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Brain disorder causes face blindness
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Seton Hill English professor Lee McClain has a rare condition called face blindness that makes it hard for her to recognize many people's faces. That's where her daughter Grace, 8, helps her. She used to think her daughter was precocious in recognizing so many people. "I thought -- how brilliant she is! But no, it's actually that I'm not."
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Lee McClain was standing at the checkout counter at Target recently when a woman approached her, gave her a big smile, and said, "Hi, how are you?"
Dr. McClain, an English professor at Seton Hill University in Greensburg, could tell that the woman knew her. She also knew that she was supposed to recognize the woman.
But she didn't. She has a rare condition known as congenital prosopagnosia, which means that she has great difficulty recognizing faces.
And even though she has lived with this deficit her whole life, she didn't realize it was an actual brain disorder until she underwent tests at Carnegie Mellon University within the last two years, when she was in her late 40s.
"I knew I wasn't good at recognizing people," Dr. McClain, 50, said in an interview. "For instance, when we went to a restaurant, I wouldn't know which waiter was ours, but I just thought that was me being careless or stupid, because other people could recognize the waiter.
"I would think, 'Well, other people are just more sensitive to service personnel than I am; I'm just a screw-up in that regard.' "
In the Target encounter, her 8-year-old daughter Grace bailed her out. She said hello and called the other woman's daughter by name, "and then that triggered this whole memory that this was the little girl in my daughter's gymnastic class who fell off the balance beam and hurt her head, and then I was able to express sympathy and share all kinds of information."
She said Grace has been her visual amanuensis since she was about 4 years old.
"I just thought she was so precocious, to say when we were out in public, 'That's the man from the grocery store,' or 'That's my Brownie leader.' I thought -- how brilliant she is! But no, it's actually that I'm not."
It is difficult to know how many people are born with prosopagnosia -- pronounced pro-suh-pag-NOZ-yuh.
Some researchers have estimated recently that as many as two out of every 100 people may have the condition, which is also called face blindness. But Jason Barton, a noted prosopagnosia researcher at the University of British Columbia, said that figure may include people who are simply at the low end of normal face recognition, and that true face blindness is probably much rarer.
And while scientists have known for decades that some people acquire face blindness after brain injuries from strokes or accidents, it is only in the last 20 years or so that they have realized that there are people like Lee McClain who are born with it.
Because most people can recognize faces so automatically, they often have a hard time grasping what prosopagnosia is like for those it affects, Dr. Barton said.
In most cases, he said, a person with face blindness can see a whole face and all its features -- eyes, nose, mouth, shape -- but can't figure out who the face belongs to.
"I like to use the analogy that one person with prosopagnosia suggested to me," he said. "Imagine you're at a pebbly beach and you pick up a handful of pebbles. You can see them clearly, right? Now throw them away from you and then go find them on the ground. It's hard. You don't recognize them. You're not trained to recognize pebbles. It's not that there's something weird about your vision, or even your memory; you just can't see the distinctions unique to one pebble."
The challenges Lee McClain faces each day, trying to figure out whether a student or staff member she walks past on the leafy Seton Hill campus is someone she ought to know, demonstrate how crucial face recognition is for most of us in our everyday lives.
It is a special skill that probably evolved in human beings from the time they began to live together in groups and had to discern friend from foe, relative from friend, tribal member from stranger.
And it has carried forward to the present.
"It's one of those cues that we've become tremendously skilled at using," Dr. Barton said. "I can use it to identify people at a glance, I can use it to target where I want to go, and what do I remember about that person, or who do I want to avoid, and I can also use it to read the intentions of the other person -- are they attracted to me, are they upset with me? Is this someone I want to get emotionally involved with?"
From a brain scientist's point of view, this skill is not only important -- it's miraculous.
Because most of us are so good at differentiating one face from another, we don't realize how alike most faces are, said Marlene Behrmann, another leading prosopagnosia researcher at CMU.
Yet our brains are not only able to detect these subtle differences between faces, but attach all kinds of biographical information to each one, and keep track of them as they change.
"The human visual system is masterful at being able to adapt to different inputs," Dr. Behrmann said. "I see you face-on today, tomorrow I see you in profile, and I have to know that is you -- I cannot fail to recognize you when I see you in a different pose or if I see you in 20 years time or I see you in different lighting conditions or if I see you passing by in your car.
"This is what the human visual system buys you -- this incredible adaptability."
The ease with which most of us do this makes it hard for some people to accept Dr. McClain's explanations of what it's like for her.
"When you tell people you have trouble recognizing faces, some of them think you're full of baloney, because it seems like a fake thing. Or they say, 'Oh, I have a hard time remembering names, too,' but then they'll think -- 'But you should still remember me.' "
Since Dr. McClain's face system is faulty, she compensates with the rest of her brain. She will use someone's voice, or size, or haircut, or clothing or the situation they're in to help tell her who the person is.
"And now, I start out being very friendly to everyone, so that after talking to them, I'll get some kind of clue about whether I know them."
The fact that she has been able to do that so well for so long helps explain why many people didn't realize she had a problem, and that she herself didn't suspect it was an actual brain disorder until the last few years.
Her shortcomings came to a head after her family moved from the East End of Pittsburgh to the Philadelphia area and then to Hempfield. In a short span of time, she met whole new groups of people who were harder and harder to recognize.
That sent her to the Internet, which is how she learned about prosopagnosia and found Dr. Behrmann.
Two years ago, she took a face recognition test, looking at sets of faces on a computer screen and then trying to recall which ones she had just seen.
Her scores verified she was in the prosopagnosia range, but she was not entirely convinced until she underwent magnetic resonance imaging last year.
That's when Dr. Behrmann showed her that the connections between the different parts of her brain involved in recognizing faces were faulty.
Those images "showed the connections are not firing the way they're supposed to," Dr. McClain said, "and that is when I really believed it -- because before that, I still thought I might be trying to find an excuse for my inadequacies."
The brain circuit imaging has been Dr. Behrmann's main contribution to prosopagnosia research.
When we look at objects or people, the images are first routed to the back of the brain, and when we gaze at faces, a special region called the fusiform face area at the bottom and sides of the brain lights up on scans, particularly on the right side.
The fusiform face area was discovered just 13 years ago by Nancy Kanwisher and colleagues at the Massachusetts Institute of Technology -- a sign of how young this research field still is.
Many brain injury patients who develop face blindness have lesions in or near the fusiform face area.
But when Dr. Behrmann did imaging of people who were born with the condition, she found that the fusiform face area lit up normally in their brains.
What wasn't working well, she discovered, were the tracts in their brains that linked the fusiform face area to other brain areas that seem to store biographical information and help people differentiate faces. These connections were less robust than in typical brains, and in some cases, were almost nonexistent. And the weaker that circuit was, the worse they did in face recognition tests.
The fact that the fusiform face area was active in their brains when she showed them a facial image, she said, helps verify that these people "see it's a face, and they know it's a face -- they just don't know who it is."
Dr. McClain has been helped by the fact that she has what she describes as a "medium case" of prosopagnosia, so that she can recognize her husband and her daughter and the people she works with each day. On the other hand, "you can imagine all the students whose feelings I've probably hurt over the years because I didn't recognize them when we passed each other."
While prosopagnosia itself may be rare, research is showing a wide range of face recognition ability among so-called normal people.
Richard Russell, a face recognition researcher at Gettysburg College, said that typical people's scores on face recognition tests can vary widely.
There might be important practical uses of that knowledge. For instance, he said, it might be good to test security officers at airports or government buildings on face recognition skills as part of the hiring process.
Also, since there have been many wrongful convictions in criminal trials because of incorrect eyewitness identifications, it might also be worth giving a face recognition test to witnesses who are going to testify in criminal trials.
All of which goes to show, he said, that "there really is just a much larger range of face recognition ability than people realize."
Want to find out how good you are at recognizing faces? You can take online face recognition tests at www.faceblind.org/facetests/index.php.
For additional information on face blindness, here are some resources:
• Marlene Behrmann at Carnegie Mellon University at www.cnbc.cmu.edu/~behrmann/mb.htm. To read her study on the brain circuit problems of people born with prosopagnosia, see http://repository.cmu.edu/cgi/viewcontent.cgi?article=1099&context=psychology.
• Jason Barton at the University of British Columbia at www.ophthalmology.ubc.ca/divisions/NeuroOp/JBarton/FrJBhome.html.
• Nancy Kanwisher's study exploring face blindness and the fusiform face area, at http://web.mit.edu/bcs/nklab/media/pdfs/RSTB20061934p.pdf.
First Published May 2, 2010 12:00 am
