A stroke can sometimes leave people with a syndrome known as hemispatial neglect as a result of damage to the parietal lobe on the right or left side of their brain. The damage means the brain ignores people, sounds, and objects on one side. Two patients explain the disruption to their everyday lives, and Dr Paresh Malhotra of Imperial College London describes his research into this baffling syndrome: https://www.theguardian.com/science/video/2012/dec/23/stroke-half-world-disappear-video