Imagine an entire day of seeing faces -- friends, co-workers, even family -- but not being able to retain those images in your mind. For 48-year-old Kiki Latimer, each time she sees someone is often like the first time. She has face blindness.

She first realized she had a problem in her 20s while working at a youth hostel. "One particular guest came back every week, and every time I didn't recognize him. He started to look at me like I was a fruitcake."

Face blindness, also known as prosopagnosia, is an impairment in the ability to recognize faces. Usually prosopagnosics are able to actually see the features on a person's visage with no difficulty; it is the retention of those images that challenges them.

Most of us have difficulty recognizing a face at one time or another. But prosopagnosics have trouble identifying others whom they have met repeatedly, or even lifelong acquaintances, including close friends or family members.

"When I was younger I remember saying 'that's not me' when I looked in the mirror," recalls Latimer. "I remember thinking it was just something weird."
Join the club

It was not until about six years ago that Latimer learned her condition actually had a name, that her case was mild to moderate in severity and that she was not alone.

Originally most scientists thought that face blindness was an extremely rare disease. But in August 2006, a German study in the American Journal of Medical Genetics found that as many as one in 50 people may have some form of prosopagnosia. A separate Web survey of 1,600 people done by Harvard University's Ken Nakayama and University College of London researchers substantiates the German study findings.

Dr. Nakayama, a psychologist at Harvard's Vision Sciences Laboratory, suggests that an even larger portion of the population may have very mild cases of face blindness. "Maybe 10 percent of people have quite mild cases, but it's still embarrassing and disabling sometimes," says Nakayama.

Some face-blind people are thought to acquire the condition as a result of a head injury, but many more are believed to have "developmental prosopagnosia," meaning they were either born with it or developed it early in life.

Dr. Nakayama hopes that higher-prevalence findings will lead to more research and ultimately, a medical treatment for face blindness. As it stands, scientists have yet to agree upon the actual cause of the disease, but many suspect it is linked to the fusiform gyrus, an area of the brain that has been shown to respond to seeing faces.

Taking cues

Until a medical treatment is found, prosopagnosics must continue to rely on common cues including hairstyle, body language or voice recognition to get by.

"If you have some sort of major distinguishing feature like big lips, or red hair, then I may be able to recognize you. But if you just have brown hair and brown eyes, I may not be able to tell. So sometimes I just kind of fake it," Latimer acknowledges.

Many people with the disease rely on the "buddy system" in social settings, using a companion to help identify others to avoid embarrassment. Others avoid parties or large gatherings altogether, opting for more intimate opportunities instead.

Contextual clues such as location also help. But without them, the face-blind are often helpless. For example, a prosopagnosic may acknowledge his next-door neighbor regularly from his driveway, but then appear to ignore the neighbor at a restaurant elsewhere, for lack of familiar context by which to recognize the neighbor.

"You can see how this can get you into quite a bit of trouble," says Nakayama. "How much of your daily life really requires you to recognize faces? It can be quite a challenge."
A challenge on many levels

Latimer has learned it's easier to explain her face blindness to acquaintances rather than risk the chance of being misunderstood as snobbish or unkind. "I don't mind if I just look like an idiot, but if I hear someone thinks I don't like them because I didn't say 'hello,' that's the hardest thing."

"Some of the stories we are starting to hear are really heartbreaking," Dr. Nakayama adds. "People recalling their childhood sometimes can't remember their sister, or their other friends on the playground."

Latimer also speaks of vulnerability from not being able to discern whether a face belongs to a friend or foe. "Luckily, though, I am very good with emotions, and I can sense if someone is hostile."

However, other prosopagnosics may not be as fortunate. Glenn, a 28-year old who developed severe face blindness after a childhood accident, requested we withhold using his last name during his interview. "It creates the possibility of inviting potential criminals to take advantage of me if they should recognize me," he explains.

Beyond the social awkwardness and security concerns that face blindness raises lie a multitude of everyday issues that are not as obvious. For Latimer, certain movie plots are particularly confusing. "If we went to a movie with three dark-haired men, I often thought there was just one. At the end I'd ask, 'What bad guy?' "

Many of the subjects that Nakayama's team has studied say they have spent much of their lives compensating for their face blindness. "They spend so much time, but somehow, they do it."