What is visual agnosia?
Visual agnosia is a neurological disorder. A person may not be able to recognize a familiar object using only sight, even when they have otherwise normal vision. A person with visual agnosia may need to rely on other senses to recognize everyday items.
For example, a person who can’t identify a banana by looking at it will likely be able to name the familiar fruit by touch, smell or taste. Or, they would look at a toothbrush and not know it’s used to clean teeth without using the other senses to recognize it.
Visual agnosia is a type of agnosia. Agnosia is a neurological disorder. It can interfere with the ability to recognize familiar objects using one of the five senses. The word agnosia comes from a Greek word meaning “lack of knowledge.”
With visual agnosia, a patient can have difficulty recognizing objects or aspects of objects by sight. This can happen because there may be damage along one of two main visual pathways in the brain. The “what” pathway relates to what you are seeing. The “where” pathway relates to the location of an object in space.
People with visual agnosia may have no other problems with their eyesight or with their memory. They likely have damage in certain parts of the cerebral cortex. These areas are responsible for processing specific aspects of vision.
Types of visual agnosia
General visual agnosia may include the inability to recognize known objects by sight. There are two main types of general visual agnosia: apperceptive visual agnosia and associative visual agnosia.
With apperceptive visual agnosia, a person may have trouble recognizing images their eyes see. Depending on the type of apperceptive visual agnosia, a person with this type of visual agnosia may not be able to:
Perceive the form or size of an object
Distinguish between objects in a group
Copy a drawing of a common object, like a tree or a shoe
With associative visual agnosia, a person may have difficulty linking an object with memories of similar objects. However, they can typically draw or verbally describe objects. For example, they may be able to look at an object and tell you it’s small, gray and smooth but not that it is a stone.
Other types of visual agnosia
There are also other types of visual agnosia. These can affect the ability to recognize certain types of things, people, places or scenes by sight. People who have one of these types of visual agnosia may also have general visual agnosia.
Other types of visual agnosia include:
Hollywood celebrity Brad Pitt has openly spoken of his struggles with “face blindness,” also known as prosopagnosia.
Autotopagnosia – Inability to recognize or name parts of their own body, such as fingers or toes
Prosopagnosia – Inability to put a name to a familiar face, such as a relative, a neighbor or a celebrity
Simultanagnosia – Inability to recognize a collection of objects, such as a set of tools, or a scene, such as a landscape
Topographagnosia – Inability to recognize familiar or famous places, such as the Grand Canyon or a friend’s living room
In many cases, people with visual agnosia may have good visual acuity, which is the sharpness of eyesight your eye doctor checks with an eye chart.
