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Brut Force

An expert on "smell psychology" describes how the fragrance industry has ruined modern mating.

by Catrinel Bartolomeu


November 27, 2007

When I made out with Matt behind the arts-and-crafts building the summer after eighth grade, his breath smelled like tennis balls. Then, a few years ago, I opened a can of tennis balls close to my face and caught a whiff of that rubbery glue. I immediately remembered Matt's sharp, speckled cheekbone lit by a fluorescent light. I liked making out with him then, I like the memory of it today, and I play tennis often.

This phenomenon is explained in The Scent of Desire, a new book by Rachel Herz, a psychologist widely recognized as the world's leading expert on the influences of smell. Using everything from cognitive-behavioral techniques to MRIs, Herz explains how our olfactory abilities help determine who we date, who we dump and what we buy, be it the directionless unemployed loser we can't stop thinking about, the gorgeous heart surgeon who repulses us, or the strawberry-scented car freshener that, for some reason, turns us on every time we slide into our hatchback. — Catrinel Bartolomeu

Your book is the first scholarly study I've read that talks about the phenomenon of breaking up with someone because of their smell. I've actually ended relationships for that reason. It's a relief to have that validated.
Our body odor is the external manifestation of our immune system. The immune-system match is particularly important for women because they have a huge cost to bear in terms of the time and energy it takes to reproduce. If the goal is to go forth and multiply, you want to make sure that any child you have is going to survive and reproduce, and the most important thing in that respect is that they're healthy. But there's no Brad Pitt of body odor — it's about the fit between your immune system and somebody else's. His immune system can't be too close to yours because it might pair up something bad. Women's sensitivity to scent is highest during ovulation, when it's most important that you're making the correct choice. But this is all thrown out of whack if you're on the pill.

Right, you note that when women are on the pill, they tend to pick inappropriate biological matches. You also wrote that cologne makes people think they're physiologically compatible when they actually aren't. Why are we so easily fooled when making such an important decision?
The sense of smell is very suggestible. It didn't evolve in a world where there was fragrance and perfume and aftershave. There's evidence suggesting in divorce rates that the [divorcée's] sense of smell was off. There's also good evidence that people who are similar in terms of their immune systems have a more difficult time conceiving, whether they're twenty or forty. So I think the reason women are having such a hard time conceiving these days is not just because they're [having children when they're] older, but also potentially because she met the guy while on the pill, or his cologne swept her off her feet, and by the time she got to really smell him it was too late because she was in love with him.

If scent and emotions are both processed in the limbic system, does that mean we have a feeling every time we smell something?
Pretty much, yes. That can vary from a minor feeling to an all-encompassing one. Smell is a hedonic sense — it immediately activates the emotional responses of like or dislike, and everything it tells you is a variation of approach or avoid.

Why do we grow accustomed to odors, but not to something like sound? In other words, why is the stench of garbage outside my apartment nowhere near as distracting as the drilling?
When we experience olfactory adaptation, the receptor literally stops responding to a chemical in the air after about twenty minutes. We adapt to all the sensations that are out there, but when the drilling starts and stops, your attention focuses on it and you're irritated.

What does it say about me if I like very spicy foods?
Do you respond to bitter tastes much? Do you like endive or kale?

I like hot peppers on my kale.
I would guess you're not a super-taster. In fact, you might be a non-taster. It essentially means you have fewer taste buds. People who are non-tasters have a much higher tolerance for burn sensation. Keep in mind, the experience of eating is such a pleasurable one that the context of food tends to modulate our response to the pleasantness or unpleasantness of heat. If I gave you the same amount of heat in a test tube, you'd probably find that too strong.

One study found that gay men gravitate towards the smell of gay men. What does this tell us?
I think it points to the fact there is reasonably good evidence that there is a biological underpinning to male homosexuality.

In the book, you mentioned a woman who could spontaneously orgasm at the smell of leather. Is leather a natural aphrodisiac?
That's Havelock Ellis's story, the woman who had an early experience masturbating in a room full of leather. What happens with smells is that they become associated with an emotion, and later they can act like the emotion itself. You smell something and it can bring you to tears or can make you feel wonderfully happy because of your past experience. There's always a physiological response to our emotions — like heightened heart rate, faster breathing — but spontaneous orgasm is a pretty full-blown physiological response. Someone else who had the same early experiences masturbating in a leather shop would maybe get a sexy aroused feeling, but not quite the same response. In general, fetishes are just our individual experiences getting conditioned to sexual reaction. And whether or not somebody develops that in the first place depends on their personality predisposition. So no, there is no evidence that shows that certain scents are aphrodisiacs in and of themselves.

Can you use smell to evoke a memory? For instance, does smelling an ex's t-shirt after he's gone really provide comfort, or is that a self-fulfilling prophecy?
Sure. People use comfort smells like clothing or other scented objects to conjure other people in their absence. The problem with doing that is that the more you smell, the less you get. It's like looking at a photo of someone you were madly in love with, and the more you look at it, the grainier it gets. So you have to be careful how you use the genie to get back to the person. You don't want to overuse it.

Is there a reliable way for businesses to use ambient scents to increase sales?
It's been shown that people purchase more when the smell in the air is conceptually congruent with the objects being sold. So it needs to be done in environments where there's a lot of turnover air, and you're not in the mall where Yankee Candle meets Cinnabon. If you're a department store, you need to be careful with what you're scenting where — it's more effective when you're dealing with one type of product. The other thing you can do is create a signature smell in addition to the font used in the store name. It's like a scent logo.

We're always hearing about plans to market a pheromone perfume. Can this actually work?
In animals pheromones are a type of chemical detection. There is no evidence to show that pheromones can be used in humans as aphrodisiacs that produce instant behavioral change. There is some evidence that women's moods are more positive when they're around men and the chemical androstedione is in the air, but being in a relaxed mood and ripping someone's clothes off are not the same.


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