“When I was about a week old I remember being in this pink cotton blanket,” Rebecca Sharrock recalls. “I’d always know when it was Mum holding me, for some reason. I just instinctively always knew and she was my favourite person.”
Considering most people’s earliest memories don’t start until around the age of four, it would be easy to assume that Sharrock’s description was a nostalgic daydream, rather than a real memory. But then again, the 27-year-old from Brisbane, Australia doesn’t have a memory like most people – she has been diagnosed with a rare syndrome called ‘Highly Superior Autobiographical Memory’, or HSAM, also known as hyperthymesia. This unique neurological condition means that Sharrock can recall every single thing she did on any given date.
People with HSAM can instantly, effortlessly and immediately recall what they did, what they wore, or where they were at any time
People with HSAM can instantly, effortlessly and immediately recall what they did, what they wore, or where they were at any time. They can remember public news and personal events all in photographic detail and with an accuracy that matches that of a tape or video recorder.
Growing up, Sharrock thought that everybody remembered like she did. Until one day: her parents called her to watch a news segment on TV about people with HSAM. “It was 23 January 2011,” she remembers. “When those people were going through their recollections, the reporters were saying ‘It’s amazing, incredible.’ I said to my parents, ‘Why are they calling this amazing, isn’t it normal?’” Sharrock’s parents explained that it wasn’t normal and they thought she might share the same condition.
'At the start of every month, I’d pick out all of the best memories that I had of previous years for that month' (Credit: Edouard Taufenbach)
After contacting the academics mentioned in the news report, Sharrock was tested and eventually diagnosed in 2013. HSAM was only discovered in the early 2000s and only around 60 people are known to have the condition worldwide.
Why are some people born with HSAM? Research is still ongoing, as the field is relatively new and there are so few people with HSAM in the world. But some research suggests that the temporal lobe (which aids in memory processing) is bigger in the brains of people with HSAM, as is the caudate nucleus, which helps in learning but may also play a role in obsessive compulsive disorder.
HSAM means that memories are recorded in vivid detail and despite being fascinating to science, it may be a scourge to some of those who experience it.
While some with HSAM describe their memories as being highly organised, Sharrock (who is also autistic) describes her brain as being “cluttered” and constantly reliving memories gives her headaches and insomnia.
’I said to my parents, ‘Why are they calling this amazing, isn’t it normal?'' (Credit: Edouard Taufenbach)
It also has a darker side as Sharrock’s mental health has suffered due to depression and anxiety. Her extraordinary memory makes her feel like she’s in an emotional time machine. “If I’m remembering an incident that happened when I was three, my emotional response to the situation is like a three-year-old, even though my mind and conscience are like an adult,” she says. This disparity between the head and heart leads to confusion and anxiety.
Sharrock has learned to try and use positive memories to override the negative ones
Despite this, Sharrock has learned to try and use positive memories to override the negative ones: “At the start of every month, I’d pick out all of the best memories that I had of previous years for that month.” Reliving positive events makes it easier to deal with the “invasive memories” that bring her down.
Sharrock says what she remembers from a particular date are things “that I came across myself that day because I don’t research when current events happened, I just remember them as I personally saw them or came across them”. While people with HSAM can remember basic news events from a certain day, often those things are also part of a personal experience or interest which may help them encode the memory.
HSAM might also give us an unprecedented insight into how babies and children view the world. Sharrock describes what caught her eye as a baby, as well as learning how to walk: “I’d be in my crib and I’d just turn my head around and look at things around me, such as the stand-up fan next to my cot. I was fascinated by that. It wasn’t until I was about one-and-a-half that it dawned on me, ‘Why don’t I get up and explore what it could be?’”
'I can control my dreams and I rarely have troubled nightmares' (Credit: Edouard Taufenbauch)
Another aspect to this ability is how it may affect dreaming in some people with HSAM. Sharrock says that now as an adult, “I can control my dreams and I rarely have troubled nightmares because I think if something scary happens I can just change the sequence.” But this wasn’t the case as a baby because once she began having dreams from the age of around 18 months, she wasn’t able to differentiate between dreaming and reality. “That’s why I’d cry at night for Mum,” she explains, “but I couldn’t verbalise it.” Perhaps people with HSAM may have a greater ability to experience lucid dreaming.
Sharrock now takes part in two research projects with the University of Queensland and the University of California, Irvine and hopes the findings can help those suffering with Alzheimer’s.
Despite having crystal clear memories of just about every event in her life, there is one thing she doesn’t remember – being born.
'My birth is the only birthday I don't remember' (Credit: Edouard Taufenbach)
“It’s the only birthday I don’t remember,” she says. “I have no memories of in the womb or coming out of my mum or anything. But I don’t think I’d want to remember that.”
But despite her mind being like a record stuck on repeat, Sharrock insists she wouldn’t change anything. “Due to my autism, I don’t like change of any sort. I want to continue thinking and feeling the way I do because it’s just how I’ve always thought and felt but I’d like to just find ways of dealing with [it]” she says. “It’s just the person I’ve always known… I want to keep that.”
This is taken from an interview with Rebecca Sharrock by Eddie Mair on BBC Radio 4’s PM programme. You can hear the full interview here.