If you ask Jill Price to remember any day of her life, she can come up with an answer in a heartbeat. She had always had a talent for remembering. Price was the first person ever to be diagnosed with what is now known as highly superior autobiographical memory, or HSAM, a condition she shares with around 60 other known people. She can remember most of the days of her life as clearly as the rest of us remember the recent past, with a mixture of broad strokes and sharp detail. Now 51, Price remembers the day of the week for every date since 1980; she remembers what she was doing, who she was with, where she was on each of these days. She can actively recall a memory of 20 years ago as easily as a memory of two days ago, but her memories are also triggered involuntarily. It is, she says, like living with a split screen: on the left side is the present, on the right is a constantly rolling reel of memories, each one sparked by the appearance of present-day stimuli. In order to figure out how HSAM worked, researchers first needed to understand what it was and was not. HSAM subjects turned out to be far better than people with average memories at recalling long-past autobiographical data; in memories that could be verified, they were correct 87% of the time. It is still unclear whether HSAM will turn out to be a fascinating curiosity, or a key that unlocks the deepest mysteries about how memory works.