Visual Object Agnosia

Synonyms

Monomodal visual amnesia; Visual amnesia

Definition

Visual object agnosia is a difficulty in recognizing objects presented visually and cannot be explained by primary visual defect, mental deterioration, disorder of attention, or a lack of familiarity with the object.

Current Knowledge

In visual object agnosia, the individual retains the ability to recognize the object through sensory modalities other than vision (e.g., by touch). Two main types of visual object agnosia have been identified: apperceptive and associative. Apperceptive visual agnosia involves a deficit presumed to lie in the production of a stable percept arising from an impairment of higher order visual perception and is thought to result from lesions of the secondary or unimodal visual association areas. Associative visual agnosiastems from the disruption of the post-perceptual stage of visual processing in which, meaning is attributed to the visual percept. Unlike in the apperceptive form, patients with...