Living Reference Work Entry

Encyclopedia of Clinical Neuropsychology

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Date: Latest Version



Agnosia is a failure to recognize a sensory stimulus that is not attributable to dysfunction of peripheral sensory mechanisms or to other cognitive impairments associated with brain damage (Bauer 2012). Agnosia is often described as a percept that is “stripped of its meaning” (Teuber 1968). The individual can respond to the presence of the stimulus but has difficulty processing the perceptual information in sufficient detail to make sense of and meaningfully recognize the stimulus. The difficulty is modality specific (e.g., visual), so the stimulus can be recognized through other sensory modalities (e.g., tactile or auditory).

Current Knowledge

Different forms of agnosia have been described that depend upon the detail with which the incoming stimulus is processed and the sensory modality and type of materials that pose difficulty. Lissauer (1890) used the terms apperceptive and associative, to classify the agnosias, terms that continue to guide descriptions of agnosia (Farah 20 ...

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