Are you a prosopagnosic?

Prosopagnosia is a condition informally known as face blindness. Once thought to be very rare and mainly the result of a brain injury, it now is thought to affect one in fifty people to some extent. A study in the American Journal of Medical Genetics reports that the condition is highly inheritable and that perhaps more than five million people in the United States have the condition. The word comes from two Greek words--prosopon for face and agnosia for ignorance. The condition varies widely. Although eyes, nose, and mouth can be seen clearly, the problem is recognizing the same set of features when seeing them again, and it complicates everything from being able to pick out a criminal from a line-up to being able to follow the plot of a movie.

In mild forms, prosopagnosics learn to memorize a limited number of faces--rather like being able to distinguish one telephone pole or rock from another. Others have trouble identifying their own family members, and in extreme cases some do not even recognize their own faces. A woman in Colorado says when standing in front of a mirror in a crowded restroom, she makes a face so she can tell which one is her own. Most people with the condition learn coping behaviors to avoid being thought of as lazy, uncaring, or snobbish. This may be why the disorder was thought to be rare. They learn to distinguish individuals by voice, hair style, gait, or body shape. Often they avoid going to places where they might run into someone they know unexpectedly. Sometimes they pretend they are lost in thought, or they are friendly to everyone--or no one--and become expert at coveting up their problem.

Researcher Thomas Gruter speculates that a specific, dominant gene is defective, and that if one parent has it, there is a 50% chance of inheriting it. At the University of London, Bradley Duchaine runs the Prosopagnosia Research Centers with Harvard University's Ken Nakayama. When Duchaine gave a battery of tests to one family, every member performed poorly--one said she thought that Elvis Presley was Brooke Shields. While neuroscientists are not sure how the brain perceives faces, it is known that the ability to do so is present at birth. Scans of the brain suggest the problem lies in the temporal or occipital lobes.