Can you remember what you did when you're, say, 12 days old? Most probably not. You may not even recall what you ate for dinner yesterday. Unlike the most of us, a 26-year-old woman from Brisbane, Australia can remember everything she ate - and much more.
Rebecca Sharrock has a very rare brain condition called Highly Superior Autobiographical Memory (HSAM), which simply means she cannot forget every detail about her life - the things that she saw and the words she heard. Anything, even the smell of honeysuckle, can make her remember a lot of things.
"Any day I've experienced, I can recall. If I had knowledge of calendars and dates at that time, I can date them. I can remember every birthday since my first birthday," said Sharrock.
It's the closest thing we'll ever have of time travel.
With her brain acting like a 24/7 superior-quality DVR, she narrates about lying in the car and getting curious about the steering wheel when she 12 days old. She can also recall her experiences even before that age, although dates are hazy since she's still very young. Her impressive memory also allowed her to retell all of the seven Harry Potter books and, when she was 2 years old, can recite all the capitals of the world.
Sharrock, however, isn't alone. At least 80 people in the world have HSAM or hyperthymesia, and just as expected, their brains are wired differently from the others.
In 2012, a study by researchers from the University of California, Irvine showed that nine sections of their brain vary from the control group. They also found that many of these differences are associated with autobiographical memory. It was also discovered that people with HSAM has a strong link of white matter between the front and middle parts of their brain.
However, the unique ability to remember doesn't mean they already have an eidetic memory. In the study, HSAM participants didn't score well during routine memory tests in the lab. Sharrock also did not.
"So it's not that they're superior learners. It's that they are very poor at forgetting," said James McGaugh, senior author of the study and the first neurobiologist to document HSAM.
While it can be considered a blessing, the condition could also be a curse. People with HSAM tend to be at risk of mental health issues like obsessive-compulsive disorders, anxiety, and depression.
For Sharrock, the biggest challenge is not so much plainly remembering everything, but going through the same emotion again and again, especially when it's a nightmare or a bad memory like being bullied in school or being injured when she was young.