The study of how the external world gets represented in our brain/mind so that we can understand and act upon what"s going on around us. Observations from patients with agnosia give us an indication of the processing that occurs during vision. Agnosia is a deficit in recognition despite normal vision. Patients with apperceptive agnosia are unable to name, match or discriminate visually presented objects. Patients can"t combine basic visual information into a complete percept, therefore they show deficits in copying as well. Patients with associative agnosia cannot associate a visual pattern with meaning. Patients are able to combine visual features into a whole, so they are able to copy well. Patient data tell us there are separate steps to visual perception. Basic visual components have to be assembled as a whole. Input comes and must be grouped, but still not enough for object recognition. What you see isn"t what you get.