Science of mental and behavioural impairments resulting from brain damage. Focuses on which processes are compromised and spared. Normal process: sensation -> stimulus representation -> semantic information (meaning, identity) Can discover what things are through other senses. Unable to form stable [pre-semantic; before identifying] representations of objects. Cannot generate stimulus representation; can get colour and orientation, but cannot integrate into single percept. Can form percept of object but cannot identify. Communication from stimulus representation to semantic information is damaged. Associative agnosia for some categories of objects but not others i. e. prosopagnosia. Areas in brain for specific functions (i. e. face) may not be true; suggests areas have neurons for many categories. Can still recognize with voice, hair, and clothing. Many people who have this usually do not tell others. Can have internal image of face, but no communication with the knowledge of the face.