In short: hyperthymesia, now usually called highly superior autobiographical memory (HSAM), is the rare ability to recall the events of your own life in detail, day by day, usually from around age 10 to 12 onwards. Give someone with HSAM a date and they can typically name the weekday and what they did. It is limited to their own lives: they are not better at memorising lists or facts, and it is not a photographic memory.
What is hyperthymesia?
Hyperthymesia is an exceptional memory for your own life. People who have it can usually recall what happened on a given date, which day of the week it fell on, and often what was in the news, for nearly every day since late childhood. Researchers describe two defining features: an unusually detailed memory for personal events, and a habit of spending a great deal of time thinking about the past.
The name was coined in 2006 by the scientists who first described it, Elizabeth Parker, Larry Cahill and James McGaugh at the University of California, Irvine. They called it "hyperthymestic syndrome", combining hyper (more than normal) with what they described as a Greek word for remembering. Most researchers now use a plainer name, highly superior autobiographical memory, or HSAM, and this page uses both.
Figures from UC Irvine's 2012 report on its HSAM research.
The first case: Jill Price
In June 2000, a woman from California emailed James McGaugh, a neuroscientist who studies memory, asking for help. She explained that she could remember every day of her life since she was a teenager, and described her memory as "non-stop, uncontrollable and totally exhausting".
McGaugh's team spent more than five years testing her. Given a random date, she could say what weekday it was, what she had done and what was happening in the world, and her answers could be checked against her diaries and public records. They published her case in the journal Neurocase in 2006, calling her "AJ" to protect her privacy. In 2008 she went public as Jill Price in a memoir, The Woman Who Can't Forget. She dates her unbroken memory to Tuesday 5 February 1980, when she was 14.
Price's case surprised the researchers in one important way: her extraordinary memory was selective. On many ordinary memory and thinking tests she was unremarkable, and she found memorising things for school hard. Her exceptional memory was for her own life.
What people with HSAM remember, and what they don't
After Price's case was published, many more people came forward. In 2012 the UC Irvine team, led by Aurora LePort, compared 11 people with HSAM with people of the same age and sex. The difference was sharp, but narrow:
- Lab memory tests: little advantage. On most standard tests and memorising tasks, people with HSAM scored much like everyone else, though they did better at recalling a short story and at matching names to faces.
- Their own past: a huge advantage. For personal and public events from about the age of 10½ onwards, they recalled far more, and far more accurately.
A follow-up study in 2016 looked at how their memories hold up over time. When asked about the past week, people with HSAM recalled about as much as everyone else. The gap opened up at longer delays: a month, a year and ten years back, they still remembered a great deal, while other people's recall fell away.
An illustration of the pattern found by LePort and colleagues (2016). Bar heights show the shape of the result, not measured values.
The authors concluded that people with HSAM take in memories normally, but store and keep them far better over time. And their memories are not flawless records. A 2013 study by Lawrence Patihis, Elizabeth Loftus and colleagues found they were just as prone to some kinds of false memory as anyone else, which suggests they rebuild memories the same way the rest of us do.
Signs of hyperthymesia
There is no official checklist of hyperthymesia symptoms, but the people studied so far share a recognisable pattern:
- Dates bring back daysGiven almost any date from late childhood onwards, they can say what day of the week it was and what they did.
- A lot of time spent in the pastThey spend an unusual amount of time thinking about their own past, often without trying to.
- Memories arrive on their ownA date, a song or a smell can bring a specific day back in detail, along with how it felt.
- A personal, not general, memoryThey are not especially good at memorising lists, numbers or school facts. The gift is for their own life.
- A love of order and collectionsMany have strong organising habits or large, carefully catalogued collections, and some show obsessive-compulsive tendencies.
- Starts around 10 to 12The day-by-day memory usually begins in late childhood, not at birth.
Studies have also found that people with HSAM score higher than average on absorption and fantasy proneness, the tendency to become deeply immersed in experiences and imagination (Patihis, 2016). One idea is that this habit of reliving experiences helps lock memories in, though that is still unproven.
Is there a hyperthymesia test?
There is no official online hyperthymesia test, and no single question that proves it. Researchers confirm HSAM in stages, checking every answer they can against records:
The challenge below gives you a taste of stage 2. It picks five random dates from your life. Before each answer, try to recall what you did that day.
The 5 dates challenge
Choose your birth year to get five random dates from age 15 to yesterday. Nothing you enter leaves your browser.
First, can you remember anything you did that day?
Which day of the week was it?
Guessing the weekday at random gets about 1 in 7 right, so one correct answer is normal. This is a taste of the research screening, not a diagnosis: real screening also checks what you remember against records.
What happens in the brain
Scientists are still working out what makes HSAM possible, and the studies are small because so few people have it. So far:
- Brain structure. The 2012 UC Irvine study found differences in nine brain structures in people with HSAM, including stronger white-matter connections between the middle and front of the brain, mostly in areas linked to autobiographical memory.
- Brain activity. A 2018 brain-imaging study in PNAS, led by Valerio Santangelo, found that people with HSAM reached their memories faster and in richer detail. Brain regions involved in finding a memory were more active, but once a memory was found, their brains looked like everyone else's while reliving it.
- The bigger picture. A 2024 systematic review of all the research concluded that no single brain difference defines HSAM. Differences in how the hippocampus, the brain's memory hub, connects with other regions are among the more consistent findings.
In other words, people with HSAM don't seem to have a special memory organ. They appear to use the ordinary memory system unusually efficiently, especially when searching for the right day.
A gift or a burden?
It is tempting to think a perfect diary in your head would be wonderful. The people who have one are more divided.
"Most have called it a gift but I call it a burden."
Jill Price, in her first email to James McGaugh, as reported by The GuardianPrice has described how memories replay without warning and bring back the feelings that went with them, so an old embarrassment or loss can feel fresh decades later. For her, the hard part is not remembering but being unable to stop.
Others talk about it far more positively. The actress Marilu Henner, known for the TV series Taxi, has spoken publicly about her memory for years and wrote a book encouraging readers to explore their own past. The research suggests a mixed picture: many people with HSAM are highly organised collectors, while some, like Price, find it hard to let go of painful days.
People known to have HSAM
Most people with HSAM are private individuals. A few have spoken publicly or been described in research:
Can you develop hyperthymesia?
As far as anyone knows, no. HSAM appears on its own in late childhood, and there is no evidence that training can create it. Studies of people with HSAM show they don't use special techniques: their memories simply stay.
That doesn't mean your own memory can't improve. Memory techniques such as the memory palace work well for lists and facts, and keeping a diary or regularly looking back at photos helps you hold on to more of your own life. Our guide to photographic memory explains what training can and can't do.
Hyperthymesia vs photographic memory
The two are often confused, but they describe very different things:
| Hyperthymesia (HSAM) | Photographic memory | |
|---|---|---|
| What is remembered | The events of your own life, by date | Anything seen, recalled like a picture |
| Evidence | Confirmed in dozens of people, studied since 2006 | Never reliably shown in an adult |
| Lists and facts | No better than average | Would be perfect, in theory |
| Starts | Around age 10 to 12 | Not applicable |
| Accuracy | Very high, but still open to false memories | Not applicable |
If you want to see how your visual memory compares, try our photographic memory test, which measures scenes, patterns, numbers, chess positions and words.
Frequently asked questions
Is hyperthymesia a disorder?
No. It is not listed as a mental disorder in any diagnostic manual. Researchers describe it as a rare memory profile. Some people with it value it, while others find that unwanted memories, and the feelings attached to them, are hard to switch off.
How rare is hyperthymesia?
Very rare. When researchers at the University of California, Irvine reported their findings in 2012, they had assessed more than 500 people who believed they had it and confirmed 33. The number of confirmed cases worldwide is still counted in dozens, not thousands.
At what age does hyperthymesia start?
In the people studied so far, the detailed day-by-day memory usually starts around the age of 10 to 12. Jill Price, the first person described, dates her own unbroken memory to 5 February 1980, when she was 14.
Can children have hyperthymesia?
Yes, it seems so. In 2026 researchers in Rome described a 13-year-old boy, known as AA, as the first documented case in early adolescence. His mother had noticed he could name the weekday of dates from years earlier and say what he had done.
Do people with hyperthymesia remember everything?
No. Their remarkable memory is for their own lives, mostly from late childhood onwards. They are not generally better than other people at memorising lists, numbers or new facts, and like everyone they can misremember details.
Is hyperthymesia the same as a photographic memory?
No. A photographic memory would mean recalling anything you have seen, like a picture. Hyperthymesia is a memory for the events of your own life, organised by date. It is real but very rare, while a true photographic memory has never been reliably shown in an adult.
Sources
- Parker, E. S., Cahill, L. and McGaugh, J. L. (2006). A case of unusual autobiographical remembering. Neurocase, 12(1), 35–49.
- LePort, A. K. R. et al. (2012). Behavioral and neuroanatomical investigation of highly superior autobiographical memory (HSAM). Neurobiology of Learning and Memory, 98(1), 78–92. Summary: UC Irvine.
- LePort, A. K. R., Stark, S. M., McGaugh, J. L. and Stark, C. E. L. (2016). Highly superior autobiographical memory: quality and quantity of retention over time. Frontiers in Psychology, 6, 2017.
- Patihis, L. et al. (2013). False memories in highly superior autobiographical memory individuals. PNAS, 110(52), 20947–20952.
- Patihis, L. (2016). Individual differences and correlates of highly superior autobiographical memory. Memory, 24, 961–978.
- Santangelo, V. et al. (2018). Enhanced brain activity associated with memory access in highly superior autobiographical memory. PNAS, 115(30), 7795–7800.
- Talbot, J. et al. (2024). Highly superior autobiographical memory (HSAM): a systematic review. Neuropsychology Review, 35, 54–76.
- Pedale, T. et al. (2026). Highly superior autobiographical memory in early adolescence: a single case study. Cortex, 202, 20–31. Summary: PsyPost.
- UCI scientists study people who can't forget, UC Irvine (2010): Jill Price's first email.
- Total recall: the people who never forget, The Guardian (reprinted by Transcend Media Service): Jill Price's email and experience.
See how your memory compares
Hyperthymesia is rare, but everyone's memory has strengths. Find yours with our free photographic memory test: five rounds, about five minutes.
Take the memory test
