Indeed, when she was asked to give the direction of the slot, her responses were no better than chance. Yet, when she was asked to place the card into the slot, her success was almost to the level of the controls. This implies that in the event of a ventral stream deficit, the dorsal stream can help with processing of special information to aid movement regardless of object recognition.More specifically, the lateral occipital complex appears to respond to many different types of objects. Prosopagnosia (inability to recognize faces) is due to damage of the fusiform face area (FFA). An area in the fusiform gyrus of the temporal lobe that has been strongly associated with a role in facial recognition. However, this area is not exclusive to faces; recognition of other objects of expertise are also processed in this area. The extrastriate body cortex (EBA) was found to be activated by photographs, silhouettes, or stick drawings of human bodies. The parahippocampal place area (PPA) of the limbic cortex has been found to be activated by the sight of scenes and backgrounds. Cerebral achromatopsia (the inability to discriminate between different hues) is caused by damage to the V8 area of the visual association cortex.The left hemisphere seems to play a critical role in recognizing the meaning of common objects. Diagnosis
Classification
Broadly, visual agnosia is divided into apperceptive and associative visual agnosia.Apperceptive agnosia is failure of object recognition even when the basic visual functions (acuity, color, motion) and other mental processing, such as language and intelligence, are normal.
is able to identify parts of objects but cannot generate a whole representation. It should not be surprising then that his visual imagery for object size, shape, and color is intact. For example, when shown a picture of an animal, he can correctly answer questions such as "are the ears up or down?" and "is the tail long or short?" He can correctly identify colors, for example that the inside of a cantaloupe is orange. Finally, C.K. can generate internal images and perceive these generated objects. For example, Finke, Pinker, and Farah instructed C.K. to imagine a scenario where a B is rotated 90 degrees to the left, a triangle is put below, and the line in the middle is removed. C.K. can correctly identify this object as a heart by picturing this transformation in his head. Evidence for double dissociation between face and object processing
Patient C.K. provided evidence for a double dissociation between face processing and visual object processing. Patients with prosopagnosia have damage to the Fusiform Face Area (FFA) and are unable to recognize upright faces. C.K. has no difficulty with face processing and matches the performance of controls when tasked with identifying upright famous faces. When shown inverted faces of famous people, C.K. performs significantly worse than controls. This is because processing inverted faces involves a piecemeal strategy. C.K.s performance is compared to patients with prosopagnosia who are impaired in face processing but perform well identifying inverted faces.