Have you ever noticed that the smell of apples and cinnamon remind you of Christmas, no matter what the season? Or no matter where you are, you think of your mom when you smell pot roast? How about catching a whiff of that certain perfume, and drifting back in time to the day you first met your wife? Whether your scent-linked memories are good or bad, you can be sure it will only take the slightest hint of an aroma to bring that memory to the forefront of your mind.
As with any other area of research, there are many ways to study the connections between olfaction and memory. In studying olfaction, verbal and visual cues are often used. Studies of memory function are conducted quite similarly. Stimuli are presented in similar fashion when testing both olfaction and memory. This makes it slightly easier for researchers to link information for memory and olfaction, and then correlate the results. Studies have been conducted to observe the type or quality of memories evoked by olfactory stimuli and how olfaction affects memories; Olfaction-related responses to memories have also been studied by market researchers to determine how different scents affect consumers’ memories of certain places or events. Memory also plays a role in studies researching the affect of labeling on olfaction and cognition.
Several different types of experiments have been conducted by numerous psychologists, biologists, and physio-psychologists to find out more about the relationship between different memory areas of the brain and olfaction. One study delves into the correlation between olfaction and autobiographical memory. I think olfaction and memory could be connected by a modification of synaptic strengths, perhaps similar to Hebb’s principle that a near simultaneous firing of synapses makes connections stronger. This could be why certain scents are so strongly tied to emotional events and stimuli such as holidays, home, and love.
Extensive research has been done in connection with marketing and consumer groups in determining what kinds of scents illicit positive responses from customers. Researchers examined the effect of consumers’ reactions to advertisements presented in fragrant atmospheres. They looked at subject’s memory and evaluation of service encounters in connection with various scents (Lee, 1997). Perhaps as a result of this and similar studies, marketers disperse enticing scents in hopes of persuading customers to purchase their products. Bakeries, for example, could fill the customer area of the store with the scent of fresh cookies. This would stimulate customers’ appetites, encouraging them to purchase more goods. Car dealerships might spray a ‘new car smell’ into a used vehicle to make it more appealing to shoppers. Researchers believe scent can affect consumer behaviors, but there is little empirical research to back up their theory. Pleasant ambient scents can enhance advertising, and may also be used heuristically in evaluating customers’ service encounters (Lee, 1997).
In other studies, olfaction and memory have been studied in conjunction with learning. Some areas of learning affected by olfaction are past experiential, social and cultural learning. For example, if a person smells something burning, they automatically look for a fire (Lee, 1997). This occurs whether the person has been in dangerous situations with fire, as it could be a reaction to experiential or social learning. Olfaction can indirectly affect learning, attitudes and behavior by inducing emotional states. Pleasant aromas can elevate mood, where noxious or otherwise unpleasant odors can make a person feel unhappy or even ill.
Memory for odors also involves learning techniques. Odors can be memorized either incidentally or intentionally, and can be tested either explicitly or implicitly. There have been few studies of odor memory when compared to the number of studies on other types of memory, such as verbal, pictorial and face memory. For the most part, odors are learned incidentally. People do not usually set out to memorize a particular smell. Studies suggest that the neural processes required for odor memorization, whether incidentally or intentionally learned, are much different from those involved in other types of nonverbal memory (Issanchou, et al., 2002). In a study of odor memory by Sylvie Issanchou, Dominique Valentin, Claire Sulmont, Jochim Degel, and Egon Peter Köster, emphasis was placed on evaluation odor memory as a learning process that is carried out in every day life. The researchers chose human faces as a comparative nonverbal stimulus. They concurred that though odors and faces are obviously quite different stimuli, they also have some important common features. Both faces and odors provide social signals, elicit emotions, and are quite difficult to describe. Both sets of stimuli are known to elicit context-dependent memories, and are difficult to forget once learned (Issanchou, 2002). Much like other nonverbal stimuli, like music and art, faces and odors are learned by repeated exposure. This is called perceptual learning.
A good example of how perceptual learning works is wine tasting. At first, two burgundy wines, such as a Pommard and a Chambolle may seem quite similar. The more a person tastes these two wines, the differences become clearer and clearer with each exposure, until the person can easily distinguish between the two. The same thing applies to odor memory. A person may recognize a face, a melody or and odor, but be unable to recall anything else about the stimulus. When this occurs with an odor memory, the phenomenon has been called the ‘tip-of-the-nose’ effect. The major difference between our ability to identify faces and our ability to identify odors is that we have developed a great expertise in identifying faces. Faces provide distinctive and useful information in identifying a known person and allows us to infer the age, gender, emotional state and sometimes the health condition of the face. Other studies on odors and odor memory show that although our capacity to differentiate between odors is equally impressive as our capacity to discriminate between faces, we are unable to specifically identify many odors. One proposed explanation for this discrepancy is that we are physiologically equipped for perceiving odors, but we do not use all our available capacities (Issanchou, 2002). This could be because the sense of smell is not as vital in daily life. Perhaps because of this, congenitally anosmic individuals are usually unaware of their loss, but prosopagnosic people are nearly always severely impaired.
Issanchou and her associates concluded that in order to accurately study odor memory as learned and applied in everyday life, researchers should keep in mind that odors are learned unintentionally, usually without awareness (2002). This is to say that they feel no task related to odor memory and learning should be given at the learning stage. They found that it is more effective, when studying environmental odors, to diffuse the odor in a room where subjects perform tasks or activities unrelated to the odor, or when the odor is dissolved into instruction sheets. As the human olfactory system is not keened to identify odors, retrieval should not focus on verbally describing or otherwise identifying odors, but focus instead on hedonic judgments or different-same judgments.
In a series of studies by Christopher Miles and Kathryn Hodder of Cardiff University in Wales, experiments were replicated from previous research and re-examined for results of both the original tests and the replicated procedures. Miles and Hodder looked at the effects of serial position on recognition memory for odors. The seven studies presented in their report looked at the contradiction in the present literature concerning the effect of serial presentation of odors on immediate recognition of test items. Typically, recognition tests give the subject a sequence of items followed by two test items, on that is familiar. The participant is then asked to identify the familiar scent. This is known as a two-alternative forced choice (2AFC) task. Using this type of testing usually produces recency effects in the absence of primacy effects (Miles, 2005).
According to Maria Larsson, the human memory is not a unitary faculty of the mind, but is made of numerous processes and systems that are tied into learning processes as well. She categorizes human memory into declarative and non-declarative memory. In this division, non-declarative memory is characterized by unintentional learning and declarative memory as learning with awareness. Evidence suggests that medial temporal/diencephalic structures are needed for declarative memory, where non-declarative memory utilizes other areas, like occipital structures and basal ganglia (Larsson, 2002). Reviews of recent studies on olfactory memory have failed to explicitly conceptualize olfactory memory in the realms of a memory-systems framework. Most research on odor memory, according to Larsson, has been oriented toward episodic and semantic memory functions, ignoring the non-declarative aspects of olfactory memory. According to the memory systems theory presented by Schacter and Tulving in 1994, information about events is stored in different memory systems and subsystems, to be used as needed. It is unknown if this also applies to olfactory memory, as little research has been done in this area (Larsson, 2002).
In Willander and Larsson’s study of autobiographical odor memory, the researchers looked at the age distributions and experiential qualities of autobiographical memories evoked by various sensory signals. They explored whether or not age affected olfaction-linked memories more than autobiographical memories from other cues. Most available data for autobiographical memory is linked to verbal stimulus. Research has shown that recall for autobiographical memories observes a pattern made up of three components: childhood amnesia, the bump, and the recency effect. Memories recalled from ages 10-30 are called the bump, as a large number of memories are remembered from that time frame. The best memory retention occurs in the last component, recency, as these are events occurring in the last decade. Studies have shown that olfactory-evoked memories lowered the age for the bump to ages 6-10 in comparison to 11-25 for verbally-cued memories (Willander & Larsson, 2006). This leads us to conclude that olfactory-cued autobiographical memories are older than memories associated with verbal cues. In Willander and Larsson’s research, memories evoked by odors were tied to the first decade of life, and memories linked to verbal and visual cues were drawn from young adulthood. Odor-related memories were associated with stronger feelings of being brought back in time and had been recalled less often outside of the research than memories tied to other cues (Willander & Larsson, 2006).
After going through the research of several researchers, those presented here seemed to be the most accurate and insightful in the area of olfaction and memory. The Hebbian principle definitely applies when it comes to repeated exposure to olfactory stimuli, as does the recency effect. People tend to remember things more easily when repeated, and olfactory memories are no exception. Olfaction can affect memory related to learning as well as autobiographical recall. The human olfactory system is not designed to identify but to distinguish between odors. Most often, an odor is linked to a memory when recalled. This memory may not include the actual source of the scent. Even though the research is not conclusive when it comes to olfactory memory, the ideas floating around are interesting.
References
Glynn, Ian. (1999) An anatomy of thought: The origin and machinery of the mind. New York, NY: Oxford University Press.
Issanchou, Sylvie, et al. (2002) Testing odor memory: Incidental versus intentional learning, implicit versus explicit memory. Olfaction, taste and cognition. New York, NY: Cambridge University Press. 211-230.
Larsson, Maria. (2002) Odor memory: A memory systems approach. Olfaction, taste and cognition. New York, NY: Cambridge University Press. 231-245.
Lee, Sanghoon. (1997) The effects of pleasant scents on consumer memory and evaluations. Dissertation abstracts international section a: Humanities and social sciences, Volume 58, 519.
Miles, Christopher. (2005) Serial position effects in recognition memory for odors: A reexamination. Memory & Cognition, Volume 33, 1303-1314.
Willander, Johan, and Larsson, Maria. (2006) Smell your way back to childhood: Autobiographical odor memory. Psychonomic bulletin and review, Volume 13, 240-244.
