Smell and Perception

“The act of smelling something, anything, is
remarkably like the act of thinking itself”
– Lewis Thomas, Late Night Thoughts on Listening to Mahler’s Ninth Symphony

A man who suffered from anosmia, or loss of the sense of smell, once commented: “It was like being struck blind. Life lost a good deal of its savor – one doesn’t realize how much “savor” is smell. You smell people, you smell books, you smell the city, you smell the spring – maybe not consciously, but as a rich unconscious background to everything else” (qtd. in Drobnick 185). Why is scent such a vital part of perception? And why do so few people fail to realize it until it is absent? If scent gives life such “savor”, then why is it so underappreciated? A large part of the problem is that perception of scent is far more involved than most people care to admit. Our culture, our society, our conditioning, these all contribute to and transform our perception of smell, and these factors are so diverse and uncontrollable that the explanations are as ephemeral as the sense itself.




We are aware of the world through our sensory experiences. The term used to describe our awareness is perception, and it’s a highly complex concept. So expansive is the study of perception, in fact, that many theorists choose to break it up into more manageable slices – how we perceive sound, or color, or taste. Of course, perception is all wrapped up in philosophy as well. Zen Buddhists and atheists alike contemplate such perceptive mysteries as the sound of one hand clapping, or the reality of the forces we cannot see. Perception is part of biology, and culture, and sociology, and, well, pretty much everything else. Sadly, though, the study of smell and perception is rather limited. There are countless reasons for this, but the simplest answer is that smell is elusive, complicated, and just not really understood yet. Scientists have very recently figured out how smell works, at least on a biological level. The 2004 Nobel Prize in Physiology or Medicine went to neuroscientists Richard Axel and Linda B. Buck for their research on scent, and Jim Drobnick says that their research is “on the verge of cracking” the basic code for scent perception and cognitive processing (2). We now know, for the most part, what goes into our noses and what our brains do with it to turn it into a smell. But smell perception is so much more complicated than that. What makes us like or dislike a smell? Genetics? Culture? The shape of the molecules? Are our perceptions of smell inherited, or instinctive, or learned? The research on our most primitive sense is still in a most primitive state.
Scent has often been, according to Drobnick, “delimited as a mere ‘biological’ sense”, but in reality, scent is “subtly involved in just about every aspect of culture, from the construction of personal identity and the defining of social status to the confirming of group affiliation and the transmission of tradition” (1). Perhaps this is why the perception of smells is such a difficult topic to discuss – one can’t really break it up into nice, neat slices – certainly, the scientific aspects alone are difficult to navigate. But scent cannot be examined simply from a biological perspective, because so much of olfaction is dependent upon cultural factors created by society and involving the environment, the people in it, and their symbolic worldviews. Drobnick explains: “no act of perception is a pure and unmediated event; each society inflects and cultivates sensory practices according to its needs and interests” (2). Drobnick suggests that taking a sociological approach to olfactory investigation will open up wonderful new methods of inquiry. Through “olfactocentrism”, he says, we can explore how scent transforms perception and thought.
To address olfaction from a cultural viewpoint, very little needs to be known about how smell works, but a basic explanation may be helpful. Rachel Herz, a psychologist who writes about smell in clear, straightforward terms, gives a fairly concise overview of the process of olfactory perception. Odors, she explains, are molecules that float through the air. When we breathe, air goes into the nostrils where these molecules land on the olfactory epithelia, a mucous membrane containing sensory neurons. The neurons are covered with cilia, and the cilia have receptors on their tips. Humans have about 20 million receptors in both nostrils (dogs have about 220 million), which is why we are considered rather poor smellers. So, here we are, with the odor molecule-filled air, being sensed by the 20 million receptors. The smell must then, of course, make a quick trip to the brain. The neurons connect directly to the brain by passing through a bony, holed structure called the cribiform plate. The axons of the neurons bundle together, forming the olfactory nerve, which sends impulses to the olfactory bulb. From the bulbs, the sensory information goes to the olfactory cortex, part of a brain area connected directly to the limbic system, where emotions are housed. Interestingly, Herz notes, the “connections between the olfactory area and the amygdala and hippocampus are more direct than the connections between these brain areas and any other sense” (“I Know What I Like” 191). Herz thinks that this is the key to why olfaction is so closely linked to both emotion and memory.
There are still a few puzzles associated with this process – for example, how the molecular makeup of an odorant gets translated into a psychological perception, and then, how we formulate a like or dislike response. According to Herz, most scientists follow what is known as the “shape theory,” which says that the molecules have different shapes and the shapes fit (or don’t fit) into the olfactory receptors. Once a correct amount of molecules fit into the receptor, the signal is sent. The pattern of electrical activity in the olfactory bulb then determines the scent we perceive (“I Know What I Like” 192). Luca Turin, though, proposes a rather different theory called the vibration theory. He says that the perception of scents is due to the different vibrational frequencies of the molecules, and molecules with similar vibrations produce similar scents. Herz says that Turin’s theory has been proved true for some scent categories, like citrus, but that the evidence still leans mostly in favor of shape theory (“I Know What I Like” 192).
Perception theories aside, however, a complete understanding of smell sensation requires much more than just a biological explanation. Herz thinks that we need “combined efforts by scientists in molecular biology, neurophysiology, and psychology” (“I Know What I Like” 192), but I think we also need ethnographers, anthropologists, and sociologists. Smell is cultural, and to really understand it, we need to study its cultural aspects.
We first must recognize how scent perception differs drastically from the traditional vision-based approach to perception. It’s logical that we tend to approach perception through visual means, because vision has long been touted as the most important sense, and it is the one we rely on most heavily. But examining the world around us while heightening the importance of smell can give great insight into perception, particularly in regards to emotion, culture, and social development. One essay called “Smellscape”, by J. Douglas Porteous, argues that “unlike the information present in vision, olfactory experiences are inherently discontinuous, fragmentary and episodic, that is, time-based” (Drobnick 86). Considering the immediacy of vision, a sense that is focused on time would provide a very different perception of the world. Instead of the focus being on perspective, scale, and distance, as they would be in a visual environment, a “smellscape” would concentrate on “intensity, complexity, and affect” (Drobnick 86). Porteous is quite confident that these olfactocentric “views” of the world “exceed ocularcentric approaches” (Drobnick 86).
Visual perception is grounded in thought and cognition, whereas olfaction is tied directly into the brain’s limbic system, which is the “seat of emotion” (Porteous 101). Porteous explains that vision distances us from the object, because we “frame views in pictures and camera lenses; the likelihood of an intellectual response is considerable” (101). Smells, by comparison, “penetrate the body and the immediate environment, and thus one’s response is much more likely to involve strong affect” (Porteous 91). Porteous’ explanation made sense to me as I compared the process of looking at a lovely banquet in a colorful magazine and actually experiencing a banquet laid out on a table. Our vision can appreciate the beauty of the food, the artistic layout, and the rich colors, the view framed in a picture, through a camera lens. But, putting the food before us, with the apple-pie cinnamon and roast turkey shaped molecules vibrating into our bodies, our response is much more intense, emotional, and surrounding. Alain Corbin quotes Saint-Lambert: “Odor gives us the most intimate sensations, a more immediate pleasure, more independent of the mind, than the sense of sight” (Corbin 177). Porteous agrees, explaining that smell is primarily an “emotional, arousing sense, unlike vision and sound, which tend to involve cognition” (Porteous 89). To Rachel Herz, though, this begs an important question: “Where does the sensory perception of a smell end and emotional appreciation of that smell begin?” (“I Know What I Like” 192). Herz feels that our emotional responses to smells are learned.
While Jim Drobnick recognizes that we have an instant positive or negative reaction to smells – a “polarized response”, he calls it, he also says that there is an “intense power of suggestion” when it comes to olfactory perception. Herz explains: “Our responses to odors are learned: our specific history with specific odors gives them meaning, making them pleasant or unpleasant to us” (“I Know What I Like” 194). She goes on to relate that odors have connotations that we learn by association. Every smell we experience is in a certain context: “semantic, social, emotional, physical”. The context always has some emotional content, positive or negative, and we associate the smell with the remembered emotion (“I Know What I Like” 194). There are many examples that illustrate this. Imagine the first time you smelled roses. Perhaps you were playing in a lovely English garden, or watching your father bring home a gift for your mother. What if, though, you first smelled roses at your mother’s funeral? Or if the mean old woman who babysat you wore a rose-scented perfume? Your association with the scent would be very different. Herz notes that the reason most of our odor preferences come from childhood is because that is when we first experienced them. She comments: “Anytime in life that we encounter a new smell, emotional-odor associative learning can take place to determine our hedonic responses to it” (Scent of Desire 38).
Perception is also affected by culture and situation. While some may say that there are certain smells that are universally disliked, Herz disagrees. She notes, for example, that in some cultures, the smell of feces represents ritual and tribal conquest, as members of a culture smear their faces and bodies with it. In other cultures, the smell of a burning body, something that Westerners “could never conceive of liking”, represents a typical cremation ceremony, and is a smell that is even accompanied with celebration – some cultures like it (Scent of Desire 44). Herz gave another interesting example that illustrates the difference in odor preferences in two English-speaking cultures, Britain and the United States. The smell of wintergreen mint, she says, is a favorite American scent, but is “highly disliked” in the United Kingdom (Scent of Desire 42). According to studies conducted in Britain in the mid 1960’s and the United States in the late 1970’s, history provides the answer. In Britain, the scent of wintergreen was used in medicines and rub-on analgesics that were popular during World War II. In the United States, the scent is almost exclusively used in candy and gum. The British associated the scent of wintergreen with medicine and war, the Americans with sweet, positive experiences (Scent of Desire 42). Herz has many more similar examples regarding how expectations and situational contexts change a scent from a pleasant to an unpleasant one, and vice versa. Mark Twain gives an example in The Invalid’s Story – a stowaway is convinced that the pungent aroma emanating from a sack is a dead body, when it is in fact strong-smelling cheese. Herz notes: “a suspicious context, and a burlap sack of a particular but ambiguous shape, created a set of expectations that influenced odor perception and even inspired drastic behavior” (Scent of Desire 55). A relatable example occurred recently in my own family. My aging grandfather had a favorite chair that, as he became increasingly unable to care for himself, developed a pungent odor. Once, leaning over the chair, several months after my grandfather passed away, my father was nauseated by the odor of the chair, and amazed that it would still be so fragrant after several months of disuse. As he sat up and commented on it, however, he noticed that my mother had opened a jar of peanut butter, and that what he thought was the chair was actually an odor he liked very much. Herz says that in her laboratory, they were able to change scent perceptions simply by changing labels. They would give the same odor a positive or negative name, such as “parmesan cheese” and “vomit”. People would act differently to the odor based upon its label, even saying that they were disgusted by it or wanted to leave the room. When they were told that they were smelling the same scent with both labels, they refused to believe it (Scent of Desire 57).
Another area where scent perception is altered is language, as Herz’ example illustrates. Herz explains that since scents are invisible and “we are obsessed with identifying the objects in our world, we look to words and scenes for help” (Scent of Desire 57). We also are limited in the words that we have available, and our like or dislike of a smell affects our descriptors. In asking subjects to describe a skunk, for instance, Herz heard everything from lemonade to sweaty socks to chocolate-garlic. She notes: “we don’t learn about odors the way we learn about other objects and experiences in our world. Our parents and teachers don’t give us any ‘smell and tell’ lessons; therefore most of us have acquired idiosyncratic connections between scents and words” (Scent of Desire 54). The book Sensorium, an exhibition catalog for a recent sensory exhibit at MIT offers another interesting perspective: “Smell bypasses conscious cognition to summon core emotional states associated with the minute chemical combinations that first stimulated the neuron for that specific scent” (Jones 13). The book later asks the important question: “Can this subversive quality account for its absence from language?” (Jones 14).
We are only just beginning to understand the complex ways olfaction is immersed in social contexts, cultures, and psychology. Recent decades have provided us with the basic codes we need to understand how smell works biologically and chemically. Recent studies are beginning to help us venture out from a perceptive world so long immersed in solely vision to, as Jim Drobnick calls it, an “olfactocentric” realm where our sense of smell is considered separately from the other senses. As we do this, we discover that the chemical and biological explanations for smell only begin to explain this elusive sense. Our perceptions of smell are learned, and our childhood, background, emotions, cultural situations, and language all impact this learning process. The implications for better understanding history, culture, and perception through the sense of smell are only just beginning to emerge from a culture that has been focused almost exclusively on vision for hundreds of years. Helen Keller once penned these words about smell: “A whiff of the universe makes us dream of worlds we have never seen, recalls in a flash entire epochs of our dearest experience…Smell is a potent wizard that transports us across a thousand miles and all the years we have lived” (Keller 181). It’s intriguing that a sense so powerful has been placed at the bottom of the sense hierarchy for so long, and thrilling that new discoveries are helping us to better understand the unseen world, the olfactocentric one.


Works Cited
Corbin, Alain. “The New Calculus of Olfactory Pleasure.” The Smell Culture Reader. Ed. Jim Drobnick. Oxford: Berg, 2006.
Drobnick, Jim, Ed. The Smell Culture Reader. Oxford: Berg, 2006.
Herz, Rachel. “I Know What I Like: Understanding Odor Preferences.” The Smell Culture Reader. Ed. Jim Drobnick. Oxford: Berg, 2006.
Herz, Rachel. The Scent of Desire. New York: William Morrow, 2007.
Jones, Caroline, Ed. sensorium: embodied experience, technology, and contemporary art. Cambridge: MIT Press, 2006.
Keller, Helen. “Sense and Sensibility.” The Smell Culture Reader. Ed. Jim Drobnick. Oxford: Berg, 2006.
Porteous, J. Douglas. "Smellscape." The Smell Culture Reader. Ed. Jim Drobnick. Oxford: Berg, 2006.