Have you ever had the experience where a smell or a taste pulls you into a world of memory? One bite of a cookie of a similar kind to those in your old school cafeteria, and suddenly you can practically see the linoleum floors and hear the squeak of plastic chairs. Most people can have these sudden reveries – I can’t.
When I have come across descriptions of this phenomenon – Proust’s madeleine scene, for instance, or the memory bubbles in the movie Inside Out – I’ve always assumed that it was some kind of metaphorical device. I had no idea that most people actually re-experience moments from their pasts in some sensory detail, even if it’s a bit shaky or faint.
I have come to understand that my version of reminiscing is not nearly as richly textured. Just now, I heard a song I once played in my high-school orchestra, and it reminded me of the time when a (lesser) violinist named Barbara almost punched me after I corrected her bowing.
But I don’t remember what she looked like, how the band room smelled, or the fear I must have felt when I noticed her little fists balling up. All I remember is the story – a tale I must have recounted immediately afterwards, and then told and retold until it wore a groove into my brain.
Sensory memories that you can replay are called episodic memories, while remembered facts and stories are known as semantic memories. This may seem like a subtle difference, but these two types of memory rely on different brain networks.
We know this because of amnesiacs such as Kent Cochrane. Cochrane was in a motorcycle accident that destroyed both of his hippocampi – deep brain structures that coordinate the replay of old memories. After his accident, he could still tell you about his life, but only as dry facts: his brain didn’t trigger a sense of warmth talking about his happiest moments with loved ones, or sadness over past loss. It was as if he had simply read a biography of himself.
I’m a science writer, so once I began to suspect that my memory was a little odd, I dived into the research and found descriptions of a condition known as severely deficient autobiographical memory. This isn’t a disorder: it just describes people on one extreme of the human memory spectrum. SDAMers rely heavily on semantic memory, while people with HSAM – highly superior autobiographical memory – put all their cards on the episodic side, and neurotypical people land somewhere in the middle. I wanted to know whether I was an outlier.
It took the better part of a year to confirm my self-diagnosis, but in relative terms, that’s lightning fast. For more than a century, serious scientists have largely ignored the topic of internal experience, on the basis that it was impossible to verify or disprove what people claimed was going on inside their minds.
But in just the past few years, that’s been changing. For example, researchers recently figured out a way to test whether people can visualise in their “mind’s eye”: one cool study found that most people’s pupils constrict in response to imagined light, but this was not true for people who cannot visualise.
I didn’t get to participate in that study, but I did sign up for a few others. In a higher-tech version of the pupil-constriction study, I got tossed into an fMRI machine and was asked to visualise places and faces. My brain just sat there doing nothing, just like the non-visualisers’ pupils.
I also participated in a study using a technique called descriptive experience sampling, which involved wearing a beeper that interrupted me at random several times a day so I could report exactly what my internal experience was in that moment.
The verdict? Almost everyone has a much livelier inner life than I do. When other people are silently talking to themselves, replaying past moments or thinking about the future, I’m just … existing. I spend about 46% of my time simply taking in sensory experiences. The rest of my waking hours, I’m mostly spacing out – an activity that scientists charitably label “unsymbolised thought”.
Reeling from the discovery that my conscious experience was so unlike most people’s, I started quizzing friends and family members about their own minds. Their answers shocked me: the inner lives of the people I’m closest to were wildly different from mine.
I once asked my friend Miriam why she seemed preoccupied, and it turned out she was mentally replaying and analysing a recent conversation she’d had with her sister, trying to turn down No Scrubs on her internal radio station, and debating what to wear to the party we were running late to.
At that moment, all that was going on in my mind was a feeling of impatience, but this emotion quickly subsided once I understood why Miriam was moving so slowly.
I used to think that my ability to focus, my fast recovery from setbacks and my inability to hold grudges were positive character traits – reflections and results of my work ethic and generosity. But I now see them as the result of my unusual brain architecture. Most people are haunted by their pasts in a way that I can’t quite comprehend, and it’s not something you guys are deciding to do. It’s just a function of how neurotypical memory works.
Am I missing out on a richly meaningful part of the human experience? Maybe. Sometimes I wish I could remember dancing with my husband at our wedding, or recall the milky smell of holding my newborn niece for the first time.
When I started this journey, part of me was hoping I could retrain my memory and learn how to relive happy moments from my life. But the more I heard about the neurotypical experience of memory, the more I came to appreciate how my brain keeps me in the present.
From what I’ve heard, negative memories pop up just as often as wedding dances. In the end, what I took from all the research wasn’t memory tips: it was a sense of wonder at the existence of the vast spectrum of human experience, with many of us perfectly happy and largely functional despite our weird brains. That, and I’ve given up trying to meditate. As it turns out, I’m diagnosably zen.
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Sadie Dingfelder is the author of Do I Know You?: A Faceblind Reporter’s Journey into the Science of Sight, Memory, and Imagination