Smelly Facts: A Collection of Little Facts

Do we take our sense of smell for granted? Do we lament the fact that it is nowhere near as sensitive as that of many other animals? It is still pretty remarkable. A few random facts today to remind us how special our sense of smell is.

· “We can smell smoke at concentrations well below that needed to trigger even the most sensitive of household smoke detectors.”
· “We can distinguish among roughly 10.000 different chemicals by their smell.” (Axel, 1995)
· “Blind people regularly identify other individuals by each person’s unique odor, and sighted people can do that too when they try.” Where does our special, identifiable odor come from? “In humans, specialized scent-producing glands (apocrine glands) are concentrated most highly in the axillary region (underarms) and also exist in high concentrations in the genital area, the alveolar area (around the nipples), the navel area, on the top of the head, and on the forehead and cheeks.” (Stoddart, 1990)
· “Much, if not most of what we call the flavor of foods is actually smell, not taste.”
· “As we get older, our sense of smell declines. By age 65, about 25 percent of people have serious olfactory impairment, and by age 80 the number is 75 percent." (Doty et al., 1984)


Note: All of the above facts are direct quotes from Peter Gray’s Psychology, 4th Edition, Worth Publishers

Image of navel: commons.wikimedia.org

Smelly Facts: Odors & Perceived Attractiveness

Visual cues -such as symmetrical features- are of great importance when judging how attractive a face is. Sensory cues however (such as a person’s voice) also play a big role in whether a face will be perceived as attractive. (Demattè et al., 2007) Could the presence (or indeed absence) of certain smells affect the perceived attractiveness of a face as well? “Olfactory Cues Modulate Facial Attractiveness”, a recent article by Demattè, Österbauer and Spence explores this question with a most interesting experiment. In this experiment, the participants (all female) were asked to rate the attractiveness of different male faces presented on a computer monitor, while simultaneously being presented in each trial with either one of four different odorants, two of which were unpleasant and two of which pleasant (geranium or male perfume VS body odor and rubber) or a neutral odor (clean air). (For those of you wondering, the judgments on the perceived pleasantness or unpleasantness of these odors were derived by a pilot study) The results demonstrated (with statistical significance) that the participants judged the faces as being more attractive when they were paired with a pleasant or neutral odor (geranium, male fragrance or clean air) and less attractive when the faces were paired with the unpleasant odors (body odor, rubber). Since clean air and pleasant odors did not differ significantly between them in the effects they exerted on the participants’ judgments, the best interpretation of these results seems to be that only unpleasant odors seem to have a modulatory effect on perceived attractiveness. I would love to see more research on this subject, especially in regards to specific fragrances that people judge as generally pleasant or unpleasant. Yes, even though taste in perfume is subjective, I do believe that there are fragrances that are generally perceived as attractive or repulsive. Related to this last thought and for all of you (us!) Shalimar lovers out there, I include the following excerpt from the aforementioned, extremely interesting article by Demattè et al.:

“The only previous study that we are aware of in which the presence of an odor was shown to modulate people's ratings of the facial attractiveness of others was reported in a book chapter by Kirk-Smith and Booth (1990). The authors found that in the presence of a perfume (the brand Shalimar; once described by Paukner 1965 as being similar to an "ideal erogenous perfume"), both men and women rated half-torso clad photographs of men and women as being significantly sexier and softer as compared with a no-perfume condition.”

References: Demattè et al., 2007
Image: commons.wikimedia.org

Smelly Facts: Olfaction and Gender Differences

Perfume enthusiasts often marvel at the individual differences that emerge when one person’s experience of a scent is compared to another’s. Our individual perception of a scent is likely tied not only to life experiences that have shaped the way we perceive certain smells, but to constitutional differences as well. One very surprising and important variable that plays a role in olfactory differences is gender. “On the average, women detect odors more readily than men, and the brain responses to odors are stronger in women than in men.” (Doty et al., 1985) Additionally, women are apparently more attentive to smells as well. For example, the smell of a potential partner plays a bigger role for women than it does for men. Furthermore, when repeatedly attending to a particular faint odor, women have the ability to become gradually and progressively more sensitive to it, until they can detect it in concentrations one-thousandth (!) of what they could at the start. (Dalton et al., 2002) However, it must be noted that this effect is not exhibited in prepubertal girls and menopausal women, so this ability seems to be tied to female hormones.

What effects might this increased sensitivity have on the different ways men and women perceive the same fragrance? Are there any implications for professional perfumers? It seems unthinkable, considering the time and enormous effort involved in training a professional nose. On the other hand, according to studies, only women of sexually reproductive age are able to detect faint odors in such minute concentrations as mentioned above. Surely that should make a difference? I realize I am following a controversial train of thought at the moment, and one I am certainly underqualified to make any assumptions on. It certainly is an interesting topic though, wouldn’t you say?

References:
Dalton, Doolittle, & Breslin, 2002
Doty, Applebaum, Zusho, & Settle 1985
Kalat, 2007

Image: www.gutenberg.org
Dalton

Smelly Facts: A Glance at Anosmia

Anosmia, the general lack of olfaction, can be congenital – that is, a person can be born anosmic. Alternatively, anosmia can occur later in life, either due to brain damage or because of vitamin A deficiency. In contrast, Specific Anosmia is the inability to detect the smell of a single chemical. A small percentage (2%-3%) of the general population for example, is unable to detect the smell of isobutyric acid – the component that makes sweat smelly. (Next time you find yourself suffering next to someone who has forgone the use of deodorant in the bus, you can perhaps distract yourself by wondering whether the reason behind their thoughtless behavior is the fact that they are anosmic to sweat and thus unable to detect their own funk!) Among perfume enthusiasts, the most commonly cited specific anosmia is of course musk anosmia, but in reality, specific anosmias span a much wider range of odors. To give a few examples aside from the aforementioned sweat and musk, other specific anosmias include fish, urine, sperm, camphor, mint and malt.

References: Amoore, 1977, Pelosi & Viti, 1978 and Kalat, 2007.