Prosopagnosia or prosopagnosia, is a perceptual deficit acquired or congenital central nervous system that prevents individuals who are affected to properly recognize people's faces, it is determined by a damaged area of the brain to the task, turn fusiform.

It was studied thoroughly in the eighteenth century by several scientists, including John Hughlings Jackson and Jean Martin Charcot. 

The term Prosopagnosia was coined in 1947 by German neurologist Joachim Bodamer and appears to be the union of Greek words πρόσωπον (prosopon, side) and αγνωσία (agnosia, not knowledge). Since that time, more than a hundred case reports have been published.

Prosopagnosics often have difficulty recognizing people that they have encountered many times. Most of the cases of prosopagnosia that have been documented have been due to brain damage suffered after maturity from head trauma, stroke, and degenerative diseases.

"The Man Who Mistook His Wife for a Hat and Other Clinical Tales", a 1985 book by neurologist Oliver Sacks describing the case histories of some of his patients, refers to the most tragic feature of the case as Dr P. who was totally unaware of his defect.

The title derives from one of the gaffes of this patient, an "eminent musician, who gradually began to show a progressive cognitive failure at everything he saw every day and to confuse between their objects and particularly people living”, at the end of an interview with Dr. Sacks confused head of his wife with his hat, and grabbed her by trying to put it in his head.

Prosopagnosia, also called face blindness, is often accompanied by other types of recognition impairments, place recognition, car recognition, facial expression of emotion, etc. though sometimes it appears to be restricted to facial identity. Prosopagnosia can create serious social problems.
Prosopagnosics often have difficulty recognizing family members, close friends, and even themselves.