She can recall almost every day back to age seven. In her earliest memories, she’s still a baby.
For decades Henner—nicknamed the Memory Kid and Univac, after an early computer—sought the perfect analogy to explain her baffling memory. “You know how a card catalog works?” she used to say. When VHS tapes became commonplace, she talked about a tape that she could cue. Then the DVD was invented, and she had the perfect metaphor: her brain had a scene selection function.
When she thinks of a certain year—say, 1976—the major dates come in first. “I see, oh yeah, Christmas was on a Saturday. My birthday was on a Tuesday. And it just starts filling in, filling in, filling in,” she says. “Simultaneous little videos are playing next to each other, all these 365 days—well, that year, 366. Some of them are a little dark and haven’t come in fully yet, but if I sat here for like 15 minutes, I could do every day of 1976.”
Henner is one of only 33 known cases of highly superior autobiographical memory (HSAM) in the world. Originally called hyperthymesia (a term Henner doesn’t like because it sounds like a malady), HSAM was identified by James McGaugh, professor of neurobiology at the University of California, Irvine, in 2006. Its two defining characteristics, McGaugh wrote in the journal Neurocase: “the person spends an abnormally large amount of time thinking about his or her personal past” and “the person has an extraordinary capacity to recall specific events from their personal past.”
When McGaugh’s team scanned Henner’s brain, they found that several regions related to memory were much larger than normal. They also tested Henner by giving her ten random dates throughout her lifetime (beginning at age 15) and asking her the day of the week, what she did, and a public event that happened within a month. Henner received a perfect score.
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