These may arise because of agnosia and oral dyspraxia.
Recognition errors are semantic (identifying a camel as a dog) whereas in apperceptive agnosia errors are typically visually based.
Predominant involvement of both temporal lobes leads to a syndrome of fluent aphasia with associative visual agnosia (semantic dementia).
Many of the same researchers who studied the visual agnosia patients have also carried out parallel research on healthy subjects.
Visual agnosia leads to a variety of severe behavioural problems.
Failure of object recognition in associative agnosia may not be total.
The removal of binocular cues disrupts the calibration of grasping in patients with visual form agnosia.
In other words, this patient is apparently incapable of using her ventral system for analyzing visual input; that is, she is suffering from an extreme type of visual form agnosia.
