direction at speed up to 9 degrees per second. When speed of targets was above 9 degrees per second, TD's performance dropped dramatically to 50% correct at a speed of 15 degrees per second and 0% correct at 24 degrees per second. When the blocks moved at 24 degrees per second, TD consistently reported the exact opposite direction of the actual movement. Pelak and Hoyt's Alzheimer's patient In 2000, a 70-year-old man presented with akinetopsia. He had stopped driving two years prior because he could no longer "see movement while driving". His wife noted that he could not judge the speed of another car or how far away it was. He had difficulty watching television with significant action or movement, such as sporting events or action-filled TV shows. He frequently commented to his wife that he could not "see anything going on". When objects began to move they would disappear. He could, however, watch the news, because no significant action occurred. In addition he had signs of Balint's syndrome (mild simultanagnosia, optic ataxia, and optic apraxia). Pelak and Hoyt's TBI patient In 2003, a 60-year-old man complained of the inability to perceive visual motion following a traumatic brain injury, two years prior, in which a large cedar light pole fell and struck his head. He gave examples of his difficulty as a hunter. He was unable to notice game, to track other hunters, or to see his dog coming towards him. Instead, these objects would appear in one location and then another, without any movement being seen between the two locations. He had difficulties driving and following a group conversation. He lost his place when vertically or horizontally scanning a written document and was unable to visualize three-dimensional images from two-dimensional blueprints. References Visual disturbances and blindness Agnosia Visual perception Neuropsychology Dementia