It can be difficult to remember people's faces at certain times, but for some, it's impossible all the time. 

A mental disorder called prosopagnosia, also known as "face blindness," disables the sufferer's capacity for remembering and recognizing faces. Those of us without the disorder can recognize our loved ones and friends by their familiar features, but to sufferers of face blindness, they are a labyrinth.

The problem doesn't lie in seeing the features, as the common moniker might imply; instead, the problem lies in recognizing and retaining them. A prosopagnosiac can actually see a woman's nose, a man's eyes, or a child's lips. But upon a second look, the nose, eyes, or lips will be totally unfamiliar.

Interestingly, most prosopagnosiacs are able to remember people themselves - they just adapt. They learn to recognize them by other features, such as their hair color, or distinctive jewelry. It can be quite difficult, though, and people unfamiliar with their condition may feel as if they are being shunned or slighted. Imagine seeing someone every day, and having them not recognize you. Wouldn't you think they dislike you, or that they think you're forgettable?

What cerebral glitch causes this disorder, and why does it only apply to faces? Neurologists and are fascinated by this unique gem of a condition. In the past - such as when a German doctor discovered the condition - it was impossible to view the parts of the brain of a living subject. However, recent advances in technology and a growing awareness of prosopagnosia have enabled research. Sufferers are able to find support groups online, and their surveys and reports go a long way to help collect information for the scientists.

Research has shown that the face blind are the same as any other person at memorizing other things - it is only faces where they uniformly have trouble. But why? The idea that some mental function only exists to recognize faces seems almost absurd - that prosopagnosiacs lack this function - but what other solution could there be? And the implications of that are astonishing - what else do the different parts do? Neurology is a new and exciting field, and the possibility of future knowledge, or mapping the brain, is tantalizing to scientists.

And if one piece of the human brain exists to recognize faces (which was undoubtedly a handy evolutionary trait), what do other parts do? Are there individualized compartments for other seemingly random things, or other facets of the human body? And what do they do? This disorder raises a countless number of intriguing questions about the biology of the brain, all of which neurologists and other scientists are sure to have answers to on the horizon.