It means they can recall or relive most of their past in extreme detail. Essentially, they can remember every day of their lives.

In the case of Queensland’s Rebecca Sharrock, the only Australian known to have HSAM, she can remember her first Christmas when she was just 14 days old, and every day since.

She visited Maitland this week to speak at a Local Government Week breakfast and we took the opportunity to chat to her.

A memory at 14 days old? Clearly there will be sceptics. And not long into the interview, Rebecca acknowledged that. But she has gone through years of testing and was officially diagnosed with HSAM in 2013.

We must admit the longer the interview goes, the more convinced we are that she is the real deal.

“It’s gaining more credibility given that the institute who identified HSAM is the McGaugh Stark Lab from the University of California, Irvine,” she said.

Regardless of what others believe, there’s no need to convince Rebecca.

For most of her life, the 28-year-old and her mother Janet Barnes ventured through the highs and lows of HSAM with little understanding or medical support, due to its rarity.

“It did dawn on me when I talked to people the way I remembered wasn’t typical, ​but I just put it down to my OCD, the way I relive experiences constantly or just can’t get over things,” she said.

“I first found out HSAM existed when I was 21. That’s when everything changed.”

Anything she has personally experienced is seared into her memory – sights, sounds, smells and touch all flood back without warning.

With such a superior memory she sounds like the best person to have on your trivia team. And yes, she does know every Harry Potter book word for word.

But as the title HSAM states, the memory must be part of her life.

She remembers every school lesson because she was there experiencing it.

“A lot of people say to me you must have been a whizz in school but I wasn’t because I have a slower processing speed, mainly because of my autism,” she said, joking she could have aced the exam if she sat it months later.

Most people find their earlier memories are more hazy than later ones, but with Rebecca it’s the other way around.

“I remember being a 3-year-old more clearly than I remember being a 25-year-old,” she said.

For example, she remembers sitting on the car seat while someone took a photo of her. She later found out that photo was taken at 12 days.

While it didn’t help her studies too much, there have been some standout benefits.

For example, her mother would have thrown out a kettle which still had a month of warranty if it wasn’t for her.

“It was a good brand and I said ‘it’s still under warranty, I went to the shop with you to buy that, you’ve got a month left until it runs out’,” she said.

Now when Janet buys something she lets Rebecca know she bought it that day, so if it breaks she can ask her when it was.

Or she’ll remind family members if they decide order something from a restaurant that they didn’t like last time.

As memories race through her mind she meets them with the consciousness of an adult, but her emotion and pain is what she felt at the time.

“I remember falling down and grazing my knee as a three-year-old and I can feel the burn on my knee,” she said. A sensation she poetically named an ‘echo of pain’.

It means that when she remembers something, she is emotionally placed back in the moment. If she remembers something that overwhelmed her as child, it will overwhelm here again, even though she is now an adult.

She knows it shouldn’t, but she is helpless to do anything about it.

Following the story of grazing her knee, her mother asked her what she had for breakfast that day.

“I had fruit loops,” she said, after a second’s pause.

“On that day for lunch we were out shopping before we went to Nanna’s house, because we lived there for a little bit.

“You picked me up a Happy Meal from McDonald’s because it was quick.”

Along recollection of her other senses, audio remains as clear as crystal in her mind.

“[As a baby] I practiced making sounds and remember trying to speak,” she said.

“It didn’t take long for me to realise that people around me were communicating but I didn’t understand their words so I was trying to practise making my own sounds.”

So does she get a break from her ever-present memories at night?

Sadly, sleep has always been a challenge for her, with distracting recollections flashing through her mind seemingly non-stop.

Negative or positive, they’re distracting either way, so she uses some classical music or a soft light to stimulate her mind and help divert her attention.

She said at the McGaugh Stark Lab showed she had a strong connectivity between her conscious and subconscious.

“They think that’s why I have access to retrieving my earliest memories, because they are usually stored in the subconscious,” she said.

“They believe everyone can recall all of their experiences it’s just that people with HSAM can retrieve them easier and the’re trying to figure out why.”

“It’s not that they’re seeing more, it’s just that they retrieve more,” added her mother.

Rebecca said this ability to retrieve had researchers looking for clues to help those with dementia and other memory limitations.

So, how does Maitland compare for someone who can recall all the amazing places she’s visited?

“It’s a lovely place, I’m so happy to have been invited down here,” she said.

“It’s nice to look at all the history and the beautiful scenes of the Hunter River

“It’s a nice memory for me to keep.”