Face blindness

Imagine going to school to pick up your child and not being certain which kid is yours. Imagine brushing your teeth every morning and not wholly recognizing the face in the mirror. All of this is unimaginable for most of us, but a basic fact of life for people with the mysterious neurological condition called "face blindness" -- or prosopagnosia - which can make it almost impossible to recognize faces, even of one's nearest and dearest. Dr. Oliver Sacks knows something about the condition, and not only because he's a neurologist, but also because Dr. Sacks himself is face blind. Lesley Stahl reports.

Most of us take for granted that we can instantly recognize people we know by looking at their faces. It's so automatic, it almost sounds silly to even say it. Friends can put on a hat, cut their hair, and still we know them by their face. We can do this for thousands upon thousands of faces without ever giving it a moment's thought. But imagine for a second what life would be like if you couldn't, if your wife or husband looked like a stranger; you couldn't tell your kids apart; couldn't recognize yourself in a mirror. Well that's what life is like for people who suffer from a mysterious condition called face blindness, or prosopagnosia, that can make it nearly impossible to recognize or identify faces.
If you've never heard of face blindness, you're not alone -- chances are your doctor hasn't either. It's been unknown to most of the medical world until very recently. Hearing about it can feel a little like entering the twilight zone. But for people who are face blind, the condition is very real...

So they have to rely on other strategies to identify people: hair, body shape, the way people walk, their voice, even style of dress. But Jacob told us it can all fall apart when someone changes their hair, like a colleague named Sylvia who he couldn't find one day until she started putting her hair into her usual ponytail.

Jacob Hodes: And she like put it into the ponytail. And once it was in place that was Sylvia. It clicked. Then she took her hair back out of that ponytail.

Lesley Stahl: Right then and there?

Jacob Hodes: Yep. She just put it in and then took it out and--

Lesley Stahl: So she went from Sylvia, not Sylvia, Sylvia, not Sylvia?

Jacob Hodes: She disappeared.

Lesley Stahl: Come on.

Jacob Hodes: Yeah....

We were baffled that a condition so extreme it could keep people from recognizing their own children could have been almost completely unknown until very recently. We asked Dr. Oliver Sacks, the famous chronicler of fascinating and bizarre neurological conditions, who wrote about face blindness in his latest book, "The Mind's Eye."...

Jo only learned there was such a thing as face blindness when she stumbled across this article, and came in to be tested in Duchaine's lab. A few hours after her second visit, in a bizarre coincidence, she and Duchaine ended up attending the same event.

Brad Duchaine: I kept placing my face in a position where she could see it.

Jo Livingston: I realized that one of the group was staring at me in a way that people don't normally.

Brad Duchaine: And so finally at one point I said, "Do you know who I am?"

Jo Livingston: "Ah."

Brad Duchaine: And she put it all together.

Duchaine had seen face blindness in action; Jo had seen the missed connections of her life.

Jo Livingston: If that had been anybody else, they would have been presumably furious, would not have spoken to me and would have probably never have spoken to me again. But I would never have known they were there.

http://www.cbsnews.com/news/face-blindness-when-everyone-is-a-stranger-20-03-2012/5/