Take a sniff of a lemon. How would you describe its fragrance without: (1) turning to words indicating only the intensity or general pleasantness of the odor (e.g. aromatic, pungent, sensuous), (2) referring to the terms lemon, citrus or fruit, (3) comparing it to another object’s odor, or (4) employing a metaphor?
Smell is such an elusive phenomenon. Western and East Asian languages often do not have easy-to-remember names for the inherent sensual qualities of smells the way they have a variety of common descriptors for colors, tastes, touch and sounds (e.g. red, bitter, coarse, tinkling) that are independent of sources responsible for those sensations. In fact, many Westerners (and probably Easterners) are mediocre at telling odors apart. Unlike other senses, smell is frequently an unobtrusive companion. As long as it is not foul or too intense, it does not detract from a person’s attention to produce its mood-altering effects the way scenery, food, hugs and music do. Sometimes, it slips away completely as people get acclimatized to it, as if it has never existed.
The hazy nature and relative low profile of smells, nonetheless, belie their powerful impact. Studies have shown that humans can pick up the scents of certain compounds at concentrations at or lower than the equivalent of three drops of the odorant in an Olympic-size pool. And that is just for consciously detected odors. Even when people do not register a smell, it can be detected without their knowledge by their olfactory systems, which, being intimately linked to the emotion-generating limbic structures in the brain, then unconsciously modify their behavior. The odor of a cleaning agent, experiments demonstrate, can induce students to clean up after themselves even when they are unaware of it. Meanwhile, sweat collected from apprehensive individuals (e.g. first-time skydivers) tend to heighten people’s attention to faces, compared to sweat from the same individuals when they are in other emotional states (e.g. the same skydivers working out on a treadmill). Given these findings, one would wonder how much of our fears and passions, including age-old prejudices and primitive instincts, actually arise from olfactory cues we are ignorant of.
Against this context, the increasing prevalence of scent marketing tactics may be rather disturbing. Luxury hotels, for instance, have started pumping tea and citrus aromas into their lobbies to enhance guests’ moods and establish emotional connections (and thus brand loyalty) with them. Similarly, some retail outlets diffuse artificial fragrances into their premises in the hope that shoppers will stay around longer. The results are probably often encouraging. A mini-mart has found that the circulation of coffee aromas around the store boosted sales of the beverage by a stunning 300 percent. These practices, however, may undermine consumers’ autonomy by, most obviously, misinforming them about the aromatic properties of food items and, in the case of novel and/or subtle odorants with unanticipated effects, influencing their decisions covertly.
The heroine of romantic comedy The Girl Who Sees Smells would most likely be unfazed by these issues. Mysteriously gaining an ability to see odors after a car accident, she could track criminals and missing people through colored shapes that mark their scents. In the hands of another production team, the special effects developed to simulate this supernatural skill would have readily come across as cheap, childish or over-the-top. The computer-generated images in this drama, however, won praise from drama reviewers for their slickness and understated elegance.
For some real-life individuals, though, seeing scents is not a fantasy that can only be experienced onscreen. In a neurological condition known as synesthesia, the stimulation of one sense is accompanied by the unusual stimulation of another sense, such that people can hear colors, taste words, feel music literally caressing their faces, etc. One real-life counterpart to the heroine reported seeing fresh air as rectangular and coffee aroma as bubbly clouds. A number of artists with the condition have even recorded their experiences in their works, the most famous of which include possible sound↔color synesthete Wassily Kandinsky‘s abstract paintings, which featured riots of colors with musical rhythms. Researchers have even demonstrated that normal individuals can be trained to develop synesthetic skills like seeing different alphabets in different colors regardless of the original ink color. Although the effects of these training programs have not lasted long, the projects are still in early stages and it is not unimaginable that outcomes can be improved with further testing and refinement. With hope, such training can be extended to smell-color associations as well.
On the technological front, scientists have developed sensors which colors change upon contact with odors. Each colorimetric odor sensor contains an array of dyes, different combinations of which bind to different vapors, such that each vapor produces a unique color “fingerprint.” This mimics the human olfactory system, in which different odors activate different combinations of spherical structures called glomeruli in the brain to facilitate smell recognition. Such sensors can potentially be used to detect toxic gases and explosives, identify pathogenic fungi in medicinal products, monitor the remaining shelf life of seafood, screen patients’ breath for vapor patterns associated with lung cancer, and so on.
If the advent of wearable technologies were to converge with the trend of colorimetric odor sensing, we may find ourselves in futuristic scenarios never seen before even in fantasy films and dramas. Imagine waving your hand over a chrysanthemum and miniature sensors embedded in your glove pick up the volatile compounds it releases. Electronics in the sensors then identify the scent and beam a signal to a Google Glass-like head-mounted display, or better still contact lens with augmented reality capabilities, you are wearing, and you see in real time a thin cloud of charming floral icons hanging over the flower. User controls may allow you to pre-select the sizes and colors of icons representing different scents and the responsiveness of the display to different concentrations of scents. If you prefer, you can wear the sensors as bracelets or, assuming that safeguards against health hazards are in place, insert them as bionic implants in your nose.
Should human ingenuity and consumer tastes permit these scent visualization developments, marketers and the olfactory landscape at large will probably have a harder time leading us by the nose. By observing how objects and places produce odors which shape human behavior, we may act with more self-consciousness and even re-configure our olfactory environments to control our impulses. Our responses to threats and incentives signaled by odor stimuli will perhaps become more refined and effective too, as we find ourselves capable of investigating and directly addressing the sources of odor-provoked fears and desires and not having to plunge into anxiety simply because of a few sweaty shirts. Smell may then be elevated from the bestial sense that philosophers like Plato disparaged it as to a faculty almost as intellectual as sight and hearing.
As with existing mobile technologies, though, scent visualization techniques pose privacy and social concerns. People may find that personal details ranging from their perfume brands, previous whereabouts and, as the drama wryly noted, meals they have had are now visible to all passers-by with visualization capacities at a glance. The onslaught of data to monitor from the augmented reality technology may also result in information overload and distraction from normal tasks. These are problems humans have to address as they grapple with the beasts of their own creation to understand the ancient inner beast that is olfaction.
One aspect of scent visualization techniques which sets them apart from many consumer-oriented augmented reality technologies, on the other hand, is that instead of pulling users into semi-make-believe worlds, they help them get in touch with reality on a deeper level. After living side by side with odors for millennia, the human race may finally start to appreciate their full diversity, prevalence, origins and transformations, witnessing up-close the magical narratives Nature has been silently weaving around them since time immemorial. Perhaps then, like they already do in the Jahai and Maniq tribes in Southeast Asia, smells will waft into the daily lexicons of a greater part of the world.