Aroma Nudges: Exploring the Effects
on Shopping Behavior in a Supermarket
Daiki Mayumi1 , Yugo Nakamura2 , Yuki Matsuda1 , Tomokazu Matsui1 ,Shinya Misaki1 , Keiichi Yasumoto1 , and Junko Nohara3
1

Nara Institute of Science and Technology, Nara, Japan{mayumi.daiki.mb9,yukimat,yasumoto}@is.naist.jp
2
Kyushu University, Fukuoka, Japany-nakamura@ait.kyushu-u.ac.jp
3
Kio University, Nara, Japanj.nohara@kio.ac.jp

Abstract. Due to the pandemic of COVID-19, product sampling at supermarkets has been restricted, and the disposal of unsold vegetables
and other perishable foods has become a problem. To explore alternatives to product sampling, this study focuses on the “aroma” generated
during product sampling and explores the effect of aroma nudges on purchasing behavior. Specifically, we focused on the scenario of promoting
the purchase of Yamato-maru eggplant, a traditional vegetable of Nara
Prefecture in Japan. We conducted an experiment in a supermarket for
two months, from June to July of 2021, the season of the Yamato-maru
eggplant. We compared the number of visits to the sales booth, the timespent in the booth, and the sales volume under four conditions: (1) nopresentation, (2) presentation of paper media, (3) presentation of thepaper and video media, and (4) presentation of a paper, video, andolfactory media. The experiment results suggest that the inclusion ofaroma nudges has a positive potential to attract consumer interest andpositively influence their purchasing decisions.
Keywords: Nudging · Olfactory Interfaces · Purchasing Analysis · Behavior Change.

1

Introduction

Demonstration sales such as product sampling in supermarkets are known tobe an effective way to motivate consumers to buy [14, 15]. However, due to thepandemic of COVID-19, sales promotion activities such as product sampling
had to be discontinued in order to prevent the spread of infection. As a result, a
decrease in sales and an increase in the amount of waste of fresh foods such as
vegetables have become a problem. Against this background, there is a need to
explore alternatives to product sampling while taking infection prevention into
consideration.
Persuasive 2022, Adjunct Proceedings of the 17th International Conference on
Persuasive Technology. Copyright © 2022 for this paper by its authors. Use permitted
under Creative Commons License Attribution 4.0 International (CC BY 4.0).

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D. Mayumi et al.

In this study, we focus on the existence of olfactory stimuli that have been lost
due to the restriction of product sampling and explore the possibility of aroma
nudges on purchasing behavior. As a first step, we have developed a prototype
of an aroma nudges system that sprays a scent appropriate for the scene on thecooking video to stimulate the consumer’s desire to “look delicious” and “wantto try it” and to improve their purchasing motivation. Our system is equippedwith a sensing mechanism to infer the flow of consumers using a depth camera.
And the system has a feedback mechanism to encourage consumers’ purchase
motivation by presenting visual, auditory, and olfactory information.
We conducted an experiment in an actual store over a period of two months
from June to July of 2021, the season of Yamato-maru eggplant. In the experiment, we compared the number of visits to the sales booth of Yamato-maru
eggplant, the time spent there, and the sales volume under four conditions: (1)no presentation, (2) presentation of paper media, (3) presentation of paper andvideo media, and (4) presentation of paper, video, and olfactory media. As aresult of the experiment, it was confirmed that the number of visits to the boothand the time spent at the booth were improved by the aroma nudges. The experiment results suggest that the inclusion of aroma nudges has a positive potential
to attract consumer interest and positively influence their purchasing decisions.

2

Related Work

Aroma is considered to be one of the most important components of the physicalenvironment of a service [4]. The effectiveness of ambient scents in influencing
consumer behavior has been supported by academic research. For example, it is
known that olfactory cues can enhance consumer behavior when they are related
to product attribute information [2]. In a study that investigated the effect ofvanilla scent on shopper behavior by installing aroma diffusers in fashion stores,
it was found to have a significant positive effect on shopper behavior (timespent in the store, purchase amount, and intention to return to the place ofpurchase) [8].
In addition, it is known that warm scents like vanilla and cinnamon produce
a powerful drive to buy things in a social environment, while cold scents like
peppermint and eucalyptus have the opposite effect. Warm scents have beenfound to increase preference for and purchase of premium and luxury brands [7].
Spangenberg et al. [12] showed that when there are pleasant smells around,consumers have the feel of spending less time in the store and that prices werelower. Therefore, it can be inferred that smells influence behavior and perception.
In recent years, various types of olfactory interfaces and interactions using
them have been proposed. Wang et al. [16] proposed piercing-type, necklace-type,and face-worn on-face olfactory devices and evaluated their social acceptability,
comfort, and the intensity of the odor perceived by both the wearer and theobserver. Amores et al. [6] proposed a necklace-type scent device that can becontrolled remotely from a smartphone and can change the intensity and frequency of scents based on biometric and contextual information. Dobbelstein

3
et al. [1] have developed a wearable scent device that can be used in daily life,
allowing the user to receive notifications of personal scents. However, to the bestof our knowledge, there have been no efforts to empirically verify the effects of
behavior change using olfactory devices.

3

Designing The Aroma Nudges System

Nudges are small cues set up by the environment to gently push people’s decisions
and actions towards a desired direction. Thaler and Sunstein, the proponents ofnudges, defined nudges as any aspect of choice architecture that changes people’s behavior in a predictable way, without forbidding choices or significantly
changing economic incentives [13]. Recently, sensory nudges [11], which act onvarious sensory systems such as vision, hearing, and smell, have been attracting
attention. Based on the concept of “IoT Nudge [10],” in which sensory nudges
are intelligently controlled by an IoT system equipped with sensing and actuation functions, in this study, we aim to realize a nudge system that acts on thesenses of sight, hearing, and smell according to the store conditions in order topromote purchasing behavior.

Fig. 1. Overview diagram of the proposed system

We propose an IoT-based nudges system called “Aroma Nudges System”
which has sensing and actuation functions including olfactory stimulation. An
overview of the Aroma Nudges System to replace product sampling is shownin Figure 1. The system is equipped with a sensing function to understand theflow of consumers and a feedback function to encourage consumers’ purchasing
behavior. Our system aims to make people think the food in the video is delicious
and increase their purchasing motivation by providing timely feedback of cooking
images and aromas based on sensing results.

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Fig. 2. Timing of aroma injection connected to cooking videos

In this study, we implement a prototype of the proposed system and investigate the effect of aroma nudges on purchase intention in a real environment.
The overview of the proposed system is shown in the blue frame (A) of the
Figure 1. The sensing mechanism is responsible for detecting the consumer’spurchasing behavior. In this study, we detect consumer behavior through skeletal detection. In the feedback mechanism, the cooking video provides visual andauditory stimulation, and the smell provides olfactory stimulation to encourage
consumers’ purchasing behavior.
The sensing mechanism plays a role in detecting the purchasing behavior of
consumers. By sensing the consumer’s behavior, the system detects buying behaviors such as reaching for a product display shelf or gazing at the shelf. In thisstudy, we constructed a system that uses skeletal detection for consumer behavior
recognition and detects purchasing behavior based on the positional coordinatesof joints. We used Intel’s RealSense as a camera and Cubemos’ Skeleton Tracking SDK4 for skeleton detection. To protect the privacy of consumers, we use
a program that removes the RGB information including the background in theimage and obtains only the skeleton information.
The feedback mechanism provides visual and auditory interventions throughcooking videos and aroma interventions linked to the cooking videos, and plays
a role in stimulating the consumer’s purchasing motivation. Unlike fruits, thesmell of Yamato-maru eggplant itself is almost imperceptible, so we adopt an
approach in which the smell of the seasoning of the dish is in during the cooking
process is injected at the right time in conjunction with the video of delicious
cooking of Yamato-maru eggplant. In the cooking video, we visualize the cooking
process of “Curry flavored tofu au gratin without baking,” which can be easily
4

https://www.intelrealsense.com/skeleton-tracking/5

Fig. 3. Setting up the experimentprepared using Yamato-maru eggplant, and use it as a cooking video to promote
purchase motivation.
We used Aroma Shooter5 provided by Aromajoin Corp. as the olfactory device that sprays smells in conjunction with the cooking video, and prepare thesmells of curry, butter, and black pepper. The Aroma Shooter can spray up to
six aroma, and the distance is about 60 cm (the distance varies depending on
air conditioning). Figure 2 shows the aroma control performed by this system.
The butter aroma represents the savory aroma of frying food. The curry scentis used to enhance the flavor of the curry in the ingredients. Finally, the threedifferent aroma are sprayed to convey the overall flavor of the raw tofu gratin:butter, curry, and black pepper. In this study, we used “Aroma Player Offline,”
an iOS application provided by AromaJoin, to control the timing of the aroma
spray. In this process, we controlled the arrival of the scent to the customer, so
it matches the food in video presentation. We took into account error from thepoint of odor injection to the consumer’s sense of smell.

4

Experiment4.1

Overview

The evaluation experiment was conducted at the AEON Mall Yamatokoriyama
store (supermarket) located in Yamatokoriyama City, Nara Prefecture in Japan,
for two months from June to July 2021, the season of Yamato-maru eggplant.
This study was conducted with the approval of the Research Ethics Committeeof Kio University (Approval No. R3-03). The experimental setup is shown in
Figure 3. In this experiment, four conditions shown in Table 1 were compared
to investigate the impact of presenting information with different modalities on
consumers’ purchasing behavior.
The experiments were conducted on Saturdays, Sundays, and national holidays, when there was no bias from special sales or point reductions at the store.
5

https://aromajoin.com/products/aroma-shooter

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D. Mayumi et al.
Table 1. Experiment Design (Date of experiment and medium of presentation)
DateExp. 1
Exp. 2Exp. 3

Intervention Presentation media

Jun. 12, Sat.

--

Jun. 13, Sun.

--

Jun. 26, Sat.

!

Paper media 2

Jun. 27, Sun.

!

Paper media 2

Jul. 3, Sat.

!

Paper media 2 , Video media (touch play)!

Paper media 2 , Video media (continuous play)

Jul. 22, Thu.

!

Paper media 2 , Video & olfactory media (touch play)1!

Paper media 2 , Video & olfactory media (continuous play)

Jul. 24, Sat.

!

Paper media 2 , Video & olfactory media (touch play)

Jul. 25, Sun.

!

Paper media 2 , Video & olfactory media (continuous play)

Jul. 4, Sun.
1

Exp. 4

1
2

Jul. 23, Fri.

These dates are a national holidays in Japan.
Handouts of recipes and pop-ups are prepared.

In the experiment, we did not conduct direct sales promotions such as handingout flyers, talking to customers, or tasting the products, so as to avoid the influence of prior publicity. In order to eliminate bias in purchasing due to pricechanges, we sold the products at the same price on all days. In Experiment 4,
which used the olfactory device, we manually started the olfactory media by
touching the tablet on Thursday and Saturday. We played it continuously on
Friday and Sunday to confirm the effect of the olfactory media on the booth.
The evaluation items were the number of visits to the booth, the time spent in
the booth, the sales of Yamato-maru eggplant, and the results of post-interviews
with consumers. The number of visits and the time spent in the booth were
evaluated based on the skeletal information in front of the booth using a depth
camera attached to the booth, excluding information on consumers who wereassumed to have passed by the booth for less than five seconds.
For sales, we compared the sales data for the same week and day of theprevious year (FY2020). The number of booth visits, the time spent at the booth,and the sales data were used to evaluate whether they significantly influencesales in sales promotion. At the time of distribution of the questionnaires, thepurpose and method of this study and ethical considerations for the survey
participants were explained orally and in questionnaires’ sheet. In addition, theparticipants were informed of the purpose and methods of this study and of
ethical considerations for survey participants both orally and in writing whenthe questionnaires were distributed.
4.2

Result and Discussion

Comparison of the number of booth visits The Figure 4 shows the resultsof the number of booth visits for each day of the experiment. The number ofvisits to the booth was highest in Experiment 4 (paper media, video media,
and smell media) shown in red. In Experiment 3, shown in green, there was a

7Fig. 4. Number of booth visits per experimental day (*touch play, **continuous play)difference in the number of booth visits compared to Experiment 4, although
the difference was only in the presence or absence of the smell media.
The results of the comparison of visits to the booth in a day are shown in
Figure 6. The number of visits increased from 3:00 p.m. to 5:00 p.m. in eachexperiment. In other words, it is thought that shoppers who are preparing fordinner were visiting in the store. The number of visitors to the booth after 5:00
p.m. in Experiment 4 (paper media, video media, and olfactory media), shownin red, tended to increase compared to the other experiments.

Comparison of time spent at the booth Next, the results of the comparisonof the percentage of time spent in the booth for each experiment are shown in the
Figure 5. Experiment 4 (paper media, video media, and olfactory media), shownon the far right, had the highest percentage of time spent per consumer of 10
seconds or more compared to the other experiments. Similarly, in Experiment 3(shown in green), compared to Experiment 4, there was a difference in the timespent in the booth only with and without the scent device.
The Kruskal-Wallis test, a nonparametric test equivalent to a one-way ANOVA,
was used to quantitatively compare the time spent in the booth in each experiment. As a result of the test, a significant difference was found between eachexperiment (p-value: 5.57×10−17 < 0.05), confirming that there was a differencein the time spent at the booth in at least one of the four evaluation experiments.
The Mann-Whitney U test, which is used as a significance test for two independent sets of samples, was then used to quantitatively compare the time spent in
the booth between each experiment. The results of the test between each experiment are shown in Table 2. As a result of the test, significant differences were
found between all experiments.

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D. Mayumi et al.

Fig. 5. Average time spent in booth per day
Table 2. Test results for time spent in the booth between each experiment
Two pairs to compare P-value presence of significant difference
Experiment 1,2
4.615×10−2
significant difference exists
Experiment 1,3
1.109×10−5
significant difference exists
Experiment 1,4
2.596×10−17
significant difference exists
Experiment 2,3
3.849×10−2
significant difference exists
Experiment 2,4
9.834×10−8
significant difference exists
Experiment 3,4
1.121×10−3
significant difference exists

Comparison of sales volume by intervention The Figure 7 below shows theresults of the comparison of sales for each type of intervention in this experimentwith the previous year (2020). The comparison was also made for the same
holidays as last year. In Experiment 1, where no intervention was conducted,
sales were 1.00 times higher than in the previous year, indicating no change.
Experiment 2, in which we intervened with paper media such as pop-ups andrecipes, produced the greatest difference, with sales 1.47 times higher than lastyear, with cooking videos 1.34 times higher than last year, and with smells 1.83
times higher than last year.
As shown above, sales tended to increase in all experiments in which interventions were conducted, and sales increased the most in the intervention
using smells. In addition, the intervention of paper media such as product pops
and recipes, and the intervention of cooking videos, which have been commonlyused as methods to promote purchasing, are also considered to contribute to theincrease in sales.
4.3

Results of the interview survey

In order to investigate the opinions and impressions of consumers regarding thebooths in this experiment, a questionnaire was conducted on a different day from

9

Fig. 6. Average number of booth visits per minutethe day of the experiment. The interview survey was conducted over two days,
with a total of 298 people completing the questionnaire. The following is a listof the opinions about the olfactory media, pop-ups and recipes.
Positive comments on the olfactory media included, “I was impressed by
the fact that it produced an aroma. I wanted to make and eat it,” “It smelled
good,” and “It was interesting and stimulated my interest.” As for the recipes
and pop-up displays, we received comments such as, “The pop-up display of
Yamato-maru eggplants hanging above was very impressive and easy to see,”“The variety of recipes was helpful,” “I don’t like elaborate recipes and can only
think of denraku at home,” and “I thought I want to try it since I received therecipe.”Negative comments included “more visible area would be better”, “inconspicuous”, and “make the booth more visible.” As for the cooking videos, we
received the opinion that “it would be good if the recipes were changed every 30
minutes.” From the results of the interviews, we had the impression that many
consumers were interested in the olfactory media, which was a device that they
had never seen before. There were no negative comments about the smell fromthe consumers, and they said that the aroma was effective in making them believe
the dish was delicious. In addition, there were opinions that consumers wanted
to actually cook the food and that they wanted to purchase the seasonings usedin the aroma, such as black pepper and curry, which led to change in consumer

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D. Mayumi et al.

Fig. 7. Comparison of sales volume by intervention (2020, 2021)

behavior. This means that aroma nudges have the potential to encourage chain
shopping behavior, such as impulse buying.

5

Conclusion

In this paper, we explored the possibility of aroma nudges on purchasing behavior. In the experiment, we compared the number of visits to the sales booth of
Yamato-maru eggplant, the time spent there, and the sales volume under four
conditions: (1) no presentation, (2) presentation of paper media, (3) presentationof paper and video media, and (4) presentation of paper, video, and olfactory
media. The results suggested that the number of visits to the booth and thetime spent in the booth increased when olfactory stimulation was provided by
the aroma of the ingredients in addition to visual and auditory stimulation, andthat this tended to increase sales. The influence of aroma on purchasing behavior like sales amount and time spent has been shown in previous studies [3, 5,9], and similar results were obtained in this experiment. In the future, we plan
to extend the duration of the experiment and increase the number of stores toinvestigate the more general effects of aroma nudges on purchasing behavior.
We will also study the timing of the scent spray and the use of airflow to createa natural aroma smelling away. Our experimental results suggest that aroma
nudges may positively impact purchase promotion. However, the use of aroma
nudges should be carefully considered. For example, sweet smells may contribute11to the purchase promotion of sweets that contain a lot of sugar, but from a healthpromotion perspective, such nudges may be undesirable. Therefore, future studies will need to discuss the potential and application of aroma nudges from an
ethical perspective.
Acknowledgements. This work was supported by JST, PRESTO Grant Number JPMJPR21P7, Japan.

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