Opportunities for Odor: Experiences with Smell and Implications for Technology
Marianna Obrist1,2, Alexandre N. Tuch3,4, Kasper Hornbæk4 m.obrist@sussex.ac.uk | a.tuch@unibas.ch | kash@diku.dk 1Culture Lab, School of Computing Science Newcastle University, UK 2School of Engineering and Informatics University of Sussex, UK 3Department of Psychology, University of Basel, CH 4Department of Computer Science, University of Copenhagen, DK
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CHI 2014, April 26 – May 01 2014, Toronto, ON, Canada
Copyright 2014 ACM 978-1-4503-2473-1/14/04…$15.00.
http://dx.doi.org/10.1145/2556288.2557008
ABSTRACT
Technologies for capturing and generating smell are emerging, and our ability to engineer such technologies and use them in HCI is rapidly developing.
Comment 1
Smell technologies continue to be developed. Making them part of smell-enhanced human-computer interactions would be a novel application. One problem, addressed here, is how to engineer smell technology for HCI.
Our understanding of how these technologies match the experiences with smell
that people have or want to have is surprisingly limited.
Comment 2
Understanding human-computer smell interactions constitutes a further problem, addressed by this paper.
We therefore investigated the experience of smell and the emotions that accompany it. We collected stories from participants who described personally memorable smell experiences in an online questionnaire.
Comment 3
The research used story-collecting as a means of acquiring human smell data.
Based on the stories we developed 10 categories of smell experience.
Comment 4
The data were organised into categories of smell experience.
We explored the implications of the categories for smell-enhanced technology design by (a) probing participants to envision technologies that match their smell story and (b) having HCI researchers brainstorm technologies using the categories as design stimuli.
Comment 5
The implications of the smell categories for smell-enhanced human-computer interactions were explored using envisioning and brain-storming techniques.
We discuss how our finding can benefit research on personal memories, momentary and first time experiences, and wellbeing.
Author Keywords : Smell; smell experiences; odor; olfaction; user experience; smell-enhanced technology; narratives; smell stories; crowd-sourcing; design brainstorming; designing for smell.
ACM Classification Keywords H.5.2 Information interfaces and presentation (e.g., HCI):
Miscellaneous. General Terms Experimentation, Human Factors, Design.
INTRODUCTION
Smell plays an important role for memories and emotions. Compared to other modalities, memories evoked by smell give stronger feelings of being brought back in time, are more emotionally loaded, are experienced more vividly, feel more pleasant, and are autobiographically older (ranging back to childhood) [15,33]. Smell is incredibly powerful in connecting humans to past events and experiences.
Matsukura et al. [22] recently proposed the Smelling Screen, an olfactory display system that can distribute smells. Earlier work in HCI has proposed other systems that capture and generate smells. For example, Brewster et al. [5] developed a smell-based photo-tagging tool, and Bodnar et al. [4] showed smell to be a less disruptive notification mechanism than visual and auditory modalities. Thus, smell technologies are already emerging. Our understanding of how these technologies match the experiences with smell that people have or want to have is surprisingly limited.
First, while technologies such as those mentioned above are often evaluated, the results mainly concern the perception of smell. The evaluations say little about the general potential of smell technologies for humans or their ability to generate particular experiences. Second, whereas earlier work states that the subjective experience of smell stimulation is crucial for the success of a system (e.g., [5]), we are unaware of work in HCI that studies the subjective experience of smell (though see [17]). Third, several hundred receptors exist for smell and we cannot rely on any primary smells to stimulate a particular experience, as might be imagined for other human senses [2]. Taken together, these points suggest that we can only link smell tenuously to particular experiences or emotions. This limits our ability to design for a spectrum of experiences.
The present paper focuses instead on experiences and emotions related to smell and links them to potential technologies. Inspired by work on user experience [14,34], we concentrate on personal memorable smell experiences and their links to emotion. From the focus on experience we developed design guidance for smell-enhanced technologies. The goal is to contribute knowledge on subjective smell experiences and their potential for design. We collected 439 smell stories, that is, descriptions of personal memorable experiences involving smell.We distributed a questionnaire through crowdsourcing, ensuring a large-scale coverage and variety of smell stories. We analyzed the stories and identified 10 main categories and 36 sub-categories. Each category was described with respect to its experiential and emotional characteristics and specific smell qualities. Besides smell stories associated with the past (e.g., memory of loved people, places, life events) we identify stories where smell played an important role in stimulating action, creating expectations, and supporting change (e.g., of behavior, attitude, mood). Smell can sometimes also be invasive and overwhelming, and can affect people’s interaction and communication. Within the categories, we identify common smell qualities and emotions, which support the exploration of opportunities for design. In particular, we discuss the implications for technology based on feedback from participants and on a brainstorming session with HCI researchers working on smell technologies.
The main contributions of this paper are:
(1) an experiencefocused understanding of smell experiences grounded in a large sample of personal smell stories, which allowed us
(2) to establish a systematic categorization and description scheme for smell experiences, leading to
(3) the identification of technology implications by participants, and
(4) the exploration of design potentialities by HCI researchers.
THE HUMAN SENSE OF SMELL
The sense of smell is the most complex and challenging human sense. Hundreds of receptors for smell exist and the mixing of the sensations, in particular with our sense of taste, is immense [2]. The sense of smell is further influenced by other senses such as vision, hearing, and touch; plays a significant role for memory and emotion; and shows strong subjective preferences. Willander and Larsson [33] showed that autobiographical memories triggered by smell were older (mostly from the first decade of life) than memories associated with verbal and visual cues (mostly from early adulthood). Moreover, smell-evoked memories are associated with stronger feelings of being brought back in time, are more emotionally loaded, and are experienced more vividly than memories elicited through other modalities [15,33]. No other sensory system makes the direct and intense contact with the neural substrates of emotion and memory, which may explain why smell-evoked memories are usually emotionally potent [15].
The emotion-eliciting effect of smell is not restricted to the context of autobiographical memories. Smell is particularly useful in inducing mood changes because they are almost always experienced clearly as either pleasant or unpleasant [8]. For instance, Alaoui-Ismaïli et al. [1] used ‘vanilla’ and ‘menthol’ smells to trigger positive emotions in their participants (mainly happiness and surprise) and ‘methyl methacrylate’ and ‘propionic acid’ to trigger negative emotions (mainly disgust and anger). Interestingly, Herz and Engen [15] pointed out that almost all responses to smell are based on associative learning principles. They argued that only smells learned to be positive or negative can elicit the corresponding hedonic response and that people, therefore, should not have any hedonic preference for novel smells. The only exceptions are smells of irritating quality that strongly stimulate intranasal trigeminal structures. Such smells often indicate toxicity. While neuroscientists and psychologists have established a detailed understanding of the human sense of smell, insight into the subjective characteristics of smell and related experiences is lacking. The exploration of this subjective layer of smell is often understood as going beyond the interest of these disciplines, but is highly relevant for HCI and user experience research.
SMELL IN HUMAN-COMPUTER INTERACTION
Ten years ago, Kaye [17] encouraged the HCI community to think about particular topics that need to be studied and understood about smell. While some attempts have been made to explore smell during recent years, the potential of smell in HCI remains under-explored. Most work on smell in HCI focuses on developing and evaluating smell-enhanced technologies. Brewster et al. [5] used smell to elicit memories, and developed a smell-based photo-tagging tool (Olfoto). Bodnar et al. [4] showed smell to be less disruptive as a notification mechanism than visual and auditory modalities. Emsenhuber et al. [9] discussed scent marketing, highlighting the technological challenges for HCI and pervasive technologies. Ranasinghe et al. [24] further investigated the use of smell for digital communication, enabling the sharing of smell over the Internet. More examples of smell-enhanced technologies can be found in multimedia applications [13], games [16], online search interfaces [19], health and wellbeing tools (e.g., http://www.myode.org/), and ambient displays [22].
The exploration of smell-enhanced technologies is mostly limited to development efforts and the evaluation of users’ smell perception of single smell stimuli. The smells used are often arbitrary and not related to experiences. This is because of the lack of knowledge pertaining to the description and classification of smells required for HCI [17]. Kaye points out that “There are specific ones [classification and description schemes] for the perfume, wine and beer industries, for example, but these do not apply to the wide range of smells that we might want to use in a user interface” (p. 653). Thus, previous work has a general and quite simple usage of smell.
THE POTENTIAL OF STUDYING SMELL EXPERIENCES
In contrast to the work reported above, the present paper focuses instead on experiences with smell and links them to potential technologies. We do so through stories of experiences with smell. Stories are increasingly used within user experience research to explore personal memories of past experiences, but also to facilitate communication in a design process [3,34]. Stories are concrete accounts of particular people and events, in specific situations [10], and are more likely to stimulate empathy and inspire design thinking than, for example, scenarios.
STUDY METHOD
We asked a large sample of participants to report smell experiences that were personal and meaningful. We refer to the description of these experiences as smell stories. These stories were captured through a questionnaire described below, which included inspirational examples of smell-enhanced technologies at its end. Based on the examples we asked participants to reflect on their experience and future technologies. The rationale of this approach was to begin from smell experiences that matter to participants, instead of starting from an application or a particular technology.
Questionnaire
We created a web-based questionnaire consisting of six parts. We started with an open question to stimulate the report of a personal memorable smell experience. This was followed by closed questions aiming to elucidate the relevant emotional and experiential characteristics, as well as the smell qualities. Participants could freely choose the story to report. The questionnaire was administered through a crowdsourcing platform to obtain a large sample of smell stories. Crowdsourcing provides valid and reliable data [20] and has been used for capturing user experiences [31].
Part 1: Smell Story
The smell stories were elicited through an initial exercise, where participants were asked to think about situations and experiences where smell played an important role. The aim was to get participants into the right frame of mind and sensitize them to smell. Next, participants were asked to describe one memorable smell experience in as much detail as possible, inspired by the questioning approach used in explicitation interviews [23]. This questioning technique is used to reconstruct a particular moment and aims to place a person back in a situation to relive and recount it. Part 1 of the survey was introduced as follows: Bring to your mind one particular memorable moment of a personal smell experience. The experience can be negative or positive. Please try to describe this particular smell experience in as much detail as possible. You can use as many sentences as you like, so we can easily understand why this moment is a memorable experience involving smell for you. Participants were asked to give a title to their story (reflecting its meaning) and indicate if the experience was positive, negative, or ambivalent (i.e., equally positive and negative). They were also asked to indicate how personally relevant the experience was (from ‘not personally relevant at all’ to ‘very personally relevant’).
Part 2: Context
Part 2 asked participants to give further details of their reported experience via open and closed follow-up questions. There were four questions on the context of the described experience, including the social context (who else was present), the place (based on the categories used by [26]), the location (as an open field), and the time when the reported experience took place (days, weeks, months, or years ago).
Part 3: The smell
Specific questions on the characteristics and qualities of the smell were asked in Part 3. Participants characterized the smell itself using a list of 72 adjectives (i.e., affective and qualitative terms) derived from the ‘Geneva Emotion and Odor Scale’ (GEOS) [7]. Participants could also add descriptions to characterize the smell in an open feedback box. In addition, they rated the smell with respect to its perceived pleasantness, intensity, and familiarity.
Part 4: Experienced emotions
In Part 4 participants had to describe how they felt about the experience as a whole, using a list of affective terms (101 in total). They could go through the list and tick the words that best described their emotions during the experience. The words were derived from Scherer [27]. Participants could also add their own words in a free-text field.
Part 5: Smell technologies
After the participants had selected, thought about, and described a particular smell episode, Part 5 linked their personal experience to technology. The participants were engaged in a envisioning exercise inspired by work on mental time travel [30]. They were shown six inspirational examples of smell technologies, namely: Olfoto: searching and tagging pictures (CHI, [5]); Smelling screen: ambient displays (IEEE, [22]); Digital smell: Sharing smell over the Web (ICST, [24]); Scent dress: interactive fabric with smell stimulation (http://www.smartsecondskin.com/); Mobile smell App: iPhone To Detect Bad Breath and Other Smells (BusinessInsider 01/2013), and Smell-enhanced cinema: Iron Man 3 Smell-Enhanced Screening (Wired 04/2013). These six technologies cover areas of relevance for HCI (mobile, ambient, wearable, personal, and entertainment computing), give realistic examples of smell technologies from research, and include recent, commercial examples.
We asked the participants to imagine any desirable change that future smell technology might make (or not) with respect to their personal smell experience. We asked them the following questions: (1) How could your experience be enhanced? (2) What technology are you thinking about? (3) Why would such a combination of your experience and the technology be desirable, or why would it not? Finally, the participants could express any other ideas for smell technology in a free-text field.
Part 6: Personal background
At the end of the questionnaire, participants answered questions on their socio-demographic and cultural background. The goal was to try to identify any geographical and cultural influences on smell attitudes (as found by Seo et al. [29]). The participants were also asked to assess their own smell sensitivity. All the questions, except for those on demographics, were mandatory. On average, the survey took 16 minutes to complete (SD = 7.57 minutes). Participants received US$ 1.50 for completing the questionnaire, corresponding to an hourly salary of 5.63 dollars.
Collected data and participants
A total of 554 participants began the questionnaire. Of these, 480 completed the questionnaire and answered three verification questions at its end. These questions required participants to describe the purpose of the study without being able to go back and look at the earlier questions or guidelines. After data cleaning, 41 stories were excluded. Fake entries (n = 11) were identified immediately, while repeated entries (n = 10), incomplete stories (unfinished sentences; n = 6), and incomprehensible stories (which did not make sense on their own; n = 14), were excluded iteratively throughout the coding process. This left us with 439 smell stories.
At the time of the study, all 439 participants (52.8% female) lived in the US; most had grown up in the US (95%). The participants’ age ranged from 18 to 67 years (M = 31.5, SD = 10.0). A majority of participants (84%) indicated being sensitive to smell (rating 4 or higher on a scale from 1 to 5).
Data analysis
The analysis process followed an open and exploratory coding approach [25]. Two researchers conducted the qualitative coding process. After coding an initial 25% of the stories, two more coding rounds (to reach 33% and then 50% of the data), led to the establishment of an agreed coding scheme. The coding scheme contained 10 main categories and 36 sub-categories, and a category entitled ‘not meaningful’ for cases where smell did not seem to have any relevance in the described experience. Based on this coding scheme, one researcher coded the remaining 50% of the data, and the second researcher coded a subsample of 25% of that data, resulting in a good inter-coder agreement (Cohen’s kappa of κ = .68) [12].
Follow up design brainstorming
In addition to the feedback from our participants, we also explored the design value of the smell stories with experts in the field. We organized a two-hour design brainstorming session with three HCI researchers, two working on smell technologies and one working on advanced interface and hardware design. None of them were from the same organization as the authors and none were familiar with the details of the study before the session.
The brainstorming session aimed to share and interpret the smell stories and followed four stages [11]: (1) prompting, (2) sharing, (3) selecting, and (4) committing. We selected 36 stories (one representative story for each sub category) as brainstorming prompts. All 36 stories were printed on A6 sheets (including the story title, the smell story, context information, and personal background). Each researcher was asked to read through the stories individually before discussing them together. They were asked the same questions as our participants (e.g., how they might imagine a connection between the experience and technology). Each researcher chose the most interesting/inspiring stories to share with the group, then they generated ideas as a group, and selected three to four ideas to be developed in more detail. The outcome of the brainstorming session is presented in the implication section, after the description of the findings from the smell stories.
FINDINGS ON EXPERIENCES WITH SMELL
In the following sections we present our findings according
to the 10 identified categories. The 439 smell stories were
organized via their primary category, as agreed by the
coders. This categorization does not define a strict line
between the categories, as they are not wholly independent,
but it does enable us to organize the material and generate a
useful dataset for design.
Below we provide for each category a rich description of the particularities of the
stories, excerpts from example stories, and their associated
smell qualities and emotions. Each category also contains
information about the participants’ own rating of the stories
as positive, negative, or ambivalent.
Category 1: Associating the past with a smell
This category is the largest and contains 157 stories. In
these stories, the participants described a past experience in
which a smell was encountered during a special event in life
(e.g., ‘Wedding Day’, ‘New House’), at a special location
(e.g., ‘The Smells of Paris’, ‘Grandma’s House’), or as part
of a tradition (e.g., ‘The Smell of Thanksgiving’ or
‘Christmas Eve’). In these stories the smell was described
as having a strong association to those particular moments
in the past, with no actual smell stimulus in the present. A
particularity of this category is the distinction between
stories describing personal memorable events versus
personal life events (e.g., ‘Disneyland’ versus ‘When my
mother died’). Smells were also associated with personal
achievement/success (e.g., ‘Scent of Published Book’,
‘New Car Smell’) and other important episodes of change,
such as “‘Fresh Start’: I was taking a job in a new city. …. I
took a plane trip across the country and the moment I took
a step off the plane and took a deep breath will always stick
with me. It felt so clean and the air actually smelled fresh
and new” [#488]. Within this story, the qualities of the
smell were for instance described as fresh, energetic, and
invigorating. Some of the emotions experienced at this
moment were courageousness and excitement. Although
this category is dominated by positive experiences (n =
127), negative experiences were also reported (n = 27),
such as ‘Car Crash’.
Category 2: Remembering through a smell
The 40 stories in this category described a recent
experience of a smell, which reminded participants about
past events, people, locations, or specific times in their life.
In contrast to the previous category (where stories describe
a direct link from the recollected past smell to the present;
e.g., the smell of ‘Grandma’s House’), this category
contains stories that describe an indirect link from the
present experienced smell stimulus
to the past event, person or place (e.g., the smell of chocolate cookies as sudden
reminder about grandma). Most stories in this category
contain reminders of childhood described as ‘sweet’,
‘reassuring’ and ‘nostalgic’ with respect to the qualities of
the smell. A sub-set of stories in this category (n = 10) also
highlight the particular power of smells to take a person
back in time. The description of such a flashback caused by
a sudden smell stimulus was described as: “‘My first love’:
It was the next day, when I was walking through the local
Macy’s that I smelled something that threw me back into
that situation, I could feel and see everything that had
happened the day before when I smelled a perfume in the
store” [#630]. Some of the qualities used to describe the
smell were attractive, erotic, and fresh. The experienced
emotions were described as amorous, aroused, excited,
hopeful, and interested. The stories in this category were
mainly positive (n = 37), except for three.
Category 3: Smell perceived as stimulating
The 62 stories in this category described experiences with a
unique, mostly unknown smell (all stories, except one, were
positive). The smells arose from different sources, such as
perfume, food, and nature. A particularity of this category is
the quality of ‘first time’ encounters with a smell across all
origins. One participant described the first time he was at a
beach: “The smell was very different from anything I had
ever experienced before. At first I was kind of grossed out
by the smell, but I grew to love it” [#921]. Another
participant described the smell of a tornado experienced for
the first time: “It was similar to the smell before rain but
had a certain sharpness to it, as if to warn of the incoming
danger. I felt like I knew this smell but at the same time, it
felt foreign to me. It wasn’t a bad smell, it was just slightly
unfamiliar” [#713]. The smell qualities and experienced
emotions were often described with mixed attributes (e.g.,
heavy, imitating, and stimulating; attentive, serious, and
calm), but still rated as positive experiences by participants.
Most of the other stories in this category reported on the
first experiences with food (e.g., ‘Slice of Heaven’) and
nature (e.g., ‘Grass’), and were described as desirable,
fresh, or pure, and provoked feelings of happiness at the
moment they occurred. Although specific memories were
established, including unique new associations (e.g.,
‘Tornado smell’), the stories in this category did not evoke
the kind of strong connections to the past as described in
Category 1 and 2.
Category 4: Smell creating desire for more
This category contains 48 stories (45 positive). Key to these
stories is that the smell grabbed the persons’ attention
unexpectedly. The smell was either associated with food
(triggering appetite), nature (triggering curiosity), or the
scent of other people (triggering attractiveness), which
motivated one to do or get something. In some stories smell
was described in relation to the sensation of newness (e.g.,
“‘The sweet smell of CPU’: …There was the smell of the
cardboard boxes it all arrived in, the smell of new metal–
perhaps it was a combination of these and other things, but
when the building was complete there was just a singular
smell that was unique to a new computer built by my own
hands” [#685]). The qualities of the smell in this story
included beneficial, heavy, sophisticated, energetic, and
pleasantly surprising. The experienced excitement was
expressed through words such as confident, delighted,
enthusiastic, impressed, or triumphant. This category also
contained one story where the smell at a funeral stimulated
reflection in the moment (e.g., ‘The scent of moving on’).
The story was rated as a positive experience and at the same
time the smell was described as clean, penetrating, and
persistent, and the participant indicated that she was afraid,
anxious, discontented, sad, tired, and uncomfortable.
Despite the negative situation described in this story, the
smell gave hope and a desire to live and move on, looking
into the future in contrast to the stories in Category 1 and 2.
Category 5: Smell allowing identification and detection
This category captures the enabling role of smell in certain
situations, such as allowing one to identify or detect a smell
(e.g., “‘Gas leak’: I was cooking something on a gas stove
and went out for a few minutes. When I came back, the fire
was extinguished but the gas was still on. My roommate
was sat at the table doing schoolwork, completely oblivious
to the poisonous gas that was filling the room. I told him to
get the hell up and open the windows and doors” [#951]).
The qualities used to describe the smell were distinguished,
penetrating, dirty, and light. The emotions related to this
situation were described as anxious, conscientious,
confident, and serious. Although the category is rather
small (n = 11), the lesson to be learnt from the shared
stories was the immediacy of the smell, allowing the
participant to act or prevent something.
Category 6: Overwhelming power of smell
This category includes 37 stories where the smell
overwhelmed the person in a positive way (n = 5; e.g., ‘The
Chocolate Factory’) but predominately in a negative way (n
= 30; e.g., ‘The Smell of Death’). In the latter case, people
described the smell as something disturbing, as something
that hit them suddenly on their way or during an activity. A
subset of the stories was recounted as traumatizing, so that
the person could still vividly remember the particular
moment in the past although years have passed and no
recent similar smell stimulation had occurred unlike in
Category 2 (e.g., “‘Visit to a local county jail’: My guide
warned me ahead of the time that it was going to be a little
foul in there, but nothing could have prepared me for the
obscenely acrid stench of hundreds of men crammed into
every available space of the jail, right down to windowless
storage rooms converted into more cells. … For days
afterwards, I couldn’t shake the smell…. There weren’t
enough showers to take it away. It’s been several years
since then, and my memory of that smell is just a strong as
ever” [#604]). In this category, the qualities of the smell
were described as heavy, penetrating, dirty, or sickening.
Amongst others, the experienced emotions were described
as alarmed, anxious, distressed, frustrated, or
uncomfortable. In contrast to Category 1 and 2 (where the
smell was associated with an event from the past or
triggered a specific memory), Category 6 is about the smell
as such during the experience and not about the memory
associated with this smell. As opposed to the first two
categories, in most stories forgetting – not remembering –
the smell was the key element.
Category 7: Smell invading private and public spaces
All the stories in this category (n = 32) described an
experience where one could not get rid of the smell. The
smell invaded private and public spaces. In contrast to the
previous category, the smell entered the person’s personal
space (the person did not enter the space where the smell
already existed) and took over the space. The loss of control
over the smell was linked to the lingering quality of the
smell (e.g., “‘Don’t want to smell that twice!’: I woke up
one morning suddenly confused and was hit with an odor so
horrible I couldn’t figure out what it was. … It was not like
the smell you get a whiff of when a skunk stinks up the
outdoors” [#530]). In the story the power of the smell,
causing them to leave the house for several hours, was
described with qualities such as foul, nauseous, penetrating,
and persistent. One of the experienced emotions was
surprisingly ‘amused’, however it was overruled by other
emotions including annoyed, anxious, disgusted, taken
aback, and uncomfortable. Despite the glimpse of humor in
some stories, this category mainly contains negative
experiences and underlines the power of the smell with its
sudden and lingering qualities.
Category 8: Social interaction is affected by the smell
Within this category, smell was related to a person’s own
smell or to the smell of others. Smell negatively affected
the interaction among people and their togetherness (e.g.,
“‘Dragon breath teacher’: Once a teacher yelled at me
during class. She got so close up into my face that I could
smell her bad breath. This made the experience much worse
because I wanted to get up and walk away but she was
grabbing me to keep me focused on her while she was
talking” [#744]). The smell qualities were described as
nauseous, penetrating, and sickening, and caused negative
emotions experienced as bitter, distressed, or insulted.
Despite frequent interactions among people, this category
only contains 11 stories. This set of stories (overall negative
experiences, apart from two) contains interesting elements
with respect to a person’s own awareness of body smell and
the overbearing effect of other peoples’ smell on one’s
comfort.
Category 9: Smell changes mood, attitude and behavior
This category contains 23 stories, which underlined the
power of smells to change a person’s mood, attitude, or
behavior. Stories reported the active regulating effect of
smells with respect to mood, but mostly (n = 14) the change
of behavior due to smells (e.g., ‘Accidental vegetarian’ or
‘Saved by the Smell!’). One story showed the active usage
of smells to change one’s mood. A participant had recently
been divorced and reported on the day her husband had
moved out: “‘White Lilac Sheets’: “I made the bed with my
lilac sheets and the atmosphere changed. I still remember
that scent and how I felt on that day. I was going to be
okay. The room didn’t look or feel or smell lonely anymore.
It looked and smelled fresh and clean and lovely and a bit
romantic and it was mine” [#526]. The qualities of the
smell were described as fresh, reassuring, and spring-like,
while the experienced emotions were determined, hopeful,
longing, tense, but also worried. Overall, the stories in this
category were reported as mainly positive (n = 12)
experiences, but also as negative (n = 7) and four stories
were rated ambivalent, neither positive nor negative.
Category 10: Smell builds up and changes expectations
This category shows the potential of smell to build up
expectations and to surprise. In the former case (11 stories)
the smell was building up expectations until the actual
contact with the trigger, such as food or a perfume (e.g.,
“‘The Smell of Hungry Anticipation’: “I was trying a new
soup for the first time. When it was brought to the table, the
soft smell of rosemary immediately hit my nostrils. …It
complimented the taste of the soup and built anticipation”
[#585]). The smell was described as mouthwatering,
healthy, and pleasantly surprising, and was further related
to emotions such as conscientious, expectant, and relaxed.
In other stories (n = 7), expectations were exceeded to the
extent that they surprised and diverted anticipations (e.g.,
‘PomVinegar Surprise’: “I could smell the pomegranate
and vinegar from about 10 steps away, and it was a very
pungent (thought not unpleasant) odor. I almost felt my
nose becoming runny and took out a tissue. When I tasted
the dish, however, the taste wasn’t nearly as sour as I
expected it to be from the smell” [#542]). The smell in this
story was described as distinguished and penetrating, and
was associated with emotions such as attentive and excited.
Key quantitative facts behind the smell stories
While the above-described categories can be used as an
inspiration and as a starting point for exploring design
opportunities for smell in HCI,
our quantitative data provides additional background information. Below, the
key quantitative information across all the collected smell
stories is summarized. The majority of the 439 collected
stories were positively valenced (n = 296), 112 were
negative, and 31 were ambivalent. On average, negative
stories tended to be slightly longer (M = 90 words) than
positive stories (M = 79 words), but the difference is
statistically not significant (U = 14600, p = .063, r = .09).
Contextual information
Most stories occurred in a context where one or more familiar persons were present (64.2%)
or where participants were alone (21.6%). The presence of
one or more strangers was reported less frequently (8.7%).
With regard to location, most of the experiences happened
at the participant’s or a friend’s home (38.1%) or in a public
building (20.7%). Quite a few participants reported that
their experience took place in the streets or another public
space (14.4%), in a natural setting (7.3%), or at work
(6.4%). The remaining participants (13.2%) indicated other
places (e.g., stranger’s home). On average the reported
experiences occurred 8.7 years ago (SD = 10.3), ranging
from 1 day to 58 years ago.
The qualities of smell
The most frequent smell qualities
reported in positive stories were pleasant (60%), fresh
(42%), sweet (38%), clean (31%), and mouthwatering
(30%). Smells in negative stories were described as
unpleasant (62%), penetrating (55%), heavy (54%), foul
(53%), and nauseous (51%). In ambivalent stories the smell
was perceived as fresh (39%), pleasant (32%), mouthwatering
(32%), attractive (26%), and penetrating (23%).
Experienced emotions
When asked to describe how they felt during their experience, participants’ used the affective
terms happy (63%), pleased (53%), joyous (42%), delighted
(41%), and excited (39%) in positive stories and
uncomfortable (55%), disgusted (51%), distressed (43%),
miserable (42%), and taken aback (29%) in negative stories.
Ambivalent experiences were most frequently described as
happy (42%), excited (39%), enthusiastic (35%), joyous
(32%), and serene (29%).
An overview of all 10 categories and 36 sub-categories
including qualitative and quantitative information
(including a full example for each sub-category, used in the
design brainstorming session) is provided as supplementary
material. All smell stories and related qualities of smell,
experienced emotions, and context information, are also
available at www.multisensory.info for further exploration.
IMPLICATIONS FOR TECHNOLOGY
This study focused first on experiences and second on the
implications for technology. This section turns to
technology. Below we summarize the feedback from the
participants on how technology would fit with their
experience, and describe input from a brainstorming session
with HCI researchers working on smell technologies and
advanced interface and hardware design, based on a sub-set
of the smell stories (one from each sub-category).
Ideas for technology from participants
Below we summarize the six areas and ideas for desirable
future smell technologies mentioned by participants in Part
5 of the questionnaire:
(1) To share smells with family/friends: allow one to
participate in a family event through remote smelling; share
smells of special moments such as the smell of a newborn
baby with distant relatives; share smells with people who
they know would appreciate it (such as through social
media); allow capturing and sharing of smells to create a
common understanding where you can’t explain it.
Participants also desired to be able to design and share new
smells from a personal database and create a personal smell
box/bottle.
(2) To support decision making: use smells for a quick
judgment in online shopping (like/dislike can be determined
easily); create smell profiles about holiday places and travel
destinations; smell match maker in dating websites for
allowing a better decision making about going on a date or
not with a person (smell enhanced profiles).
(3) To regulate mood actively/passively: smell to relive
good experiences whenever you want to get in a better
mood; to calm yourself down in stressful moments such as
in traffic jam or at work; as a reminder of past memories
you would have forgotten otherwise but that can cheer you
up when you feel depressed and life seems too difficult.
(4) To combine with other technologies and activities:
integrate smell into radio; combine smell with music such
as with ‘soundhound’ or ‘shazam’ apps; smell-enhanced
advertisement on TV (for food channels); enhance visits of
concerts, theater and performances with smell; allow underwater
smelling when diving.
(5) To combine with everyday objects: enhance wristband
with smell for keeping a preferred perfume lingering; have
special glasses to see and smell the beach; smell-enhanced
jewelry and clothes. One participant imagined her wedding
ring enhanced with the smell of that day.
(6) To make oneself and others aware about body smell: to
avoid embarrassing moments; provide invisible cues to a
person about her/his smell level; quick smell check after
sporting activities.
The first idea matches the experiences in Categories 1 and
2, where particular events/moments in life are associated
with a smell. The desire for capturing and sharing these
experiences enhanced with smell becomes prevalent and
suggests design implications for real-time smell-enhanced
technologies (e.g., mobile phone, photo or video camera).
The second idea can be linked to Category 5, allowing
people to identify and detect a smell. Moreover, smells are
seen as very powerful for supporting quick decision-making
(e.g., smell-enhanced website navigation and searching).
The third idea shows a direct link to Category 9 and the
potential of smell to change mood. Interestingly participants
whose story was in Category 1 or 2 were wishing for the
possibility to capture pleasant smells, for instance from
their childhood, and released to them in the present. This
desire for smell-enhanced technologies or products is also
apparent in the fourth and fifth ideas, where technology,
objects, or even activities can be enhanced through smells
from the past, or actual smells sourced through nature (e.g.,
diving in the ocean). Finally, the sixth idea is linked to
Category 8, aiming to avoid embarrassing moments in
social interactions.
Participants also expressed concerns about future smell
technologies. They were concerned about the possible
misuse of smell when sharing it through the Internet or
mobile phones (e.g., teasing people with smells, how to
trust a smell message), and about the potential manipulation
through smell (e.g., TV ads, online shopping). Some
participants were also afraid to get sick, catch an allergy, or
become addicted if they are exposed to chemical
stimulations from technology. Finally, one participant
raised the question of copyright and ownership of smells
(e.g., ‘can I share others’ smells?’).
Ideas for technology from HCI researchers
Below we outline the ideas that emerged from the two-hour
brainstorming session prompted by 36 smell stories (one
from each sub-category). Four groups of design ideas
emerged from this session and are described below:
(1) Smell-enhanced performance regulator: a technology
stimulating smell in order to structure the day, taking
activities and moods into account, and combining different
smells to avoid habituation (training and evaluation phase
needed). Smell as a reminder to take a break or as
motivation to keep going a bit longer to meet the deadline
[inspired by #526 ‘White Lilac Sheets’, Category 9].
(2) Autonomous smell agent: a technology spreading
ambient cues (e.g., a robot) to guide someone to a certain
place, to build up expectations, and motivate action. Smell
trails in the environment can also make hidden information
accessible, for instance, before entering a room (e.g., smell
warning: tense working atmosphere) [inspired by #801
‘Don’t forget to check your gas stove before you leave the
house’, Category 5].
(3) Reminder alert with smell: a technology to remind us
about important events, birthdays, and appointments.
Although we have reminders on mobile phones and
computers, they are often ignored, snoozed or in the worst
case forgotten about. A smell can provide a pleasant
reminder to say ‘it is time to call your mom’ by presenting
the smell of your favorite dish your mom makes for you.
On the other hand, if more critical, bad smells can be very
powerful as a reminder and are not easily ignored [inspired
by #530 ‘Don’t want to smell that twice’, Category 7].
(4) Smell-enhanced storytelling: a technology that
stimulates storytelling around a digitized version of an
incense stick. A stick was imagined with different layers,
representing smells related to a loved person who passed
away. When friends or family members come together, for
instance at an anniversary year, they can add new smells to
be shared in the group and thus trigger new stories about
the dead person. It is as if looking through a photo album,
telling the stories from the past, and using the smells as
anchor points for keeping the memory alive [inspired by
#672 ‘The Scent of Moving On’, Category 4].
We saw that the smell stories, even if they only provided
limited information (story, story title, context, gender, and
age), triggered vivid discussions, created empathy, and
stimulated the sharing of personal smell experiences. The
four ideas described above provide a starting point for
exploring smell in HCI. The categorization along with
additional background information on smell qualities and
experienced emotions (see supplementary material) can
inspire further explorations of smell technologies.
DISCUSSION
Our findings about experiences with smell in combination
with the ideas for technologies just presented show several
design opportunities for smell. Below we do not provide
solutions for smell-enhanced technology designs, rather we
illustrate where our findings might be relevant to stimulate
novel designs in existing areas of interest within HCI. We
see three anchor points for smell-enhanced technology.
First, the smell stories in Categories 1 and 2 suggest design
opportunities for remembering and recalling the past. Our
findings might enrich ongoing research on the design for
personal memories. Apart from enhancing research
supporting the capturing and sharing of personal
experiences (e.g., in family relationships [18]) through
smell, our findings support research to support people who
are living with memory loss (e.g., patients with dementia
[32]), where smell can play an important role in
remembering the past. An increasing body of research also
explores the potential of digital technologies to support our
memory in everyday tasks (e.g., reminder systems), to
recall past events and experiences (e.g., life-logging tools),
to design end-of-life technologies allowing reminiscence of
passed away people [21], and to record and reproduce
smells [35]. All this research shows the potential of smell to
enrich experiences, for instance by enhancing personal
memories such as photos or videos with smell. Based on
their study of a smell-based photo-tagging system, Brewster
et al. [5] stated that participants asked for personal smells to
be added. The information on how to classify such smells
was still missing; the present analysis allows us to relate
smell qualities to particular types of experiences.
When designing with smell, as for any memory-based
technology, access to such memories has to be considered
carefully to preserve their uniqueness. One participant
wrote: “I could see it being desirable in that it would allow
me to experience the scent whenever I want, but it’s kind of
a two edged sword in that experiencing that scent time and
time again will make it common place” [#513]. The power
of smell might not persist if always available, thus
participants suggested to either restrict the access and
retrieval of smells to special times (e.g., at ‘grandmas
birthday’) or to link them to a certain social setting (e.g.,
smelling only in company with ‘your sister’). This way the
uniqueness of the smell can be preserved.
Second, the stories in Categories 3 to 8 as well as 10 draw
the attention away from past memories and suggest design
opportunities for the present moment. Designing for in-situ
stimulation, the ability to capture and share smells in the
moment, and the capability to mask and neutralize bad
smells creates a vast space for smell interaction design. One
suggestion made by participants was the combination of
smell and social media, such as “An app that would allow
me to store smells, send smells, or attach smells to a picture
that I could post on social media or Instagram or
something”. This supports existing research on the delivery
of smells through the Internet [24]. We draw attention to
three additional design directions concerned with (1) first
time experiences with smell, (2) the power of smell to build
up expectations, and (3) the potential of designing for bad
smells. User experience designers put a lot of effort into
designing ‘out-of-the-box’ and first time experiences to
create positive experiences [13]. Our categorization not
only provides designers with rich descriptions of such first
time experiences, but also describes the related qualities of
smells in combination with descriptors of the experienced
emotions. This can be used to stimulate positive smellenhanced
experiences with technology, build up
expectations, and create anticipation as studied within
experience research [33]. Typically this anticipation stage is
influenced by a variety of aspects (e.g., advertisements,
product descriptions, accounts from existing customers).
Smell stories in Category 10 provide evidence for the
power of smell to build up expectations, create surprise by
exceeding anticipated experiences, and enhance momentary
experiences through capturing and sharing pleasant smells.
Categories 6 to 8 contain stories about bad smells, which
are wished to be neutralized or masked to change the
experience from something negative to something positive.
While the idea of outbalancing smells seems to be
desirable, the design brainstorming session stimulated a
discussion on the usage of bad smell in design, particularly
as part of the design idea (3) Reminder alert with smell.
Designing for bad smells might not seem appropriate at
first, but through intensity manipulation it can open up an
interesting space for design. Similar to a snooze function,
which slowly increases volume, smell stimulations could be
added to certain events (e.g., reminder for mother’s
birthday). Starting with a pleasant smell, it could turn
slowly into something unpleasant if you did not act.
Category 8 also contained stories recounting social
experiences with smell, where the smell of a person or of
other people caused embarrassment or discomfort. Despite
the importance and frequency of social contact in everyday
life, few such stories were shared. They might not seem
meaningful enough to be memorable or to be shared. Yet,
this set of stories holds potential for personal and social
smell-enhanced awareness systems, as well as for wearable
technologies, and smart fabrics. Technology could, as stated
by a participant, “…make the people in those settings feel
more comfortable if I interact with them… My holding my
nose could be insulting and impede communication.”
Third, the smell stories in Category 9 suggest design
opportunities reaching out to the future through positive
stimulation, with potential relevance for wellbeing and
behavior change research in HCI. The stories shared in this
category were about the power of smell to regulate mood,
change attitudes, and behavior. Designing for smell could
be combined with behavior change research in HCI (e.g.,
tools to support healthy nutrition and diet), and thought of
in relation to positive psychology and research on
wellbeing. Seligman and Csikszentmihalyi [28] suggested
that happiness can be learned and cultivated and that
positive psychology can help change how a person feels.
They point to the power of positive emotions for our health,
happiness and wholeness. We would suggest that our
findings add an understanding of the positive emotional
impact of smells that might be a valuable research strategy
in wellbeing research (e.g., for regulating mood).
Smell can have a regulating impact on a person’s mood and can, as in
one case explicitly reported, be used to regulate mood
(‘White Lilac Sheets’). The participant wrote, “I guess the
experience could have been enhanced by some kind of
mood moderator. Something that would have sensed my
sadness and filled the room or house with comforting
scents” [#526]. The participant pointed out that technology
would not change the situation to something more positive,
as it just was not a happy time at all, but that it could
support the sad moments in this transitional period of life.
Limitations
We would like to acknowledge three limitations of this
work. First, by using Amazon Mechanical Turk for
recruiting and asking participants to describe personal
relevant experiences, we were limited to the US and do not
know to what extent the smell stories are representative of
more general experiences with smell. We are aware about
cultural and geographical differences (as described by Seo
et al. [29]), which require further studies with a more
diverse group of participants. Second, collecting narratives
by means of an online questionnaire has an influence on
how people narrate their experience and deprives us of the
advantages of an interview situation where we can engage
in a dialogue with the participant to explore the meaning
behind the shared experience in more depth as described by
Bruner [6]. We tried to collect information beyond the
initial trigger of the shared smell stories in order to allow
the establishment of meaningful categorizations and the
creation of a basic understanding of experiences with smell
in HCI.
Third, our approach provides an overview on the
emerging field of smell-enhanced technologies. Future
studies will, we hope, lead to in-depth research into
experiences with smell inspired by our identified categories.
CONCLUSIONS
Despite interactive technologies increasingly disappearing
into our environment (in ubiquitous and mobile computing)
and becoming essential in everyday life, the senses used to
interact with technology are still limited.
We have discussed the opportunities for smell in HCI based on an
analysis of 439 smell stories. We identified 10 primary
categories for stories about experiences with smell, which
help discuss the potential implications for technology.
Implications were drawn from feedback from our
participants envisaging desired connections between their
own personal experience and future smell technology. The
implications for designing for smell were further enriched
through ideas from an initial brainstorming session with
HCI researchers. Our findings provide guidance for smell
enhanced technology design, not only giving a
categorization of the role of smell in personal experiences,
but also extracting the qualities of smell across the smell
stories and the experienced emotions. We argue that this
research enriches existing technology driven research on
smell in HCI and provides a fruitful starting point when
designing for experiences with smell.
ACKNOWLEDGMENTS
This work is supported by the Marie Curie IEF Action of
the European Union (FP7-PEOPLE-2010-IEF) and the
Swiss National Science Foundation (PBBSP1 144196). We
thank our participants and especially Annika Haas for her
valuable support in designing the supplementary material.
REFERENCES
1. Alaoui-Ismaïli, O., Robin, O., Rada, H., Dittmar, A.,
Vernet-Maury, E. Basic Emotions Evoked by Odorants:
Comparison Between Autonomic Responses and Self-
Evaluation. Physiology & Beh. 62, 4 (1997), 713–720.
2. Bakalar, N. Sensory science: Partners in flavour. Nature
486, 7403 (2012), S4–S5.
3. Baumeister, R.F., Newman, L.S. How Stories Make
Sense of Personal Experiences: Motives that Shape
Autobiographical Narratives. Personality and Social
Psychology Bulletin 20, 6 (1994), 676–690.
4. Bodnar, A., Corbett, R., Nekrasovski, D. AROMA:
ambient awareness through olfaction in a messaging
application. Proc. ICMI, (2004), 183–190.
5. Brewster, S., McGookin, D., Miller, C. Olfoto:
designing a smell-based interaction. Proc. CHI (2006),
653–662.
6. Bruner, J. Life as narrative. Social Research: An
International Quarterly 71, 3 (2004), 691–710.
7. Chrea, C., Grandjean, D., Delplanque, S., Cayeux, I., Le
Calvé, B., Aymard, L., Velazco, MI., Sander, D.,
Scherer, KR. Mapping the Semantic Space for the
Subjective Experience of Emotional Responses to
Odors. Chem. Senses 34, 1 (2009), 49–62.
8. Ehrlichman, H., Bastone, L. The use of odour in the
study of emotion. In S. Van and G.H. Dodd, (Eds.),
Fragrance: The psychology and biology of perfume.
Elsevier, (1992), 143–159.
9. Emsenhuber, B. Scent Marketing: Making Olfactory
Advertising Pervasive. In J. Müller, F. Alt and D.
Michelis (Eds.), Pervasive Advertising. Springer,
(2011), 343–360.
10. Erickson, T. Design as storytelling. Interactions 3, 4
(1996), 30–35.
11. Faste, H., Rachmel, N., Essary, R., Sheehan, E.
Brainstorm, Chainstorm, Cheatstorm, Tweetstorm: new
ideation strategies for distributed HCI design. Proc. CHI
(2013), 1343–1352.
12. Fleiss, J.L., Levin, B., Paik, M.C. Statistical Methods
for Rates and Proportions. John Wiley & Sons, (2013).
13. Ghinea, G., Ademoye, O. The sweet smell of success:
Enhancing multimedia applications with olfaction.
TOMCCAP 8, 1 (2012), 2.
14. Hassenzahl, M. Experience Design: Technology for All
the Right Reasons. Syn. Lect. on HCI 3, 1 (2010), 1–95.
15. Herz, R.S., Engen, T. Odor memory: review and
analysis. Psy. Bulletin & Review. 3, 3 (1996), 300–313.
16. Jonsson, F., Verhagen, H. Senses working overtime: on
sensuous experiences and public computer game play.
Proc. ACE (2011), 56:1–56:8.
17. Kaye, J. “Jofish.” Making Scents: aromatic output for
HCI. Interactions 11, 1 (2004), 48–61.
18. Kazakos, K., Howard, S., Vetere, F. Revisiting the
relationship between reunion and technology-mediated
separation in periodically transitioning families. Proc.
CSCW (2013), 1157–1168.
19. Loumakis, F., Stumpf, S., Grayson, D. This image
smells good: effects of image information scent in
search engine results pages. CIKM (2011), 475–484.
20. Mason, W., Suri, S. Conducting behavioral research on
Amazon’s Mechanical Turk. Behavior Research
Methods 44, 1 (2012), 1–23.
21. Massimi, M., Moncur, W., Odom, W., Banks, R., Kirk,
D. Memento mori: technology design for the end of life.
Proc. CHI EA (2012), 2759–2762.
22. Matsukura, H., Yoneda, T., Ishida, H. Smelling Screen:
Development and Evaluation of an Olfactory Display
System for Presenting a Virtual Odor Source. IEEE
TVCG 19, 4 (2013), 606–615.
23. Petitmengin, C. Describing one’s subjective experience
in the second person: An interview method for the
science of consciousness. Phenomenology and the
Cognitive Sciences 5, 3-4 (2006), 229–269.
24. Ranasinghe, N., Karunanayaka, K., Cheok, A.D.,
Fernando, O.N.N., Nii, H., Gopalakrishnakone, P.
Digital taste and smell communication. Proc. BodyNets,
(2011), 78–84.
25. Saldana, J. The Coding Manual for Qualitative
Researchers. SAGE (2012).
26. Scherer, K.R. Appraisal considered as a process of
multilevel sequential checking. Appraisal processes in
emotion: Theory, methods, research 92, (2001), 120.
27. Scherer, K.R. What are emotions? And how can they be
measured? Social Science Inf. 44, 4 (2005), 695–729.
28. Seligman, M.E.P., Csikszentmihalyi, M. Positive
psychology: An intro. Am. Psy. 55, 1(2000), 5–14.
29. Seo, H.-S., Guarneros, M., Hudson, R., et al. Attitudes
toward Olfaction: A Cross-regional Study. Chem.
Senses 36, 2 (2011), 177–187.
30. Suddendorf, T., Corballis, M.C. The evolution of
foresight: What is mental time travel, and is it unique to
humans? Beh. & Brain Sciences 30, 3 (2007), 299–313.
31. Tuch, A.N., Trusell, R., Hornbæk, K. Analyzing users’
narratives to understand experience with interactive
products. Proc. CHI (2013), 2079–2088.
32. Wallace, J., Wright, P.C., McCarthy, J., Green, D.P.,
Thomas, J., Olivier, P. A design-led inquiry into
personhood in dementia. Proc. CHI (2013), 2617–2626.
33. Willander, J., Larsson, M. Smell your way back to
childhood: Autobiographical odor memory. Psy.
Bulletin & Review 13, 2 (2006), 240–244.
34. Wright, P., McCarthy, J. Experience-Centered Design:
Designers, Users, and Communities in Dialogue. Syn.
Lect. on HCI 3, 1 (2010), 1–123.
35. Wyszynski, B., Yamanaka, T., Nakamoto, T. Recording
and reproducing citrus flavors using odor recorder.
Sensors&Actuators B: Chemical 106, 1(2005), 388–393.
