Prosopagnosia (Greek: “prosopon” = “face”, “agnosia” = “not knowing”) is a disorder of face perception where the ability to recognize faces is impaired, while the ability to recognize other objects may be relatively intact. The term originally referred to a condition following acute brain damage, but a congenital form of the disorder has been proposed, which may be inherited by about 2.5% of the population. The specific brain area usually associated with prosopagnosia is the fusiform gyrus.
Few successful therapies have so far been developed for affected people, although individuals often learn to use ‘piecemeal’ or ‘feature by feature’ recognition strategies. This may involve secondary clues such as clothing, gait, hair color, body shape, and voice. Because the face seems to function as an important identifying feature in memory, it can also be difficult for people with this condition to keep track of information about people, and socialize normally with others.
Prosopagnosia on Wikipedia.