Patient DF is a woman with visual apperceptive agnosia who has been studied extensively due to the implications of her behavior for the two streams theory of visual perception. Though her vision remains intact, she has trouble visually locating and identifying objects. Her agnosia is thought to be caused by a bilateral lesion to her lateral occipital cortex, an area thought by dual-stream proponents to be the ventral "object recognition" stream.[1] Despite being unable to identify or recognize objects, DF can still use visual input to guide her action.