A few years ago a wee article I wrote was published in a small institutional journal where I was employed in Tokyo. I wanted to find out if scent had any affect on the cognitive process of learning, so I did a little bit of digging. I had forgotten about this piece until today, while updating my teaching credentials. It’s not available online (unless you count the PDF I uploaded to an academic social network site), and it’s mine to share, so I’ve reproduced it below for your reading (hopefully) pleasure.

I am a self-confessed perfume fanatic. I have so many different bottles of olfactory art works in my home that it takes me a while to count them. Ironically, my passion for perfume developed after I moved to a country that is acknowledged as not having the same level of appreciation for fragrance as do some other nations, such as those of the Middle East. Depending on the scent I am wearing, the situation, and the peculiarities of the individuals who get a whiff of me, my use of perfume has surely been the cause of offense. Despite this, overhearing the whispered comment,「いい匂いですね」[(She) smells good, eh?] has become a common occurrence as I walk around my classrooms. I even get complimented to my face from time to time, which I not only find pleasing, but also interesting, as Japanese is not a language that employs the practice of complimenting as a form of ice-breaking or small talk to the same extent as English.

My interest in fragrance has sent me scavenging the Internet in search for answers to the question of why some people find some smells attractive when others do not, and why this depends so much on the individual, their culture, and even their age. When first introduced to a new scent, the human brain links it to a person, thing, event, or moment. The brain forges a link between the smell and a memory, associating lilies with funerals or chlorine with summer by the pool. The next time that scent is perceived, the link is already there, ready to elicit the emotion or mood associated with the memory the scent evokes. Lilies might be irritating and the smell of chlorine might cause happiness, and yet the reasons are not clear to the person experiencing those feelings.

This is part of the reason why people like and dislike different smells (Dowdey, n.d.). “As humans, we’re not immediately predisposed to respond to a scent and believe that it is good or bad,” says psychology and odor expert Rachel Herz, “When we like or don’t like a smell, that is learned.” This can be seen at the individual level: “Some people may smell a rose and be reminded of their father’s funeral. Others may like the smell of skunk because they have a positive attachment to it from childhood.” Likewise, this is true at the cultural level: In North American, a popular ingredient in candy and gum is wintergreen, but as wintergreen is often used to make medicine in the UK, the odor is less enticing there (Science of Scent, 2005). Finally, preferences are seen also at the generational level: “People born before 1930 love natural smells like grass and horses, while people born later are fond of synthetic smells like Play-Doh and SweeTarts” (Vlahos, 2007).

Marcel Proust was one of the first to write about memory recall as a strong, unconscious reaction to a smell. When someone smells something that triggers a very detailed, visual, and emotional memory of a childhood event they thought they had long forgotten, they are experiencing the “Proust Effect,“ which Chu and Downes assert to be a better cue for memory than the other senses, because odor memory falls off less rapidly than other sensory memory (2000).

But can scent have any impact on learning? Is my いい匂い [good smell] affecting my students’ learning in any way? Right brain function has tremendous potential for things like mass-memory and automatic processing. In most people, however, the pathways between their left and right brains have not been fully constructed, so this potential never fully develops. Science has found that certain scents, used properly, can be highly effective tools in building these neural pathways. Here’s a peek into some of the research on the positive effects of exposure to good smells:

Acute exposure to pleasant fragrances has been shown to facilitate the performance of mathematical tasks (Baron 1990), vigilance tasks (Warm et al. 1991), and word construction and, decoding of written messages (Baron and Bronfen, 1994; Baron and Thomley, 1994). Data gathered from research by Akpinar in 2005 showed that certain essential oil aromas increase students’ attention levels and enhance their memory, generally indicating positive effects on cognitive learning. Although lavender is known for its sedative qualities, Sakamoto (2005) found that “during recess periods after the accumulation of fatigue it can prevent deterioration performance in subsequent work sessions.”

Oliver and Moss (2012) suggest that the pine-like scent of rosemary oil may improve speed and accuracy when performing certain mental tasks. In their research, 20 people were asked to perform subtraction exercises and a task to see how quickly they could process new information before and after being exposed to the scent of rosemary. Participants’ blood levels of rosemary’s main chemical component – of 1, 8-cineole – were measured after the experiment. Results saw a strong correlation between amounts of 1, 8-cineole in the bloodstream and high task scores. Specialists do not fully understand how essences such as rosemary can improve mental ability, but an increasing body of literature shows that positive mood is triggered by scents, and this in turn is linked to an increase in productivity and performance, as well as many other benefits such as stress reduction.

Freeman showed that smell memory is context dependent and can be modified and updated when facing new experiences, implying that our olfactory sense is continuously dynamic (1991). Applying this knowledge to education, Björn Rasch and his colleagues at the University of Lübeck found that smelling the scent of roses while learning a task and then being exposed to the same smell during sleep helps memories to solidify. The section of the brain called the hippocampus is believed to serve as the temporary in-box for memory, where new knowledge or experiences are loaded and stored until they can be filed elsewhere for long-term storage and access.

During sleep, the memories in the hippocampus are reactivated and transferred to the cortex. As one might imagine, a lot of this short-term data never makes it to more permanent storage in the brain, but with scent being used as a trigger, such as in the case above of the roses, a lot more information makes the journey over. Simulating this experience for one’s own benefit is not that straightforward, however. Rasch discovered that timing was crucial for the test to work; the rose smell had to be switched on and off during the night so that the brain would not get used to it, and the smell was only effective during “slow wave” sleep, a sleep stage wherein the hippocampus is most sensitive. Not only this, but the smell trick is useful only for certain types of learning that rely on the hippocampus. It is not useful for remembering the skills needed for playing an instrument or perform a sport, for example (2007).

Certainly, trying to emulate precisely the study above may prove a little tricky, but it will not stop me from sharing the results of Rasch’s research with my students, and getting them to do a little bit of their own experimentation: While studying for a test, students could wear a perfume or essential oil that they really like on their wrist, and smell it periodically while studying. They could then make sure they are wearing that exact scent on test day, or perhaps carry something like a scarf scented with the fragrance, and again smell it periodically during the exam. Perhaps the smell will unlock something in their brain during test time that will allow them to more easily access the information they had previously reviewed?

Based on the work that has been done so far in the field of smell, students may not even have to go that far; simply surrounding themselves with favorable scents while studying may increase their learning efficacy, pushing memories out of short term and into long term storage. There appears to be a lot that teachers could do to help, such as employing room spray or essential oil diffusers where possible.

One would have to take care to use the right type of fragrance, however. Certain types of scent stimulation, like food, can disrupt the accelerated learning functions of our brain. Chemical smells from some air fresheners, perfume, and even some essential oils can also be distracting and could block learning. To avoid the issue of chemical sensitivity, and to be more consistent in using the same odorous materials as studies involving scent have employed, pure essential oil usage would perhaps be the better choice. Aromatherapists tout the use of certain essential oils to provoke specific outcomes.

Research is lacking in the area, but perhaps the popular practice of using scent in this way can no longer be so readily brushed off as pure pseudoscience, despite the fact that a lot off aromatherapy marketing is full of exaggerated and false claims, especially in the area of health. In addition to the scents of rose, rosemary, and lavender mentioned above, peppermint, lemon, jasmine, grapefruit, frankincense, cinnamon, and vetiver are mentioned in aromatherapy literature as having a positive effect on learning and creativity. While more scientific evidence is in the making, why not try these scents in the classroom? At the very least they will produce a more pleasant learning environment for students.

One thing is for sure: As long as students respond as positively as I do to the fumes wafting off my person, I will continue to enjoy wearing my fragrances to class.

References

Akpinar, B. (2005). Do scents affect people’s moods or work performance? Pakistan Journal of Social Sciences, 3(7), 952-960.

Baron, R.A. (1990). Environmentally Induced Positive Affect: Its Impact on Self-Efficacy, Task Performance, Negotiation, and Conflict. Journal of Applied Social Psychology, 20(5), 368-384.

Baron, R.A., & Thomley, J. (1994). A whiff of reality: Positive affect as a potential mediator of the effects of pleasant fragrances on task performance and helping. Environment and Behavior, 26(6), 766-784.

Baron, R.A., & Bronfen, M.M. (2006). A Whiff of Reality: Empirical Evidence Concerning the Effects of Pleasant Fragrances on Journal of Applied Social Psychology, 24(13), 1129-1220.

Chu, S., & Downes, J.J. (2000). Odour-evoked Autobiographical Memories: Psychological Investigations of Proustian Phenomena. Chemical Senses, 25(1), 111-116.

Do scents affect people’s moods or work performance?: Scientific American. (2002, November 11). Scientific American. Retrieved August 18, 2013, from http://www.scientificamerican.com/article.cfm?id=do-scents-affect-peoples

Dowdey, S. (n.d.). How Smell Works. HowStuffWorks “Science”. Retrieved August 19, 2013, from http://science.howstuffworks.com/life/human-biology/smell3.htm

Freeman, W.J. (1991). The Physiology of Perception. Scientific American, 264(2), 78-85.

Herz, R.S. (2005). Odor-associative Learning and Emotion: Effects on Perception and Behavior. Chemical Senses, 30((supp 1)), i250-i251. Retrieved August 18, 2013, from http://chemse.oxfordjournals.org/content/30/suppl_1/i250.full.pdf+html

Moss, M., & Oliver, L. (2012). Plasma 1,8-cineole correlates with cognitive performance following exposure to rosemary essential oil aroma. Therapeutic Advances in Psychopharmacology, 2(3), 103-113 .

Rasch, B., Buchel, C., Gais, S., & Born, J. (2007). Odor Cues During Slow-Wave Sleep Prompt Declarative Memory Consolidation. Science, 315(5817), 1426-1429. Retrieved August 18, 2013, from http://www.sciencemag.org/content/315/5817/1426.full

Sakamoto, R., Minoura, K., Usui, A., Ishizuka, Y., & Kanba, S. (2005). Effectiveness of Aroma on Work Efficiency: Lavender Aroma during Recesses Prevents Deterioration of Work Performance. Chemical Senses, 30(8), 683-691. Retrieved August 19, 2013, from http://chemse.oxfordjournals.org/content/30/8/683.full.pdf+html

Science of Scent. (2005, January 5). Brown University. Retrieved August 18, 2013, from http://brown.edu/Administration/News_Bureau/2004-05/04-069.html

Vlahos, J. (2007, September 9). Scent and Sensibility. The New York Times. Retrieved August 19, 2013, from http://www.nytimes.com/2007/09/09/realestate/keymagazine/909SCENT-txt.html

Warm, J.S., Dember, W.N., & Parasuraman, R. (1991). Effects of olfactory stimulation on performance and stress in a visual sustained attention task. Journal of the Society of Cosmetic Science, 42, 199-210. Retrieved August 19, 2013, from http://journal.scconline.org/pdf/cc1991/cc042n03/p00199-p00210.pdf