visual agnosia

Agnosia is a neurological disorder characterized by the loss of the ability to recognize objects, sounds, smells, tastes, or other sensory stimuli. This occurs without obvious deficits in memory or sensory function, as the sensory organs themselves remain intact. Agnosia typically results from damage to the brain regions responsible for integrating experience and perception, often caused by events like stroke or carbon monoxide poisoning.1

Visual agnosia, a common type, involves the inability to recognize what is seen. It can be apperceptive, where the shape or structure of an object cannot be perceived, or associative, where the meaning of a seen object cannot be ascribed. For example, someone with prosopagnosia, a form of associative agnosia, cannot recognize faces. Optic ataxia is a related condition where visual guidance over reaching with the hand and arm is lost, leading to inaccurate visually guided movements. This is often due to damage in the parietal and occipital lobes of the brain.12