Smell it! Smell it!

by Michelle T. de los Santos

Nothing is more memorable than a smell. One scent can be unexpected, momentary and fleeting, yet conjure up a childhood summer beside a lake in the mountains; another, a moonlit beach; a third, a family dinner of pot roast and sweet potatoes during a myrtle-mad August in a Midwestern town. Smells detonate softly in our memory like poignant land mines hidden under the weedy mass of years. Hit a tripwire of smell and memories explode all at once. A complex vision leaps out of the undergrowth. ~Diane Ackerman,

A Natural History of the Senses

I am inspired to share one of my own studies (with my co-workers Aca and Kym, hi Psych 115 group mates! HAHA) since in my Psych 135 class, we talked about olfactory stuff and my Psych 115 study relates to it. It’s about scents-ability.
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It goes like this…Smell has the power to trigger memories almost more than any other sense. Yet it is rarely given much attention compared to visual and auditory senses. While many studies have been conducted about memory for smell, few have been done to investigate smell as a trigger for memory. Hence, the researchers (me and my co-workers) are on the question of the effectiveness of a scent as memory cue due to its familiarity/unfamiliarity. In our study, we hypothesized unfamiliar scents to be more effective memory cues than familiar scents. The underlying assumption is that more attention is paid to the unfamiliar odour; hence, the more deeply it may be processed and then serve to facilitate memory. A familiar scent may not be given much attention. Also, a familiar scent is expected to be associated with many memories and previously learned information aside from the information presented in the study. Taking into consideration the type of memory to be remembered, we also put the question of higher recall of words with sexual content than non-sexual words into the test. Compared to neutral words and even negative emotional words, studies show that sexual words grasp the attention of individuals more. Greater attention leads to seeing more detail and deeper processing of the material. This deep processing supports better memory. Also there is higher item distinctiveness in sexual words. These effects of sexual words on memory may be rooted in the emotionality or emotional arousal caused by the words. In this study, sexual words are hypothesized to be remembered better that non-sexual words in a free recall task. The final aim of our study is to investigate the interaction effects between scent familiarity and word content. We hypothesize that there will be higher recall for sexual words in the presence of the unfamiliar odour than in the presence of the familiar odour; there will also be higher recall of non-sexual words in the presence of unfamiliar odour than the familiar.
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However, I will only talk about our first concern (the scent stuff) since my focus here is to share the olfactory studies that I used in our scent-ability study. I will share three significant articles about my focus – that, scent can act as a memory trigger. Hope these can help you readers enhance your memory, in a way :)

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Memory and Scent

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It is logical to ask how the olfactory system is expected to evoke such strong memories in this study. The olfactory system’s powerful effect on human memory is due to the olfactory receptors’ axons that terminate in the olfactory bulb. Therefore, olfactory receptors have a more immediate connection to the brain than any of the other senses.

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The primary olfactory cortex forms a direct anatomical link with the amygdala-hippocampal complex of the limbic system. Only two synapses separate the olfactory nerve from the amygdala, which is critical for the expression and experience of emotion, and human emotional memory. Only three synapses separate the olfactory nerve from the hippocampus, involved in the selection and transmission of information in working memory, short and long-term memory transfer, and various declarative memory functions. No other sensory system makes this kind of direct and intense contact with the neural substrates of emotion and memory (Juhl, 1998).

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Scent as Memory Trigger
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Sensory input, being a trigger for memory retrieval (Eich as cited in Hofland and Dieter, 1992), would mean that the presence of visual, acoustic, and olfactory stimuli is a predictor of recall and recognition.

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Scent, as a trigger for memory, can be related to two theories: cue-dependent memory and state-dependent memory. The former states that a cue, a scent present during memory encoding, triggers the same memory if presented again at retrieval. The same is echoed in the encoding specificity principle. The latter maintains that if encoding and retrieval is to occur in similar circumstances, information recall would be better (Hofland, Dieter & Lantinga, 1992).
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Hofland, Dieter, and Lantinga (1992) conducted a study which tested these two theories. They hypothesized that if smell can be used as a memory trigger, then having a smell at encoding and retrieval of information was expected to result in better memory retrieval than having either the smell only at encoding or no smell present. Memory scores were measured for the three levels of the independent variable, the smell condition (smell at encoding and retrieval, smell at encoding only, and no smell condition). One-way ANOVA showed that the scent did not influence memory scores. Smell, as a cue, did not significantly increase memory scores.

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The results did not give significant evidence that the lemon smell was an effective memory cue. Therefore, the cue-dependent and state-dependent memory theories were not supported. However, the control of the independent variable in this study is flawed, because both the smell condition and non-smell conditions were tested in the same room at the same time. A high probability of scent mingling was present. Also, the sample size of only 52 participants is not sufficient to represent the population and the results of such study cannot be generalized for the whole population.

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Juhl (1998) conducted a follow-up study to investigate the Encoding Specificity Theory, which is similar to the Cue-dependent and State-dependent Memory theory. He hypothesized that the presence of an odor, paired with a set of instructions would increase the scores on a memory test. Four groups of participants were present in the study, all informed that they would be asked to take a short memory test and rate their levels of anxiety, before and after the experiment. Two groups were instructed to smell a swab of cotton before, during and after studying a word list, told that the odor increases recall. The other two groups were given the same procedural instructions but were told, however, that the odor reduces anxiety.

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The findings of this study conclude that the odor neither increased the memory test scores nor decreased the anxiety levels in our participants. The mean scores of words recalled correctly ranged from 10 to almost twelve, with this small deviation it was not surprising that no main effects were found to be significant.

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Deethardt (2002) conducted a study that hypothesized that conditions where information to be memorized was accompanied by odors resulted in better recall of the information than conditions where information was memorized without the accompaniment of odors. (The hypothesis of this research experiment was that an experimental group, that had to smell an odor and memorize a word with the odor, would be able to recall more words than a control group that did not smell any odor.)

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The results of the t test showed the difference between the mean score of the experimental and control group to be significant (t (42) = -3.71, p = .001) but in the opposite direction of the original hypothesis.

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However, a second problem that may have affected the outcome of the study is the amount of time that the participants were actually allowed to smell the odorants with which they were required to associate a word. In this research, the participants were only allowed to smell each odor for 15 seconds. Then they were given a five minute break and then tested again to see if they could remember the odor and the word that was associated with it. According to past research, odors are not immediately retained very well, but they may be retained significantly better over time. This research could have yielded stronger results in favor of the original alternative hypothesis if the participants were given more time to encode the actual smells and then given a longer amount of time to process the smells in their memory.

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There! Diffrent views but we can never say the truth, we'll never know, because perhaps, it still depend on a person. It's still one's personal choice if scent really help or trigger their memory then why not try it. Especially, if their "hiyang" with it. So, smell it! smell it! Haha! Indeed, perception really comes with sensation. I really learned a lot in my Psych 135 class, very interesting and amazing topics, i'll definitely miss it! :)

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By the way, my Psych 115 study's result didn't show a significant effect (the main effect of scent familiarity is non-significant), so yeah HAHA Perhaps, because we also encountered some problems while conducting our experiment. Like convenience sampling was used, limited sample, the physiological effects of prolonged inhalation of the scent we used and it’s potency as a scent, gender of the participants was not controlled due to lack of initial concern by the researchers, things like that.

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Base on my own experience as a researcher, improvements could be done on the present study by future researchers. One is to use a better method of participant recruitment, such as asking for only a certain number of males and females to sign up. Since a large number of similar studies show effects gender differences, controlling for gender would be an improvement in future studies. Having even number of male and female participants and testing them in a separate group could reduce gender differences as a confound variable. Future studies may investigate a larger sample to increase the external validity of the study. Another improvement would be choosing a better, appropriate scent and identifying its physiological effects to avoid confounding. Inspection of cue distinctiveness in terms of the odour’s novelty and contextual appropriateness could also be considered. With a better theoretical model, controlled extraneous variables, clarification of findings and consistency, precision and formal experimentation, a potential experiment for future research may be conducted that would support the original study.

Thank you! >:D<

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References:

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Deethardt, M. R. (2002). The Effects of Olfactory Stimulation on Short-term Memory. Learning, Memory and Cognition, 1(3), 68-85.
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Hofland, S., Dieter, R. A., & Lantinga S. B. (1992). Lemon Smell as a Memory Trigger. Psych-E,1(3), 75-83.

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Juhl, R. H. (1998). A Study of Odors Effects on Memory and Anxiety. Learning, Memory and Cognition,4(2),113-120.