What Is Agnosia?
Agnosia is a term used to define a condition where people are unable to recognize faces or other objects in their environment. People with agnosia may have difficulty recognizing familiar faces, but they will not lose track of the world around them. They may even see things that others do not perceive such as animals or insects. There are several different forms of agnosia and each one has its own causes and effects. However, all forms of agnosia share certain characteristics.
The most common form of agnosia is called “visual” agnosia. Visual agnosia refers to a deficit in recognizing facial features (faces) and other objects in the surrounding environment.
Other forms include: auditory, olfactory, gustatory and somatosensory.
Visual Agnosia Symptoms
People with visual agnosia usually cannot identify faces, but they will recognize familiar ones. For example, if someone were to walk into your room while you are sleeping and ask you who is in there, you would probably not be able to tell him or her apart from anyone else.
You might notice that the person looks like a friend or family member rather than a stranger. People with visual agnosia will tend to not recognize furniture, clothing and other objects either.
However, people who suffer from this condition usually do respond to environmental cues. If a storm is coming, they will probably seek shelter.
If a person is screaming in terror or pain, they will probably try to help. In fact, people who suffer from visual agnosia tend to have relatively normal intelligence, but may be prone to behavior problems. This is because they are unable to recognize appropriate social cues. While these people may not be able to recognize faces, they can learn to recognize voices and other sounds relatively quickly.
The most common causes of visual agnosia are injuries to the occipital cortex, which is located at the back of the brain. This area deals with vision, color perception and depth perception.
If this area is damaged, the patient may not be able to recognize faces or other objects. This can happen as the result of a stroke, aneurysm, trauma or brain tumor.
If you think you are suffering from visual agnosia, it is important to see a doctor immediately. The sooner the condition is identified and treated, the better your prognosis.
Although most cases of visual agnosia are caused by brain injury or disease, there are other causes which need to be ruled out as well. For example, vitamin deficiencies can also cause similar symptoms.
If your condition is due to a brain injury or disease, your doctor may recommend surgery, drug therapy or physical and occupational therapy as treatment options. In some cases, the patient’s prognosis is relatively good.
Even if the condition cannot be reversed completely, most sufferers of visual agnosia can learn to cope with their symptoms with a little help.
Sources & references used in this article:
Visual agnosia by MJ Farah – 2004 – books.google.com
Agnosia, apraxia, aphasia: Their value in cerebral localization by JM Nielsen – 1946 – pure.mpg.de
Perception and action in ‘visual form agnosia’ by AD Milner, DI Perrett, RS Johnston, PJ Benson… – Brain, 1991 – academic.oup.com
Agnosia for faces (prosopagnosia) by H Hecaen, R Angelergues – Archives of neurology, 1962 – jamanetwork.com