Mirror Agnosia is momentary confusion with mirrors. Lewis Carol was known to have suffered from migraine attacks caused by arterial spasms. If they affected his right parietal lobe, it might not only have inspired him to write “Through the Looking Glass,” but might help explain his general obsession with mirrors, mirror writing and left-right reversal.
— V.S. Ramachandran, Phantoms in the Brain

Agnosia: a rare disorder characterized by the lack of ability to recognize individuals, objects, shapes, sounds, or smells. There is no loss of “memory.” It is caused by neurological damage in the brain, specifically in the “occipital” or “parietal lobes.” (NCIt)

Failure of recognition that cannot be attributed to elementary sensory defects, mental, or linguistic deterioration, or attentional disturbances. Often limited to one sensory modality. (Koch, 217) Characterized by an inability to recognize and identify objects and people even though the specific sensory modality (such as vision or hearing) is not defective nor is there any significant loss of memory or intellect. (RamachandranTTB, 294)


Auditory Associative Agnosia: inability to identify environmental sounds by their sources. Result of damage to “left temporal lobe.” (Goldberg, 30)

Capgras Syndrome: a rare syndrome in which the person is convinced that close relatives - usually parents, spouse, children or siblings - are impostors. Might recognize the faces of loved ones but not feel the emotional reaction normally associated with that person. (RamachandranTTB, 296) A rare neuropsychiatric disorder whose primary feature is the delusion that relatives or close acquaintances are not the persons that they are known to be. Visual recognition appears intact but familiar persons are thought be imposters, that is, they appear similar or identical to known individuals but are not. (NCIt) The patient insists that a loved one, has been taken over by an impostor who looks, talks, and feels exactly the way she used to do before the alien replaced her. (Koch, 218) Also referred to as ‘Capgras delusion.’

Finger Agnosia: a brain disorder in which patients can no longer name which finger the neurologist is pointing to or touching. (Ramachandran, 19) (Brain) map disorder. The inability to distinguish the fingers on your hand. (Blakeslee, 105, 213) (Typically caused by) lesions in the “inferior parietal lobule” in the “left hemisphere.” (Blumenfeld, 43)

Mirror Agnosia: momentary confusion with mirrors. (Ramachandran, 124) Also referred to as ‘looking glass syndrome.’

Prosopagnosia: a specific visual inability to recognize faces. In ‘associative prosopagnosia,’ the patient is unable to recognize famous or familiar faces. (Koch, 343) The inability to recognize a familiar face or to learn to recognize new faces. (MeSH) Impaired ability to recognize other human faces in the absence of a vision disorder. It may be a “congenital” disorder or the result of brain injury. (NCIt) Also referred to as ‘face blindness.'

Visual Agnosia: an inability to recognize or interpret objects by sight. (NCIt) Patients, after a "stroke," are unable to recognize familiar objects visually. People with this condition, can have perfectly normal "visual acuity,"  "color perception," visual fields, and so on - yet be totally unable to recognize or identify what they are seeing. (Sacks2, 56) Typically, a visual agnosia patient can't recognize a set of keys on a chain dangling in front of her. If she grabs them or if they are jingled, (however), she immediately knows what they are. (Koch, 217)

Alexia: the patient cannot read because he is unable to identify the letters and words, but he retains the ability to write and his speech is normal. (OxfordMed) Not that uncommon, although it usually comes on suddenly, following a stroke or other brain injury. (Sacks2, 5) A receptive visual aphasia characterized by the loss of a previously possessed ability to comprehend the meaning or significance of handwritten words, despite intact vision. This condition may be associated with posterior cerebral “artery” “infarction” and other brain diseases. (MeSH) Also referred to as ‘acquired dyslexia,’ and ‘word blindness.’

Aphasic Alexia: inability to read or write. Often has an accompanying disorder of speech. (OxfordMed) Also referred to as ‘visual asymbolia.’

Musical Alexia: an inability to read musical notation. (Sacks2, 6)

Simultanagnosia: a symptom describing the inability to comprehend more than one element of a visual picture at a given moment, or to integrate the whole visual picture. (NCIt)