Some people claim to never forget a face. And the ability can prove to be socially awkward.

A new study finds some people can remember faces of people they met years ago and only in passing. Others of us, of course, aren't blessed with that ability. In fact about 2 percent of the population have prosopagnosia, a condition characterized by great difficulty in recognizing faces.

The "super-recognizers," as they're being called, excel at recalling faces and suggest that there is — as with many things — a broad spectrum of ability in this realm. The research involved administering standardized face recognition tests. The super-recognizers scored far above average on these tests — higher than any of the normal control subjects.

"There has been a default assumption that there is either normal face recognition, or there is disordered face recognition," said Richard Russell, a postdoctoral researcher in the Department of Psychology at Harvard. "This suggests that's not the case, that there is actually a very wide range of ability."

Super-recognizers recognize other people far more often than they are recognized. So they often compensate by pretending not to recognize someone they met in passing, so as to avoid appearing to attribute undue importance to a fleeting encounter, Russell said.

"Super-recognizers have these extreme stories of recognizing people," says Russell. "They recognize a person who was shopping in the same store with them two months ago, for example, even if they didn't speak to the person. It doesn't have to be a significant interaction; they really stand out in terms of their ability to remember the people who were actually less significant."

The finding could be important in courts, where one person's eyewitness testimony might thus be more credible than another based on their varying abilities to recognize a face. A study in 2005 found that people sometimes claim to identify criminals when the sheer physical distances of their accounts suggest facial recognition would not have been possible.

People from different cultures have different face-recognition skills, a study last year found. Westerners often concentrate on individual details, while East Asians tend to focus on how details relate to each other.

One woman in the new study said she had identified another woman on the street who served as her as a waitress five years earlier in a different city. Critically, she was able to confirm that the other woman had in fact been a waitress in the different city.

Often, super-recognizers are able to recognize another person despite significant changes in appearance, such as aging or a different hair color.

The research is detailed in the journal Psychonomic Bulletin & Review. The research was funded by the U.S. National Eye Institute and the U.K. Economic and Social Research Council.

Russsel sees an interesting historical aspect to the finding.

"Until recently, most humans lived in much smaller communities, with many fewer people interacting on a regular basis within a group," he said. "It may be a fairly new phenomenon that there's even a need to recognize large numbers of people."