Uninvited
The Proust Phenomenon and the Complications of Triggering It
I had recently moved to Brooklyn, still bad with directions, and a little tipsy on my way home from Manhattan. Feeling a little too unsteady to brave the trains, I stood at the curb and raised my hand for a cab. Very 90’s sitcom of me, I know. I got in, gave the address, and we pulled off into the night. Vague electronic music on the radio. My forehead against the cool glass, watching building lights streak by. And then, out of nowhere, that catch in the throat, the sting of tears held back.
I breathed in. My driver was wearing cologne, something as common as Axe or Old Spice for all I can remember now. It was what my ex used to wear. Suddenly I wasn’t in the back of a taxi in Brooklyn, I was in their room, mid-argument, feeling all that hurt in real time. I stopped holding it in and cried the rest of the ride home.
Marcel Proust gave this experience its name, the Proustian effect, though he never called it that himself. In the first volume of À la recherche du temps perdu (In Search of Lost Time), the narrator dips a madeleine into linden tea and is flooded with the whole of his forgotten childhood in Combray, the garden, the square, his aunt’s bedroom, all of it “emerging from my cup of tea.” Proust is credited with coining the term involuntary memory to describe what happened to him. Later his name was turned into an adjective, and the “Proust phenomenon” or “Proust effect” became shorthand for any sensory cue (though it’s almost always smell) that drags up a specific, vivid, emotionally loaded memory without being asked to.
Why Smell
Every other sensory signal passes through the thalamus, the brain’s relay station, and the part of the brain responsible for processing language. This essentially translates these signals into language before passing to other parts of the brain. Smell skips that step entirely. Olfactory signals go directly to the amygdala, which handles emotion, and the hippocampus, which handles long-term memory. This means that after smelling, you feel and remember before anything resembling conscious, describable thoughts are formed. Vision and hearing get filtered and organized on the way in. Smell arrives already wired into the parts of the brain that decide how something feels.
At the Timone Hospital in Marseille, a patient was undergoing intracranial monitoring ahead of epilepsy surgery, electrodes already resting against the amygdala to help map seizure activity, when doctors ran a routine stimulation test. Scent was not delivered in the room, but after electronic simulation of the brain, the patient described a sudden, specific memory and a smell in the room which triggered it. The neurologist Fabrice Bartolomei and his co-authors wrote that the electrical current alone, applied directly to the amygdala, had produced something indistinguishable from an odor-triggered memory.
Another study I found interesting is Rachel Herz and Jonathan Schooler’s 2002 paper. They took three specific cues, the smell of popcorn, fresh-cut grass, and a campfire, and presented each one to participants in three different forms. As an odor, as a photograph of the source, or simply via its spoken name. The odor-triggered memories weren’t more vivid or more detailed than the ones triggered visually, but they were described as significantly more emotional. People reported feeling more “brought back” to the original moment, like they were there again rather than remembering having been there. The memories participants recalled were, on average, around 15.8 years old. This was observed in other studies, demonstrating that often an involuntary memory forms early and lays formant perhaps for decades.
This phenomenon is used strategically in many areas. Fast-food chains, have researched this, and have deliberately design smells to carry a customer back to a personal memory rather than just signal a product. Perfume houses and retailers lean on the same logic, selling a feeling rather than a formula. Marketing writers describe this as “weaponizing nostalgia,” a phrase that’s a little on the nose (wink wink), but not wrong about what the emotional shortcut is doing.
Scent art and olfactory design mostly work in the register of association and atmosphere. What I keep wondering, working in this medium myself, is whether it’s possible for a work of art to reliably deliver someone into a specific, individual, autobiographical memory, on purpose, the way that cologne did to me in the cab. Cretien Van Campen’s book on this exact question, The Proust Effect, is the most direct treatment I’ve found, and even there the conclusion leans toward “the senses are doorways,” plural and probabilistic, rather than a key that opens one exact door every time. This is what I have found too. The same scent might elicit a whole plethora of responses.
I’ve also noticed that this phenomenon isn’t something you can easily summon within yourself on command. When looking for a reason why, I looked at a 2025 EEG study by Malte Kobelt, Gerd Waldhauser, Marie-Christin Fellner, and Nikolai Axmacher. They compared the two modes of memory retrieval (voluntary and involuntary) directly and found they run on different processes. Voluntary recall is a goal-directed search, effortful and intentional, and it tends to surface memories that are otherwise hard to reach. Involuntary recall requires no search at all, it takes whatever is most accessible and hands it over unprompted, and the two showed measurably different patterns of brain activity during the act of retrieval itself. I interpreted this finding as a demonstration that expecting a memory to arrive might change the way your brain goes looking for it. Maybe this is exactly why bracing myself for nostalgia gets me recognition rather than the full, vivid effect.
On another note, Jonathan Schooler, Herz’s co-author on the Proust study, is also the researcher behind “verbal overshadowing.” In a 1990 study with Tonya Engstler-Schooler, participants watched a video of a staged robbery, and those who were asked to write out a detailed description of the robber’s face afterward were measurably worse at picking that same face out of a lineup than participants who did nothing but wait. Putting the memory into words seemed to displace it. If that might also apply to smell the way it does to faces, the act of anticipating a Proustian moment, describing to myself the memory of what I’m hoping to feel, might quietly work against my desire to feel this effect. I don’t know if there is a way to train around this, but maybe there is a way to try to setup conditions for multiple possible memories rather than one.
Sadness, not Nostalgia
Most writing on this effect talks about comforting memories (i.e. a grandmother’s kitchen, cut grass, a familiar cake). The research itself is a bit more neutral. Odor-evoked memories are measurably more emotional than memories triggered other ways, regardless of whether that emotion is pleasant or painful. Although the popular framing skews warm almost without exception, that hasn’t been my experience. My most vivid involuntary memories arrive attached to loss, to people I no longer have, to sadness rather than joy. I can’t ignore that this might have something to do with living with lifelong depression and anxiety. This might just mean that my most emotional memories skew toward grief rather than comfort. The mechanism doesn’t seem to care about valence. What gets stored is whatever hit hardest, and for some of us that’s not always the nice thing.
This leads me toward a question about trauma though. If a smell can involuntarily deliver you back into an argument with an ex-partner in the backseat of a cab,couldn’t it just as easily deliver a trauma survivor back into the moment they’re trying to recover from, with zero warning? This isn’t a hypothetical question, this really does happen. Psychiatrists Eric Vermetten and J. Douglas Bremner documented it directly with combat veterans. They traced how specific smells triggered full flashbacks decades after a war. For one Vietnam veteran, it was burnt rubber and diesel exhaust specifically, not smoke or fuel in general, that could pull him straight back.
That specificity is the whole problem for treatment. If the trauma is tied to one particular odor, a generic stand-in used in a lab setting, coffee, vanilla, a candle, isn’t obviously going to reach it. Silvia Pizzoli and colleagues proposed one way around this in a 2021 paper, outlining how virtual reality combined with real odor delivery could let a clinician introduce a patient’s own trauma-relevant smells gradually and under controlled conditions, rather than waiting for the wrong version to show up uninvited. Currently, this is just a proposal, not an established protocol, but the direction, treating the trigger as something to be individually identified and constructed rather than generically acquired, is a gap I think matters.
What I’m Actually Trying to Build Toward
I am thinking about all of this with the reoccurring interest in memory encoding and recall technology that uses scent as the trigger. I think in the persuit of this, I need to create scents quite deliberately and individually tailored, rather than general ones. A rose is not just a rose when it comes to smell. The species, environment, lifespan of the rose all play a huge effect on how it smells, so getting any rose oil will not guarantee I offer the smell that a person is thinking of when they say “the smell of roses.” The research gives me some insights, but I am still unsure how I would create a reliable method for eliciting a specific memory through a specific scent on purpose. Whether smell can trigger memory was settled by Proust and confirmed in a dozen labs since. The question I want answered, is how to build a doorway sturdy enough that it opens, for one specific person, on command.
References
Herz, Rachel S., and Jonathan W. Schooler. “A Naturalistic Study of Autobiographical Memories Evoked by Olfactory and Visual Cues: Testing the Proustian Hypothesis.” The American Journal of Psychology, vol. 115, no. 1, 2002, pp. 21-32. JSTOR, https://doi.org/10.2307/1423672.
Bartolomei, Fabrice, et al. “The ‘Proust Phenomenon’: Odor-Evoked Autobiographical Memories Triggered by Direct Amygdala Stimulation in Human.” Cortex, vol. 90, 2017, pp. 173-175. https://doi.org/10.1016/j.cortex.2016.12.005
Kobelt, Malte, et al. “Involuntary and Voluntary Memory Retrieval Relies on Distinct Neural Representations and Oscillatory Processes.” PLOS Biology, vol. 23, no. 8, 2025. https://doi.org/10.1371/journal.pbio.3003258
Schooler, Jonathan W., and Tonya Y. Engstler-Schooler. “Verbal Overshadowing of Visual Memories: Some Things Are Better Left Unsaid.” Cognitive Psychology, vol. 22, no. 1, 1990, pp. 36-71.
Vermetten, Eric, and J. Douglas Bremner. “Olfaction as a Traumatic Reminder in Posttraumatic Stress Disorder: Case Reports and Review.” The Journal of Clinical Psychiatry, vol. 64, no. 2, 2003, pp. 202-207.
Pizzoli, Silvia F. M., et al. “Olfactory Virtual Reality: A New Frontier in the Treatment and Prevention of Posttraumatic Stress Disorder.” Brain Sciences, vol. 11, no. 8, 2021, p. 1070. MDPI, https://www.mdpi.com/2076-3425/11/8/1070
Khalifah, Khairul Azrin, et al. “The Scent of a Brand: The Proustian Phenomenon and Meaning-Making in Fast-Food Branding.” International Journal of Academic Research in Economics and Management Sciences, 2023.
Van Campen, Cretien. The Proust Effect: The Senses as Doorways to Lost Memories. Oxford University Press, 2014. https://doi.org/10.1093/acprof:oso/9780199685875.001.0001
I knew about the concept of the Proust effect but not the name! Great read!