英语时差：她的脸

Imagine not being able to recognize faces. You could see faces, but you'd be entirely unable to distinguish one face from another. All faces would look more or less the same--an amorphous assemblage of eyes, ears, noses, lips, and chins. To put it mildly, that would be strange. For some unlucky people, having a problem with facial recognition is more than just strange. It's an affliction known as prosopagnosia, or face blindness.

It might be hard to imagine what it would be like to suffer from face blindness, given that most of us take for granted the ability to read facial expressions for clues to a person's emotional state. Being face blind is a bit like being tone deaf and unable to distinguish one musical note from another. Tone deafness is arguably less of a burden, however. Not being able to hum along with a Mozart sonata or a Metallica dirge may be annoying, but it pales in comparison to not being able to tell faces apart. In the most severe cases, people who suffer from face blindness can't even recognize the faces of family members.

Scientists believe that face blindness is caused by damage to a part of the brain called the fusiform face area, or FFA. As research continues, scientists hope to learn more about how the FFA allows us to recognize and read faces and how damage to this area could result in face blindness.

Meanwhile, people with face blindness must find ways to cope. Some recognize others by the way they walk or by their voice. But those are weak substitutes for what's contained in a face.