Did you hear the news item reporting that a famous actor apparently is convinced that he suffers from face blindness or prosopagnosia, (from the Greek prosopon for face and agnosia for ignorance)? it’s not that the individuals are unable to recognize a human face, it’s that they have difficulty recognizing the same set of features when they see them again. For a good many years prosopagnosia was believed to be very rare and stem from some type of brain injury. That impression has changed based on studies by a team of German researchers. Their conclusions, published in the American Journal of Medical Genetics, showed that this is a highly heritable condition (e.g., they speculate it may be caused by a defect in a single dominant gene). It is more common than previously believed, estimated to affect about 1 in 50 people. Of course the condition varies widely: some individuals are able to memorize a limited number of faces, while others have difficulty recognizing their own face in group pictures. Most prosopagnosics learn to cope early on by training themselves to distinguish people based on cues like hairstyle, voice, gait, or body shape; or avoiding places where they could unexpectedly run into someone they know; or pretending to be lost in thought (unfortunately giving rise to the assumption that they are “stuck up”); or acting friendly to everyone; and so on. While I typically have some sense about whether or not I’ve seen a specific face before, I rarely know WHERE that was. My modus operandi is simply to say, “I believe we’ve met before. Please remind be when and where.” Knowing about prosopagnosia and its estimated prevalence gives you the option of not taking it personally when it appears someone has failed to recognize you . . .