lot of information about the condition, discussion groups, etc.

Anonymous said...

Hi Steve, I joined a group called "Face Blind Folks" there is a lot of information about Prosopagnosia, I also discovered that along with face recognition problems many, like my self, have other conditions, like orientation problems (I get lost every other day), it has a wide spectrum of severity ranging from mild to severe where someone won`t recognize their own relatives, when I was some 8 years old failed to recognize my own mother when she changed her hair color. talking with other prosopagnostics, there are hundreds of anecdotes, some funny, some almost tragic, personaly I prefer the funy side and try to laugh at my mistakes.
My mail is globalmonitor@hotmail.com and please write any time you want.
Best regards, Arturo

DB said...

When I fail to notice a change in my wife's hairstyle (as I usually do), am I exhibiting anti-prosopagnosia? That is, I recognize the person and not the details? I'm going to see how that flies next time.

Blog Archive