Saturday, February 28, 2009

The Straight Skinny on Thin-Making Perfumes

Sali Oguri, who blogs on perfume and music at Pink Manhattan, has a new piece on about perfumes that make the wearer seem thinner.
Every now and then, we hear about some new “scientific”
discovery that a scent or formula was proven to make us
more attractive to the opposite sex.

Right now, the talk of perfumistaville is the Spicy Floral
perfume, often reported (even on AOL yesterday) that it
makes men think women are up to 12 lbs. lighter than they
really are.
Oguri puts the word scientific in scare quotes, but in fact there is evidence that a woman can make men think she weighs less by wearing a certain type of fragrance. The work was done by Alan Hirsch, a Chicago M.D. who runs a smell and taste clinic, holds several patents, and has written six books about smell.

Hirsch used a 5’9”, 245 pound woman as a model. On different days she wore one of three test scents as 50 men estimated her weight. Here’s how he describes the results:
Among the men tested, neither odor 1 (citrus floral) nor
odor 2 (sweet pea & lily of the valley) seemed to affect the
perception of weight. However, odor 3 (floral and spice)
significantly reduced the perception of the woman’s weight
by an average of 4.1 pounds. More remarkably, those men
who found the floral and spice odor to be pleasant perceived
the woman to be a full 12 pounds less than her actual weight.
Hirsch has filed for a patent based on the concept. In “Method of altering weight perception” (United States Patent Application 20040137086, July 15, 2004) his main claim is:
A method of modifying perception of body weight, comprising
the step of: administering to a person for inhalation an effective
amount of a composition comprising a hedonically positive
mixture of a floral odorant and a spice odorant, wherein the
person perceives the body weight to be about 5-10% less than
actual body weight.
What kinds of odors qualify as floral and spice?
Examples of floral odorants include jasmine, lilac, lily of the
valley, magnolia, rose, lavender, geranium, hyacinth, orange
blossom, apple blossom, carnation, and mixtures thereof.
Examples of spice odorants include cinnamon, ginger, cloves,
nutmeg, oriental spice, and mixtures thereof. In a preferred
embodiment, a mixed floral odorant and a mixed spice odorant
are employed.
So how does a smell alter a guy’s perception of a woman’s weight? Orguri speculates about the multisensory impressions produced by smell:
Perhaps the trick here is to keep the fragrance high-pitched,
just as light and airy instrumentation in music with harps
and flutes can make an audience visualize sprites.
I think she’s on the right track. Smell is linked to the other senses. For example, I’ve shown that people naturally relate smells to auditory pitch: some smells are matched to high notes, others to low notes. (You can download a copy here.) We casually speak about some smells being “light” and others “heavy.” It wouldn’t surprise me if the “weight” of a scent altered our estimate of another person’s body weight.

Thursday, February 26, 2009

American Smellscapes: Almond Blossoms in California

Dennis Wyatt of The Manteca Bulletin writes about a fantastic seasonal smellscape unfolding in the orchards of California’s Central Valley.
Just over a week ago the almond trees were bare, skeletons
against a winter sky. A week from now, blotches of green will
start appearing everywhere among branches as the most
magical snowfall on earth starts—gently falling almond blossoms.
Today, the sweet scent of the pink and white blossoms is drifting for miles over the almond growing towns that lie between the Bay Area and Yosemite.
Not venturing out into the countryside the next few days is
akin to cheating yourself of the chance to see nature in all of
its regal glory. Take time Saturday before rainy weather returns.
Drive down Jack Tone with the windows down. Walk along
Union Road north or south of Manteca at the edge of the city limits.
Bicycle down side roads out of Manteca and west of Ripon – Veritas,
Tinnin, Sedan, Brady, Fig, and Frederick to name a few.
What I’d give to be teleported to Manteca right now.

[Photo by Colleen Tompkins]

Tuesday, February 24, 2009

Speed Smells: Road Warrior Edition

This report in the Chicago Sun-Times is an eye-opener: rather than build a lab at home and risk having their house or trailer seized by police, some meth cooks set up overnight operations in a motel room. In by 10 p.m., out by 8 a.m., often leaving a hazardous and foul smelling mess behind. Since the restriction on sales of OTC cold meds, the number of in-room meth lab busts has decreased; but it still averages about 120 a year.

Here’s a tip from a professional decontamination guy: be wary of using the coffee maker in your hotel room—the meth cooks may have used the glassware and it could contain toxic residue.

Saturday, February 21, 2009

Come One, Come All

It’s the Avery and Stuart Show!

Live & in-person

7:00 p.m.
Monday, February 23rd, 2009
Purchase College Performing Arts Center
735 Anderson Hill Road
Purchase, New York

Prof. Stuart Firestein and Dr. Avery Gilbert present
Scents & Sensibility: The Science of Smell in Everyday Life.

Tickets $15 (cheap!)

Call the Box Office at 914-251-6200
or go to

Sponsored by Purchase College
The New York Academy of Sciences

Monday, February 16, 2009

First Nerve Vocalizes

When I was in elementary school, my next door buddy Arthur Cothary and I got our hands on a copy of MAD magazine featuring “Alfred E. Newman Vocalizes.” Inside was a 33⅓ rpm recording titled It’s a Gas. We put it on the turntable and sat back. At Alfred’s first burp, Arthur and I were rolling on the floor in stitches. By the third burp we were laughing so hard we couldn’t breath.

This morning your First Nerve host and narrator was live in-studio at WNYC on the Leonard Lopate Show, talking about smell. You can cue it up right here and listen to a blogger vocalize.

Saturday, February 14, 2009

Nose of the Robo Dog

In “Our Olfactory Destiny,” the final chapter of What the Nose Knows, I look ahead to what the future might bring in terms of smell. One topic is electronic noses: chemical sensors linked to neural network software. Today, these smelling machines are focused on specialized tasks such as tracking quality control in food ingredients. My guess is that robotic noses will eventually take over the dirty and dangerous jobs that humans don’t want: monitoring emissions from animal feed lots and sewage treatment plants, or searching for land mines.

I also describe how many e-nose labs are using materials and designs that mimic real biological noses. One group in Britain, for example, has lined its e-nose with synthetic snot—a 10-micron-thick layer of odor-retentive polymer called Parylene C.

DARPA—the Defense Advanced Research Projects Agency—recently funded a multi-institutional project called RealNose that seeks to design an electronic device modeled on a biological one: the dog. The goal is to understand the principles of fluid dynamics and odor transport in the dog nose and apply them to an artificial system. Pretty cool.

Members of the RealNose team include several mechanical engineering professors at Penn State University, whose contributions are described in this article.

Exit question: Will an electronic dog nose try to sniff its own butt?

Thursday, February 12, 2009

I Smell Dead People: Premiere Edition

Today being Friday the 13th, it seems a fitting day to launch First Nerve’s periodic update on those macabre instances in which a smell leads to the discovery of a decaying corpse.

The squeamish and the irony-impaired should immediately click away, preferably to some bright, safe, happy place where it always smells like sunshine and fresh laundry. The rest of you Uncle Fester types can pull your shirts up over your noses and follow me down the dank, dark path to the place where the smelly setup varies but the grim punch line remains the same.

A classic scenario occurred in Oklahoma City this week. The manager of an apartment building was checking out complaints of a “foul odor” coming from one of the units at 801 East Drive. Inside he found the body of a 64-year-old man. According to police, trauma to the body suggests foul play.

In Las Vegas, in late January, a landlord summoned police to a rental home at South Rancho Drive and West Sahara Avenue. Once inside, the officer followed a “bad smell” to a closet in which a dead body was hidden. The man had been shot. What happened next was unexpected: the officer was approached by one Perry Danley, who admitted that he had shot the victim in “roommate dispute.” Danley is now facing charges of murder with a deadly weapon.

Here’s one from the “in plain view” category. In mid-January, a worker at a rest stop on I-95 near Jacksonville, Florida, noticed a “foul odor” coming from a car in which a man and woman had been sleeping on reclined seats. He called State Troopers who found that the pair—a couple traveling from Kentucky—were in fact dead, and had been so for several days. Carbon monoxide poisoning is suspected.

And finally, the Orange County Register reports on the murder trial of Bahram Nazeri of Irvine, California, which was set to begin this week. He is accused of stabbing to death his wife and mother-in-law back in 2006. According to reporter Sean Emery:
Authorities believe Nazeri tried to hide the bodies in the
downstairs bathroom, telling his 6 and 8-year-old daughters
that their mother had gone on a business trip, and that they
shouldn’t open the bathroom door.

Prosecutors say Nazeri tried to cover the smell during the
next few days by continually filling the bathtub with ice. But a
visitor to the house on Aug. 22 reportedly became suspicious
when they noticed a foul odor, as well as what they described
as Nazeri’s odd behavior, and contacted Irvine police.
So long until next time!

UPDATE February 17, 2009  Suspect arrested in Oklahoma City case.

UPDATE February 25, 2009 Nazeri GUILTY.

Wednesday, February 11, 2009

My Smelly Valentine

How important to women is smell when choosing a lover? More specifically, is how a guy smells more important than how he looks?

For years, the default scientific answers were “smell is important” and “smell is more important than looks.” The answers were drawn from studies by psychologist Rachel Herz. In 1997, based on a survey of college students, she concluded that women “considered olfactory information to be the single most important variable in mate choice,” and that “female sexual interest is more affected by body odor than any other sensory stimulus.”

The underlying numbers are interesting. In response to the statement, “How someone smells can make a big difference to me,” women gave an average rating of 5.58, where 1 indicates “strongly disagree” and 7 indicates “strongly agree.” Ratings given to the other senses—how a man “looks” (5.15), “feels” (4.63) and “sounds” (4.48)—were lower, but not by much. Women rated smell as most important, but smell outscored looks by less than half a point. (For what it’s worth, men rated both sight and sound at 5.79 points.)

In 2002, Herz gave a modified version of her questionnaire to 198 college students. She concluded that when selecting a lover, “women considered a man’s smell to be more important than ‘looks,’ ‘voice,’ or ‘how his skin feels.’” Again, there was only about one-third of a point difference between women’s ratings for smell (5.59) and looks (5.26)

In 2005, a team of English psychologists led by Mark Sergeant repeated the second Herz study by putting her questionnaire online; it was filled out by 440 people. Once again, women rated how a man smells (5.73) as more important than how he looks (5.17) when they were selecting a lover. This time, smell beats looks by three-quarters of a point.

So the conventional scientific wisdom regarding female mate choice is that smell trumps looks. But this past December, social psychologist Joshua Foster completely upset the apple cart. He published a study in which women rated the actual body odor of men and actual photographs of their faces. The title of his paper gives away the result: “Beauty is mostly in the eye of the beholder.”

Foster got the materials for his experiment by taking portrait photos of 21 men and then having them wear fresh T-shirts to bed for two nights in a row. For the test session, Foster randomly paired the shirts and photos, and asked 22 women to take a look and a sniff. They rated the pleasantness, sexiness and attractiveness of the shirt smell and the photo. Half the women rated shirts and photos separately; the other half rated the photo and shirt simultaneously and gave a single score to the combination.

Foster found that the pleasantness, sexiness, and attractiveness ratings were all similar, so he collapsed them into single scores for body odor attractiveness, facial attractiveness, and combined BO/face attractiveness. He was interested in how well BO and facial scores by themselves predicted the combined BO/face scores. Statistical analysis showed that “visual cues influenced [combined] attractiveness judgments more than olfactory cues.” Foster concludes that
sight is more important that smell when women
judge the attractiveness of men.
So who are we to believe: Herz and Sergeant or Foster? Foster’s experiment better represents the real-world conditions in which women evaluate potential mates: they look at actual faces and smell actual BO. In contrast, the Herz and Sergeant studies rely on “retrospective self-report methods,” an inherently less reliable research method that asks women to recall the importance of attractiveness cues. Foster argues that
when judgments of attractiveness are made without
the filter of memory, visual cues are significantly more
important than olfactory cues.
My inclination as a scientist has always been to trust behavioral observation over questionnaire data, and contemporaneous judgment over recollection. Therefore my money’s on Foster.

Tuesday, February 10, 2009

Of Mice and Men

Scientific progress in olfaction has been slower than in the other senses. There is general agreement about why this is: it is difficult to deliver precise amounts of odor in an experimental setup, there are large differences in odor perception from person to person, and until relatively recently no one knew the nature of the olfactory receptors in the nose.

We’ve overcome some of these obstacles. The receptor question was solved by Linda Buck and Richard Axel in work that earned them the Nobel Prize in 2004. There are now many designs available for computer-controlled olfactometers. Individual differences in smell ability, however, are just a fact of life.

I have come to believe that other, more subtle, obstacles are holding us back, namely certain habits of thought. I mention a couple of these in What the Nose Knows. Take the notion that smell is primarily an emotional sense: this belief lulls us into underestimating how cognitive olfaction truly is. Memory (where did I smell that before?), comparison (I think that one smells woodier), and interpretation (this smells too feminine for a family hand soap), are all higher order cognitive functions. The brain is very thoughtful about the sensations that the nose supplies.

Another conceptual roadblock is the anti-genetic bias of many psychologists. Their default assumption is that differences in odor perception are the exclusive result of experience and learning, and that genetics and biology have little relevance. Yet genetic variability in olfactory receptors and its effect on perception have barely been explored. I argue that genetics may account for many of the individual differences in perception. We certainly won’t know until we look.

A third obstacle is the lazy mental habit of referring sensory properties to the molecules that stimulate them. Chemists, for example, tend to say things like “phenylethanol has a detection threshold concentration of such-and-so parts per million.” Wrong! Perception is a function of the perceiving organism, not the molecule. What we should say is, “The average person’s detection threshold for phenylethanol is such-and-so parts per million.” Odor molecules, like light of varying wavelengths, exist in the external world. But smells, like rainbows, exist only in our heads.

Is this just semantics? Yes, but semantics matter. If we don’t speak and think clearly about a scientific problem, we can end up on a wild goose chase.

These thoughts came to mind when I read a new paper from the University of Lyon, in France. A research team led by Nathalie Mandairon compared the smell preferences of mice and men. How does one do that? By measuring the time that humans and mice spent sniffing each of nineteen different odors. The more a mouse likes a given smell, the longer it spends sniffing it. Similarly, we tend to sniff longer at pleasant smells and more briefly at unpleasant ones.

Using sniff-time data, Mandairon and her colleagues were able to compare apples to apples even though their experimental subjects were different species. The data showed that both groups respond to odors similarly: men find pleasant what mice find pleasant, and vice versa. This is an interesting, if not unexpected, result. After all, we share a broad mammalian heritage with mice and their diet has co-evolved with ours (they’ve been feeding on our grain stores and leftovers for millennia).

Just as interesting to me was how Mandairon et al. discuss the results. They reason that if mice share our perceptions of odor pleasantness, there must be some basis beyond “culture, life experience and learning” that accounts for the commonality. Hmmmm . . . what could that possibly be? They hint at it here:
This suggests that . . . we are endowed with a partly predetermined
neural basis for these odor hedonic representations . . .

They edge closer to it here:
Perception of the hedonic aspects of odorants is thus a complex
process which involves both innate and learned components.

Innate? Partly predetermined? Are they daring to suggest . . . why, yes!
 . . . predispositions in odor preference may be underlain by
genetically programmed neural circuits . . .
In an entire paper on similarities in odor perception between mice and men, genetics is mentioned exactly once. When it comes to this political hot potato, neuroscience researchers can be as timid as church mice.

Tiptoeing around genetics for political correctness is understandable, if not praiseworthy. What I can’t understand is Mandairon’s endorsement of a mathematical model that predicts odor pleasantness. The idea is that odor pleasantness is “partially dependent on the odorants’ physicohemical properties.” Of course this has to be true at some level: different molecules produce different smells because they have different structures. But Mandairon et al. go beyond tautology; the shared response of mice and men suggests
that olfactory preferences are indeed partially engraved
in the structure of the odorant molecule
there is an initial part of the [odor] percept which is innate
and engraved in the odorant structure.
Perceptions engraved on the molecule? This is simply a bizarre way to think. What else is engraved on a molecule of phenylethanol: Visual associations to red roses? The name of my florist? An olfactory memory of my dead grandmother?

Perceptions happen in the central nervous system of an organism. To talk as if odor pleasantness resides in the structural features of a molecule is animistic thinking, pure and simple.

Monday, February 9, 2009

Speed Smells: Eustis, FL edition

Deputies respond to a guy threatening someone with a gun in the town of Eustis, Florida, northwest of Orlando. They notice empty Sudafed containers and “the foul odor of a meth lab” on the guy’s property. Closer inspection reveals the meth lab is concealed in a silo ten feet below ground.

Pretty clever setup, but the smell gives you away every time.

Channel 9 WFTV has the video.

Saturday, February 7, 2009

D’oh! ‘Professeur de Parfums’ Flunks Neuroanatomy

Who is Roja Dove? According to his own web site, he is
a vast fountain of fragrance knowledge . . .

the world’s leading fragrance authority . . .
the world’s sole “Professeur de Parfums.”
When Marie-Hélène Wagner interviewed the Professeur on the Scented Salamander perfume blog in 2007, he coughed up this howler:
And so the reason I love white blossoms in particular, they contain a
molecule called “indole” and the indolic note also naturally exists in
the animal notes. So because of the way our brain processes odor.
You have the emotional part, the cerebellum, which is
responsible for processing scent, as I’m sure you know
, and
then you have the rational part. So when you smell this scent, the
rational part of your brain smells it as a large bouquet of flowers but
the irrational part, the emotional part picks up on indole and what it
immediately thinks . . . sex.
Well, anyone can fumble his neuroanatomy under intense questioning by a fragrance blogger. But a few months later, Rebecca Howard interviewed His Professorship for the Daily Mail:
. . . according to fragrance expert Dr Roja Dove we should think
much more carefully about what we spray on our bodies as the
way we smell not only influences how we feel but can also have
an effect on the way people percieve [sic] us. ‘Odours are
processed in the cerebellum, by the limbic system
explains Dove.
Sigh. The last time I checked, the limbic system is not in the cerebellum, the cerebellum is not the “emotional part” of the brain, nor is it “responsible for processing scent.”

Luckily for the Professeur’s customers, fragrance consultation isn’t brain surgery.

Thursday, February 5, 2009

Sweet NYC Mystery Solved

At a press conference today, New York City Mayor Michael Bloomberg announced that the mysterious sweet smell that has covered parts of the city sporadically over the past few years was the result of fenugreek seeds being processed at the International Frutarom Corporation plant across the Hudson River in North Bergen, NJ.

Investigators located the source by mapping the time and location of odor complaints phoned into the city’s emergency hotlines. (I used a similar method last week to point the finger at Roxana, IL, as the source of the big stink inundating St. Louis.) The city’s odor map is available at I have to say that at first glance it doesn’t make a compelling visual case for a single point source.

The city’s press release lacks chemical detail as well. It says the smell resulted from Frutarom “processing foenugreek [sic] seeds to produce food additives.” That’s OK as far as it goes. But in all likelihood the smell is due to one particular molecule found in fenugreek, known informally as “caramel furanone,” or more precisely as sotolone, or even more precisely (and too alarmingly for a soothing press event) as 4,5-dimethyl-3-hydroxy-2(5H)-furanone, illustrated above.

Sotolone has a maple syrup-like odor and is, in fact, used to flavor artificial maple syrup. It was recently identified as the molecule responsible for the odor of maple syrup urine disease, an inherited metabolic anomaly that can be fatal. A weird form of pseudo-maple syrup urine disease was reported recently: mothers who eat fenugreek just before delivery (it’s a folk medicine for encouraging lactation, among other things) have babies that smell suspiciously like maple syrup, which throws the delivery room staff into high alert.

Sotolone is also a key aroma compound in soy sauce and various kinds of wine.

Wednesday, February 4, 2009

Minha conversa com Simone, no Brasil.

Brazilian perfume blogger Simone posts an interview with me at
her site + Q Perfume.

The First Nerve Interview: Prof. Donald H. McBurney

[This is the first in what I hope will be an ongoing series of interviews with scientists doing the newest and most intriguing research on smell.]

A while back I wrote about new research on “olfactory comfort,” the phenomenon of people sniffing, or even sleeping with, the worn clothing of a person from whom they are physically separated. The research was led by Donald H. McBurney, Professor Emeritus of Psychology at the University of Pittsburgh.

I caught up with Prof. McBurney by email and asked him a few questions about his research.

FN: You’ve been interested in wide variety of topics: everything from the taste of chili pepper to the evolutionary aspects of physical attractiveness. How do you characterize yourself as a scientist and psychologist?

DM: I was trained as a sensory psychologist, specializing in the psychophysics of taste and smell. This is a small part of what is considered two of the minor senses, so I have always looked for parallels in other senses. Also, because sensory psychology is among the more biological areas of psychology, I was drawn to evolutionary psychology when it came along. The work on physical attractiveness started when I saw a methodological flaw in some published research, and got an undergraduate student interested in it.

FN: Your interest in the chemical senses began when the field was much less developed than it is today. What first drew you to it?

DM: Pure accident. I was offered a position in Carl Pfaffmann’s lab as a grad student, and got interested in the work.

FN: What specifically got you interested in the science of human body odor?

DM: It is something that is obviously very important to people, based on the effort and money we spend to control it, and the social consequences of body odor. Yet it had received almost no scientific attention. I thought that made it worth attention.

FN: What are the next things we need to find out about olfactory comfort?

DM: We have some unpublished data that suggest interesting relations between olfactory comfort and attachment theory. This would take someone with expertise in both olfaction and personality theory, not a common combination.

FN: What are most important achievements in the field of human olfaction to happen during your career?

DM: I would rather not stick my neck out on that. I do think the progress in understanding the genetics of olfaction has much promise for the future.

FN: What are the biggest current challenges in the study of odor perception?

DM: Control of stimulus at the receptor makes measurement very difficult. In addition, there is a lack of motivation to study odor because it is not as crucial as vision and audition for communication.

FN: How well informed is the public about the current science of smell and taste?

DM: Taste and smell research tends to make the news sometimes because it seems a bit out of the ordinary, as with the work on sniffing T-shirts.

FN: Any other thoughts?

DM: Taste and smell lie at the intersection of many important and interesting areas, such as food intake and health, sexual behavior, and social behavior.

Tuesday, February 3, 2009

Redefining “Fresh and Clean”

The Wall Street Journal’s Ellen Byron asks “Is the Smell of Moroccan Bazaar Too Edgy for American Homes?”

Byron gives a concise history of how the fragrances of American cleaning products have evolved from a primitive condition of bleach and ammonia to the complex, fantasy accords we smell today. She also describes how consumer products giants like Procter & Gamble and Clorox keep up with the ever-changing aesthetic definition of “fresh and clean.”

In discussing scent marketing in What the Nose Knows, I emphasized that smelling nice isn’t enough—a fragrance has to make sense in the context of the product’s overall message. Thus, my favorite part of Byron’s story is where she quotes Michael Ott, director of research and development for Clorox:
Pine-Sol, also owned by Clorox, avoids fragrances that seem
too gentle. Current Pine-Sol fragrances include Wild Flower
Blast and Mountain Energy.

“The scent experience needs to be aligned with the message
you’re trying to communicate—Pine-Sol needs to scream
‘power,’” Mr. Ott says. “You’ll never have a rose-petal Pine-Sol;
that’s almost comical.”
Exactly right.

Sunday, February 1, 2009

Another Endangered Smellscape: Franklin, VA

Since the 1930s, the paper mill in the small town of Franklin, VA has been one of those olfactory beacons on the American smellscape that people find disagreeable until they remind themselves, in a phrase echoed across the land, that the local stink is also “the smell of money.”

According to reporter Joanne Kimberlin of The Virginian-Pilot newspaper, International Paper’s plant in Franklin employs about 1,100 people—a big fraction of the town’s 8,400 residents. The rotten egg smell associated with it is something they’ve been willing to put up with for generations in return for a steady paycheck. As in other such news stories, local old-timers remember the odor as being far worse in the past. Their recollections appear to be accurate: a spokesman for the mill tells Kimberlin that total reduced sulfur output (the main source of odor) has been cut 95 percent in the last decade.

The advent of modern pollution controls has dimmed the intensity of Franklin’s olfactory beacon, no doubt to the relief of downwind cities. According to Kimberlin the stink would occasionally carry as far as Norfolk in the old days, a distance of some 40 miles.

With less sulfur comes less smell and, inevitably, a less memorable impression. The loss of a stink is unlikely to be mourned, but it’s a loss none the less. And with it may fade the collective bargain made by the citizens of Franklin: namely that a little rotten egg smell is an acceptable price for employment and the manufacture of a valued product. NIMBYism is luxury they decided they could live without.