ABSTRACT
Visual agnosic disorders are impairments in “higher order” or “complex” visual capacities based on both visual–perceptual and visual–cognitive functions and their interactions. Cognition comes into play in nearly every aspect of visual perception, because of the multiple involvement of cognitive capacities such as attention, memory, and planning in the detection, discrimination, identification, and recognition of visual stimuli, and in the visual guidance of motor activities. A clear differentiation between genuine agnosic symptoms and secondary impairments is also of great importance for treatment. Visual object agnosia refers to the difficulty in identifying and recognising objects in the visual modality, while their identification and recognition is preserved in another modality, i.e. when allowed to handle the object or hear its sound when in use. The term topographical agnosia is often used to describe various difficulties with geographical orientation either in the real world or on maps, or both.
