Oliver Sacks on face blindness

One evening, while we were watching TV, a short video preview came on, announcing that the channel was going to show Jurassic Park over the coming weekend. As the preview played, my husband turned to me and said, "I didn't know Harrison Ford was in Jurassic Park."

"That's because he's not," I said.

"Sure he is. Right there," my husband said, pointing at an image of Sam Neil fleeing a Tyrannosaurus Rex.

And that was how I learned that my husband had spent his life not really recognizing individual actors on TV, and in the movies. Given a film featuring two leads of approximately the same race, sex, age and hair color—and barring any distinctive costuming—Baker quickly loses track of the plot. (He still has no idea what the hell happened in The Departed.)

Luckily for Baker, these problems don't seem to affect him much in the real world. He can't tell the difference between Harrison Ford and Sam Neil, but he knows the faces of friends, family, and business acquaintances. The same can't be said for people, including the neurologist and science writer Oliver Sacks, who suffer from full-on, clinical prosopagnosia—or "face blindness", the complete inability to distinguish one face from any other. For them, the world is full of strangers.

I knew Sacks had written about prosopagnosia—most notably in The Man Who Mistook His Wife for a Hat. But I didn't realize he actually had the disorder himself. In this video clip from a session on social memory and neurobiology at last year's World Science Festival in New York, Sacks recounts what can happen when nobody's face is familiar, not even your own.