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As Light as Your Scent: Effects of Smell and Sound on Body Image Perception
Abstract
How people mentally represent their body appearance (i.e., body image perception - BIP) does not always match their actual body. BIP distortions can lead to a detriment in physical and emotional health. Recent works in HCI have shown that technology can be used to change people’s BIP through visual, tactile, proprioceptive, and auditory stimulation. This paper investigates, for the first time, the effect of olfactory stimuli, by looking at a possible enhancement of a known auditory effect on BIP. We present two studies building on emerging knowledge in the field of crossmodal correspondences. First, we explored the correspondences between scents and body shapes. Then, we investigated the impact of combined scents and sounds on one’s own BIP. Our results show that scent stimuli can be used to make participants feel lighter or heavier (i.e., using lemon or vanilla) and to enhance the effect of sound on perceived body lightness. We discuss how these findings can inform future research and design directions to overcome body misperception and create novel augmented and embodied experiences.
... This study contributes empirical knowledge to research on sonification for body perception (e.g. [19,27,50,122,128]) by formally addressing the role of individual differences. Two additional contributions are: the user evaluation of the SoniWeight Shoes' prototype [35] that, with its technical improvements, now is digital, more portable and lighter than [122]; and a methodological novelty in the use of quantitative body maps [141] as a tool for HCI research. ...
... 3.3.1 Apparatus and Materials. We used SoniWeight Shoes, a realtime footstep sound modification system adapted from related studies [19,27,122,123,128]. This version prioritizes portability and ergonomics for enhanced comfort, reduced data loss and extended walking distances. ...
... Described in detail in [35] and in Supplementary Material, the system comprises strap sandals with attached microphones (Core Sound) for capturing footstep sounds. Unlike earlier versions [19,27,122,123,128], our system incorporates a DSP electronic board (Bela.io) to amplify and modify the sound spectrum. Three sound feedback conditions were created, namely "High Frequency" (HF), amplifying 1-4 kHz components and attenuating 83-250 Hz by 12 dB; "Low Frequency" (LF), amplifying 83-250 Hz and attenuating above 1 kHz by 12 dB; and "Control" (C), maintaining natural footsteps equally amplified across frequency bands, i.e., with flat frequency response. ...
Changes in body perception influence behavior and emotion and can be induced through multisensory feedback. Auditory feedback to one's actions can trigger such alterations; however, it is unclear which individual factors modulate these effects. We employ and evaluate SoniWeight Shoes, a wearable device based on literature for altering one's weight perception through manipulated footstep sounds. In a healthy population sample across a spectrum of individuals (n=84) with varying degrees of eating disorder symptomatology, physical activity levels, body concerns, and mental imagery capacities, we explore the effects of three sound conditions (low-frequency, high-frequency and control) on extensive body perception measures (demographic, behavioral, physiological, psychological, and subjective). Analyses revealed an impact of individual differences in each of these dimensions. Besides replicating previous findings, we reveal and highlight the role of individual differences in body perception, offering avenues for personalized sonification strategies. Datasets, technical refinements, and novel body map quantification tools are provided.
... The results show that some scents are associated to temperature but that there is a cultural variation in those associations, arguing against their universality. Brianza et al. [10] used VAS to explore associations between three scents and "hot" and "cold" words visually displayed as anchors. However, no significant results were found. ...
... Smell and Bodily Features. Recently, it has been shown that the perception of our own body can be influenced by smell [10,60], which becomes increasingly relevant in the wider context of wearable design [7,22,57]. From prior work, we have selected two relevant features that explore the relationship between smell and the body: body silhouettes (i.e., 2D body silhouettes, thin-thick) and gender (i.e., masculinity-femininity). ...
... Body Silhouettes. Brianza et al. [10] have studied the concept of body image perception (BIP) through the VAS paradigm by exploring CCs between lemon and vanilla scents and 2D body silhouettes as a visual representation of different body types. They found associations between lemon scent and thin body silhouettes and between vanilla scent and thick body silhouettes. ...
It has long been known that our sense of smell is a powerful one that affects emotions and behaviors. Recently, interest in the sense of smell has been growing exponentially in HCI. However, the potential of smell to inspire design is still underexplored. In this paper, we first investigated crossmodal correspondences between scents and selected features relevant for design (clustered in sensory, bodily, and qualitative features). Then, we created a set of cards (EssCards) to visually summarize the key findings to inspire designers. We carried out two preliminary design exploration sessions using the EssCards. Based on our findings, we discuss how to inspire and challenge design opportunities around the sense of smell and reflect upon applications for smell as inspirational material for designing future interactions and experiences.
... lemon is high-pitch) [18]. This classification moves us closer to some of the recent explorations of scent stimuli in the context of crossmodal associations [9]. Other approaches include scent classifications via chemical receptors and neural structures, and also via cognitive association [15,65,91,92,106]. ...
... 'best guesses') of scent in application designs (e.g. scent-visual associations for driving-relevant notifications [82], body image perception influenced by scent-sound associations [9]). As stated at the beginning, each of the four key factors are interrelated. ...
The human sense of smell is powerful. However, the way we use smell as an interaction modality in human–computer interaction (HCI) is limited. We lack a common reference point to guide designers’ choices when using smell. Here, we map out an olfactory design space to provide designers with such guidance. We identified four key design features: (i) chemical, (ii) emotional, (iii) spatial, and (iv) temporal. Each feature defines a building block for smell-based interaction design and is grounded in a review of the relevant scientific literature. We then demonstrate the design opportunities in three application cases. Each application (i.e., one desktop, two virtual reality implementations) highlights the design choices alongside the implementation and evaluation possibilities in using smell. We conclude by discussing how identifying those design features facilitates a healthy growth of this research domain and contributes to an intermediate-level knowledge space. Finally, we discuss further challenges the HCI community needs to tackle.
... On the other hand, smell also plays a crucial role in social interactions, aiding in identifying family members and loved ones, and infuencing empathetic responses [74,79,93]. Smells can even afect how we see our own body image, increase physical performance, and promote efcient cognitive functions [16,17,106]. Smell aids spatial navigation, allowing humans to orient themselves and track odours like dogs (despite the dominance of sight and hearing) [56,89]. ...
... Advances in immersive environments such as virtual reality (VR) and wearable devices have developed kinship interfaces involving scent, temperature, and smell to reshape multi-sensory experiences. Odor stimuli can influence the perception of body lightness or heaviness [44], while temperature perception can promote social proximity concepts and influence human behavior [45]. Likewise, the sense of taste plays a crucial role in our understanding of the consumption process and reflects emotional states. ...
This study presents a comprehensive literature review on the convergence of affective computing, interactive installation art, multi-dimensional sensory stimulation, and artificial intelligence (AI) in measuring emotional responses, demonstrating the potential of artificial intelligence in emotion recognition as a tool for sustainable development. It addresses the problem of understanding emotional response and measurement in the context of interactive installation art under artificial intelligence (AI), emphasizing sustainability as a key factor. The study aims to fill the existing research gaps by examining three key aspects: sensory stimulation, multi-dimensional interactions, and engagement, which have been identified as significant contributors to profound emotional responses in interactive installation art. The proposed approach involves conducting a process analysis of emotional responses to interactive installation art, aiming to develop a conceptual framework that explores the variables influencing emotional responses. This study formulates hypotheses that make specific predictions about the relationships between sensory stimulation, multi-dimensional interactions, engagement, and emotional responses. By employing the ASSURE model combined with experimental design, the research methodology ensures a systematic and comprehensive study implementation. The implications of this project lie in advancing the understanding of emotional experiences in interactive installation art under AI, providing insights into the underlying mechanisms that drive these experiences, and their influence on individual well-being from a sustainable perspective. The contributions of this research include bridging the identified research gaps, refining theoretical frameworks, and guiding the design of more impactful and emotionally resonant interactive artworks with sustainability in mind. This research seeks not only to fill the existing gaps in understanding emotional experiences in interactive installation art, but also to guide the development of immersive and emotionally engaging installations, ultimately advancing the broader field of human–computer interaction, promoting individual well-being, and contribute to sustainable development.
... Recent studies have demonstrated the effectiveness of such an approach in motivating physical activity in physically inactive people, or in rehabilitation in people with chronic conditions [31,49,50,[84][85][86]. Haptic feedback has also been explored in this context, for instance, a force illusion that creates the illusion of limbs drifting and favours a movement reflex [73] or haptic metaphors combined with textiles to alter body perceptions [88]. Even olfactory cues have been shown to influence body perception both in VR ( [70,71]) and in combination with auditory cues ( [11]). ...
Body perception transformation technologies augment or alter our own body perception outside of our usual bodily experience. As emerging technologies, research on these technologies is limited to proofs-of-concept and lab studies. Consequently, their potential impact on the way we perceive and experience our bodies in everyday contexts is not yet well understood. Through a speculative design inquiry, our multidisciplinary team envisioned utopian and dystopian technology visions. We surfaced potential roles, goals and values that current and future body perception transformation technologies could incorporate, including non-utilitarian purposes. We contribute insights on such roles, goals and values to inspire current and future work. We also present three provocations to stimulate discussions. Finally, we contribute methodologically with insights into the value of speculative design as a fruitful approach for articulating and bridging diverse perspectives in multidisciplinary teams.
... To study this, most research has relied on a/synchrony between signals from different combinations of sensory modalities (Aspell et al., 2013;Ehrsson et al., 2005;Macauda et al., 2014;Tajadura-Jiménez et al., 2012;Tsakiris et al., 2006), however the contribution of bodily smells to illusory embodiment has, to our knowledge, not been addressed. Recent studies showed that (a) visuo-olfactory congruent cues increase embodiment of an arbitrary object (a grapefruit) seen in the position of the own body , and (b) the feeling of bodily lightness/heaviness was modulated by a concurrent scent (Brianza et al., 2019), thereby suggesting that prior associations of odors might influence bodily self-consciousness. ...
Conflicting multisensory signals may alter embodiment to produce self-identification with a foreign body, but the role of olfaction in this process has been overlooked. We studied in healthy participants how sex (male and female sweat odors) and gender (male and female cosmetic scents) olfactory stimuli contribute to embodiment. Participants saw, on a head mounted display, the first-person perspective of a sex mismatching person. Synchronous visuotactile stimulation was applied to enhance illusory embodiment. Simultaneously, they smelled either sex- or gender- congruent or incongruent stimuli. We assessed implicit (skin conductance responses to visual threats) and explicit (questionnaire) measures of embodiment. Stronger responses to threat were found when participants smelled the sex-congruent compared to the sex-incongruent odor, while no such differences were found for the cosmetic scents. According to the questionnaire, embodiment did not differ between conditions. Post-experimental assessment of the presented cues, suggest that while both sweat odors were considered generally male, cosmetic scents were not. The presented scents were generally not associated to the embodied body. Our results suggest that sex-related body odors influence implicit but not explicit aspects of embodiment and are in line with unique characteristics of olfaction in other aspects of cognition.
... There is also an emerging literature on the possibility of modifying body image by means of olfactory cues in the context of one's virtual reality (VR) avatar (see Brianza et al., 2019). The latter researchers used a computerbased body visualization tool following one minute of walking in VR, with the scents being sprayed three times during that period. ...
In recent decades, there has been an explosion of research into the crossmodal influence of olfactory cues on multisensory person perception. Numerous peer-reviewed studies have documented that a variety of olfactory stimuli, from ambient malodours through to fine fragrances, and even a range of chemosensory body odours can influence everything from a perceiver’s judgments of another person’s attractiveness, age, affect, health/disease status, and even elements of their personality. The crossmodal and multisensory contributions to such effects are reviewed and the limitations/peculiarities of the research that have been published to date are highlighted. At the same time, however, it is important to note that the presence of scent (and/or the absence of malodour) can also influence people’s (i.e., a perceiver’s) self-confidence which may, in turn, affect how attractive they appear to others. Several potential cognitive mechanisms have been put forward to try and explain such crossmodal/multisensory influences, and some of the neural substrates underpinning these effects have now been characterized. At the end of this narrative review, a number of the potential (and actual) applications for, and implications of, such crossmodal/multisensory phenomena involving olfaction are outlined briefly.
... [11]) and haptic and visual bodily feedback (e.g. [7]), smell stimuli [4], taste and texture stimuli [8] have been used to enhance experiences of the body and how we interact with the environment. Multisensory feedback has a role in exploring body perception and presentation [6], facilitate everyday function, foster coping capabilities, restore distorted body perceptions (e.g. ...
The emerging possibilities of multisensory interactions provide an exciting space for disability and open up opportunities to explore new experiences for perceiving one's own body, it's interactions with the environment and also to explore the environment itself. In addition, dynamic aspects of living with disability, life transitions, including ageing, psychological distress, long-term conditions such as chronic pain and new conditions such as long-COVID further affect people's abilities. Interactions with this diversity of embodiments can be enriched, empowered and augmented through using multisensory and cross-sensory modalities to create more inclusive technologies and experiences. To explore this, in this workshop we will explore three related sub-domains: immersive multi-sensory experiences, embodied experiences, and disability interactions and design. The aim is to better understand how we can re-think the senses in technology design for disability interactions and the dynamic self, constructed through continuously changing sensing capabilities either because of changing ability or because of the empowering technology. This workshop will: (i) bring together HCI researchers from different areas, (ii) discuss tools, frameworks and methods, and (iii) form a multidisciplinary community to build synergies for further collaboration.
... We are seeing initial efforts, sometimes from an artistic design perspective, to explore smell-based emotionally responsive wearable technology. For example, smell has been shown to influence how we feel about ourselves (Tillotson, 2017;Amores et al., 2018), affect our body image perception (BIP) (Brianza et al., 2019) and support sleep and dreaming (Carr et al., 2020). More opportunities around smell can be studied with respect to human sensory perception and integration due to these ongoing technological advances. ...
Multisensory integration research has allowed us to better understand how humans integrate sensory information to produce a unitary experience of the external world. However, this field is often challenged by the limited ability to deliver and control sensory stimuli, especially when going beyond audio–visual events and outside laboratory settings. In this review, we examine the scope and challenges of new technology in the study of multisensory integration in a world that is increasingly characterized as a fusion of physical and digital/virtual events. We discuss multisensory integration research through the lens of novel multisensory technologies and, thus, bring research in human–computer interaction, experimental psychology, and neuroscience closer together. Today, for instance, displays have become volumetric so that visual content is no longer limited to 2D screens, new haptic devices enable tactile stimulation without physical contact, olfactory interfaces provide users with smells precisely synchronized with events in virtual environments, and novel gustatory interfaces enable taste perception through levitating stimuli. These technological advances offer new ways to control and deliver sensory stimulation for multisensory integration research beyond traditional laboratory settings and open up new experimentations in naturally occurring events in everyday life experiences. Our review then summarizes these multisensory technologies and discusses initial insights to introduce a bridge between the disciplines in order to advance the study of multisensory integration.
... This result suggests that the auditory feedback of an action can recalibrate the mental representation of one's own arm length. In that line, additional research explored the impact of smell combined with sound on the body perception, and found that scent stimuli had an impact of participants own weight perception and enhance the effect of sound of the perceived body lightness [Brianza et al. 2019]. While those last works were not conducted in VR, they open up a wide range of questions regarding the potential influence of auditory feedback on the way we perceive avatars, and reinvigorate the interest in exploring the influence of auditory cues on the SoE. ...
The term "avatar" refers to the representation of users in a virtual world, in the case where they are immersed in Virtual Reality with a Head-Mounted Display and therefore cannot see their own body. Avatars have now become a major requirement in immersive virtual reality applications, increasing the need to better understand and identify the factors that influence users’ sense of embodiment towards their avatar. In this thesis, we defined three axes of research to explore the influence of several factors on the sense of embodiment, based on a categorization that did not only consider factors related to the avatar, but also factors related to the virtual environment and the user. In the first part, we have studied the influence of shared virtual environments on the sense of embodiment, in a study where users performed a task together in the same virtual environment, and in another experiment in which users even shared the control of the same avatar. In a second part, we explored interrelations within avatar-related factors influencing the sense of embodiment, using a new methodological approach with a subjective matching technique. Finally, in a third part, we investigated the influence of users’ individual differences on the sense of embodiment.
... BIP refers to "perceptions, attitudes and beliefs pertaining to one's own body" [49], comprising emotional attitudes towards it. For instance, Brianza et al., [16] found that lemon scent is significantly associated with a thin body while vanilla with a thick body. They also showed subjective reports of feeling lighter when smelling lemon and heavier when smelling vanilla. ...
The Sense of Agency (SoA) is crucial in interaction with technology, it refers to the feeling of 'I did that' as opposed to 'the system did that' supporting a feeling of being in control. Research in human-computer interaction has recently studied agency in visual, auditory and haptic interfaces, however the role of smell on agency remains unknown. Our sense of smell is quite powerful to elicit emotions, memories and awareness of the environment, which has been exploited to enhance user experiences (e.g., in VR and driving scenarios). In light of increased interest in designing multimodal interfaces including smell and its close link with emotions, we investigated, for the first time, the effect of smell-induced emotions on the SoA. We conducted a study using the Intentional Binding (IB) paradigm used to measure SoA while participants were exposed to three scents with different valence (pleasant, unpleasant, neutral). Our results show that participants? SoA increased with a pleasant scent compared to neutral and unpleasant scents. We discuss how our results can inform the design of multimodal and future olfactory interfaces.
Wearables integrating movement sonification can support body-perception changes and relatedly physical activity; yet, we lack design principles for such sonifications. Through two mixed-methods studies, we investigate sound pitch and movement direction interaction effects on self-perception during squats exercises. We measured effects on body-perception, affective quality of the experience, actual and perceived movement, and compared them to two control conditions: no-sound and vibrotactile feedback. Results show that regardless of movement direction, ascending pitch enhances several body feelings and overall experience quality, while descending pitch increases movement acceleration. These effects were moderated by exercise physical demand. Sound and vibrotactile feedback enhanced flexibility and strength feelings respectively and contributed to exercise completion in different ways. Sound was perceived as an internal-to-body force while vibrotactile feedback as an external-to-body force. Feedback effects were stronger in people with lower fitness levels. We discuss results in terms of malleability of body-perceptions and highlight opportunities to support demanding physical activity through wearable devices.
Many technologies for promoting physical activity (PA) give limited importance to critical variables for engagement in PA, such as negative body perceptions. Here, we aim to address this gap by incorporating barriers and experienced body sensations into the design process for wearables and body-based devices thus expanding the design space for such technologies. We first report four co-design workshops with physically inactive participants (n=9); in these workshops, we explored tangible tools (i) to sensitize people to body sensations experienced when facing barriers to PA and (ii) to ideate how haptic and auditory feedback could transform body sensations to increase body-awareness and engagement in PA; results show several interactive sensorial patterns with potential to inform the design of body transformation wearables. These were validated through a follow-up workshop (n=13 participants) and reflections based on insights from a literature review. Our findings are significant for the design of ubiquitous technology to support and initiate PA in everyday contexts through a novel approach of transforming body perceptions/ sensations related to PA barriers. We contribute design inspirations and cards for identifying barriers to PA and to empower designers and researchers to integrate them early in the design process.
Ultrasonic mid-air haptic technology allows for the perceptual rendering of textured surfaces onto the user's hand. Unlike real textured surfaces, however, mid-air haptic feedback lacks implicit multisensory cues needed to reliably infer a texture's attributes (e.g., its roughness). In this paper, we combined mid-air haptic textures with congruent sound feedback to investigate how sonification could influence people's (1) explicit judgment of the texture attributes, (2) explicit sensations of their own hand, and (3) implicit motor behavior during haptic exploration. Our results showed that audio cues (presented solely or combined with haptics) influenced participants' judgment of the texture attributes (roughness, hardness, moisture and viscosity), produced some hand sensations (the feeling of having a hand smoother, softer, looser, more flexible, colder, wetter and more natural), and changed participants' speed (moving faster or slower) while exploring the texture. We then conducted a principal component analysis to better understand and visualize the found results and conclude with a short discussion on how audio-haptic associations can be used to create embodied experiences in emerging application scenarios in the metaverse.
Recent interest in design through the artificial intelligence (AI) lens is rapidly increasing. Designers, as a special user group interacting with AI, have received more attention in the Human-Computer Interaction community. Prior work has discussed emerging challenges that persist in designing for AI. However, few systematic reviews focus on AI for design to understand how designers and AI can augment each other's complementary strengths in design collaboration. In this work, we conducted a landscape analysis of AI for design, via a systematic literature review of 93 papers. The analysis first provides a bird's eye view of overall patterns in this area. The analysis also reveals three themes interpreted from the paper corpus associated with AI for design, including AI assisting designers, designers assisting AI, and characterizing designer-AI collaboration. We discuss the implications of our findings and suggested methodological proposals to guide HCI toward research and practices that center on collaborative creativity.
As technology develops to allow for the integration of additional senses into interactive experiences, there is a need to bridge the divide between the real and the virtual in a manner that stimulates the five senses consistently and in harmony with the sensory expectations of the user. Applying the philosophy of a neurological condition known as synaesthesia and crossmodal correspondences, defined as the coupling of the senses, can provide numerous cognitive benefits and offers an insight into which senses are most likely to be ‘bound’ together.
This thesis aims to present a design paradigm called ‘virtual synaesthesia’ the goal of the paradigm is to make multisensory experiences more human-orientated by considering how the brain combines senses in both the general population (crossmodal correspondences) and within a select few individuals (natural synaesthesia). Towards this aim, a literature review is conducted covering the related areas of research umbrellaed by the concept of ‘virtual synaesthesia’. Its research areas are natural synaesthesia, crossmodal correspondences, multisensory experiences, and sensory substitution/augmentation. This thesis examines augmenting interactive and multisensory experiences with strong (natural synaesthesia) and weak (crossmodal correspondences) synaesthesia. This thesis answers the following research questions: Is it possible to replicate the underlying cognitive benefits of odour-vision synaesthesia? Do people have consistent correspondences between olfaction and an aggregate of different sensory modalities? What is the nature and origin of these correspondences? And Is it possible to predict the crossmodal correspondences attributed to odours? The benefits of augmenting a human-machine interface using an artificial form of odour-vision synaesthesia are explored to answer these questions. This concept is exemplified by transforming odours transduced using a custom-made electronic nose and transforming an odour's ‘chemical footprint’ into a 2D abstract shape representing the current odour. Electronic noses can transform odours in the vapour phase generating a series of electrical signals that represent the current odour source. Weak synaesthesia (crossmodal correspondences) is then investigated to determine if people have consistent correspondences between odours and the angularity of shapes, the smoothness of texture, perceived pleasantness, pitch, musical, and emotional dimensions. Following on from this research, the nature and origin of these correspondences were explored using the underlying hedonic (values relating to pleasantness), semantic (knowledge of the identity of the odour) and physicochemical (the physical and chemical characteristics of the odour) dependencies. The final research chapter investigates the possibility of removing the bottleneck of conducting extensive human trials by determining what the crossmodal correspondences towards specific odours are by developing machine learning models to predict the crossmodal perception of odours using their underlying physicochemical features.
The work presented in this thesis provides some insight and evidence of the benefits of incorporating the concept ‘virtual synaesthesia’ into human-machine interfaces and research into the methodology embodied by ‘virtual synaesthesia’, namely crossmodal correspondences. Overall, the work presented in this thesis shows potential for augmenting multisensory experiences with more refined capabilities leading to more enriched experiences, better designs, and a more intuitive way to convey information crossmodally.
Previous studies suggest a stronger influence of visual signals on body image in individuals with eating disorders (EDs) than healthy controls; however, the influence of other exteroceptive sensory signals remains unclear. Here we used an illusion relying on auditory (exteroceptive) signals to manipulate body size/weight perceptions and investigated whether the mechanisms integrating sensory signals into body image are altered in subclinical and clinical EDs. Participants’ footstep sounds were altered to seem produced by lighter or heavier bodies. Across two experiments, we tested healthy women assigned to three groups based on self-reported Symptomatology of EDs (SED), and women with Anorexia Nervosa (AN), and used self-report, body-visualization, and behavioural (gait) measures. As with visual bodily illusions, we predicted stronger influence of auditory signals, leading to an enhanced body-weight illusion, in people with High-SED and AN. Unexpectedly, High-SED and AN participants displayed a gait typical of heavier bodies and a widest/heaviest visualized body in the ‘light’ footsteps condition. In contrast, Low-SED participants showed these patterns in the ‘heavy’ footsteps condition. Self-reports did not show group differences. The results of this pilot study suggest disturbances in the sensory integration mechanisms, rather than purely visually-driven body distortions, in subclinical/clinical EDs, opening opportunities for the development of novel diagnostic/therapeutic tools.
Previous research has shown the influence of smell on emotions, memories, and body image. However, most of this work has taken place in laboratory settings and little is known about the influence of smell in real-world environments. In this paper, we present novel insights gained from a field study investigating the emotional effect of smell on memories and body image. Taking inspiration from the cultural design probes approach, we designed QuintEssence, a probe package that includes three scents and materials to complete three tasks over a period of four weeks. Here, we describe the design of QuintEssence and the main findings based on the outcomes of the three tasks and a final individual interview. The findings show similar results between participants based on the scent. For example, with cinnamon, participants experienced feelings of warmth, coziness, happiness, and relaxation; they recalled blurred memories of past moments about themselves and reported a general feeling of being calm and peaceful towards their bodies. Our findings open up new design spaces for multisensory experiences and inspire future qualitative explorations beyond laboratory boundaries.
Research has shown that conflicting multisensory signals may alter embodiment to the point of self-identifying with a foreign body, but the role of olfaction in this process has been overlooked. Here, we study in healthy participants how sex (male and female sweat odors) and gender (male and female cosmetic scents) olfactory stimuli contribute to embodiment. Participants saw from the perspective of a sex mismatching person in virtual reality and received synchronous visuo-tactile stimulation to elicit illusory embodiment of the seen body while smelling either sex- or gender- congruent stimuli. We assessed implicit (skin conductance responses to visual threats) and explicit (questionnaire) measures of embodiment. Stronger responses to threat were found when participants smelled the sex-congruent compared to the sex-incongruent odor, while no such differences were found for the cosmetic scents. According to the questionnaire, embodiment did not differ between conditions. Post-experimental assessment of the presented cues, suggest that while both sweat odors were considered generally male, cosmetic scents were not. The presented scents were generally not associated to the embodied body. Our results suggest that sex-related body odors influence implicit but not explicit aspects of embodiment and are in line with unique characteristics of olfaction in other aspects of cognition.
Bodily self-identification has shown to be easily altered through spatiotemporally congruent multimodal signals. While such manipulations are mostly studied through visuo-tactile or visuo-motor stimulation, here we investigated whether congruent visuo-olfactory cues might enhance illusory self-identification with an arbitrary object. Using virtual reality, healthy individuals saw a grapefruit from its supposed first-person perspective that was touched in synchrony with their own body. The touch attempted to replicate what was seen as softly squeezing the grapefruit. Crucially, when we additionally presented the smell of a grapefruit in synchrony with the squeezing, they self-identified stronger with the fruit than when they smelled strawberry. The sense of body has been shown to be remarkably plastic, to the point that healthy participants can feel illusory embodiment over notably different bodies than their own (e.g.
When in a stressful situation, access to adult attachment figures (e.g., romantic partners) is an important means by which adults regulate stress responses. The practice of smelling a partner's worn garment is reported as a self-treatment against stress. Here, we experimentally determined whether exposure to a partner's body odor attenuates adults' subjective discomfort and psychophysiological responses, and whether such effects are qualified by adult attachment security. In a blocked design, participants (N = 34) were presented with their partner's body odor, their own body odor, the odor of a clean t-shirt and rose odor, while exposed to weak electric shocks to induce discomfort and stress responses. Results showed that partner body odor reduces subjective discomfort during a stressful event, as compared with the odor of oneself. Also, highly secure participants had attenuated skin conductance when exposed to partner odor. We conclude that partner odor is a scent of security, especially for attachment-secure adults.
When we drop an object from our hands, we use internal models of both our body height and object-motion to predict when it will hit the floor. What happens if the sensory feedback finally received from the impact conflicts with this prediction? The present study shows that such conflict results in changes in the internal estimates of our body height: When the object people dropped takes longer than expected to hit the floor, they report feeling taller and behave as if their legs were longer. This provides the first evidence of cross-modal recalibration of body-height representations as a function of changes in the distant environment. Crucially, the recalibration results from a mismatch between the predicted and actual outcome of an action, the ball’s release and impact, which are causally-related but separated in space and time. These results suggest that implicit models of object-motion can interact with implicit and explicit models of one’s body height.
When designing olfactory interfaces, HCI researchers and practitioners have to carefully consider a number of issues related to the scent delivery, detection, and lingering. These are just a few of the problems to deal with. We present OSpace - an approach for designing, building, and exploring an olfactory interaction space. Our paper is the first to explore in detail not only the scent-delivery parameters but also the air extraction issues. We conducted a user study to demonstrate how the scent detection/lingering times can be acquired under different air extraction conditions, and how the impact of scent type, dilution, and intensity can be investigated. Results show that with our setup, the scents can be perceived by the user within ten seconds and it takes less than nine seconds for the scents to disappear, both when the extraction is on and off. We discuss the practical application of these results for HCI.
We introduce inScent, a wearable olfactory display that can be worn in mobile everyday situations and allows the user to receive personal scented notifications, i.e. scentifications. Olfaction, i.e. the sense of smell, is used by humans as a sensorial information channel as an element for experiencing the environment. Olfactory sensations are closely linked to emotions and memories, but also notify about personal dangers such as fire or foulness. We want to utilize the properties of smell as a notification channel by amplifying received mobile notifications with artificially emitted scents. We built a wearable olfactory display that can be worn as a pendant around the neck and contains up to eight different scent aromas that can be inserted and quickly exchanged via small scent cartridges. Upon emission, scent aroma is vaporized and blown towards the user. A hardware - and software framework is presented that allows developers to add scents to their mobile applications. In a qualitative user study, participants wore the inScent wearable in public. We used subsequent semi-structured interviews and grounded theory to build a common understanding of the experience and derived lessons learned for the use of scentifications in mobile situations.
Many studies have reported that subjective taste intensity is enhanced by odors which are congruent, for example a sweet taste and a vanilla odor. Some reports have suggested that subjective taste is more strongly enhanced by retronasal than by orthonasal odors; others have suggested that taste enhancements by both odor routes are identical. Differences between the two routes include the direction of airflow accompanying breath. Thus, it is possible that the order of gustatory and olfactory stimuli when breathing through either route while drinking is a determining factor for taste-odor integration. To reveal the natural relationship between taste intensity enhancement by odors and breath, synchronization of odor stimulation with the breath is necessary. Here, we examined whether the enhancement of a sweet taste is induced by a vanilla odor presented in various combinations of odor routes, immediately before and immediately after drinking. The results showed that a retronasal odor after drinking enhanced taste, but an orthonasal odor before drinking did not. The retronasal odor before drinking and the orthonasal odor after drinking did not enhance the sweet taste. These results show that congruency with the natural order of stimulus and kinetic sensation is a determining factor for odor-induced taste enhancement.
It is often assumed odors are associated with hot and cold temperature, since odor processing may trigger thermal sensations, such as coolness in the case of mint. It is unknown, however, whether people make consistent temperature associations for a variety of everyday odors, and, if so, what determines them. Previous work investigating the bases of cross-modal associations suggests a number of possibilities, including universal forces (e.g., perception), as well as culture-specific forces (e.g., language and cultural beliefs). In this study, we examined odor-temperature associations in three cultures—Maniq (N = 11), Thai (N = 24), and Dutch (N = 24)—who differ with respect to their cultural preoccupation with odors, their odor lexicons, and their beliefs about the relationship of odors (and odor objects) to temperature. Participants matched 15 odors to temperature by touching cups filled with hot or cold water, and described the odors in their native language. The results showed no consistent associations among the Maniq, and only a handful of consistent associations between odor and temperature among the Thai and Dutch. The consistent associations differed across the two groups, arguing against their universality. Further analysis revealed cross-modal associations could not be explained by language, but could be the result of cultural beliefs.
Neuroscientific studies have shown that human's mental body representations are not fixed but are constantly updated through sensory feedback, including sound feedback. This suggests potential new therapeutic sensory approaches for patients experiencing body-perception disturbances (BPD). BPD can occur in association with chronic pain, for example in Complex Regional Pain Syndrome (CRPS). BPD often impacts on emotional, social, and motor functioning. Here we present the results from a proof-of-principle pilot study investigating the potential value of using sound feedback for altering BPD and its related emotional state and motor behavior in those with CRPS. We build on previous findings that real-time alteration of the sounds produced by walking can alter healthy people's perception of their own body size, while also resulting in more active gait patterns and a more positive emotional state. In the present study we quantified the emotional state, BPD, pain levels and gait of twelve people with CRPS Type 1, who were exposed to real-time alteration of their walking sounds. Results confirm previous reports of the complexity of the BPD linked to CRPS, as participants could be classified into four BPD subgroups according to how they mentally visualize their body. Further, results suggest that sound feedback may affect the perceived size of the CRPS affected limb and the pain experienced, but that the effects may differ according to the type of BPD. Sound feedback affected CRPS descriptors and other bodily feelings and emotions including feelings of emotional dominance, limb detachment, position awareness, attention and negative feelings toward the limb. Gait also varied with sound feedback, affecting the foot contact time with the ground in a way consistent with experienced changes in body weight. Although, findings from this small pilot study should be interpreted with caution, they suggest potential applications for regenerating BDP and its related bodily feelings in a clinical setting for patients with chronic pain and BPD.
Humans have the ability to think in abstract ways. Experiments over the last 90 years have shown that stimuli from the external world can be evaluated on an abstract spectrum with 'Kiki' on one end and 'Bouba' on the other. People are in concordance with each other with respect to calling a jagged-edgy-sharp bordered two dimensional shape 'Kiki' and a curvy-smooth-round two dimensional shape 'Bouba'.. The proclivity of this correspondence is ubiquitous. Moreover, the Kiki-Bouba phenomenon seems to represent a non-arbitrary abstract connection between 2 or more stimuli. Studies have shown that cross-modal associations between and withinaudioception, opthalmoception, tactioception and gustatoception can be demonstrated by using Kiki-Bouba as a cognitive 'convergence point'. This review includes a critical assessment of the methods, findings, limitations, plausible explanations and future directions involving the Kiki-Bouba effect. Applications include creatingtreatments and training methods to compensate for poor abstract thinking abilities caused by disorders like schizophrenia and autism, for example. Continuing research in this area would help building a universal model of consciousness that fully incorporates cross-sensory perception at the biological and cognitive levels.
In today's Western society, concerns regarding body size and negative feelings toward one's body are all too common. However, little is known about the neural mechanisms underlying negative feelings toward the body and how they relate to body perception and eating-disorder pathology. Here, we used multisensory illusions to elicit illusory ownership of obese and slim bodies during functional magnetic resonance imaging. The results implicate the anterior insula and the anterior cingulate cortex in the development of negative feelings toward the body through functional interactions with the posterior parietal cortex, which mediates perceived obesity. Moreover, cingulate neural responses were modulated by nonclinical eating-disorder psychopathology and were attenuated in females. These results reveal how perceptual and affective body representations interact in the human brain and may help explain the neurobiological underpinnings of eating-disorder vulnerability in women.
Background
Patients with anorexia nervosa (AN) have a persistent distorted experience of the size of their body. Previously we found that the Rubber Hand Illusion improves hand size estimation in this group. Here we investigated whether a Full Body Illusion (FBI) affects body size estimation of body parts more emotionally salient than the hand. In the FBI, analogue to the RHI, participants experience ownership over an entire virtual body in VR after synchronous visuo-tactile stimulation of the actual and virtual body.
Methods and Results
We asked participants to estimate their body size (shoulders, abdomen, hips) before the FBI was induced, directly after induction and at ~2 hour 45 minutes follow-up. The results showed that AN patients (N = 30) decrease the overestimation of their shoulders, abdomen and hips directly after the FBI was induced. This effect was strongest for estimates of circumference, and also observed in the asynchronous control condition of the illusion. Moreover, at follow-up, the improvements in body size estimation could still be observed in the AN group. Notably, the HC group (N = 29) also showed changes in body size estimation after the FBI, but the effect showed a different pattern than that of the AN group.
Conclusion
The results lead us to conclude that the disturbed experience of body size in AN is flexible and can be changed, even for highly emotional body parts. As such this study offers novel starting points from which new interventions for body image disturbance in AN can be developed.
International trade, population migration, changes in living conditions (i.e., consumption transition, nutritional transition), and changes in production, marketing, and availability of consumer goods (i.e., production transition) have brought about continuous and rapid changes in the human environment. Such changes have improved the health and economic status of many people in developing countries. At the same time, a parallel phenomenon is occurring: the rapid emergence and expansion of modifiable risk behaviors. These behaviors adversely affect the national health of developing countries and that of future generations because of their impact on maternal, child, and adolescent health. Furthermore, these behaviors are increasing at a faster rate than interventions to curb their growth are being implemented. We discuss the current status of five modifiable risk behaviors--alcohol consumption, tobacco use, overweight and obesity, low fruit and vegetable consumption, and physical inactivity--to emphasize the need for global advocacy and local action to enhance policy formulation and diffusion of interventions necessary to moderate the spread of these behaviors.
The goal of this research was to investigate women's sensitivity to changes in their perceived weight by altering the body mass index (BMI) of the participants' personalized avatars displayed on a large-screen immersive display. We created the personalized avatars with a full-body 3D scanner that records the participants' body geometry and texture. We altered the weight of the personalized avatars to produce changes in BMI while keeping height, arm length, and inseam fixed and exploited the correlation between body geometry and anthropometric measurements encapsulated in a statistical body shape model created from thousands of body scans. In a 2 × 2 psychophysical experiment, we investigated the relative importance of visual cues, namely shape (own shape vs. an average female body shape with equivalent height and BMI to the participant) and texture (own photorealistic texture or checkerboard pattern texture) on the ability to accurately perceive own current body weight (by asking the participant, "Is it the same weight as you?"). Our results indicate that shape (where height and BMI are fixed) had little effect on the perception of body weight. Interestingly, the participants perceived their body weight veridically when they saw their own photo-realistic texture. As compared to avatars with photo-realistic texture, the avatars with checkerboard texture needed to be significantly thinner in order to represent the participants' current weight. This suggests that in general the avatars with checkerboard texture appeared bigger. The range that the participants accepted as their own current weight was approximately a 0.83% to ?6.05% BMI change tolerance range around their perceived weight. Both the shape and the texture had an effect on the reported similarity of the body parts and the whole avatar to the participant's body. This work has implications for new measures for patients with body image disorders, as well as researchers interested in creating personalized avatars for games, training applications, or virtual reality.
Auditory feedback accompanies almost all our actions, but its contribution to body-representation is understudied. Recently it has been shown that the auditory distance of action sounds recalibrates perceived tactile distances on one’s arm, suggesting that action sounds can change the mental representation of arm length. However, the question remains open of what factors play a role in this recalibration. In this study we investigate two of these factors, kinaesthesia, and sense of agency. Across two experiments, we asked participants to tap with their arm on a surface while extending their arm. We manipulated the tapping sounds to originate at double the distance to the tapping locations, as well as their synchrony to the action, which is known to affect feelings of agency over the sounds. Kinaesthetic cues were manipulated by having additional conditions in which participants did not displace their arm but kept tapping either close (Experiment 1) or far (Experiment 2) from their body torso. Results show that both the feelings of agency over the action sounds and kinaesthetic cues signaling arm displacement when displacement of the sound source occurs are necessary to observe changes in perceived tactile distance on the arm. In particular, these cues resulted in the perceived tactile distances on the arm being felt smaller, as compared to distances on a reference location. Moreover, our results provide the first evidence of consciously perceived changes in arm-representation evoked by action sounds and suggest that the observed changes in perceived tactile distance relate to experienced arm elongation. We discuss the observed effects in the context of forward internal models of sensorimotor integration. Our results add to these models by showing that predictions related to action sounds must fit with kinaesthetic cues in order for auditory inputs to change body-representation.
An ever more sedentary lifestyle is a serious problem in our society. Enhancing people's exercise adherence through technology remains an important research challenge. We propose a novel approach for a system supporting walking that draws from basic findings in neuroscience research. Our shoe-based prototype senses a person's footsteps and alters in real-time the frequency spectra of the sound they produce while walking. The resulting sounds are consistent with those produced by either a lighter or heavier body. Our user study showed that modified walking sounds change one's own perceived body weight and lead to a related gait pattern. In particular, augmenting the high frequencies of the sound leads to the perception of having a thinner body and enhances the motivation for physical activity inducing a more dynamic swing and a shorter heel strike. We here discuss the opportunities and the questions our findings open.
Our bodies are the most intimately familiar objects we encounter in our perceptual environment. Virtual reality provides a unique method to allow us to experience having a very different body from our own, thereby providing a valuable method to explore the plasticity of body representation. In this paper, we show that women can experience ownership over a whole virtual body that is considerably smaller or larger than their physical body. In order to gain a better understanding of the mechanisms underlying body ownership, we use an embodiment questionnaire, and introduce two new behavioral response measures: an affordance estimation task (indirect measure of body size) and a body size estimation task (direct measure of body size). Interestingly, after viewing the virtual body from first person perspective, both the affordance and the body size estimation tasks indicate a change in the perception of the size of the participant's experienced body. The change is biased by the size of the virtual body (overweight or underweight). Another novel aspect of our study is that we distinguish between the physical, experienced and virtual bodies, by asking participants to provide affordance and body size estimations for each of the three bodies separately. This methodological point is important for virtual reality experiments investigating body ownership of a virtual body, because it offers a better understanding of which cues (e.g. visual, proprioceptive, memory, or a combination thereof) influence body perception, and whether the impact of these cues can vary between different setups.
Physical activity is important for improving quality of life in people with chronic pain. However, actual or anticipated pain exacerbation, and lack of confidence when doing physical activity, make it difficult to maintain and build towards long-term activity goals. Research guiding the design of interactive technology to motivate and support physical activity in people with chronic pain is lacking. We conducted studies with: (1) people with chronic pain, to understand how they maintained and increased physical activity in daily life and what factors deterred them; and (2) pain-specialist physiotherapists, to understand how they supported people with chronic pain. Building on this understanding, we investigated the use of auditory feedback to address some of the psychological barriers and needs identified and to increase self-efficacy, motivation and confidence in physical activity. We conclude by discussing further design opportunities based on the overall findings.
A fundamental aspect of the "I" of conscious experience is that the self is experienced as a single coherent representation of the entire, spatially situated body. The purpose of the present study was to investigate agency for the entire body. We provided participants with performance-related auditory cues and induced online sensorimotor conflicts in free walking conditions investigating the limits of human consciousness in moving agents. We show that the control of full-body locomotion and the building of a conscious experience of it are at least partially distinct brain processes. The comparable effects on agency using audio-motor and visuo-motor cues as found in the present and previous agency work may reflect common supramodal mechanisms in conscious action monitoring. Our data may help to refine the scientific criteria of selfhood and are of relevance for the investigation of neurological and psychiatric patients with disturbance of selfhood.
Attention is intrinsic to our perceptual representations of sensory inputs. Best characterized in the visual domain, it is typically depicted as a spotlight moving over a saliency map that topographically encodes strengths of visual features and feedback modulations over the visual scene. By introducing smells to two well-established attentional paradigms, the dot-probe and the visual-search paradigms, we find that a smell reflexively directs attention to the congruent visual image and facilitates visual search of that image without the mediation of visual imagery. Furthermore, such effect is independent of, and can override, top-down bias. We thus propose that smell quality acts as an object feature whose presence enhances the perceptual saliency of that object, thereby guiding the spotlight of visual attention. Our discoveries provide robust empirical evidence for a multimodal saliency map that weighs not only visual but also olfactory inputs.
An illusory sensation of ownership over a surrogate limb or whole body can be induced through specific forms of multisensory stimulation, such as synchronous visuotactile tapping on the hidden real and visible rubber hand in the rubber hand illusion. Such methods have been used to induce ownership over a manikin and a virtual body that substitute the real body, as seen from first-person perspective, through a head-mounted display. However, the perceptual and behavioral consequences of such transformed body ownership have hardly been explored. In Exp. 1, immersive virtual reality was used to embody 30 adults as a 4-y-old child (condition C), and as an adult body scaled to the same height as the child (condition A), experienced from the first-person perspective, and with virtual and real body movements synchronized. The result was a strong body-ownership illusion equally for C and A. Moreover there was an overestimation of the sizes of objects compared with a nonembodied baseline, which was significantly greater for C compared with A. An implicit association test showed that C resulted in significantly faster reaction times for the classification of self with child-like compared with adult-like attributes. Exp. 2 with an additional 16 participants extinguished the ownership illusion by using visuomotor asynchrony, with all else equal. The size-estimation and implicit association test differences between C and A were also extinguished. We conclude that there are perceptual and probably behavioral correlates of body-ownership illusions that occur as a function of the type of body in which embodiment occurs.
This article reviews research pertaining to mass media as a causal risk factor for negative body image and disordered eating in females. The specific purpose is to clarify the impact of mass media by applying seven criteria that extend those of Kraemer et al. (1997) and Stice (2002). Although media effects clearly meet a majority of the criteria, this analysis indicates that, currently, engagement with mass media is probably best considered a variable risk factor that might well be later shown to be a causal risk factor. Recommendations are made for further research, with an emphasis on longitudinal investigations, studies of media literacy as a form of prevention, and clarification of psychosocial processes that moderate and mediate media effects.
Experiments in cross-modal matching suggest that smells can be arranged by odor quality along the color dimensions of hue and lightness Here we report that subjects readily adjust the loudness-equalized pitch of an auditory tone to match a stimulus odor The results allow odors to be arranged in sequence by their pitch-equivalents The tone matches appear to be based on perceptual features of olfaction other than stimulus intensity or pleasantness The results suggest that features of odor quality may be more accessible and structured than previously acknowledged.
We explored the concept body image disturbance (BID) by utilizing the subjective experience of 32 women (aged 20-39 years) diagnosed with AN (DSM-V). Using methods from Grounded Theory we identified four phenotypes of BID-"Integration," "Denial," "Dissociation," and "Delusion"-which differed according to whether the patients overestimated their own body size ("Subjective reality"), and whether they acknowledged the objective truth that they were underweight ("Objective reality"). The results suggest that BID should be conceptualized as a dynamic failure to integrate subjective experiences of one's own body appearance with an objective appraisal of the body. Conceptual, diagnostic and clinical implications are discussed.
Background:
Body change illusions have been of great interest in recent years for the understanding of how the brain represents the body. Appropriate multisensory stimulation can induce an illusion of ownership over a rubber or virtual arm, simple types of out-of-the-body experiences, and even ownership with respect to an alternate whole body. Here we use immersive virtual reality to investigate whether the illusion of a dramatic increase in belly size can be induced in males through (a) first person perspective position (b) synchronous visual-motor correlation between real and virtual arm movements, and (c) self-induced synchronous visual-tactile stimulation in the stomach area.
Methodology:
Twenty two participants entered into a virtual reality (VR) delivered through a stereo head-tracked wide field-of-view head-mounted display. They saw from a first person perspective a virtual body substituting their own that had an inflated belly. For four minutes they repeatedly prodded their real belly with a rod that had a virtual counterpart that they saw in the VR. There was a synchronous condition where their prodding movements were synchronous with what they felt and saw and an asynchronous condition where this was not the case. The experiment was repeated twice for each participant in counter-balanced order. Responses were measured by questionnaire, and also a comparison of before and after self-estimates of belly size produced by direct visual manipulation of the virtual body seen from the first person perspective.
Conclusions:
The results show that first person perspective of a virtual body that substitutes for the own body in virtual reality, together with synchronous multisensory stimulation can temporarily produce changes in body representation towards the larger belly size. This was demonstrated by (a) questionnaire results, (b) the difference between the self-estimated belly size, judged from a first person perspective, after and before the experimental manipulation, and (c) significant positive correlations between these two measures. We discuss this result in the general context of body ownership illusions, and suggest applications including treatment for body size distortion illnesses.
Many human olfactory experiments call for fast and stable stimulus-rise times as well as exact and stable stimulus-onset times. Due to these temporal demands, an olfactometer is often needed. However, an olfactometer is a piece of equipment that either comes with a high price tag or requires a high degree of technical expertise to build and/or to run. Here, we detail the construction of an olfactometer that is constructed almost exclusively with "off-the-shelf" parts, requires little technical knowledge to build, has relatively low price tags, and is controlled by E-Prime, a turnkey-ready and easily-programmable software commonly used in psychological experiments. The olfactometer can present either solid or liquid odor sources, and it exhibits a fast stimulus-rise time and a fast and stable stimulus-onset time. We provide a detailed description of the olfactometer construction, a list of its individual parts and prices, as well as potential modifications to the design. In addition, we present odor onset and concentration curves as measured with a photo-ionization detector, together with corresponding GC/MS analyses of signal-intensity drop (5.9%) over a longer period of use. Finally, we present data from behavioral and psychophysiological recordings demonstrating that the olfactometer is suitable for use during event-related EEG experiments.
Background:
Altering the normal association between touch and its visual correlate can result in the illusory perception of a fake limb as part of our own body. Thus, when touch is seen to be applied to a rubber hand while felt synchronously on the corresponding hidden real hand, an illusion of ownership of the rubber hand usually occurs. The illusion has also been demonstrated using visuomotor correlation between the movements of the hidden real hand and the seen fake hand. This type of paradigm has been used with respect to the whole body generating out-of-the-body and body substitution illusions. However, such studies have only ever manipulated a single factor and although they used a form of virtual reality have not exploited the power of immersive virtual reality (IVR) to produce radical transformations in body ownership.
Principal findings:
Here we show that a first person perspective of a life-sized virtual human female body that appears to substitute the male subjects' own bodies was sufficient to generate a body transfer illusion. This was demonstrated subjectively by questionnaire and physiologically through heart-rate deceleration in response to a threat to the virtual body. This finding is in contrast to earlier experimental studies that assume visuotactile synchrony to be the critical contributory factor in ownership illusions. Our finding was possible because IVR allowed us to use a novel experimental design for this type of problem with three independent binary factors: (i) perspective position (first or third), (ii) synchronous or asynchronous mirror reflections and (iii) synchrony or asynchrony between felt and seen touch.
Conclusions:
The results support the notion that bottom-up perceptual mechanisms can temporarily override top down knowledge resulting in a radical illusion of transfer of body ownership. The research also illustrates immersive virtual reality as a powerful tool in the study of body representation and experience, since it supports experimental manipulations that would otherwise be infeasible, with the technology being mature enough to represent human bodies and their motion.
Historical and psychophysical literature has demonstrated a perceptual interplay between olfactory and auditory stimuli-the neural mechanisms of which are not understood. Here, we report novel findings revealing that the early olfactory code is subjected to auditory cross-modal influences. In vivo extracellular recordings from the olfactory tubercle, a trilaminar structure within the basal forebrain, of anesthetized mice revealed that olfactory tubercle single units selectively respond to odors-with 65% of units showing significant odor-evoked activity. Remarkably, 19% of olfactory tubercle single units also showed robust responses to an auditory tone. Furthermore, 29% of single units tested displayed supraadditive or suppressive responses to the simultaneous presentation of odor and tone, suggesting cross-modal modulation. In contrast, olfactory bulb units did not show significant responses to tone presentation nor modulation of odor-evoked activity by tone-suggesting a lack of olfactory-auditory convergence upstream from the olfactory tubercle. Thus, the tubercle presents itself as a source for direct multimodal convergence within an early stage of odor processing and may serve as a seat for psychophysical interactions between smells and sounds.
Supporting exercise adherence through technology remains an important HCI challenge. Recent works showed that altering walking sounds leads people perceiving themselves as thinner/lighter, happier and walking more dynamically. While this novel approach shows potential for physical activity, it raises critical questions impacting technology design. We ran two studies in the context of exertion (gym-step, stairs-climbing) to investigate how individual factors impact the effect of sound and the duration of the after-effects. The results confirm that the effects of sound in body-perception occur even in physically demanding situations and through ubiquitous wearable devices. We also show that the effect of sound interacted with participants' body weight and masculinity/femininity aspirations, but not with gender. Additionally, changes in body-perceptions did not hold once the feedback stopped; however, body-feelings or behavioural changes appeared to persist for longer. We discuss the results in terms of malleability of body-perception and highlight opportunities for supporting exercise adherence.
When in a stressful situation, access to adult attachment figures (e.g., romantic partners) is an important means by which adults regulate stress responses. The practice of smelling a partner’s worn garment is reported as a self-treatment against stress. Here, we experimentally determinted whether exposure to a partner’s body odor attenuates adults’ subjective discomfort and psychophysiological responses, and whether such effects are qualified by adult attachment security. In a blocked design, participants (N=34) were presented with their partner’s body odor, their own body odor, the odor of a clean t-shirt, and rose odor, while exposed to weak electric shocks to induce discomfort and stress responses. Results showed that partner body odor reduces subjective discomfort during a stressful event, as compared with the odor of oneself. Also, highly secure participants had attenuated skin conductance when exposed to partner odor. We conclude that partner odor is a scent of security, especially for attachment-secure adults.
The primary goal of this study was to examine the associations between baseline body image dissatisfaction (BID) and subsequent anxiety trajectories in a diverse, community sample of adolescent girls and boys. Participants were 581 adolescents (baseline age: M = 16.1, SD = 0.7; 58% female; 65% non-Hispanic White) from U.S. public high schools. Self-report questionnaires were administered during school at 3 annual assessment waves. Latent growth curve modeling examined the association between baseline BID and growth factors of anxiety disorder symptom trajectories. Covariates included baseline gender, age, race/ethnicity, parental education attainment, body mass index standard scores, and depressive symptoms. Higher BID at baseline was significantly associated with higher initial symptoms of generalized anxiety disorder (GAD), panic disorder (PD), social anxiety disorder (SAD), and significant school avoidance (SSA; ps = .001–.04) but was unrelated to initial separation anxiety disorder (SEP) symptoms (p = .27). Higher baseline BID also was associated with attenuated decreases in SAD symptoms across time (p = .001). Among adolescents with low baseline anxiety symptoms only, higher BID was associated with more attenuated decreases in SAD symptoms (p = .01) and greater increases in PD symptoms (p = .02). BID was unrelated to changes in GAD, SEP, and SSA symptoms (ps = .11–.94). Findings suggest that BID is associated with concurrent symptoms of multiple anxiety disorders and may have a prospective link to SAD and PD symptoms during adolescence. As such, assessing body image issues may be important to assess when identifying adolescents at risk for exacerbated SAD and PD symptoms.
This study uses novel biometric figure rating scales (FRS) spanning body mass index (BMI) 13.8 to 32.2 kg/m2 and BMI 18 to 42 kg/m2. The aims of the study were (i) to compare FRS body weight dissatisfaction and perceptual distortion of women with anorexia nervosa (AN) to a community sample; (ii) how FRS parameters are associated with questionnaire body dissatisfaction, eating disorder symptoms and appearance comparison habits; and (iii) whether the weight spectrum of the FRS matters. Women with AN (n = 24) and a community sample of women (n = 104) selected their current and ideal body on the FRS and completed additional questionnaires. Women with AN accurately picked the body that aligned best with their actual weight in both FRS. Controls underestimated their BMI in the FRS 14–32 and were accurate in the FRS 18–42. In both FRS, women with AN desired a body close to their actual BMI and controls desired a thinner body. Our observations suggest that body image disturbance in AN is unlikely to be characterized by a visual perceptual disturbance, but rather by an idealization of underweight in conjunction with high body dissatisfaction. The weight spectrum of FRS can influence the accuracy of BMI estimation. Copyright © 2017 John Wiley & Sons, Ltd and Eating Disorders Association.
An ever more sedentary lifestyle is a serious problem in our society. Enhancing people’s exercise adherence through technology remains an important research challenge. We propose a novel approach for a system supporting walking that draws from basic findings in neuroscience research. Our shoe-based prototype senses a person’s footsteps and alters in real-time the frequency spectra of the sound they produce while walking. The resulting sounds are consistent with those produced by either a lighter or heavier body. Our user study showed that modified walking sounds change one’s own perceived body weight and lead to a related gait pattern. In particular, augmenting the high frequencies of the sound leads to the perception of having a thinner body and enhances the motivation for physical activity inducing a more dynamic swing and a shorter heel strike. We here discuss the opportunities and the questions our findings open.
Almost every bodily movement, from the most complex to the most mundane, such as walking, can generate impact sounds that contain spatial information of high temporal resolution. Despite the conclusive evidence about the role that the integration of vision, touch and proprioception plays in updating body-representations, hardly any study has looked at the contribution of audition. We show that the representation of a key property of one’s body, like its length, is affected by the sound of one’s actions. Participants tapped on a surface while progressively extending their right arm sideways, and in synchrony with each tap participants listened to a tapping sound. In the critical condition, the sound originated at double the distance at which participants actually tapped. After exposure to this condition, tactile distances on the test right arm, as compared to distances on the reference left arm, felt bigger than those before the exposure. No evidence of changes in tactile distance reports was found at the quadruple tapping sound distance or the asynchronous auditory feedback conditions. Our results suggest that tactile perception is referenced to an implicit body-representation which is informed by auditory feedback. This is the first evidence of the contribution of self-produced sounds to body-representation, addressing the auditory-dependent plasticity of body-representation and its spatial boundaries.
This study examines the effects of scent on hedonic experience in online shopping and then, which investigates olfactory cues such as citrus-mint and citrus-vanilla that improve the buyer's emotional state by creating an atmospherics. We selected a citrus-based scent as an olfactory cue eliciting the feelings of pleasure and arousal. In this experiment, an olfactory cue was manipulated as an independent variable in three between-subjects designs. This research shows that the application of a citrus-mint ambient cue can help online shoppers achieve a pleasant and arousing mood and enhance online shopping experience.
Given the sensory poverty of virtual environments, such as those found in computer games that rely, in the main, solely on audio-visual interfaces, how best do we attain the experience of presence in those environments when presence requires the construction of a coherent (in the sense of realism) place in which to be and in which to act? The paper explores this question through an investigation of the senses of hearing and smell and suggests the possibility of introducing the experience of odours into such environments through the use of sound.
Despite the fact that the design process can exploit a rich communication between the designer and the end users in terms of desired visual and audio sensory feedback, the vocabulary for less exploited aspects of the interaction (i.e., emotional, experiential) is still ambiguous. This is particularly a challenge when considering the increased interest in designing for a wider spectrum of experiences and interfaces (e.g., tangible, multimodal, multisensory interaction). In this paper, we present preliminary findings on the effect of scented material on physical creations using scented and unscented modeling clay. We compare features from the abstract creations from of three groups (i.e., vanilla scented, lemon scented, or unscented material). Our preliminary results confirm pre-existing mappings across shapes and scents. We discuss the various properties of the creations and discuss their relevance based on previous work and in particular its potential for HCI in the design of future interactive experiences.
Our clothes are objects we interact with constantly. They represent our attitude and the circumstances we live in. In the following we will present an example of how this information can be used. Scarfy is a system based on a scarf which augments the natural interaction between a person and her clothes. Scarfy is able to detect the way it is tied and it can deliver information by shape-change and vibration. In this paper we explore the technical and fabrication approaches of technologically extended clothes and their input and output generation and discuss future applications.
Previous studies have examined the experience of owning a virtual surrogate body or body part through specific combinations of cross-modal multisensory stimulation. Both visuomotor (VM) and visuotactile (VT) synchronous stimulation have been shown to be important for inducing a body ownership illusion, each tested separately or both in combination. In this study we compared the relative importance of these two cross-modal correlations, when both are provided in the same immersive virtual reality setup and the same experiment. We systematically manipulated VT and VM contingencies in order to assess their relative role and mutual interaction. Moreover, we present a new method for measuring the induced body ownership illusion through time, by recording reports of breaks in the illusion of ownership ('breaks') throughout the experimental phase. The balance of the evidence, from both questionnaires and analysis of the breaks, suggests that while VM synchronous stimulation contributes the greatest to the attainment of the illusion, a disruption of either (through asynchronous stimulation) contributes equally to the probability of a break in the illusion.
Although it has been shown that immersive virtual reality (IVR) can be used to induce illusions of ownership over a virtual body (VB), information on whether this changes implicit interpersonal attitudes is meager. Here we demonstrate that embodiment of light-skinned participants in a dark-skinned VB significantly reduced implicit racial bias against dark-skinned people, in contrast to embodiment in light-skinned, purple-skinned or with no VB. 60 females participated in this between-groups experiment, with a VB substituting their own, with full-body visuomotor synchrony, reflected also in a virtual mirror. A racial Implicit Association Test (IAT) was administered at least three days prior to the experiment, and immediately after the IVR exposure. The change from pre- to post-experience IAT scores suggests that the dark-skinned embodied condition decreased implicit racial bias more than the other conditions. Thus, embodiment may change negative interpersonal attitudes and thus represent a powerful tool for exploring such fundamental psychological and societal phenomena.
Pavlovian fear conditioning has been thoroughly studied in the visual, auditory and somatosensory domain, but evidence is scarce with regard to the chemosensory modality. Under the assumption that Pavlovian conditioning relies on the supra-modal mechanism of salience attribution, the present study was set out to attest the existence of chemosensory aversive conditioning in humans as a specific instance of salience attribution. fMRI was performed in 29 healthy subjects during a differential aversive conditioning paradigm. Two odors (rose, vanillin) served as conditioned stimuli (CS), one of which (CS+) was intermittently coupled with intranasally administered CO2. On the neural level, a robust differential response to the CS+emerged in frontal, temporal, occipito-parietal and subcortical brain regions, including the amygdala. These changes were paralleled by the development of a CS+-specific connectivity profile of the anterior midcingulate cortex (aMCC), which is a key structure for processing salience information in order to guide adaptive response selection. Increased coupling could be found between key nodes of the salience network (anterior insula, neo-cerebellum) and sensorimotor areas, representing putative input and output structures of the aMCC for exerting adaptive motor control. In contrast, behavioral and skin conductance responses did not show significant effects of conditioning, which has been attributed to contingency unawareness. These findings imply substantial similarities of conditioning involving chemosensory and other sensory modalities, and suggest that salience attribution and adaptive control represent a general, modality-independent principle underlying Pavlovian conditioning.
We report two experiments designed to investigate cross-modal correspondences between a range of seven olfactory stimuli and both the pitch and instrument class of sounds as well as the angularity of visually presented shapes. The results revealed that odors were preferentially matched to musical features: For example, the odors of candied orange and iris flower were matched to significantly higher pitches than the odors of musk and roasted coffee. Meanwhile, the odor of crème brûlée was associated with a more rounded shape than the musk odor. Moreover, by simultaneously testing cross-modal correspondences between olfactory stimuli and matches in two other modalities, we were able to compare the ratings associated with each correspondence. Stimuli judged as happier, more pleasant, and sweeter tended to be associated to both higher pitch and a more rounded shape, whereas other ratings seemed to be more specifically correlated with the choice of either pitch or shape. Odors rated as more arousing tended to be associated with the angular shape, but not with a particular pitch; odors judged as brighter were associated with higher pitch and, to a lesser extent, rounder shapes. In a follow-up experiment, we investigated whether people could match specific pieces of music (composed to represent odors) to three of the odors (candied orange, crème brûlée, and ginger cookies). In one case (candied orange), a majority of the participants matched the odor to the intended piece of music. In another case (ginger cookies), another piece of music (than the one intended) was preferred. Finally, in the third case (crème brûlée), people showed no preference in matching the odor to the pieces of music. Both theoretical and practical implications of these results are discussed.
Olfactory experiences represent a domain that is particularly rich in crossmodal associations. Whereas associations between odors and tastes, or other properties of their typical sources such as color or temperature, can be straightforwardly explained by associative learning, other matchings are much harder to explain in these terms, yet surprisingly are shared across individuals: The majority of people, for instance, associate certain odors and auditory features, such as pitch (Belkin, Martin, Kemp, & Gilbert, Psychological Science 8:340-342, 1997; Crisinel & Spence, Chemical Senses 37:151-158, 2012b) or geometrical shapes (Hanson-Vaux, Crisinel, & Spence, Chemical Senses 38:161-166, 2013; Seo, Arshamian, et al., Neuroscience Letters 478:175-178, 2010). If certain odors might indeed have been encountered while listening to certain pieces of music or seeing certain geometrical shapes, these encounters are very unlikely to have been statistically more relevant than others; for this reason, associative learning from regular exposure is ruled out, and thus alternative explanations in terms of metaphorical mappings are usually defended. Here we argue that these associations are not primarily conceptual or linguistic, but are grounded in structural perceptual or neurological determinants. These cases of crossmodal correspondences established between contingent environmental features can be explained as amodal, indirect, and transitive mappings across modalities. Surprising associations between odors and contingent sensory features can be investigated as genuine cases of crossmodal correspondences, akin to other widespread cases of functional correspondences that hold, for instance, between auditory and visual features, and can help reveal the structural determinants weighing on the acquisition of these crossmodal associations.
Crossmodal correspondences between odors and visual stimuli-particularly colors-are well-established in the literature, but there is a paucity of research involving visual shape correspondences. Crossmodal associations between 20 odors (a selection of those commonly found in wine) and visual shape stimuli ("kiki"/"bouba" forms-Köhler W. 1929. Gestalt psychology. New York: Liveright.) were investigated in a sample of 25 participants (mean age of 21 years). The odors were rated along a form scale anchored by 2 shapes, as well as several descriptive adjective scales. Two of the odors were found to be significantly associated with an angular shape (lemon and pepper) and two others with a rounded shape (raspberry and vanilla). Principal component analysis indicated that the hedonic value and intensity of odors are important in this crossmodal association, with more unpleasant and intense smells associated with more angular forms. These results are discussed in terms of their practical applications, such as in the use of bottle, logo, or label shape by marketers of perfume and wine to convey the prominent notes through congruent odor-shape pairing. In conclusion, these results support the existence of widespread crossmodal associations (or correspondences) between odors and visual shape stimuli.
Almost every bodily movement, from the most complex to the most mundane, such as walking, can generate impact sounds that contain 360° spatial information of high temporal resolution. Given the strong connection of auditory cues to our body actions, and the dependency of body-awareness on the interaction between peripheral sensory inputs and mental body-representations, one could assume that audition plays a specific role in this interaction. Despite the conclusive evidence for the role that the integration of vision, touch and proprioception plays in updating body-representations [1
• de Vignemont F.
• Ehrsson H.H.
• Haggard P.
Bodily illusions modulate tactile perception.Curr. Biol. 2005; 15: 1286-1290
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• Haggard P.
• Christakou A.
• Serino A.
Viewing the body modulates tactile receptive fields.Exp. Brain Res. 2007; 180: 187-193
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], hardly any study has looked at the contribution of audition. We show that the representation of a key property of one's body, like its length, is affected by the sound of one's actions. Participants tapped on a surface while progressively extending their right arm sideways, and in synchrony with each tap participants listened to a tapping sound. In the critical condition, the sound originated at double the distance at which participants actually tapped. After exposure to this condition, tactile distances on the test right arm, as compared to distances on the reference left arm, felt bigger than those before the exposure. No evidence of changes in tactile distance reports was found at the quadruple tapping sound distance or the asynchronous auditory feedback conditions. Our results suggest that tactile perception is referenced to an implicit body-representation which is informed by auditory feedback. This is the first evidence of the contribution of self-produced sounds to body-representation, addressing the auditory-dependent plasticity of body-representation and its spatial boundaries.
TapTap is a wearable haptic system that allows nurturing human touch to be recorded, broadcast and played back for emotional th erapy. Haptic input/output modules in a convenient modular scarf provide affectionate touch that can be personalized. We present a working prototype informed by a pilot study.
The main contribution of this paper is to realize computer generated augmented flavors and establish a method to integrate gustatory information into computer human interactions. There are several reasons for the scarcity of research on gustatory information. One reason is that taste sensations are affected by a number of factors, such as vision, olfaction and memories. This produces a complex cognition mechanism for a user's gustatory sensation, and makes it difficult to build up a gustatory display which produces a specific taste on demand.
Our hypothesis is that the complexity of gustatory sensation can be applied to the realization of a "Pseudo-gustatory" display that presents the desired flavors by means of a cross-modal effect elicited by visual and olfactory augmented reality. We propose the Edible Marker system, which can detect the state [number/shape/6-degree-of-freedom (DOF) coordinate] of each piece of bitten or divided food in real time, and the "Pseudo-gustation" method to change the perceived taste of food by changing its appearance and scent. We construct "MetaCookie+" as an implementation and discuss its validity through an exploratory study.
In many everyday situations, our senses are bombarded by many different unisensory signals at any given time. To gain the most veridical, and least variable, estimate of environmental stimuli/properties, we need to combine the individual noisy unisensory perceptual estimates that refer to the same object, while keeping those estimates belonging to different objects or events separate. How, though, does the brain "know" which stimuli to combine? Traditionally, researchers interested in the crossmodal binding problem have focused on the roles that spatial and temporal factors play in modulating multisensory integration. However, crossmodal correspondences between various unisensory features (such as between auditory pitch and visual size) may provide yet another important means of constraining the crossmodal binding problem. A large body of research now shows that people exhibit consistent crossmodal correspondences between many stimulus features in different sensory modalities. For example, people consistently match high-pitched sounds with small, bright objects that are located high up in space. The literature reviewed here supports the view that crossmodal correspondences need to be considered alongside semantic and spatiotemporal congruency, among the key constraints that help our brains solve the crossmodal binding problem.
This study aimed to investigate the cross-modal association of an "abstract symbol," designed for representation of an odor, with its corresponding odor. First, to explore the associations of abstract symbols with odors, participants were asked to match 8 odors with 19 different abstract symbols (Experiment 1). Next, we determined whether congruent symbols could modulate olfactory perception and olfactory event-related potentials (ERPs) (Experiment 2). One of two odors (phenylethanol (PEA) or 1-butanol) was presented with one of three conditions (congruent or incongruent symbol, no-symbol), and participants were asked to rate odor intensity and pleasantness during olfactory ERP recordings. Experiment 1 demonstrated that certain abstract symbols could be paired with specific odors. In Experiment 2 congruent symbol enhanced the intensity of PEA compared to no-symbol presentation. In addition, the respective congruent symbol increased the pleasantness of PEA and the unpleasantness of 1-butanol. Finally, compared to the incongruent symbol, the congruent symbol produced significantly higher amplitudes and shorter latencies in the N1 peak of olfactory ERPs. In conclusion, our findings demonstrated that abstract symbols may be associated with specific odors.
Obesity in older adults is a growing public health problem. Excess weight causes biomechanical burden to lower extremity joints and contribute to joint pathology. The aim of this study was to identify specific characteristics of gait associated with body mass index (BMI). Preferred and maximum speed walking and related gait characteristics were examined in 164 (50-84 years) participants from Baltimore Longitudinal Study of Aging (BLSA) able to walk unassisted. Participants were divided into three groups based on their BMI: normal weight (19< or =BMI<25 kg/m(2)), overweight (25< or =BMI<30 kg/m(2)) and obese (BMI 30< or =BMI<40 kg/m(2)). Total ankle generative mechanical work expenditure (MWE) in the anterior-posterior (AP) plane was progressively and significantly lower with increase in BMI for both preferred (p=0.026) and maximum speed walking (p<0.001). In the medial-lateral (ML) plane, total knee generative MWE was higher in obese participants in the preferred speed task (p=0.002), and total hip absorptive MWE was higher in obese in both preferred speed (p<0.001) and maximum speed (p=0.002) walking task compared to the normal weight participants. Older adults with obesity show spatiotemporal gait patterns that may help in reducing contact impacts. In addition, in obese persons mechanical energy usages tend to be lower in the AP plane and higher in the ML plane. Since forward progression forces are mainly implicated in normal walking, this pattern found in obese participants is suggestive of lower energetic efficiency.
Empirical research on the bodily self has only recently started to investigate how the link between a body and the experience of this body as mine is developed, maintained or disturbed. The Rubber Hand Illusion has been used as a model instance of the normal sense of embodiment to investigate the processes that underpin the experience of body-ownership. This review puts forward a neurocognitive model according to which body-ownership arises as an interaction between current multisensory input and internal models of the body. First, a pre-existing stored model of the body distinguishes between objects that may or may not be part of one's body. Second, on-line anatomical and postural representations of the body modulate the integration of multisensory information that leads to the recalibration of visual and tactile coordinate systems. Third, the resulting referral of tactile sensation will give rise to the subjective experience of body-ownership. These processes involve a neural network comprised of the right temporoparietal junction which tests the incorporeability of the external object, the secondary somatosensory cortex which maintains an on-line representation of the body, the posterior parietal and ventral premotor cortices which code for the recalibration of the hand-centred coordinate systems, and the right posterior insula which underpins the subjective experience of body-ownership. The experience of body-ownership may represent a critical component of self-specificity as evidenced by the different ways in which multisensory integration in interaction with internal models of the body can actually manipulate important physical and psychological aspects of the self.