气味如何塑造记忆：The Science of Happiness 探讨嗅觉与记忆、情绪的联系

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Discover how our sense of smell can transport us back to meaningful memories, shape our emotions, and influence the brain systems involved in memory and mood.

Summary: Smell is one of our most powerful and underappreciated senses, with a unique ability to evoke memories and emotions. On this episode of The Science of Happiness, we look at the science behind smell’s close relationship with memory, emotion, and our environment and we explore how paying attention to the scents around us can bring us back into our bodies and help us feel more connected to the present moment. 

How To Do This Practice: 

1. Step outside: Spend 10–15 minutes somewhere you can notice natural scents, such as a park, garden, or neighborhood.
2. Breathe through your nose: Take a few slow breaths in through your nose and notice the scents carried in the air.
3. Pay attention: Notice what catches your attention; don’t be concerned with trying to identify smells
4. Follow your curiosity: Move toward different plants, trees, flowers, or other natural elements and see how their scents change.
5. Notice what comes up: Pay attention to any memories, emotions, or sense of place that a particular scent evokes.
6. Stay present: Take a moment to appreciate the experience and notice how you feel after giving your sense of smell your full attention.

Today’s Guests:

SAMIN NOSRAT is a chef, TV Host, and best selling author of the book "Salt, Fat, Acid, Heat."

ciaosamin.com

LUCIA JACOBS is a Professor Emerita of Psychology at UC Berkeley.

psychology.berkeley.edu/people/lucia-f-jacobs

Related Science of Happiness episodes:

What Humans Can Learn From Trees: https://tinyurl.com/48te84ps

Are You Remembering the Good Times: https://tinyurl.com/ysbwrnr4

How to Be in Harmony in Nature—Wherever You Are, With Yuria Celidwen: https://tinyurl.com/5n6pfsn2

How To Ground Yourself in Nature: https://tinyurl.com/25ftdxpm

The Unexpected Joy of Slow Looking: https://tinyurl.com/4uudwwc2

Message us or leave a comment on Instagram @scienceofhappinesspod. E-mail us at 

happinesspod@berkeley.edu or use the hashtag #happinesspod.

Help us share The Science of Happiness! Leave us a 5-star review on Apple Podcasts or share this link with someone who might like the show: https://tinyurl.com/2p9h5aap

Transcription:

SAMIN NOSRAT: I went down to the Berkeley Marina. Then a breeze came from the bay, and I got my first whiff of seawater, bay water. That salty water smell, which is a very core, core, core smell. Like that is in the atoms of my soul. It's like a savory, salty, slightly funky smell. It's not super strong, but it's just enough for me to pick up on my nose, and what that brings up for me is tide pooling as a kid, and you saw what, in Southern California, is called the marine layer, this thick layer of fog. We would be driving into the marine layer in the mornings. That was just such a fundamental memory. It really is, I would say, "transporting" is a good word. I really am at the meeting of land and sea when I'm breathing that, and I'm very aware of the ocean environment and the ocean life and the sea life and being at the edge of the world in a way.

Like many people, I had a complicated childhood. To me, one uncomplicated thing about that is my relationship to the ocean, and then my relationship to the water. So I always love being transported.

DACHER KELTNER: Welcome to The Science of Happiness. I'm Dacher Keltner.

Think about the last time a smell stopped you in your tracks. Maybe it was fresh-cut grass, ocean air, rain on dry earth, rosemary, or a spice that instantly transported you back to childhood. Of all our senses, smell is closely connected to the part of the brain involved in our behavioral and emotional responses. That's why certain odors spark strong emotions and trigger memories. It's an incredibly powerful and underappreciated sense that can affect how we feel physically and mentally.

Today, we'll hear from Samin Nosrat, a chef, TV host, and bestselling author, on how she uses her sense of smell as a gateway to memory, identity, and emotional wellbeing.

SAMIN NOSRAT: A big part of my cooking happens in the garden, and so, smell is so important there, and such a wonderful part of it. As much as I can in my life, whether it's cooking, gardening, or anything, I'm always looking for opportunities to get out of my head and into my body.

DACHER KELTNER: Later, we bring in my colleague Lucia Jacobs, Professor Emerita of Psychology here at UC Berkeley, where I teach my Science of Happiness course.

Lucia shares the science behind why smell has such a profound impact on our mood, and how it may be far more important to our wellbeing than most of us realize.

LUCIA JACOBS: There's evidence of nasal microbiome diversity. There may be a direct relationship for the gut. At the same time, it's synchronizing your whole brain, activating your emotional centers, activating your memory centers.

It's incredibly important.

DACHER KELTNER: But first, my conversation with Samin Nosrat, after this quick break.

Welcome back to The Science of Happiness. I'm Dacher Keltner. Today, we're exploring how paying closer attention to the smells in our environment, especially natural scents, might help us feel more grounded, present, and connected to things that are larger than the self. Our guest is chef, author, and television host Samin Nosrat.

Her best-selling book, "Salt Fat Acid Heat," celebrates food as a deeply sensory, embodied experience. Her most recent book, "Good Things," shares a blend of recipes and memories and rituals that arise from them that situate food in the much broader story of life.

For Samin, scent is usually something she experiences in the kitchen. But for our show, we asked her to step outside and do a scent walk, which means going outside for 10 to 15 minutes, breathing deeply through the nose, and paying attention to the smells around to see what the mind discovers.

Samin, thanks so much for being here.

SAMIN NOSRAT: Oh, I am so happy to be here.

DACHER KELTNER: It's an honor to have you.

SAMIN NOSRAT: Thank you.

DACHER KELTNER: Today we're gonna focus on smell and scent, and it's this part of food that's obvious but yet non-obvious, and there's a new science that's really talking about that scent is really undervalued and unappreciated and it's actually this very sophisticated system, 12 million cells in your nose that process fragrances, and it's one of the oldest modalities.

I'm really curious, when did you realize that food and cooking and the aromas around it connect you to something that's about your deep identity and the world that you live in?

SAMIN NOSRAT: I think even before I was a cook, I think as a kid. Coming into the house, my family's from Iran. My mom really prided herself on cooking Persian food for us, and so, our home always smelled different. So, coming home when my mom was cooking, there were the smells of saffron, of rice, the tahdig at the bottom of the pot getting crispy.

DACHER KELTNER: Yeah.

SAMIN NOSRAT: There's a dried lime, sometimes called an Omani lime, that has a very particular sort of bitter sour smell and taste that if that's there... You know, my mom would throw a whole lime or two into certain stews, and that perfumed the house in this way that was just very familiar and very iconic.

DACHER KELTNER: I wanna dig deep into the memory effects of scent and identity that you're talking about. And in the science of scent, it's clear the olfactory system goes straight to the memory, bypassing a lot of structures in the brain. And in "Good Things," your wonderful book, you write about the scent of garlic —

SAMIN NOSRAT: Yeah.

DACHER KELTNER: In your grandparents' backyard. Tell us how that was part of your identity.

SAMIN NOSRAT: Yeah. So, my paternal grandparents lived in San Diego not far from us, and we had this weekly ritual of going to their house for Saturday lunch. There was not a lot of stuff to keep us engaged and entertained, and so, we had to learn how to entertain ourselves. And often that was in the backyard, drawing hopscotch on the sidewalk or whatever.

And it felt like every time we were there, which was almost always like clockwork on Saturdays, there was just this smell. This very strong smell in the backyard that I never understood what it was or where it came from, and it was so, so, so powerful.

And I knew what garlic smelled like. You know, my mom cooks with garlic, my grandparents, everyone. Like, I was familiar with garlic, but there was something just so strong about how much garlic was being used. And it turned out that my grandparents' next-door neighbors were a Filipino family. And they also had their cooking traditions —

DACHER KELTNER: Yeah.

SAMIN NOSRAT: on the weekends, and there's a lot of garlic in Filipino cooking, and especially in adobos.

And so there's, for me, this very strong association of that, almost overwhelming, “I can't take it anymore” smell. That almost as a kid I felt offended. I was like, “We're just trying to do hopscotch in peace!”

DACHER KELTNER: You know, we call this the Proust effect, that these memories come out of scents. And I'm just curious, does scent tell you different things about dishes than taste?

SAMIN NOSRAT: I feel like scent is first of all like a really underutilized and underappreciated sense in the kitchen when you're working. It's a really important tool. I can be across the room and smell, you know, beets in the oven that I forgot were in there, and now, all the water has evaporated, and that steam is like, now all the juices are caramelizing. And there's a way you can sort of attune the nose and it's like another muscle that you have to train.

What's interesting is, I'm not sure — in fact, the scent walk really reinforced this for me — I'm not sure I have that strong of a sense of smell, or that good of a sense of smell.

DACHER KELTNER: Are you confessing something here? Or…

SAMIN NOSRAT: Yeah. I mean, it's interesting 'cause smell is such a huge part of taste. It's like 80% of your experience of taste is smell.

And sometimes I wonder. I'm like, "Oh, I wonder if the reason I like things so heavily sea salted and so acidic is actually because I have a relatively weak sense of smell." Maybe! A big part of my cooking actually happens in the garden, and so smell is so important there, and such a wonderful part of it. 

I think as much as I can in my life, whether it's cooking, gardening, or anything, I'm always looking for opportunities to get out of my head and into my body, and I have found that using smell to help me breathe and then, and hence, help me calm down is also helpful. So sometimes I'll just pick some leaves of geranium or verbena, or  I'll dab a few dots of essential oil on my collar or my scarf to just help me remember to breathe.

DACHER KELTNER: Yeah. In the body. I do that, too, every day.

SAMIN NOSRAT: Yeah.

DACHER KELTNER: I wanna provide a context for the scent walk. You know, we're learning from the science of scent that is really just exploding. The scents around us, they can affect our neurophysiology. Like, you smell rosemary, and you feel calmer. The scents around us give a sense of place. We notice where we are in space. We trust people depending on their kind of smell.

So before you went on the scent walk, what did you expect from it? What did you think this more intentional contemplative approach to scent would bring you?

SAMIN NOSRAT: I went down to the Berkeley Marina.

DACHER KELTNER: Nice.

SAMIN NOSRAT: And I did that to set myself up for success. I just was like, "What if there's nothing to smell where I go?" I knew that there would be, hopefully, some sort of a sea bay saltwater smell.

So I got out of the car. I was there with my small dog, Fava, and you know, she smells everything. Even if I'm not smelling, I think observing Fava appreciate scent is really good for me, 'cause there's just a way where there's information in everything for her. And she's so curious.

Favi and I are here at the park. Down by the bay. I came here because I knew there would at least be one profoundly powerful scent, and I was not wrong.

It was quite cool and breezy and gray this morning when I went. And in a way, that started setting a tone. And so then a breeze came from the bay, and I got my first whiff of seawater, bay water, that salty water smell, which is a very core, core, core smell. Like that is in the atoms of my soul. What that brings up for me is tide pooling as a kid.

It takes me back to my childhood. I grew up at the beach. And here in particular with the foggy morning, it really reminds me of what in San Diego is called the marine layer. It really is, I would say, "transporting" is a good word.

I feel like I'm at the coast in a way that even though I live just a few miles from there, I don't always feel like I'm at the coast. Whereas I really am at the meeting of land and sea-

DACHER KELTNER: Yeah.

SAMIN NOSRAT: When I'm breathing that. And I'm very aware of being at the edge of the world in a way.

Like many people, I had a complicated childhood. And also to me, one uncomplicated thing about that is my relationship to the ocean and then my relationship to the water. So I always love being transported.

DACHER KELTNER: I'm curious, what other scents did you pick up as you did your scent walk?

SAMIN NOSRAT: The main other scent I would say was the wild fennel. Really, the primary reason I went there is because there's so much wild fennel that grows there. And it's really at its peak aroma right now. The wild fennel is transitioning out of its flowery pollen stage into seed, and it smells so strong and so sweet.

And it's very, very, very fragrant. So I knew I would get one hit of something at least. So I remember as a young cook when I first encountered wild fennel as a cook at Chez Panisse, and there was kind of this frenzy. Like, people love this ingredient. It brings up a very dynamic period of my life.

Also, you know, I have spent much of my life, maybe all of it, feeling a little bit uncomfortable in my own bones. Well, not all of it, but much of it, and certainly in my early 20s. Then, it settled into this period where I had so much joy figuring out what kind of cook I was, and what kind of things I cared about. And like, "Yeah, I wanna go on this adventure, and, you know, go collect fennel and cook with it."

And that was such a big period of curiosity, of learning, of opening myself to the world, meeting new people, having new experiences. And so, a lot of that came up for me, too, that pure joy of wanting to completely immerse myself in a new world.

DACHER KELTNER: You've talked very candidly about your anxiety and struggles, and I really appreciate that.

I think it's good for people to hear that. And I will also note, two books, a show, very compressed times, tours, public events, change in identity, and how hard it is to get out of your mind and your conceptual world when you're a writer and producing content, like you. So, what do you think about the scent walk and the experience of smelling as a way to get into the body?

SAMIN NOSRAT: I mean, it's a very simple tool available to all of us, so I really appreciate that. I also, when I first learned about the awe walks, started doing that, and I did feel a noticeable change in my life. And so anything like this that can just be a simple offering to my daily life, like I said, to get me out of my head and into my body, is really helpful.

'Cause I do spend too much time in my head. And so any, any sort of thing to remind me that I have a body (LAUGHS) is pretty good.

DACHER KELTNER: Well, Samin Nosrat, thank you for taking time out of a very busy day and a lot of responsibilities in the world to be on our show. 

SAMIN NOSRAT: It's an honor. 

DACHER KELTNER: It's an honor for us. 

SAMIN NOSRAT: Thank you, Dacher.

DACHER KELTNER: Up next, we hear about why our sense of smell has such a remarkable connection to memory and emotion.

LUCIA JACOBS: Your brain sticks out these little fingers through your skull, through this thing called the cribriform plate, and sticks it out inside your nose and catches chemicals. And so literally, it's in the outside world.

DACHER KELTNER: Psychologist Lucia Jacobs shares the science behind scent and the brain, up next.

Welcome back to The Science of Happiness. I'm Dacher Keltner.

Today, we're talking about how your sense of smell can go hand in hand with your wellbeing. Joining us is one of the most creative scientists I've met, my colleague Lucia Jacobs, who's a professor emerita of psychology at UC Berkeley. She explores in her current research how smell, the environment, and the nasal microbiome intersect with human experience. Lucia, thanks for being here on the show.

LUCIA JACOBS: Thank you. It's such a delight to be here.

DACHER KELTNER: Human neuroscience has emphasized vision, you know, because we're a visual species. But tell us more about the under-privileging of the sense of smell and why you're so bullish about its importance in our conscious experience.

LUCIA JACOBS: It really started with Aristotle dissing olfaction as an animalistic, primitive sense.

And then there was a lot of misunderstanding in the 19th century. But mostly it's because we're countering primates, and we've evolved amazing color vision. We've got better color vision than any other primate. And in fact, our group of primates has lost a second olfactory system that most mammals have, which is called the vomeronasal system.

So I mean, it makes sense that us old world primates are gonna think first about vision. But at the same time, if you teach some subjects something, and then they sit for an hour, and then you ask them how much they remember, how much did they consolidate, if they've sat with their mouth taped closed, they remember better than if they sat with their nose taped closed.

We're finding human memory consolidation is affected by nasal respiration, that nasal respiration is a master synchronizer of brain function. That includes brain function during sleep, during REM sleep.

DACHER KELTNER: Yeah. Just dwelling a moment on memory, I remember I grew up around eucalyptus trees in Southern California, and they have an incredible fragrance. And then I moved to the country out in the Sierras, where it was really pines and cedars and was lucky enough to wander those foothills. And I remember going to college at UC Santa Barbara and smelling the eucalyptus trees, and I started to almost weep because I had this deep sense of home and memories from being two and three.

So, how does that work? How does a chemical come into my nose and suddenly I'm thinking about being a child with my mom and dad and my brother?

LUCIA JACOBS: Your brain sticks out these little fingers through your skull, through something called the cribriform plate, and sticks it out inside your nose and catches chemicals. And so, literally, it's in the outside world. And then it's about three synapses to the hippocampus, which is necessary for episodic memories.

What's ironic is that episodic memory is really considered a higher form of memory, and it's debated whether other species have it. It's so human. It's so important. And yet, one of the most powerful triggers of episodic memory is this really primitive sense coming from the outside. And then three synapses, bang, bang, bang. It's in the hippocampus. And Rachel Herz's work has shown that olfaction, because you've got this massive projection to emotional centers, amygdala, there's no such thing as a odor that's encoded dispassionately. They're always coded with an emotional valence.

It's debated how many odors we can encode. Some people said a trillion, some people said less, but certainly more distinctive odors than distinctive visual stimuli. Coffee is determined by 800 different odorants. It's so complicated, in fact, and it's encoded by an ensemble very similar to the way memory's encoded.

In the hippocampus, memory is encoded as these ensembles of neurons. 

DACHER KELTNER: Right, almost maps.

LUCIA JACOBS: Exactly, and we haven't really cracked that map code, just like we haven't really cracked it in olfaction, but they're so closely related, you almost cannot separate the hippocampus and olfaction.

DACHER KELTNER: I feel this viscerally, and I understand you, but I can't make sense of it.

You said that the sense of smell is embodied. And when I'm around certain scents, you know, the scent of the Pacific Ocean or cedar, I just not only go back to place, like you're saying, and memory and meaningful moments in life, but it shifts my body in ways I can't quite describe. So tell us about that, how scent is embodied.

LUCIA JACOBS: I'm coming from the philosophers who think about embodied cognition, the idea that cognition is not just a brain. Cognition is a body. It's a body that has to act. And more than that, it's embedded in an environment, and that's where olfaction really shines because we live in this chemical soup that's invisible but is incredibly important, and the olfactory system doesn't go through the thalamus, which is the higher center of attention. We don't really have conscious access to a lot of our olfactory cognition, which is probably another reason why we haven't really given it the credit that it deserves.

DACHER KELTNER: When people smell things out in the natural world, they smell, the chemical compounds coming off a cedar tree or a flower or they pass by a dead animal, and they smell the carrion or just, there's just all this emotionality wrapped up with our sense of smell.

Some of it's obvious, you know, stuff is disgusting, rotting, so we stay away from that. Like you said, it's enacted. But how do you think about the richness of our emotional life mapping onto our sense of smell?

LUCIA JACOBS: There's a huge impact of culture, and one culture thinks rotting meat is fantastic. Someone else thinks stinky cheese is fantastic. That’s the other interesting thing, so much of how you perceive odors is learnt.

It isn't like there's an odor, and everyone smells it the same way. It depends on your lived experience, your culture, what you expect when you see something and start sniffing. It's incredibly plastic. But because of that, if you grow up in a culture that there's certain important natural fragrances or the smell of a certain forest, like a eucalyptus, or for example, frankincense, which is now an endangered tree species, and yet the incense has been used as a powerful cultural touchstone for three thousand years.

But we're losing the species. And then once we lose it, we lose that piece of our history and our culture. It's emotional because it's not just, "Oh, we're losing it." It's like a real gut punch to be losing something, an odor you grew up with that makes you feel secure, that gives you a feel of social cohesion.

DACHER KELTNER: A lot of people are talking about the microbiome right now and this remarkable flora in our gut, and you write about the nasal microbiome. What the heck? What is that?

LUCIA JACOBS: I mean, we've got microbiomes all over our body, in our lungs, in our gut. I just read this, our gut microbiome is the most complex microbial ecosystem on the planet because it's not just bacteria, it's archaea, it's viruses, it's fungi, and they're all working together.

They produce neurotransmitters. The brain talks to the gut, and one way we get stuff into our gut is through our nose. And it turns out that that ecosystem changes with your environment. And more important, all day long, you're sniffing air, and air is carrying spores and fungi and viruses and bacteria, all that kind of stuff. And that comes in, and basically, it comes into your nose, and then you swallow it, and it goes down to your gut.

In fact, workers who live in clean rooms that are sterile on purpose, they have health problems, they have mood problems. So, given that the olfactory system is so intimately connected with the emotional system and the memory system, it's not surprising that when you lose your sense of smell, there's well-documented increases in anxiety and depression.

Connor Lashus, who's a graduate student in our consortium, did a pilot study, and it was eight students in the city and five students in the forest, and he swabbed their nose before and after eight weeks and also did self-reported mood and affect and rumination and found that, in fact, the students out there working on doing forestry-type tasks for thirty hours a week, they got more beneficial bacteria in their nasal biome, and their mood and their affect and all of that improved significantly compared to the students who were University of Washington students in a city campus.

There's evidence that nasal microbiome diversity, there may be a direct relationship for the gut. At the same time, it's synchronizing your whole brain, activating your emotional centers, activating your memory centers. It's incredibly important.

DACHER KELTNER: You've given us a lot of actionable knowledge, embodied knowledge, Lucia, just how important the sense of smell is to our memory and to our sense of place and our cognitive function and our emotional lives and our health and well-being.

How do I go find it for just a couple of minutes here and there during the week?

LUCIA JACOBS: You don't need an enormous amount of time in nature. And in fact, it turns out that it's short exposures, frequent short exposures to a natural odor environment. It doesn't have to be active. You don't have to be out there lifting weights. You can be sitting and just looking. Set yourself 15 minutes a day, go out literally and smell the roses, literally smell the roses, and try to mix it up. And just the way we're supposed to eat the rainbow vegetables, go out and smell the rainbow vegetables.

DACHER KELTNER: Lucia Jacobs, it's great to be in conversation with you. Thanks so much for joining us.

LUCIA JACOBS: This has been great as always. Thank you.

DACHER KELTNER: Coming up, we look at life after deportation and what it takes to rebuild when you're facing enormous hardship with the support of community, resilience, and meaning making.

UNKNOWN SPEAKER: There was quite a few nights that I slept in the park and I slept on the bench. And I worked at lumber yards, and I'd go to work and I would have those 200 pesos, 150 pesos, and buy myself a little sandwich, get on the bus, and the next day, same old, same thing over.

It's like waking up every morning and telling myself, "Hey, it's gonna be a better day today. You're gonna be okay. You know how to do things. It's just a matter of time, and it's a matter of patience."

DACHER KELTNER: That's next time on The Science of Happiness.

This episode was produced by our associate producer, Anna Zou. Also, thanks to associate producer Emily Brower and producer Truc Nguyen. Our sound designer is Jennie Cataldo of Accomcompany Studios. Our executive producer is Shuka Kalantari. I'm Dacher Keltner. Have a great day.