It is an impairment in recognition or assigning meaning to a stimulus that is accurately perceived and not associated with a generalized deficit in intelligence, memory, language or attention.

[1] The disorder appears to be very uncommon in a "pure" or uncomplicated form and is usually accompanied by other complex neuropsychological problems due to the nature of the etiology.

[7][9] Environmental toxins and pathogens have also been implicated, such as, carbon monoxide poisoning or herpes encephalitis and infrequent developmental occurrences have been documented.

[11] The etiology of the cognitive impairment, as well the areas of the brain affected by lesions and stage of recovery are the primary determinants of the pattern of deficit.

[8] Warrington (1975)[15] offered that the problem lies in impaired access to generic engrams (memory traces) that describe categories of objects made up of a multitude of similar elements.

[9] For example, a distinction is made between functional and visual components of various stimuli, such that impairment to these aspects of the memory trace will inhibit the re-injection process needed to complete the object representation.

[7] Individuals may retain semantic knowledge of the items, as exemplified during tasks where objects are presented through alternate modalities, through touch or verbal naming or description.

Some associative visual object agnostics retain the ability to categorize items by context or general category, though unable to name or describe them.

This type of deficit is typically associated with head injury or stroke, though other medical conditions have been implicated, such as, herpes encephalitis.

This condition is associated with damage to the medial occipito-temporal gyri, including the fusiform and lingual gryi, as the suggested location of the brain's face recognition units.

Both disorders linked to damage in the occipito-temporal cortex, especially in the left hemisphere, which is believed to play a significant role in color memory.

Detailed testing is conducted, using specially formulated assessment materials, and referrals to neurological specialists is recommended to support a diagnosis via brain imaging or recording techniques.

[1] Testing usually consists of object identification and perception tasks including: Sensory modality testing allows practitioners to assess for generalized versus specific deficits, distinguishing visual agnosias from optic aphasia, which is a more generalized deficit in semantic knowledge for objects that spans multiple sensory modalities, indicating an impairment in the semantic representations themselves.

[1] The affected individual may not realize that they have a visual problem and may complain of becoming "clumsy" or "muddled" when performing familiar tasks such as setting the table or simple DIY.

[16] Because agnosias result from brain lesions, no direct treatment for them currently exists, and intervention is aimed at utilization of coping strategies by patients and those around them.

[2] However, even with forms of compensation, some affected individuals may no longer be able to fulfill the requirements of their occupation or perform common tasks, such as, eating or navigating.