Could you have this memory disorder?
Susie McKinnon doesn’t remember being a child or remember being any age other than she is now: in her 60s. She can’t remember special events, either. She knows she went to her nephew’s wedding. She knows her husband went with her. But she can’t actually remember being there.
In fact, she has very few memories from her life – but she doesn’t have amnesia.
事实上，她只对人生中极少数的事情有印象 — 但她得的不是失忆症。
For many years, McKinnon had no idea she was different. We tend to assume our minds work in the same way. We don’t often discuss what having a memory feels like. McKinnon assumed that when people told in-depth stories about their past, they were just making up the details to entertain people. But then a friend who was training in medicine asked if she could try out a memory test on her as part of her of studies. This is when both of them realised McKinnon’s autobiographical memory was lacking.
McKinnon researched amnesia, but the stories of people who lost their memories as a result of illness or brain injuries didn’t seem to fit her experience. She could remember that events had happened; she just didn’t recall what it was like to be there. A little more than a decade ago, after breaking her foot and having little to fill her time, she began reading about research on mental time travel and made the decision to contact a research scientist working in the field.
She was nervous the day she sent an email to Brian Levine, a memory scientist at the Rotman Research Institute at Baycrest in Toronto. Levine called it was one of the most exciting days of his career. The result of their communication was the identification of a new syndrome – Severely Deficient Autobiographical Memory.
莱文（Brian Levine）是多伦多贝克斯特医院罗特曼研究所研究记忆的科学家。麦金农忐忑不安地给莱文发了一封电子邮件。莱文称那是他职业生涯中最为激动的一天。经过交流，麦金农的病症得到确诊，那是一种新的病症 — 自传式记忆重度缺失（Severely Deficient Autobiographical Memory，SDAM）。
Humans have the extraordinary ability to mentally time travel, going backwards and forwards in our minds at will. Think back to being in the classroom at primary school, or imagine that next weekend you’re sitting on a beach towel watching dolphins cross the horizon. It’s probably not just the facts about those situations that you imagine; you picture the actual experience of being there. This is what McKinnon is unable to do.
As Brian Levine told me on All in the Mind on BBC radio, “For her, past events are experienced almost as if they were in the third person, as if they could have been someone else’s past episodes.”
正如莱文在BBC广播节目 All in the Mind（《尽在头脑中》 ） 告诉我的，“对她而言，发生过的事情几乎像是第三人叙事，仿佛是别人的往事。”
To an extent we all do this, forgetting most things that happen to us, but for McKinnon it’s much more extreme.
This syndrome is very different from amnesia, which usually occurs after a particular event or brain injury, and makes it difficult for the person to retain new information in order to make new memories. People with Severely Deficient Autobiographical Memory or SDAM can learn and retain new information – but that information is devoid of the richness of real life experience. If McKinnon can remember details about an event, it’s because she’s seen a photo or deliberately learnt a story about what happened. She can’t picture being there or what she was wearing or who she was with.
As she said to me on All in the Mind, “It could just have well have been somebody else attending a family wedding and not me. Inside my head I don’t have any proof that I was there. It doesn’t feel like it’s something that I did.”
正如她在All in the Mind 节目中对我所说，“就好像是别人曾去参加了亲戚的婚礼，而不是我。在我的大脑里，没有证据显示我曾在现场。感觉不像是我参与过的事。”
This means McKinnon can’t experience the nostalgia of reliving the best times in life – but the upside is that she can’t recall the pain associated with the bad things either. Something difficult like the death of a family member feels just as intense at the time, but the feeling soon fades. And it could make her a nicer person too. She doesn’t hold grudges, because she can’t conjure up the emotion that made her feel bad in the first place.
As for the cause, so far researchers can’t find any disease or injury associated with the condition and have to conclude that people are probably born with it. But Levine and his team are studying possible links with other conditions.
McKinnon also has aphantasia, which means she can’t picture images.Is this preventing her from holding rich recollections of events in mind, compared to other people? It’s hard to know for sure. Decades of memory research have shown that we reconstruct an event in our minds each time we recall it – but we don’t know if we all do this in the same way. Some people might see an image or video in the mind’s eye; others might think more in terms of abstract ideas or facts.
Catherine Loveday, professor of cognitive neuroscience at the University of Westminster, wonders whether there are parallels with our memory of very early life. We are able to describe events that happened to us before the age of three, because we might have heard a lot about them or seen photos. But we find it difficult to recall what the experience felt like.
At the moment the prevalence of SDAM is unknown, although Levine and his team are trying to find out, with an online survey. Five thousand people have already taken part, with many saying they believe they have this condition. This is of course a self-selecting sample, but the numbers suggest it might not be rare.
Levine’s team is investigating the idea that autobiographical memory might lie on a spectrum. SDAM might lie at one end, while people with highly superior autobiographical memory who barely forget anything, however mundane, are at the other.
So does it matter if you have this condition? If it’s not affecting the way you live your life, probably not.
For McKinnon, she’s always lived like this – so knowing that it’s an actual condition which has probably been with her all her life is simply interesting and makes sense of the differences she’s sometimes noticed between her and other people. And she now understands that other people are not making up stories. “I’ve never had it any other way. So for me it’s not a loss,” she says. “Since I’ve never really had that ability, I can’t really feel the lack of it.”
And McKinnon sees another advantage of not being about to dwell on the past or daydream about the future: “I know that a lot of people strive for that notion of really being in the moment, but it’s effortless for me because it’s the only way my brain operates. So I really am in the moment all the time.”