scent111110.jpg What do pumpkin pie, cinnamon buns, licorice, toast, bleach, rain and linen have in common? They are all scents that evoke potent emotional and physiological reactions in humans. The question is, what kind of reactions? The answer may make you change what you serve for your Thanksgiving feast ... and how you clean up before the guests arrive.

“Nothing revives the past so completely as a smell that was once associated with it." Vladimir Nabokov said that. Brown University psychologist Rachel Herz would agree. She says that smell is distinct from the other primary senses because it is connected to the olfactory cortex, the part of the brain responsible for emotions and memory. "In other words, the ability to experience and express emotion grew directly out of our brain’s ability to process smell.” Humans have about 5 million to 6 million olfactory receptors (compared with 220 million in dogs) according to The Smell Report, published by the Social Issues Research Centre, a U.K.-based nonprofit social research organization.

So what does the science (if we choose to accept it) tell us about the potency of certain scents?

Pumpkin pie: Bake with caution. One study found that pumpkin pie (when paired with lavender) is for men one of the most sexually arousing scents. The next most arousing odors were a combination of cinnamon buns, doughnuts and licorice; pumpkin pie and doughnuts; orange; and lavender and doughnuts. Cranberry, on the other hand, appeared to be only minimally titillating. All factors to consider while menu planning, right?

Good n' Plenty candy, cucumber and baby powder: These three scents are among the most sexually tantalizing smells for women. Who knew?

Toast: In several British smell surveys, toast has come out on top as the most popular scent, due in part to a chemical reaction that occurs when the bread is toasted (which generates scents similar to caramel and strawberries) and to the strong association with childhood memories of breakfast (toast is big in the commonwealth countries, remember).

Cherries and barbequed meat: Scents that, according to one study, are a sexual turn-off for women.

Cleaning products: Maybe you are trying to impress your mother-in-law with your domestic prowess. Or maybe you are trying to compensate for a poorly ventilated kitchen. Whatever the motivation, for many of you, having a clean-smelling house is an important part of hosting. According to an article in the Wall Street Journal, for decades a clean home has been synonymous with the smell of ammonia and bleach. In the 1970s and 1980s, it was all about pine and lemon. Cucumber melon was another smell de jour in the 1980s, and scents evoking "fresh rain" were big during the 1990s, followed in recent years by the smell of "linen" (whatever that means, exactly).

The bottom line is that these days, if you want your house to seem "clean" it must smell like a cleaning product- at least according to consumer research. "Your home could look clean, but if there's an absence of scent, you don't really know," says Scott Beal, a Procter & Gamble brand manager for the company's Febreze line. "Scent is a signal you've done something." Of 3,331 cleaning-product introductions in 2008, 93% contained a fragrance, more than twice as many products as in 2004. Interestingly, this explosion of scented cleaning products comes at a time when Americans spend far less time cleaning (about 40% fewer hours in 2005 than in 1965).

It seems that we Americans have an almost Puritanical preoccupation with cleanliness, from the overuse of antibacterial soaps to the excessive spraying and pumping of air fresheners. Somewhere along the line we have associated the smell of clean with a "clean" (or more morally upright) lifestyle. According to a study called "The Smell of Virtue," a clean-smelling house may make us actually behave better. In the experiment, the subjects in rooms sprayed with citrus-scented Windex acted in a more fair and generous manner than people in non-scented rooms. Another experiment found that in the room infused with scented products, participants were more likely to volunteer for a cause and were more willing to donate money than participants in a non-scented room.

Some 75 percent of American households use air fresheners, with room sprays the most popular type. In 2007, 328 new products were introduced to the market.

Neutrality. If you want your house to just smell like, well, your house, try focusing more on eliminating bad smells rather than covering them up with strong "clean" smells. Spray the room with a misting bottle of water, which will help absorb stinky smells. Or open some windows. Get some house plants. Don't cook fish the night before. Keep your gym shoes in the closet. Change the sheets. Open more windows. By eschewing smelly products you may be doing yourself a favor. A 2007 analysis by the Natural Resources Defense Council (NRDC) found that 12 of the 14 common air fresheners tested contain phthalates, chemicals that may affect hormones and reproductive development, especially in babies. The federal government does not currently test these products or require manufacturers to meet specific safety standards. If you must go with a scented spray, try Febreze Air Effects or Renuzit Subtle Effects, neither of which contains detectable levels of phthalates.

For me, the smell of coffee, baked bread, and fresh basil are the most comforting. I like fresh air. I like Marc Jacobs perfume and the smell of baby powder. I don't like strong syrupy scents (those Bath n Body Works moisturizers that smell like cake?). I despise patchouli and I am turned off by too much incense. The smell of chlorine reminds me of long afternoons at the public pool. The smell of BBQ reminds me of camping. I have a strange affinity for the smell of Band-Aids.

What are your favorite smells?
What smells turn you on (and off)?
What are your natural tricks for making your home smell clean and fresh?

(Image: Swiftlet Farming).