What the Nose Knows - Avery Gilbert [43]
It may not even matter whether the actual smell is good or bad. Spin can alter these perceptions as well. Dalton tested odors that were pleasant (wintergreen), unpleasant (butyl alcohol, a solventlike smell), and neutral (isobornyl acetate, a balsamlike note). Negative spin made all three smell stronger. Information bias is very effective at distorting the clear evidence of our senses—the brain easily trumps the nose.
Biasing information doesn’t have to come from an authority figure in a lab coat. Dalton tested two people at a time in the environmental chamber. One was an unsuspecting volunteer, the other a carefully scripted actor pretending to be naive. The actor kept up an ongoing verbal and behavioral commentary about the odor in the air. This peer-to-peer kibitzing worked splendidly. When the spin was negative, 70 percent of volunteers reported health symptoms (everything from throat irritation to dizziness to stomachache); when it was positive, only 12 percent did so. Given a scent in the air—any scent—acquaintances can literally talk you into feeling sick.
The commonly acknowledged power of scent derives in large part from the power of suggestion. Negative placebo effects may exacerbate the symptoms of “sick building syndrome”—for example, if you believe that the musty smell in your office is from a toxic mold—while positive placebo effects explain the popularity of aromatherapy treatments. Beneficial mood change is one of the biggest claims made for aromatherapy. For example, lavender is usually extolled as relaxing and neroli as stimulating. A recent study showed that positive spin can completely reverse the aromatherapeutic effects of these two scents. When told the lavender they were smelling “has relaxing properties,” people did in fact relax, as measured by changes in heart rate and skin conductance. Yet when told it “has stimulating properties,” the same measures showed—presto change-o—that people were stimulated. The same reversal happened with neroli. It takes only the slightest waving of hands to create a positive placebo effect in aromatherapy.
The effects of spin often play out in everyday life. When the crew of a Norwegian air ambulance noted a cabbagelike smell in flight, they figured the patient they were transporting had passed gas and they ignored it. When the smell reappeared on another flight later that day, the crew was puzzled; it was unusual for two patients to be so extraordinarily gassy. Soon flames were shooting through the cockpit and the pilots were forced to make an emergency landing. The fartlike smell was smoldering insulation on electrical wires. The crew was in a medical mind-set, not a mechanical one, and their preexisting expectations led to a near-fatal misreading of what their noses were telling them.
Smells don’t happen to a passive nose alone. The brain actively regulates the physical and cognitive aspects of odor perception: it exerts moment-by-moment control of sniffing to govern how much scent enters the nose; it systematically dials down the intensity of one smell to prepare us for the next; it automatically makes a provisional interpretation of a smell, based on context cues, to prime us for a behavioral response. From sniff to spin, the nose and brain constantly reshape our awareness of the smellscape.
CHAPTER 5
A Nose for the Mouth
Blindfold a person and make him clasp his nose tightly, then put into his mouth successively small pieces of beef, mutton, veal, and pork, and it is safe to predict that he will not be able to tell one morsel from another. The same results will be obtained with chicken, turkey, and duck; with pieces of almond, walnut, and hazelnut….
—HENRY THEOPHILUS FINCK (1886)
WHEN IT COMES TO FOOD, I’M A SMELL CHAUVINIST: taste is boring. The tongue supplies just five channels of information: bitter, sweet, sour, salty, and umami. (My Japanese colleagues insisted for years that monosodium glutamate delivered more than a salty impression. The discovery in 1996 of glutamate receptors on the