Face Blindess: Why Some People Don't Always Recognize You (VIDEO)

In 1985, Columbia Professor and acclaimed neurologist Oliver Sacks, M.D., wrote "The Man Who Mistook His Wife For a Hat." In the book, Dr. Sacks recounted case histories of patients that were unable to or struggled with identifying a person's face -- in one case, a man could not recognize his wife's face from a hat.

This phenomenon is called prosopagnosia, or more commonly "face blindness," a disorder that may be inherited by about 2.5 percent of the population, according to a study on face recognition.

"Being social beings we need to recognize each other, and we do so in all sorts of ways, by the way people move, by the way they dress, their voices, where they are, but in particular we are very good at recognizing each others faces," Sacks said recently in a video he recorded on the disorder.

Sacks described a face recognition spectrum, in which 80 percent of the population is "face normal." Those who fall low on the spectrum have trouble recognizing faces and those high on the spectrum he refers to as "super recognizers."

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