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Kim KH, Noh K, Lee J, Lee S, Lee SJ. NEGR1 Modulates Mouse Affective Discrimination by Regulating Adult Olfactory Neurogenesis. BIOLOGICAL PSYCHIATRY GLOBAL OPEN SCIENCE 2024; 4:100355. [PMID: 39170714 PMCID: PMC11338060 DOI: 10.1016/j.bpsgos.2024.100355] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2023] [Revised: 06/01/2024] [Accepted: 06/06/2024] [Indexed: 08/23/2024] Open
Abstract
Background Affective recognition and sensory processing are impaired in people with autism. However, no mouse model of autism comanifesting these symptoms is available, thereby limiting the exploration of the relationship between affective recognition and sensory processing in autism and the molecular mechanisms involved. Methods With Negr1 -/- mice, we conducted the affective state discrimination test and an odor habituation/dishabituation test. Data were analyzed using the k-means clustering method. We also employed a whole-cell patch clamp and bromodeoxyuridine incorporation assay to investigate underlying mechanisms. Results When encountering mice exposed to restraint stress or chronic pain, wild-type mice discriminated between them by either approaching the stressed mouse or avoiding the painful mouse, whereas Negr1 -/- mice showed unbiased social interactions with them. Next, we demonstrated that both wild-type and Negr1 -/- mice used their olfaction for social interaction in the experimental context, but Negr1 -/- mice showed aberrant olfactory habituation and dishabituation against social odors. In electrophysiological studies, inhibitory inputs to the mitral cells in the olfactory bulb were increased in Negr1 -/- mice compared with wild-type mice, and subsequently their excitability was decreased. As a potential underlying mechanism, we found that adult neurogenesis in the subventricular zone was diminished in Negr1 -/- mice, which resulted in decreased integration of newly generated inhibitory neurons in the olfactory bulb. Conclusions NEGR1 contributes to mouse affective recognition, possibly by regulating olfactory neurogenesis and subsequent olfactory sensory processing. We propose a novel neurobiological mechanism of autism-related behaviors based on disrupted adult olfactory neurogenesis.
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Affiliation(s)
- Kwang Hwan Kim
- Department of Brain and Cognitive Science, College of Natural Science, Seoul National University, Seoul, Republic of Korea
- Department of Physiology and Neuroscience, Dental Research Institute, Seoul National University School of Dentistry, Seoul, Republic of Korea
- Department of Microbiology and Molecular Biology, Chungnam National University, Daejeon, Republic of Korea
| | - Kyungchul Noh
- Department of Physiology and Neuroscience, Dental Research Institute, Seoul National University School of Dentistry, Seoul, Republic of Korea
| | - Jaesung Lee
- Department of Physiology and Neuroscience, Dental Research Institute, Seoul National University School of Dentistry, Seoul, Republic of Korea
- Interdisciplinary Program in Neuroscience, College of Natural Sciences, Seoul National University, Seoul, Republic of Korea
| | - Soojin Lee
- Department of Microbiology and Molecular Biology, Chungnam National University, Daejeon, Republic of Korea
| | - Sung Joong Lee
- Department of Physiology and Neuroscience, Dental Research Institute, Seoul National University School of Dentistry, Seoul, Republic of Korea
- Interdisciplinary Program in Neuroscience, College of Natural Sciences, Seoul National University, Seoul, Republic of Korea
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Albayay J, Zampieri M, Sartori L, Castiello U, Parma V. Competitive (but not cooperative) body odors bias the discrimination of action intentions towards cooperation. Acta Psychol (Amst) 2024; 248:104392. [PMID: 39003995 DOI: 10.1016/j.actpsy.2024.104392] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2024] [Revised: 05/18/2024] [Accepted: 07/09/2024] [Indexed: 07/16/2024] Open
Abstract
Odors help us to interpret the environment, including the nature of social interactions. But, whether and how they influence the ability to discriminate the intentional states embedded in actions is unclear. In two experiments, we asked two independent groups of participants to discriminate motor intentions from videos showing one agent performing a reach-to-grasp movement with another agent with a cooperative or a competitive intent, and the same movement performed alone at either natural- or fast-speed, as controls. Task-irrelevant odor primes preceded each video presentation. Experiment 1 (N = 19) included masked cooperative and competitive body odors (human sweat collected while the donors were engaged in cooperative and competitive activities), whereas Experiment 2 (N = 20) included a common odor (cedarwood oil) and no odor (clean air) as primes. In an odor-primed, two-alternative forced choice task, participants discriminated the intention underlying the observed action. The results indicated that the odor exposure modulated the discrimination speed across different intentions, but only when the action intentions were hard to discriminate (cooperative vs. individual natural-speed, and competitive vs. individual fast-speed). Contrary to our hypothesis, a direct odor-action intention compatibility effect was not found. Instead, we propose a negative arousal compatibility-like effect to explain our results. Discrimination of high arousing action intentions (i.e., competitive) took longer when primed by high arousing odors (common odor and competitive body odor) than by low arousing odors (cooperative body odor and no odor). Discrimination of low arousing action intentions (i.e., cooperative) took longer when primed by low arousing odors than by high arousing odors. All in all, competitive (but not cooperative) body odors bias the discrimination of action intentions towards cooperation.
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Affiliation(s)
- Javier Albayay
- Department of General Psychology, University of Padova, Via Venezia 8, 35131 Padova, Italy; Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Centre, Kapittelweg 29, 6525 EN Nijmegen, the Netherlands.
| | - Matteo Zampieri
- Neuroscience Area, International School for Advanced Studies, Via Bonomea 265, 34151 Trieste, Italy
| | - Luisa Sartori
- Department of General Psychology, University of Padova, Via Venezia 8, 35131 Padova, Italy.
| | - Umberto Castiello
- Department of General Psychology, University of Padova, Via Venezia 8, 35131 Padova, Italy.
| | - Valentina Parma
- Monell Chemical Senses Center, 3500 Market Street, Philadelphia, PA 19104, United States of America.
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Larrigaldie I, Damon F, Mousqué S, Patris B, Lansade L, Schaal B, Destrez A. Do sheep (Ovis aries) discriminate human emotional odors? Anim Cogn 2024; 27:51. [PMID: 39060454 PMCID: PMC11282138 DOI: 10.1007/s10071-024-01895-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2024] [Revised: 07/15/2024] [Accepted: 07/16/2024] [Indexed: 07/28/2024]
Abstract
While sheep can detect and discriminate human emotions through visual and vocal cues, their reaction to human body odors remains unknown. The present study aimed to determine whether sheep (Ovis aries) can detect human odors, olfactorily discriminate stressed from non-stressed individuals, and behave accordingly based on the emotional valence of the odors. Axillary secretions from 34 students were collected following an oral examination (stress odor) or a regular class (non-stress odor). Fourteen female and 15 male lambs were then exposed to these odors through a habituation-dishabituation procedure. The habituation stimulus was presented four times for one minute, followed by the dishabituation stimulus presented once for one minute. Behavioral variables included spatiality relative to target odors, approach/withdrawal, ear positioning, sniffing, ingestion, and vocalization. Both female and male lambs more often positioned their ears backwards/forwards, and asymmetrically when exposed to the dishabituation stimulus, but regardless of their stress or non-stress value. They also changed their approach behavior when exposed to the dishabituation stimuli. Lambs displayed some behavioral signs of discrimination between the habituation and dishabituation odors, but regardless of their relation to stress or non-stress of human donors. In sum, this exploratory study suggests that young sheep respond negatively to the odor of unfamiliar humans, without showing any specific emotional contagion related to the stress odor. This exploratory study suggests young ovines can detect human body odor, a further step toward understanding the human-sheep relationship.
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Affiliation(s)
- Izïa Larrigaldie
- Development of Olfaction in Cognition and Communication Lab, Centre des Sciences du Goût et de l'Alimentation, CNRS, Université Bourgogne, Institut Agro Dijon, Dijon, France.
| | - Fabrice Damon
- Development of Olfaction in Cognition and Communication Lab, Centre des Sciences du Goût et de l'Alimentation, CNRS, Université Bourgogne, Institut Agro Dijon, Dijon, France
| | - Solène Mousqué
- Development of Olfaction in Cognition and Communication Lab, Centre des Sciences du Goût et de l'Alimentation, CNRS, Université Bourgogne, Institut Agro Dijon, Dijon, France
- Institut Agro Dijon, Dijon, France
| | - Bruno Patris
- Development of Olfaction in Cognition and Communication Lab, Centre des Sciences du Goût et de l'Alimentation, CNRS, Université Bourgogne, Institut Agro Dijon, Dijon, France
| | - Léa Lansade
- Unité de Physiologie de la Reproduction et des Comportements, IFCE, Inrae, CNRS, Université de Tours, Nouzilly, France
| | - Benoist Schaal
- Development of Olfaction in Cognition and Communication Lab, Centre des Sciences du Goût et de l'Alimentation, CNRS, Université Bourgogne, Institut Agro Dijon, Dijon, France
| | - Alexandra Destrez
- Development of Olfaction in Cognition and Communication Lab, Centre des Sciences du Goût et de l'Alimentation, CNRS, Université Bourgogne, Institut Agro Dijon, Dijon, France
- Institut Agro Dijon, Dijon, France
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Ferdenzi C, Fournel A, Baldovini N, Poupon D, Ligout D, Thévenet M, Bouet R, Bensafi M. Influence of the human body odor compound HMHA on face perception. Perception 2024; 53:180-196. [PMID: 38216326 DOI: 10.1177/03010066231222473] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2024]
Abstract
Body odors convey information about the individuals, but the mechanisms are not fully understood yet. As far as human reproduction is concerned, molecules that are produced in sexually dimorphic amounts could be possible chemosignals. 3-hydroxy-3-methylhexanoic acid (HMHA) is one of them-more typical of men. Here, we investigated the possibility that the perception of gender and attractiveness in human faces could be implicitly influenced by this compound. Clearly feminine, ambiguous and clearly masculine faces were primed with an odor of HMHA, a control odor or air. Based on 100-ms face presentation, 40 raters had to identify the face's gender as quickly as possible and provide attractiveness evaluations. 3-hydroxy-3-methylhexanoic acid tended to be perceived as less pleasant and induced lower sniff duration in women compared with men. As to the effects of HMHA on face perception (vs. control conditions), we found that gender identification and the associated response time were unaffected by HMHA. Attractiveness of the faces, however, increased in presence of HMHA, but not in a sex-specific manner and only for unattractive faces with ambiguous gender. In sum, this study found no evidence in favor of a possible role of this sexually dimorphic compound in intrasexual competition nor in intersexual attraction.
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Agron S, de March CA, Weissgross R, Mishor E, Gorodisky L, Weiss T, Furman-Haran E, Matsunami H, Sobel N. A chemical signal in human female tears lowers aggression in males. PLoS Biol 2023; 21:e3002442. [PMID: 38127837 PMCID: PMC10734982 DOI: 10.1371/journal.pbio.3002442] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Accepted: 11/21/2023] [Indexed: 12/23/2023] Open
Abstract
Rodent tears contain social chemosignals with diverse effects, including blocking male aggression. Human tears also contain a chemosignal that lowers male testosterone, but its behavioral significance was unclear. Because reduced testosterone is associated with reduced aggression, we tested the hypothesis that human tears act like rodent tears to block male aggression. Using a standard behavioral paradigm, we found that sniffing emotional tears with no odor percept reduced human male aggression by 43.7%. To probe the peripheral brain substrates of this effect, we applied tears to 62 human olfactory receptors in vitro. We identified 4 receptors that responded in a dose-dependent manner to this stimulus. Finally, to probe the central brain substrates of this effect, we repeated the experiment concurrent with functional brain imaging. We found that sniffing tears increased functional connectivity between the neural substrates of olfaction and aggression, reducing overall levels of neural activity in the latter. Taken together, our results imply that like in rodents, a human tear-bound chemosignal lowers male aggression, a mechanism that likely relies on the structural and functional overlap in the brain substrates of olfaction and aggression. We suggest that tears are a mammalian-wide mechanism that provides a chemical blanket protecting against aggression.
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Affiliation(s)
- Shani Agron
- The Azrieli National Center for Human Brain Imaging and Research, Weizmann Institute of Science, Rehovot, Israel
- The Department for Brain Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Claire A. de March
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, United States of America
- Department of Neurobiology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Reut Weissgross
- The Azrieli National Center for Human Brain Imaging and Research, Weizmann Institute of Science, Rehovot, Israel
- The Department for Brain Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Eva Mishor
- The Azrieli National Center for Human Brain Imaging and Research, Weizmann Institute of Science, Rehovot, Israel
- The Department for Brain Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Lior Gorodisky
- The Azrieli National Center for Human Brain Imaging and Research, Weizmann Institute of Science, Rehovot, Israel
- The Department for Brain Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Tali Weiss
- The Azrieli National Center for Human Brain Imaging and Research, Weizmann Institute of Science, Rehovot, Israel
- The Department for Brain Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Edna Furman-Haran
- The Azrieli National Center for Human Brain Imaging and Research, Weizmann Institute of Science, Rehovot, Israel
| | - Hiroaki Matsunami
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, United States of America
- Department of Neurobiology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Noam Sobel
- The Azrieli National Center for Human Brain Imaging and Research, Weizmann Institute of Science, Rehovot, Israel
- The Department for Brain Sciences, Weizmann Institute of Science, Rehovot, Israel
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Di Cicco F, Evans RL, James AG, Weddell I, Chopra A, Smeets MAM. Intrinsic and extrinsic factors affecting axillary odor variation. A comprehensive review. Physiol Behav 2023; 270:114307. [PMID: 37516230 DOI: 10.1016/j.physbeh.2023.114307] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Revised: 07/14/2023] [Accepted: 07/27/2023] [Indexed: 07/31/2023]
Abstract
Humans produce odorous secretions from multiple body sites according to the microbiomic profile of each area and the types of secretory glands present. Because the axilla is an active, odor-producing region that mediates social communication via the sense of smell, this article focuses on the biological mechanisms underlying the creation of axillary odor, as well as the intrinsic and extrinsic factors likely to impact the odor and determine individual differences. The list of intrinsic factors discussed includes sex, age, ethnicity, emotions, and personality, and extrinsic factors include dietary choices, diseases, climate, and hygienic habits. In addition, we also draw attention to gaps in our understanding of each factor, including, for example, topical areas such as the effect of climate on body odor variation. Fundamental challenges and emerging research opportunities are further outlined in the discussion. Finally, we suggest guidelines and best practices based on the factors reviewed herein for preparatory protocols of sweat collection, data analysis, and interpretation.
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Affiliation(s)
- Francesca Di Cicco
- Faculty of Social and Behavioural Sciences, Utrecht University, Heidelberglaan 1, Utrecht, CS 3584, the Netherlands.
| | - Richard L Evans
- Unilever Research & Development, Port Sunlight Laboratory, Bebington, UK
| | - A Gordon James
- Unilever Research & Development, Colworth House, Sharnbrook, UK
| | - Iain Weddell
- Unilever Research & Development, Port Sunlight Laboratory, Bebington, UK
| | - Anita Chopra
- Unilever Research & Development, Port Sunlight Laboratory, Bebington, UK
| | - Monique A M Smeets
- Faculty of Social and Behavioural Sciences, Utrecht University, Heidelberglaan 1, Utrecht, CS 3584, the Netherlands; Unilever Research & Development, Rotterdam, the Netherlands
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7
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Wunder A, Ludwig J, Haertl T, Arnhardt S, Schwinn L, Chellapandian DC, Weinmair E, Mühle C, Thürauf N, Kornhuber J, Rohleder N, Loos HM, Freiherr J. Can you smell my stress? Influence of stress chemosignals on empathy and emotion recognition in depressed individuals and healthy controls. Physiol Behav 2023; 270:114309. [PMID: 37517662 DOI: 10.1016/j.physbeh.2023.114309] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Revised: 06/29/2023] [Accepted: 07/27/2023] [Indexed: 08/01/2023]
Abstract
Human body odors contain chemical signals that play a key role in our non-verbal communication regarding health, genetic identity, immune system, fitness, and emotional state. Studies on human chemosignaling in individuals with psychiatric diseases are scarce but indicate altered smell perception and emotion recognition in depressed individuals. In the present project, we aimed to investigate the influence of chemosensory substances in social stress sweat on emotion recognition, perspective taking, affective responsiveness as well as stress level in healthy and depressed individuals. Therefore, chemosensory stimuli (sweat samples from Trier social stress test (TSST) and friendly-TSST (fTSST)) were obtained from 39 healthy participants (19 females). In a next step, chemosensory stimuli and an odor-free blank (cotton pad) were used to stimulate another group of 40 healthy participants (20 females) and 37 individuals with depression (24 females). Those stimuli were examined regarding their influence on subjective feelings of stress, emotion perception and empathic reactions using an empathy test. Furthermore, physiological data (breathing, heart rate, skin conductance response, stress hormones) of the participants were collected during chemosensory stimulation. Depressed individuals improved their ability of perspective taking and affective responsiveness for the emotion grief when presented with stress chemosignals compared to no chemosignals. Healthy individuals remained unaffected regarding perspective taking and affective responsiveness. Both depressed and healthy individuals showed no increased stress hormone cortisol and α-amylase values during the social stress chemosignals condition, but reduced values for fTSST condition compared to no chemosignals respectively. The results imply that stress chemosignals do not trigger a stress reaction, but for depressed individuals they lead to a better emotion assessment for grief. This research contributes to a deeper understanding of the effects of social stress chemosignals on healthy and depressed individuals. Knowing the impact of human chemosignals on emotional processing is crucial for a better understanding of non-verbal human interaction.
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Affiliation(s)
- Annkatrin Wunder
- Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Department of Psychiatry and Psychotherapy, Schwabachanlage 6, 91054 Erlangen, Germany.
| | - Janina Ludwig
- Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Department of Psychiatry and Psychotherapy, Schwabachanlage 6, 91054 Erlangen, Germany
| | - Tobias Haertl
- Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Chair of Aroma and Smell Research, Department of Chemistry and Pharmacy, Henkestrasse 9, 91054 Erlangen, Germany
| | - Sally Arnhardt
- Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Department of Psychiatry and Psychotherapy, Schwabachanlage 6, 91054 Erlangen, Germany
| | - Leo Schwinn
- Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Machine Learning and Data Analytics Lab, Department Artificial Intelligence in Biomedical Engineering, Carl-Thiersch-Strasse 2b, 91052 Erlangen, Germany
| | - Deepak Charles Chellapandian
- Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Department of Psychiatry and Psychotherapy, Schwabachanlage 6, 91054 Erlangen, Germany
| | - Elisabeth Weinmair
- Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Chair of Health Psychology, Department of Psychology, Nägelsbachstrasse 49a, 91052 Erlangen, Germany
| | - Christiane Mühle
- Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Department of Psychiatry and Psychotherapy, Schwabachanlage 6, 91054 Erlangen, Germany
| | - Norbert Thürauf
- Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Department of Psychiatry and Psychotherapy, Schwabachanlage 6, 91054 Erlangen, Germany
| | - Johannes Kornhuber
- Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Department of Psychiatry and Psychotherapy, Schwabachanlage 6, 91054 Erlangen, Germany
| | - Nicolas Rohleder
- Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Chair of Health Psychology, Department of Psychology, Nägelsbachstrasse 49a, 91052 Erlangen, Germany
| | - Helene M Loos
- Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Chair of Aroma and Smell Research, Department of Chemistry and Pharmacy, Henkestrasse 9, 91054 Erlangen, Germany; Fraunhofer Institute for Process Engeneering and Packaging (IVV), Giggenhauser Str. 35, 85354 Freising, Germany
| | - Jessica Freiherr
- Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Department of Psychiatry and Psychotherapy, Schwabachanlage 6, 91054 Erlangen, Germany; Fraunhofer Institute for Process Engineering and Packaging (IVV), Sensory Analytics and Technologies, Giggenhauser Str. 35, 85354 Freising, Germany.
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Richard Ortegón S, Carlos O, Robert-Hazotte A, Lelgouarch A, Desoche C, Kawabata Duncan K, Tagai K, Fournel A, Bensafi M, Race B, Ferdenzi C. Investigating the human chemical communication of positive emotions using a virtual reality-based mood induction. Physiol Behav 2023; 264:114147. [PMID: 36893999 DOI: 10.1016/j.physbeh.2023.114147] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Revised: 01/02/2023] [Accepted: 03/05/2023] [Indexed: 03/09/2023]
Abstract
Humans can communicate their emotions to others via volatile emissions from their bodies. Although there is now solid evidence for human chemical communication of fear, stress and anxiety, investigations of positive emotions remain scarce. In a recent study, we found that women's heart rate and performance in creativity tasks were modulated by body odors of men sampled while they were in a positive vs. neutral mood. However, inducing positive emotions in laboratory settings remains challenging. Therefore, an important step to further investigate the human chemical communication of positive emotions is to develop new methods to induce positive moods. Here, we present a new mood induction procedure (MIP) based on virtual reality (VR), that we assumed to be more powerful than videos (used in our previous study) to induce positive emotions. We hypothesized that, consequently, given the more intense emotions created, this VR-based MIP would induce larger differences between the receivers' responses to the positive body odor versus a neutral control body odor, than the Video-based MIP. The results confirmed the higher efficacy of VR to induce positive emotions compared with videos. More specifically, VR had more repeatable effects between individuals. Although positive body odors had similar effects to those found in the previous video study, especially faster problem solving, these effects did not reach statistical significance. These outcomes are discussed as a function of the specificities of VR and of other methodological parameters, that may have prevented the observation of such subtle effects and that should be understood more in-depth for future studies on human chemical communication.
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Affiliation(s)
- Stéphane Richard Ortegón
- University Claude Bernard Lyon 1, CNRS UMR5292, INSERM U1028, Lyon Neuroscience Research Center, CH Le Vinatier, Bât. 462 Neurocampus, 95 boulevard Pinel, Bron Cedex 69675, France; Shiseido Group EMEA, 56A rue du Faubourg Saint-Honoré, Paris 75008, France
| | - Olivia Carlos
- Shiseido Group EMEA, 56A rue du Faubourg Saint-Honoré, Paris 75008, France
| | | | - Anne Lelgouarch
- University Claude Bernard Lyon 1, CNRS UMR5292, INSERM U1028, Lyon Neuroscience Research Center, CH Le Vinatier, Bât. 462 Neurocampus, 95 boulevard Pinel, Bron Cedex 69675, France
| | - Clément Desoche
- University Claude Bernard Lyon 1, CNRS UMR5292, INSERM U1028, Lyon Neuroscience Research Center, CH Le Vinatier, Bât. 462 Neurocampus, 95 boulevard Pinel, Bron Cedex 69675, France
| | - Keith Kawabata Duncan
- Shiseido Co., Ltd MIRAI Technology Institute, 1-2-11 Takashima, Nishi-Ku, Yokohama-shi, Kanagawa 220-0011, Japan
| | - Keiko Tagai
- Shiseido Co., Ltd MIRAI Technology Institute, 1-2-11 Takashima, Nishi-Ku, Yokohama-shi, Kanagawa 220-0011, Japan
| | - Arnaud Fournel
- University Claude Bernard Lyon 1, CNRS UMR5292, INSERM U1028, Lyon Neuroscience Research Center, CH Le Vinatier, Bât. 462 Neurocampus, 95 boulevard Pinel, Bron Cedex 69675, France
| | - Moustafa Bensafi
- University Claude Bernard Lyon 1, CNRS UMR5292, INSERM U1028, Lyon Neuroscience Research Center, CH Le Vinatier, Bât. 462 Neurocampus, 95 boulevard Pinel, Bron Cedex 69675, France
| | - Bénédicte Race
- Shiseido Group EMEA, 56A rue du Faubourg Saint-Honoré, Paris 75008, France
| | - Camille Ferdenzi
- University Claude Bernard Lyon 1, CNRS UMR5292, INSERM U1028, Lyon Neuroscience Research Center, CH Le Vinatier, Bât. 462 Neurocampus, 95 boulevard Pinel, Bron Cedex 69675, France.
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How priming with body odors affects decision speeds in consumer behavior. Sci Rep 2023; 13:609. [PMID: 36635353 PMCID: PMC9834684 DOI: 10.1038/s41598-023-27643-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Accepted: 01/05/2023] [Indexed: 01/14/2023] Open
Abstract
To date, odor research has primarily focused on the behavioral effects of common odors on consumer perception and choices. We report a study that examines, for the first time, the effects of human body odor cues on consumer purchase behaviors. The influence of human chemosignals produced in three conditions, namely happiness, fear, a relaxed condition (rest), and a control condition (no odor), were examined on willingness to pay (WTP) judgments across various products. We focused on the speed with which participants reached such decisions. The central finding revealed that participants exposed to human odors reached decisions significantly faster than the no odor control group. The main driving force is that human body odors activate the presence of others during decision-making. This, in turn, affects response speed. The broader implications of this finding for consumer behavior are discussed.
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de Groot JHB, Haertl T, Loos HM, Bachmann C, Kontouli A, Smeets MAM. Unraveling the universality of chemical fear communication: evidence from behavioral, genetic, and chemical analyses. Chem Senses 2023; 48:bjad046. [PMID: 37944028 PMCID: PMC10718800 DOI: 10.1093/chemse/bjad046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Indexed: 11/12/2023] Open
Abstract
Abundant evidence indicates that humans can communicate threat-related information to conspecifics through their body odors. However, prior research has been primarily conducted on Western (WEIRD) samples. In this study, we aimed to investigate whether threat-related information can be transmitted by individuals of East Asian descent who carry a single-nucleotide polymorphism (SNP) 538G → A in the ABCC11 gene, which significantly reduces (noticeable) body odor. To examine this, we recruited 18 self-identified male East Asian AA-homozygotes and 18 self-identified male Western individuals who were carriers of the functional G-allele. We collected samples of their fear-related and neutral body odors. Subsequently, we conducted a double-blind behavioral experiment in which we presented these samples to 69 self-identified female participants of Western Caucasian and East Asian backgrounds. The participants were asked to rate faces that were morphed between expressions of fear and disgust. Notably, despite the "odorless" phenotypical expression of the ABCC11-mutation in East Asians, their fear odor caused a perceptual fear bias in both East Asian and Caucasian receivers. This finding leaves open the possibility of universal fear chemosignaling. Additionally, we conducted exploratory chemical analysis to gain initial insights into the chemical composition of the body odors presented. In a subsequent pre-registered behavioral study (N = 33), we found that exposure to hexadecanoic acid, an abundant compound in the fear and neutral body odor samples, was sufficient to reproduce the observed behavioral effects. While exploratory, these findings provide insight into how specific chemical components can drive chemical fear communication.
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Affiliation(s)
- Jasper H B de Groot
- Behavioural Science Institute, Radboud University, Nijmegen, 6525 XZ, the Netherlands
| | - Tobias Haertl
- Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, 91054, Germany
| | - Helene M Loos
- Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, 91054, Germany
- Department of Chemistry and Pharmacy, Fraunhofer Institute for Process Engineering and Packaging, Freising 85354, Germany
| | - Christin Bachmann
- Department of Social, Health, & Organizational Psychology, Utrecht University, Utrecht, 3584 CS, the Netherlands
| | - Athanasia Kontouli
- Department of Social, Health, & Organizational Psychology, Utrecht University, Utrecht, 3584 CS, the Netherlands
| | - Monique A M Smeets
- Department of Social, Health, & Organizational Psychology, Utrecht University, Utrecht, 3584 CS, the Netherlands
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11
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Roberts SC, Třebická Fialová J, Sorokowska A, Langford B, Sorokowski P, Třebický V, Havlíček J. Emotional expression in human odour. EVOLUTIONARY HUMAN SCIENCES 2022; 4:e44. [PMID: 37588919 PMCID: PMC10426192 DOI: 10.1017/ehs.2022.44] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Revised: 09/02/2022] [Accepted: 09/08/2022] [Indexed: 11/06/2022] Open
Abstract
Recent work has demonstrated that human body odour alters with changing emotional state and that emotionally laden odours can affect the physiology and behaviour of people exposed to them. Here we review these discoveries, which we believe add to a growing recognition that the human sense of smell and its potential role in social interactions have been underappreciated. However, we also critically evaluate the current evidence, with a particular focus on methodology and the interpretation of emotional odour studies. We argue that while the evidence convincingly indicates that humans retain a capacity for olfactory communication of emotion, the extent to which this occurs in ordinary social interaction remains an open question. Future studies should place fewer restrictions on participant selection and lifestyle and adopt more realistic experimental designs. We also need to devote more consideration to underlying mechanisms and to recognise the constraints that these may place on effective communication. Finally, we outline some promising approaches to address these issues, and raise some broader theoretical questions that such approaches may help us to answer.
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Affiliation(s)
| | | | | | - Ben Langford
- UK Centre for Ecology and Hydrology, Penicuik, UK
| | | | - Vít Třebický
- Faculty of Physical Education and Sport, Charles University, Prague, Czech Republic
| | - Jan Havlíček
- Faculty of Science, Charles University, Prague, Czech Republic
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12
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Padilla-Coreano N, Tye KM, Zelikowsky M. Dynamic influences on the neural encoding of social valence. Nat Rev Neurosci 2022; 23:535-550. [PMID: 35831442 PMCID: PMC9997616 DOI: 10.1038/s41583-022-00609-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/27/2022] [Indexed: 11/09/2022]
Abstract
Social signals can serve as potent emotional triggers with powerful impacts on processes from cognition to valence processing. How are social signals dynamically and flexibly associated with positive or negative valence? How do our past social experiences and present social standing shape our motivation to seek or avoid social contact? We discuss a model in which social attributes, social history, social memory, social rank and social isolation can flexibly influence valence assignment to social stimuli, termed here as 'social valence'. We emphasize how the brain encodes each of these four factors and highlight the neural circuits and mechanisms that play a part in the perception of social attributes, social memory and social rank, as well as how these factors affect valence systems associated with social stimuli. We highlight the impact of social isolation, dissecting the neural and behavioural mechanisms that mediate the effects of acute versus prolonged periods of social isolation. Importantly, we discuss conceptual models that may account for the potential shift in valence of social stimuli from positive to negative as the period of isolation extends in time. Collectively, this Review identifies factors that control the formation and attribution of social valence - integrating diverse areas of research and emphasizing their unique contributions to the categorization of social stimuli as positive or negative.
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Affiliation(s)
- Nancy Padilla-Coreano
- Department of Neuroscience, College of Medicine, University of Florida, Gainesville, FL, USA
| | - Kay M Tye
- HHMI-Salk Institute for Biological Studies, La Jolla, CA, USA.
| | - Moriel Zelikowsky
- Department of Neurobiology, School of Medicine, University of Utah, Salt Lake City, UT, USA
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13
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Ravreby I, Snitz K, Sobel N. There is chemistry in social chemistry. SCIENCE ADVANCES 2022; 8:eabn0154. [PMID: 35749498 PMCID: PMC9232116 DOI: 10.1126/sciadv.abn0154] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2021] [Accepted: 05/10/2022] [Indexed: 05/20/2023]
Abstract
Nonhuman terrestrial mammals sniff themselves and each other to decide who is friend or foe. Humans also sniff themselves and each other, but the function of this is unknown. Because humans seek friends who are similar to themselves, we hypothesized that humans may smell themselves and others to subconsciously estimate body odor similarity, which, in turn, may promote friendship. To test this, we recruited nonromantic same-sex friend dyads and harvested their body odor. We found that objective ratings obtained with an electronic nose, and subjective ratings obtained from independent human smellers converged to suggest that friends smell more similar to each other than random dyads. Last, we recruited complete strangers, smelled them with an electronic nose, and engaged them in nonverbal same-sex dyadic interactions. We observed that dyads who smelled more similar had more positive dyadic interactions. In other words, we could predict social bonding with an electronic nose. We conclude that there is indeed chemistry in social chemistry.
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Rekow D, Baudouin JY, Durand K, Leleu A. Smell what you hardly see: Odors assist visual categorization in the human brain. Neuroimage 2022; 255:119181. [PMID: 35413443 DOI: 10.1016/j.neuroimage.2022.119181] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Revised: 01/06/2022] [Accepted: 04/04/2022] [Indexed: 01/23/2023] Open
Abstract
Visual categorization is the brain ability to rapidly and automatically respond to a certain category of inputs. Whether category-selective neural responses are purely visual or can be influenced by other sensory modalities remains unclear. Here, we test whether odors modulate visual categorization, expecting that odors facilitate the neural categorization of congruent visual objects, especially when the visual category is ambiguous. Scalp electroencephalogram (EEG) was recorded while natural images depicting various objects were displayed in rapid 12-Hz streams (i.e., 12 images / second) and variable exemplars of a target category (either human faces, cars, or facelike objects in dedicated sequences) were interleaved every 9th stimulus to tag category-selective responses at 12/9 = 1.33 Hz in the EEG frequency spectrum. During visual stimulation, participants (N = 26) were implicitly exposed to odor contexts (either body, gasoline or baseline odors) and performed an orthogonal cross-detection task. We identify clear category-selective responses to every category over the occipito-temporal cortex, with the largest response for human faces and the lowest for facelike objects. Critically, body odor boosts the response to the ambiguous facelike objects (i.e., either perceived as nonface objects or faces) over the right hemisphere, especially for participants reporting their presence post-stimulation. By contrast, odors do not significantly modulate other category-selective responses, nor the general visual response recorded at 12 Hz, revealing a specific influence on the categorization of congruent ambiguous stimuli. Overall, these findings support the view that the brain actively uses cues from the different senses to readily categorize visual inputs, and that olfaction, which has long been considered as poorly functional in humans, is well placed to disambiguate visual information.
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Affiliation(s)
- Diane Rekow
- Development of Olfactory Communication & Cognition Lab, Center for Taste, Smell & Feeding Behavior, Université Bourgogne Franche-Comté, CNRS, Inrae, Institut Agro Dijon, 21000, Dijon, France.
| | - Jean-Yves Baudouin
- Laboratoire Développement, Individu, Processus, Handicap, Éducation (DIPHE), Département Psychologie du Développement, de l'Éducation et des Vulnérabilités (PsyDÉV), Institut de psychologie, Université de Lyon (Lumière Lyon 2), 5, avenue Pierre-Mendès-France, 69676, Bron, France
| | - Karine Durand
- Development of Olfactory Communication & Cognition Lab, Center for Taste, Smell & Feeding Behavior, Université Bourgogne Franche-Comté, CNRS, Inrae, Institut Agro Dijon, 21000, Dijon, France
| | - Arnaud Leleu
- Development of Olfactory Communication & Cognition Lab, Center for Taste, Smell & Feeding Behavior, Université Bourgogne Franche-Comté, CNRS, Inrae, Institut Agro Dijon, 21000, Dijon, France.
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15
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Cengiz GF, Serin Hİ, Cengiz C. Evaluation of olfactory bulb volume and olfactory sulcus depth in patients with panic disorder and depressive disorder: An MRI study. Indian J Psychiatry 2022; 64:171-177. [PMID: 35494332 PMCID: PMC9045350 DOI: 10.4103/indianjpsychiatry.indianjpsychiatry_466_21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Revised: 11/02/2021] [Accepted: 02/10/2022] [Indexed: 11/05/2022] Open
Abstract
BACKGROUND Although some studies have shown decreases in the olfactory bulb (OB) volume and olfactory function in depressive disorder, there are no studies investigating OB volume in patients with panic disorder. AIM The aim of this study was to investigate whether there was a change in OB volume and olfactory sulcus (OS) depth in patients with panic and depressive disorder when compared with the control group, and which group was more affected by comparing the two disease groups. METHODS Data of 51 patients with panic disorder and 56 patients with depressive disorder were obtained by scanning the database of the hospital retrospectively. The control group consisted of 56 subjects without panic and depressive disorder. OB volume and OS depth measurements were performed on cranial magnetic resonance imaging (MRI). RESULTS Bilateral OB volume of the panic and depressive disorder groups were significantly lower than those of the control group. The lowest volume was found in depressive patients. There was no significant difference between the groups with respect to OS measurements. When OB volume and OS depth differences between the genders were evaluated, a statistically significant difference was not determined. CONCLUSION Reduced OB volume was determined in both panic and depressive disorder patients, and clarification of these preliminary findings may contribute to the pathophysiology of panic and depressive disorders.
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Affiliation(s)
- Gül Ferda Cengiz
- Department of Psychiatry, Nose and Throat, Bozok University School of Medicine, Yozgat, Turkey
| | - Halil İbrahim Serin
- Department of Radiology, Nose and Throat, Bozok University School of Medicine, Yozgat, Turkey
| | - Ceyhun Cengiz
- Department of Ear, Nose and Throat, Bozok University School of Medicine, Yozgat, Turkey
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16
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17
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Tognetti A, Durand V, Dubois D, Barkat-Defradas M, Hopfensitz A, Ferdenzi C. The smell of cooperativeness: Do human body odours advertise cooperative behaviours? Br J Psychol 2021; 113:531-546. [PMID: 34882779 DOI: 10.1111/bjop.12544] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Revised: 11/17/2021] [Accepted: 11/26/2021] [Indexed: 11/27/2022]
Abstract
Several physical features influence the perception of how cooperative a potential partner is. While previous work focused on face and voice, it remains unknown whether body odours influence judgements of cooperativeness and if odour-based judgements are accurate. Here, we first collected axillary odours of cooperative and uncooperative male donors through a public good game and used them as olfactory stimuli in a series of tasks examining whether and how they influence cooperative decision-making in an incentivized economic game and ratings of cooperativeness. Our results show that having access to the donor's body odours provided a strategic advantage to women during economic decisions (but not to men): with age, women were more likely to cooperate with cooperative men and to avoid interacting with uncooperative men. Ratings of cooperativeness were nonetheless unrelated to the donors' actual cooperativeness. Finally, while men with masculine and intense body odours were judged less cooperative, we found no evidence that donors' actual cooperativeness was associated with less masculine or less intense body odour. Overall, our findings suggest that, as faces and voices, body odours influence perceived cooperativeness and might be used accurately and in a non-aware manner as olfactory cues of cooperativeness, at least by women.
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Affiliation(s)
- Arnaud Tognetti
- Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden.,Institute for Advanced Study in Toulouse, Toulouse, France
| | - Valerie Durand
- ISEM, CNRS, IRD, University of Montpellier, Montpellier, France
| | - Dimitri Dubois
- CEE-M, CNRS, INRAE, Institut Agro, University of Montpellier, Montpellier, France
| | | | - Astrid Hopfensitz
- EMLyon business school, Ecully, France.,GATE, Groupe d'Analyse et de Théorie Economique, Ecully, France
| | - Camille Ferdenzi
- Centre de Recherche en Neurosciences de Lyon, Université Claude Bernard Lyon 1, Lyon, France
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A Preliminary Investigation of Interspecific Chemosensory Communication of Emotions: Can Humans ( Homo sapiens) Recognise Fear- and Non-Fear Body Odour from Horses ( Equus ferus caballus). Animals (Basel) 2021; 11:ani11123499. [PMID: 34944275 PMCID: PMC8697966 DOI: 10.3390/ani11123499] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Revised: 11/18/2021] [Accepted: 12/06/2021] [Indexed: 12/22/2022] Open
Abstract
Simple Summary Thus far, little attention has been paid to interspecific odour communication of emotions, and no studies have examined whether humans are able to recognise animal emotions from body odour. Thus, the aim of the present study was to address this question. Body odour samples were collected from 16 two-year-old thoroughbred horses in fear and non-fear situations, respectively. The horse odour samples were then assessed by 73 human odour raters. We found that humans, as a group, were able to correctly assign whether horse odour samples were collected under a fear- or a non-fear condition, respectively. An open question remains, which is whether humans could simply distinguish between little versus much sweat and between high intensity versus low intensity or were able to recognise horses’ fear and non-fear emotions. To conclude, the present results indicate that olfaction might contribute to the human recognition of horse emotions. However, these results should be addressed with caution in light of the study’s limitations and only viewed as exploratory for future studies. Abstract Mammalian body odour conveys cues about an individual’s emotional state that can be recognised by conspecifics. Thus far, little attention has been paid to interspecific odour communication of emotions, and no studies have examined whether humans are able to recognise animal emotions from body odour. Thus, the aim of the present study was to address this question. Body odour samples were collected from 16 two-year-old thoroughbred horses in fear and non-fear situations, respectively. The horse odour samples were then assessed by 73 human odour raters. We found that humans, as a group, were able to correctly assign whether horse odour samples were collected under a fear- or a non-fear condition, respectively. Furthermore, they perceived the body odour of horses collected under the fear condition as more intense, compared with the non-fear condition. An open question remains, which is whether humans could simply distinguish between little versus much sweat and between high intensity versus low intensity or were able to recognise horses’ fear and non-fear emotions. These results appear to fit the notion that the ability to recognise emotions in other species may present an advantage to both the sender and the receiver of emotional cues, particularly in the interaction between humans and domesticated animals. To conclude, the present results indicate that olfaction might contribute to the human recognition of horse emotions. However, these results should be addressed with caution in light of the study’s limitations and only viewed as exploratory for future studies.
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Damon F, Mezrai N, Magnier L, Leleu A, Durand K, Schaal B. Olfaction in the Multisensory Processing of Faces: A Narrative Review of the Influence of Human Body Odors. Front Psychol 2021; 12:750944. [PMID: 34675855 PMCID: PMC8523678 DOI: 10.3389/fpsyg.2021.750944] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Accepted: 09/06/2021] [Indexed: 01/08/2023] Open
Abstract
A recent body of research has emerged regarding the interactions between olfaction and other sensory channels to process social information. The current review examines the influence of body odors on face perception, a core component of human social cognition. First, we review studies reporting how body odors interact with the perception of invariant facial information (i.e., identity, sex, attractiveness, trustworthiness, and dominance). Although we mainly focus on the influence of body odors based on axillary odor, we also review findings about specific steroids present in axillary sweat (i.e., androstenone, androstenol, androstadienone, and estratetraenol). We next survey the literature showing body odor influences on the perception of transient face properties, notably in discussing the role of body odors in facilitating or hindering the perception of emotional facial expression, in relation to competing frameworks of emotions. Finally, we discuss the developmental origins of these olfaction-to-vision influences, as an emerging literature indicates that odor cues strongly influence face perception in infants. Body odors with a high social relevance such as the odor emanating from the mother have a widespread influence on various aspects of face perception in infancy, including categorization of faces among other objects, face scanning behavior, or facial expression perception. We conclude by suggesting that the weight of olfaction might be especially strong in infancy, shaping social perception, especially in slow-maturing senses such as vision, and that this early tutoring function of olfaction spans all developmental stages to disambiguate a complex social environment by conveying key information for social interactions until adulthood.
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Affiliation(s)
- Fabrice Damon
- Developmental Ethology and Cognitive Psychology Laboratory, Centre des Sciences du Goût et de l’Alimentation, Inrae, AgroSup Dijon, CNRS (UMR 6265), Université Bourgogne Franche-Comté, Dijon, France
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Levey EJ. Analyzing from Home: The Virtual Space as a Flexible Container. Psychodyn Psychiatry 2021; 49:425-440. [PMID: 34478328 DOI: 10.1521/pdps.2021.49.3.425] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
This manuscript explores the experience of teleanalysis for analyst and patient during the COVID-19 pandemic through the lenses of embodied intersubjective relating, the neurobiology of social engagement, and technologically mediated human interaction. At the beginning of the pandemic, many analytic dyads were embarking on remote work for the first time. More than a year later, we are facing the question of whether we will ever return to in-person work. In order to unpack this question, it is useful to consider how in-person analysis and in-person interaction more generally differ from remote interaction. Multiple nonverbal modalities are responsible for affective coregulation in intersubjective relating, including voice, body, and shared physical space. While conscious awareness tends to concentrate on auditory and visual inputs, other sensory inputs also impact affective experience. The impact of physical distance upon psychoanalytic treatment is compared with that of the couch. The shift in the balance of power introduced by teleanalysis is considered. Analyzing and being analyzed from home bend the frame of psychoanalysis, complicating notions about distance and intimacy and opening new spaces in which meaning can be cocreated. The COVID-19 pandemic presents an opportunity for psychoanalysis to engage more deeply with the questions raised by teleanalysis in order to enhance our understanding of its impact on treatment.
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Affiliation(s)
- Elizabeth J Levey
- Staff Psychiatrist at the Chester M. Pierce M.D. Division of Global Psychiatry at Massachusetts General Hospital, Instructor in the Department of Psychiatry at Harvard Medical School, and Assistant Professor of Clinical Psychiatry at the Institute for Juvenile Research at the University of Illinois College of Medicine
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21
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Drosophila melanogaster Stress Odorant (dSO) Displays the Characteristics of an Interspecific Alarm Cue. J Chem Ecol 2021; 47:719-731. [PMID: 34402994 DOI: 10.1007/s10886-021-01300-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Revised: 07/01/2021] [Accepted: 07/13/2021] [Indexed: 10/20/2022]
Abstract
Organisms depend on visual, auditory, and olfactory cues to signal the presence of danger that could impact survival and reproduction. Drosophila melanogaster emits an olfactory alarm signal, termed the Drosophila stress odorant (dSO), in response to mechanical agitation or electric shock. While it has been shown that conspecifics avoid areas previously occupied by stressed individuals, the contextual underpinnings of the emission of, and response to dSO, have received little attention. Using a binary choice assay, we determined that neither age and sex of emitters, nor the time of the day, affected the emission or avoidance of dSO. However, both sex and mating status affected the response to dSO. We also demonstrated that while D. melanogaster, D. simulans, and D. suzukii, have different dSO profiles, its avoidance was not species-specific. Thus, dSO should not be considered a pheromone but a general alarm signal for Drosophila. However, the response levels to both intra- and inter-specific cues differed between Drosophila species and possible reasons for these differences are discussed.
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22
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Maa EH, Arnold J, Bush CK. Epilepsy and the smell of fear. Epilepsy Behav 2021; 121:108078. [PMID: 34111768 DOI: 10.1016/j.yebeh.2021.108078] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Revised: 05/11/2021] [Accepted: 05/12/2021] [Indexed: 11/19/2022]
Abstract
OBJECTIVE In our canine scent detection research involving a specific volatile organic compound (VOC) associated with human epileptic seizure, we began to suspect involvement of the primitive neural networks associated with production of a previously undescribed human alarm pheromone as the origin of our seizure scent. We hypothesized that if we presented fear-scented sweat to our canine seizure scent detection team, and they identified the fear scent as their seizure scent, then that would suggest that they are identical compounds. METHODS Following consent and approval, sweat samples taken from volunteers associated with the Brooke Gordon Comprehensive Epilepsy Center at Denver Health were processed by the Canine Assistants (CA) service dog team that had been imprinted to recognize the unique seizure scent from our previous study. In part one, sweat samples were collected from subjects, who had no prior history of epilepsy or seizures, under two different testing environments: watching a scary movie (It) and a neutral/comedy movie (Airplane!). In part two, a larger follow-up study utilizing fear sweat, exercise sweat, epilepsy sweat, and other distractor scents were provided in a multiple choice paradigm to better understand the inter-rater reliability of the canine responses. RESULTS In part one, our canine seizure scent detection team identified fear-scented sweat samples as their seizure scent in 4 of 5 study participants. There was almost perfect agreement of seizure scent detection during fear scent trials between the canine seizure scent detectors with a kappa value of 0.814 (95% CI: 0.668-0.960). In part two, (utilizing eleven different subjects) our canine scent detection team identified samples of either fear or seizure sweat with a sensitivity of 82% and a specificity of 100% (no false positives) from among the multiple choices offered. Additionally, there was 92% agreement between the members of the canine scent detection team. SIGNIFICANCE While this hypothesis testing study is small and deserves replication, it confirms that the Canine Assistants seizure scent detection team consistently and accurately identified fear-scented sweat as their seizure scent, implying that the VOC, menthone, is common to both conditions. This further implies that human seizure propagation and fear network circuitry may share a common anatomy, and that menthone may not only be an early seizure biomarker, but a newly described human alarm pheromone.
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Affiliation(s)
- E H Maa
- Denver Health Medical Center, 777 Bannock Street, Denver, CO 80204, United States; Department of Neurology, University of Colorado, 1635 Aurora Court, Aurora, CO 80045, United States.
| | - J Arnold
- Canine Assistants, 3160 Francis Road, Milton, GA 30004, United States
| | - C K Bush
- Department of Neurology, University of Colorado, 1635 Aurora Court, Aurora, CO 80045, United States
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Spence C. The scent of attraction and the smell of success: crossmodal influences on person perception. Cogn Res Princ Implic 2021; 6:46. [PMID: 34173932 PMCID: PMC8233629 DOI: 10.1186/s41235-021-00311-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Accepted: 06/09/2021] [Indexed: 11/20/2022] Open
Abstract
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.
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Affiliation(s)
- Charles Spence
- Crossmodal Research Laboratory, Department of Experimental Psychology, University of Oxford, Anna Watts Building, Oxford, OX2 6BW, UK.
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Meister L, Pause BM. It's trust or risk? Chemosensory anxiety signals affect bargaining in women. Biol Psychol 2021; 162:108114. [PMID: 33979670 DOI: 10.1016/j.biopsycho.2021.108114] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Revised: 04/30/2021] [Accepted: 05/05/2021] [Indexed: 01/11/2023]
Abstract
It is well documented how chemosensory anxiety signals affect the perceiver's physiology, however, much less is known about effects on overt social behavior. The aim of the present study was to investigate the effects of chemosensory anxiety signals on trust and risk behavior in men and women. Axillary sweat samples were collected from 22 men during the experience of social anxiety, and during a sport control condition. In a series of five studies, the chemosensory stimuli were presented via an olfactometer to 214 participants acting as investors in a bargaining task either in interaction with a fictitious human co-player (trust condition) or with a computer program (risk condition). It could be shown that chemosensory anxiety signals reduce trust and risk behavior in women. In men, no effects were observed. Chemosensory anxiety is discussed to be transmitted contagiously, preferentially in women.
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Affiliation(s)
- Lukas Meister
- Department of Experimental Psychology, Heinrich-Heine-University Düsseldorf, Germany
| | - Bettina M Pause
- Department of Experimental Psychology, Heinrich-Heine-University Düsseldorf, Germany.
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25
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Male mice and cows perceive human emotional chemosignals: a preliminary study. Anim Cogn 2021; 24:1205-1214. [PMID: 33839953 DOI: 10.1007/s10071-021-01511-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Revised: 03/04/2021] [Accepted: 04/01/2021] [Indexed: 12/13/2022]
Abstract
Olfactory cues of individuals of the same species or from different species may induce changes in behaviors and physiological reactions in mammals. However, there are few studies on the influence of human odor on animal behavior and welfare, especially those of rodents and farm animals. The present study aimed to investigate whether the odor of a stressed human (in sweat) would modify the behavior of mice and cows. We hypothesized that laboratory and farm animals can perceive human emotions though olfactory cues and that human emotional chemosignals can modify their behavioral reactions and welfare. Two odors of human axillary sweat were collected from engineering students (n = 25, 14 females and 11 males; 21.1 ± 0.7 years old, range: 19-23 years old): a "stress" odor collected after an exam and a "non-stress" odor collected after a standard class. Two experiments were then conducted to test the discrimination of these two odors by male mice (n = 20) under standard conditions and by cows (n = 10) under farm conditions. During the experiments, the behavioral responses of the animals to both odors (through a dispenser for the mice and a bucket for the cows) were observed. The mice produced significantly (p = 0.004) more fecal pellets with the stress odor dispenser than with the non-stress-odor dispenser. The cows spent significantly (p = 0.04) more time smelling the non-stress-odor bucket than control. For both species, the other behaviors observed did not differ significantly between the odors. Mice and cows seemed to perceive and react to stressful human chemosignals. Mice showed physiological reactions that indicated stress in response to the stress odor of humans, while cows showed preference reactions in response to the non-stress odor of humans. This preliminary study showed that laboratory and farm animals, such as male mice and cows, seemed to discriminate certain odors emitted by humans that were likely related to different emotions. Animals may recognize stressful human chemosignals, associate these signals with negative husbandry practices or human-animal relationships, and consequently modify their behavior.
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26
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Gomes N, Semin GR. The Function of Fear Chemosignals: Preparing for Danger. Chem Senses 2021; 46:6132829. [PMID: 33569586 DOI: 10.1093/chemse/bjab005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
It has been shown that the presence of conspecifics modulates human vigilance strategies as is the case with animal species. Mere presence has been found to reduce vigilance. However, animal research has also shown that chemosignals (e.g., sweat) produced during fear-inducing situations modulate individuals' threat detection strategies. In the case of humans, little is known about how exposure to conspecifics' fear chemosignals modulates vigilance and threat detection effectiveness. This study (N = 59) examined how human fear chemosignals affect vigilance strategies and threat avoidance in its receivers. We relied on a paradigm that simulates a "foraging under threat" situation in the lab, integrated with an eye-tracker to examine the attention allocation. Our results showed that the exposure to fear chemosignals (vs. rest chemosignals and a no-sweat condition) while not changing vigilance behavior leads to faster answers to threatening events. In conclusion, fear chemosignals seem to constitute an important warning signal for human beings, possibly leading their receiver to a readiness state that allows faster reactions to threat-related events.
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Affiliation(s)
- Nuno Gomes
- William James Center for Research, ISPA - Instituto Universitário, Lisbon, Portugal
| | - Gün R Semin
- William James Center for Research, ISPA - Instituto Universitário, Lisbon, Portugal.,Faculty of Social and Behavioral Sciences, Utrecht University, Utrecht, the Netherlands
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27
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Ye Y, Lu Z, Zhou W. Pheromone effects on the human hypothalamus in relation to sexual orientation and gender. HANDBOOK OF CLINICAL NEUROLOGY 2021; 182:293-306. [PMID: 34266600 DOI: 10.1016/b978-0-12-819973-2.00021-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Pheromones are chemicals that serve communicational purposes within a species. In most terrestrial mammals, pheromones are detected by either the olfactory epithelium or the vomeronasal organ and processed by various downstream structures including the medial amygdala and the hypothalamus to regulate motivated behaviors and endocrine responses. The search for human pheromones began in the 1970s. Whereas bioactive ligands are yet to be identified, there has been accumulating evidence that human body odors exert a range of pheromone-like effects on the recipients, including triggering innate behavioral responses, modulating endocrine levels, signaling social information, and affecting mood and cognition. In parallel, results from recent brain imaging studies suggest that body odors evoke distinct neural responses from those observed with common nonsocial odors. Two endogenous steroids androsta-4,16,- dien-3-one and estra-1,3,5(10),16-tetraen-3-ol are considered by some as candidates for human sex pheromones. The two substances produce sexually dimorphic effects on human perception, mood, and physiological arousal. Moreover, they reportedly elicit different hypothalamic response patterns in manners contingent on the recipients' sex and sexual orientation. Neuroendocrine mechanisms underlying the effects of human chemosignals are not yet clear and await future detailed analyses.
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Affiliation(s)
- Yuting Ye
- State Key Laboratory of Brain and Cognitive Science, Institute of Psychology, Chinese Academy of Sciences, Beijing, China; Department of Psychology, University of Chinese Academy of Sciences, Beijing, China
| | - Zhonghua Lu
- Brain Cognition and Brain Disease Institute, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
| | - Wen Zhou
- State Key Laboratory of Brain and Cognitive Science, Institute of Psychology, Chinese Academy of Sciences, Beijing, China; Department of Psychology, University of Chinese Academy of Sciences, Beijing, China.
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28
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Poncet F, Leleu A, Rekow D, Damon F, Durand K, Schaal B, Baudouin JY. Odor-evoked hedonic contexts influence the discrimination of facial expressions in the human brain. Biol Psychol 2020; 158:108005. [PMID: 33290848 DOI: 10.1016/j.biopsycho.2020.108005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Revised: 11/30/2020] [Accepted: 12/01/2020] [Indexed: 10/22/2022]
Abstract
The influence of odor valence on expressive-face perception remains unclear. Here, three "valenced" odor contexts (pleasant, unpleasant, control) were diffused while scalp electroencephalogram (EEG) was recorded in 18 participants presented with expressive faces alternating at a 6-Hz rate. One facial expression (happiness, disgust or neutrality) repeatedly arose every 6 face pictures to isolate its discrimination from other expressions at 1 Hz and harmonics in the EEG spectrum. The amplitude of the brain response to neutrality was larger in the pleasant vs. control odor context, and fewer electrodes responded in the unpleasant odor context. The number of responding electrodes was reduced for disgust in both odor contexts. The response to happiness was unchanged between odor conditions. Overall, these observations suggest that valenced odors influence the neural discrimination of facial expressions depending on both face and odor hedonic valence, especially for the emotionally ambiguous neutral expression.
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Affiliation(s)
- Fanny Poncet
- Developmental Ethology and Cognitive Psychology Group, Centre des Sciences du Goût et de l'Alimentation, UMR 6265 CNRS-Université Bourgogne Franche-Comté-Inrae-AgroSup, Dijon, France.
| | - Arnaud Leleu
- Developmental Ethology and Cognitive Psychology Group, Centre des Sciences du Goût et de l'Alimentation, UMR 6265 CNRS-Université Bourgogne Franche-Comté-Inrae-AgroSup, Dijon, France.
| | - Diane Rekow
- Developmental Ethology and Cognitive Psychology Group, Centre des Sciences du Goût et de l'Alimentation, UMR 6265 CNRS-Université Bourgogne Franche-Comté-Inrae-AgroSup, Dijon, France
| | - Fabrice Damon
- Developmental Ethology and Cognitive Psychology Group, Centre des Sciences du Goût et de l'Alimentation, UMR 6265 CNRS-Université Bourgogne Franche-Comté-Inrae-AgroSup, Dijon, France
| | - Karine Durand
- Developmental Ethology and Cognitive Psychology Group, Centre des Sciences du Goût et de l'Alimentation, UMR 6265 CNRS-Université Bourgogne Franche-Comté-Inrae-AgroSup, Dijon, France
| | - Benoist Schaal
- Developmental Ethology and Cognitive Psychology Group, Centre des Sciences du Goût et de l'Alimentation, UMR 6265 CNRS-Université Bourgogne Franche-Comté-Inrae-AgroSup, Dijon, France
| | - Jean-Yves Baudouin
- Laboratoire "Développement, Individu, Processus, Handicap, Éducation" (DIPHE), Department Psychologie du Développement, de l'Éducation et des Vulnérabilités (PsyDÉV), Institut de psychologie, Université de Lyon (Lumière Lyon 2), Bron, France
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29
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Dal Bò E, Gentili C, Cecchetto C. Human Chemosignals and Brain Activity: A Preliminary Meta-analysis of the Processing of Human Body Odors. Chem Senses 2020; 45:855-864. [PMID: 33179726 DOI: 10.1093/chemse/bjaa067] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Across phyla, chemosignals are a widely used form of social communication and increasing evidence suggests that chemosensory communication is present also in humans. Chemosignals can transfer, via body odors, socially relevant information, such as specific information about identity or emotional states. However, findings on neural correlates of processing of body odors are divergent. The aims of this meta-analysis were to assess the brain areas involved in the perception of body odors (both neutral and emotional) and the specific activation patterns for the perception of neutral body odor (NBO) and emotional body odor (EBO). We conducted an activation likelihood estimation (ALE) meta-analysis on 16 experiments (13 studies) examining brain activity during body odors processing. We found that the contrast EBO versus NBO resulted in significant convergence in the right middle frontal gyrus and the left cerebellum, whereas the pooled meta-analysis combining all the studies of human odors showed significant convergence in the right inferior frontal gyrus. No significant cluster was found for NBOs. However, our findings also highlight methodological heterogeneity across the existing literature. Further neuroimaging studies are needed to clarify and support the existing findings on neural correlates of processing of body odors.
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Affiliation(s)
- Elisa Dal Bò
- Padova Neuroscience Center (PNC), University of Padua, Via Orus 2/B, Padua, Italy.,Department of General Psychology, University of Padua, Via Venezia 8, Padua, Italy
| | - Claudio Gentili
- Padova Neuroscience Center (PNC), University of Padua, Via Orus 2/B, Padua, Italy.,Department of General Psychology, University of Padua, Via Venezia 8, Padua, Italy
| | - Cinzia Cecchetto
- Department of General Psychology, University of Padua, Via Venezia 8, Padua, Italy
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30
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de Groot JHB, Croijmans I, Smeets MAM. More Data, Please: Machine Learning to Advance the Multidisciplinary Science of Human Sociochemistry. Front Psychol 2020; 11:581701. [PMID: 33192899 PMCID: PMC7642605 DOI: 10.3389/fpsyg.2020.581701] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Accepted: 10/05/2020] [Indexed: 12/12/2022] Open
Abstract
Communication constitutes the core of human life. A large portion of our everyday social interactions is non-verbal. Of the sensory modalities we use for non-verbal communication, olfaction (i.e., the sense of smell) is often considered the most enigmatic medium. Outside of our awareness, smells provide information about our identity, emotions, gender, mate compatibility, illness, and potentially more. Yet, body odors are astonishingly complex, with their composition being influenced by various factors. Is there a chemical basis of olfactory communication? Can we identify molecules predictive of psychological states and traits? We propose that answering these questions requires integrating two disciplines: psychology and chemistry. This new field, coined sociochemistry, faces new challenges emerging from the sheer amount of factors causing variability in chemical composition of body odorants on the one hand (e.g., diet, hygiene, skin bacteria, hormones, genes), and variability in psychological states and traits on the other (e.g., genes, culture, hormones, internal state, context). In past research, the reality of these high-dimensional data has been reduced in an attempt to isolate unidimensional factors in small, homogenous samples under tightly controlled settings. Here, we propose big data approaches to establish novel links between chemical and psychological data on a large scale from heterogeneous samples in ecologically valid settings. This approach would increase our grip on the way chemical signals non-verbally and subconsciously affect our social lives across contexts.
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Affiliation(s)
- Jasper H. B. de Groot
- Faculty of Social and Behavioural Sciences, Utrecht University, Utrecht, Netherlands
- Behavioural Science Institute, Radboud University, Nijmegen, Netherlands
| | - Ilja Croijmans
- Faculty of Social and Behavioural Sciences, Utrecht University, Utrecht, Netherlands
| | - Monique A. M. Smeets
- Faculty of Social and Behavioural Sciences, Utrecht University, Utrecht, Netherlands
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31
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Han P, Weber C, Hummel T. Brain response to intranasal trimethylamine stimulation: A preliminary human fMRI study. Neurosci Lett 2020; 735:135166. [PMID: 32574795 DOI: 10.1016/j.neulet.2020.135166] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Revised: 06/04/2020] [Accepted: 06/15/2020] [Indexed: 11/29/2022]
Abstract
The trace amine-associated receptors (TAARs) are a second class of olfactory receptors in humans. They are activated by volatile amines, including pheromone-like odors. However, in humans the neural processing of TAAR-associated signals is not known. Using functional magnetic resonance imaging, the current study investigated brain activation following intra-nasal stimulation with trimethylamine (TMA), an agonist of human TAAR5, and three "canonical" odors with varied valence (an unpleasant odor [n-butanol], a neutral to unpleasant odor [civet musk], and a pleasant odor [phenyl ethyl alcohol]) in 12 healthy young participants. Our hypothesis driven analysis showed that TMA induced a trend for stronger left amygdala activation as compared to the other odors (Family-Wise Error corrected p = 0.08). Whole-brain exploratory analyses revealed superior activation of the cerebellum and caudate to TMA compared to canonical odors, and stronger activation of the anterior cingulate and somatosensory regions (postcentral gyrus and mid cingulate) in response to canonical odors compared to TMA. The current results provide initial evidence on differential central processes of a TAAR mediated stimulus compared to odors targeting canonical olfactory receptors. Future research are needed to elucidate the physiological and psychological relevance of TAARs in humans.
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Affiliation(s)
- Pengfei Han
- Interdisciplinary Center on Smell and Taste, Department of Otorhinolaryngology, TU Dresden, Dresden, Germany; Faculty of Psychology, Southwest University, Chongqing, China; The Key Laboratory of Cognition and Personality, Ministry of Education, Chongqing, China.
| | - Catharina Weber
- Interdisciplinary Center on Smell and Taste, Department of Otorhinolaryngology, TU Dresden, Dresden, Germany
| | - Thomas Hummel
- Interdisciplinary Center on Smell and Taste, Department of Otorhinolaryngology, TU Dresden, Dresden, Germany
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32
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Wisman A, Shrira I. Sexual Chemosignals: Evidence that Men Process Olfactory Signals of Women's Sexual Arousal. ARCHIVES OF SEXUAL BEHAVIOR 2020; 49:1505-1516. [PMID: 32026223 PMCID: PMC7299914 DOI: 10.1007/s10508-019-01588-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2018] [Revised: 11/05/2019] [Accepted: 11/12/2019] [Indexed: 05/27/2023]
Abstract
Research suggests that humans can communicate emotional states (e.g., fear, sadness) via chemosignals. However, thus far little is known about whether sexual arousal can also be conveyed through chemosignals and how these signals might influence the receiver. In three experiments, and a subsequent mini meta-analysis, support was found for the hypothesis that men can process the scent of sexually aroused women and that exposure to these sexual chemosignals affect the subsequent perceptions and sexual motivation of men. Specifically, Experiment 1 revealed that men evaluate the axillary sweat of sexually aroused women as more attractive, compared to the scent of the same women when not sexually aroused. In addition, Experiment 2 showed that exposure to sexual chemosignals increased the men's sexual arousal. Experiment 3 found support for the thesis that exposure to sexual chemosignals would increase sexual motivation. As predicted, men devoted greater attention to and showed greater interest in mating with women who displayed sexual cues (e.g., scantily dressed, in seductive poses). By contrast, exposure to the sexual chemosignals did not alter males' attention and mating interest toward women who displayed no sexual cues. It is discussed how sexual chemosignals may function as an additional channel in the communication of sexual interest and how contextual factors can influence the dynamics of human sexual communication.
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Affiliation(s)
- Arnaud Wisman
- School of Psychology, Keynes College, University of Kent, Canterbury, Kent, CT2 7NP, UK.
| | - Ilan Shrira
- Department of Psychology, Pennsylvania State University, University Park, PA, USA
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33
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Silva F, Gomes N, Korb S, Semin GR. Not All Emotions Are Equal: Fear Chemosignals Lower Awareness Thresholds Only for Fearful Faces. Chem Senses 2020; 45:601-608. [DOI: 10.1093/chemse/bjaa047] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Abstract
Exposure to body odors (chemosignals) collected under different emotional states (i.e., emotional chemosignals) can modulate our visual system, biasing visual perception. Recent research has suggested that exposure to fear body odors, results in a generalized faster access to visual awareness of different emotional facial expressions (i.e., fear, happy, and neutral). In the present study, we aimed at replicating and extending these findings by exploring if these effects are limited to fear odor, by introducing a second negative body odor—that is, disgust. We compared the time that 3 different emotional facial expressions (i.e., fear, disgust, and neutral) took to reach visual awareness, during a breaking continuous flash suppression paradigm, across 3 body odor conditions (i.e., fear, disgust, and neutral). We found that fear body odors do not trigger an overall faster access to visual awareness, but instead sped-up access to awareness specifically for facial expressions of fear. Disgust odor, on the other hand, had no effects on awareness thresholds of facial expressions. These findings contrast with prior results, suggesting that the potential of fear body odors to induce visual processing adjustments is specific to fear cues. Furthermore, our results support a unique ability of fear body odors in inducing such visual processing changes, compared with other negative emotional chemosignals (i.e., disgust). These conclusions raise interesting questions as to how fear odor might interact with the visual processing stream, whilst simultaneously giving rise to future avenues of research.
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Affiliation(s)
- Fábio Silva
- William James Center for Research, Department of Education and Psychology, University of Aveiro, Campus Universitário de Santiago, Aveiro, Portugal
| | - Nuno Gomes
- William James Center for Research, ISPA—Instituto Universitário, Rua Jardim do Tabaco, Lisbon, Portugal
| | - Sebastian Korb
- Department of Psychology, University of Essex, Colchester, UK
- Department of Cognition, Emotion, and Methods in Psychology, University of Vienna, Liebiggasse, Wien, Austria
| | - Gün R Semin
- William James Center for Research, ISPA—Instituto Universitário, Rua Jardim do Tabaco, Lisbon, Portugal
- Faculty of Social and Behavioral Sciences, Utrecht University, Heidelberglaan, Utrecht, The Netherlands
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34
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Sarolidou G, Tognetti A, Lasselin J, Regenbogen C, Lundström JN, Kimball BA, Garke M, Lekander M, Axelsson J, Olsson MJ. Olfactory Communication of Sickness Cues in Respiratory Infection. Front Psychol 2020; 11:1004. [PMID: 32581919 PMCID: PMC7296143 DOI: 10.3389/fpsyg.2020.01004] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Accepted: 04/22/2020] [Indexed: 11/13/2022] Open
Abstract
Animals detect sick conspecifics by way of body odor that enables the receiver to avoid potential infectious transmission. Human observational studies also indicate that different types of disease are associated with more or less aversive smells. In addition, body odors from otherwise healthy human individuals smell more aversive as a function of experimentally induced systemic inflammation. To investigate if naturally occurring immune activation also gives rise to perceivable olfactory changes, we collected body odor samples during two nights from individuals with a respiratory infection as well as when they were healthy. We hypothesized that independent raters would rate the body odor originating from sick individuals as smelling more aversive than when the same individuals were healthy. Even though body odor samples from sick individuals nominally smelled more intense, more disgusting, and less pleasant and healthy than the body odor from the same individuals when healthy, these effects were not statistically significant. Moreover, raters filled out three questionnaires, Perceived Vulnerability to Disease, Disgust Scale, and Health Anxiety, to assess potential associations between sickness-related personality traits and body odor perception. No such association was found. Since experimentally induced inflammation have made body odors more aversive in previous studies, we discuss whether this difference between studies is due to the level of sickness or to the type of trigger of the sickness response.
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Affiliation(s)
- Georgia Sarolidou
- Division of Psychology, Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Arnaud Tognetti
- Division of Psychology, Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Julie Lasselin
- Division of Psychology, Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden.,Stress Research Institute, Stockholm University, Stockholm, Sweden
| | - Christina Regenbogen
- Division of Psychology, Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden.,Research Center Jülich, Institute of Neuroscience and Medicine: Jülich Aachen Research Alliance-Institute Brain Structure Function Relationship (Institut für Neurowissenschaften und Medizin-10), Jülich, Germany.,Department of Psychiatry, Psychotherapy and Psychosomatics, Rheinisch Westfälische Technische Hochschule Aachen University, Aachen, Germany
| | - Johan N Lundström
- Division of Psychology, Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden.,Monell Chemical Senses Center, Philadelphia, PA, United States.,Department of Psychology, University of Pennsylvania, Philadelphia, PA, United States.,Stockholm University Brain Imaging Centre, Stockholm, Sweden
| | - Bruce A Kimball
- Monell Chemical Senses Center, Philadelphia, PA, United States
| | - Maria Garke
- Division of Psychology, Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Mats Lekander
- Division of Psychology, Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden.,Stress Research Institute, Stockholm University, Stockholm, Sweden.,Osher Center for Integrative Medicine, Karolinska Institutet, Stockholm, Sweden
| | - John Axelsson
- Division of Psychology, Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden.,Stress Research Institute, Stockholm University, Stockholm, Sweden.,Osher Center for Integrative Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Mats J Olsson
- Division of Psychology, Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
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35
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de Groot JHB, Kirk PA, Gottfried JA. Encoding fear intensity in human sweat. Philos Trans R Soc Lond B Biol Sci 2020; 375:20190271. [PMID: 32306883 PMCID: PMC7209933 DOI: 10.1098/rstb.2019.0271] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/13/2019] [Indexed: 12/14/2022] Open
Abstract
Humans, like other animals, have an excellent sense of smell that can serve social communication. Although ample research has shown that body odours can convey transient emotions like fear, these studies have exclusively treated emotions as categorical, neglecting the question whether emotion quantity can be expressed chemically. Using a unique combination of methods and techniques, we explored a dose-response function: Can experienced fear intensity be encoded in fear sweat? Specifically, fear experience was quantified using multivariate pattern classification (combining physiological data and subjective feelings with partial least-squares-discriminant analysis), whereas a photo-ionization detector quantified volatile molecules in sweat. Thirty-six male participants donated sweat while watching scary film clips and control (calming) film clips. Both traditional univariate and novel multivariate analysis (100% classification accuracy; Q2: 0.76; R2: 0.79) underlined effective fear induction. Using their regression-weighted scores, participants were assigned significantly above chance (83% > 33%) to fear intensity categories (low-medium-high). Notably, the high fear group (n = 12) produced higher doses of armpit sweat, and greater doses of fear sweat emitted more volatile molecules (n = 3). This study brings new evidence to show that fear intensity is encoded in sweat (dose-response function), opening a field that examines intensity coding and decoding of other chemically communicable states/traits. This article is part of the Theo Murphy meeting issue 'Olfactory communication in humans'.
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Affiliation(s)
- Jasper H. B. de Groot
- Department of Neurology, University of Pennsylvania, 3400 Spruce Street, Philadelphia, PA 19104, USA
- Department of Psychology, Utrecht University, Heidelberglaan 1, Utrecht 3584 CS, The Netherlands
| | - Peter A. Kirk
- Department of Neurology, University of Pennsylvania, 3400 Spruce Street, Philadelphia, PA 19104, USA
| | - Jay A. Gottfried
- Department of Neurology, University of Pennsylvania, 3400 Spruce Street, Philadelphia, PA 19104, USA
- Department of Psychology, University of Pennsylvania, 3720 Walnut Street, Philadelphia, PA 19104, USA
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36
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Calvi E, Quassolo U, Massaia M, Scandurra A, D'Aniello B, D'Amelio P. The scent of emotions: A systematic review of human intra- and interspecific chemical communication of emotions. Brain Behav 2020; 10:e01585. [PMID: 32212329 PMCID: PMC7218249 DOI: 10.1002/brb3.1585] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Revised: 01/05/2020] [Accepted: 02/09/2020] [Indexed: 12/21/2022] Open
Abstract
OBJECTIVE The sense of olfaction has been considered of minor importance in human communication. In recent years, evidence has emerged that humans might be influenced by unconscious messages sent through chemosignals in body odors. Data concerning the ability of humans to recognize fear, maybe related to the evolutionary role of these emotions in the fight-or-flight reactions, are well known. METHODS To further understand the role of emotional chemosignals in mediating communication in humans and its influence on animal behaviors, we conducted a systematic literature review. RESULTS Chemosignals derived from axillary odors collected under a variety of emotional stimuli and sad tears in humans affect receivers' social interactions, danger detection and risk-taking behavior, social aspects of eating, and performance under stressing conditions. In addition, beyond the fight-or-flight response, even the body odors of happiness can be perceived by others. Furthermore, human chemosignals can influence behaviors and stressful responses in animals, particularly dogs and horses, which may partially explain their special relationship with humans. CONCLUSION Our review highlights the importance of chemosignaling in human intra- and interspecific interactions and suggests the need for further investigations, both in physiological conditions and in patients with psychiatric or neurodegenerative disorders.
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Affiliation(s)
- Elisa Calvi
- Department of Medical Sciences, University of Turin, Turin, Italy
| | - Umberto Quassolo
- Department of Medical Sciences, University of Turin, Turin, Italy
| | | | - Anna Scandurra
- Department of Biology, University of Naples "Federico II", Naples, Italy
| | - Biagio D'Aniello
- Department of Biology, University of Naples "Federico II", Naples, Italy
| | - Patrizia D'Amelio
- Department of Medical Sciences, University of Turin, Turin, Italy.,Department of Medicine, Geriatric Medicine and Geriatric Rehabilitation, CHUV, Lausanne University Hospital, Lausanne, Switzerland
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37
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Roberts SC, Misztal PK, Langford B. Decoding the social volatilome by tracking rapid context-dependent odour change. Philos Trans R Soc Lond B Biol Sci 2020; 375:20190259. [PMID: 32306868 DOI: 10.1098/rstb.2019.0259] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Odours can have a significant influence on the outcome of social interactions. However, we have yet to characterize the chemical signature of any specific social cue in human body odour, and we know little about how changes in social context influence odour chemistry. Here, we argue that adoption of emerging analytical techniques from other disciplines, such as atmospheric chemistry, might become game-changing tools in this endeavour. First, we describe the use of online chemical ionization time-of-flight mass spectrometry to sensitively measure many hundreds of gas-phase volatile organic compounds in real time. By analysing ambient air emanating from undisturbed individuals or groups, the technique enables a continuous recording of an instantaneous odour change in response to external stimuli and changing social context. This has considerable advantages over the traditional approach of periodic sampling for analysis by gas chromatography. We also discuss multivariate statistical approaches, such as positive matrix factorization, that can effectively sift through this complex datastream to identify linked groups of compounds that probably underpin functional chemosignals. In combination, these innovations offer new avenues for addressing outstanding questions concerning olfactory communication in humans and other species, as well as in related fields using odour, such as biometrics and disease diagnostics. This article is part of the Theo Murphy meeting issue 'Olfactory communication in humans'.
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Affiliation(s)
- S Craig Roberts
- Division of Psychology, Faculty of Natural Sciences, University of Stirling, Stirling FK9 4LA, UK
| | - Pawel K Misztal
- Department of Civil, Architectural and Environmental Engineering, The University of Texas at Austin, Austin, TX 78712, USA.,Centre for Ecology & Hydrology, Edinburgh EH26 0QB, UK
| | - Ben Langford
- Centre for Ecology & Hydrology, Edinburgh EH26 0QB, UK
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38
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Fialová J, Třebický V, Kuba R, Stella D, Binter J, Havlíček J. Losing stinks! The effect of competition outcome on body odour quality. Philos Trans R Soc Lond B Biol Sci 2020; 375:20190267. [PMID: 32306874 DOI: 10.1098/rstb.2019.0267] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Dominance hierarchy is often established via repeated agonistic encounters where consistent winners are considered dominant. Human body odour contains cues to psychological dominance and competition, but it is not known whether competition outcome (a marker of a change in dominance hierarchy) affects the hedonic quality of human axillary odour. Therefore, we investigated the effect of winning and losing on odour quality. We collected odour samples from Mixed Martial Arts fighters approximately 1 h before and immediately after a match. Raters then assessed samples for pleasantness, attractiveness, masculinity and intensity. We also obtained data on donors' affective state and cortisol and testosterone levels, since these are known to be associated with competition and body odour quality. Perceived body odour pleasantness, attractiveness and intensity significantly decreased while masculinity increased after a match irrespective of the outcome. Nonetheless, losing a match affected the pleasantness of body odour more profoundly, though bordering formal level of significance. Moreover, a path analysis revealed that match loss led to a decrease in odour attractiveness, which was mediated by participants' negative affective states. Our study suggests that physical competition and to some extent also its outcome affect the perceived quality of human body odour in specific real-life settings, thus providing cues to dominance-related characteristics. This article is part of the Theo Murphy meeting issue 'Olfactory communication in humans'.
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Affiliation(s)
- Jitka Fialová
- Faculty of Science, Charles University, Viničná 7, Prague 128 43, Czech Republic.,National Institute of Mental Health, Topolová 748, Klecany 250 67, Czech Republic
| | - Vít Třebický
- National Institute of Mental Health, Topolová 748, Klecany 250 67, Czech Republic.,Faculty of Physical Education and Sport, Charles University, José Martího 31, Prague 162 52, Czech Republic
| | - Radim Kuba
- Faculty of Science, Charles University, Viničná 7, Prague 128 43, Czech Republic
| | - David Stella
- Faculty of Science, Charles University, Viničná 7, Prague 128 43, Czech Republic.,National Institute of Mental Health, Topolová 748, Klecany 250 67, Czech Republic
| | - Jakub Binter
- Faculty of Science, Charles University, Viničná 7, Prague 128 43, Czech Republic
| | - Jan Havlíček
- Faculty of Science, Charles University, Viničná 7, Prague 128 43, Czech Republic.,National Institute of Mental Health, Topolová 748, Klecany 250 67, Czech Republic
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Smeets MA, Rosing EA, Jacobs DM, van Velzen E, Koek JH, Blonk C, Gortemaker I, Eidhof MB, Markovitch B, de Groot J, Semin GR. Chemical Fingerprints of Emotional Body Odor. Metabolites 2020; 10:E84. [PMID: 32121157 PMCID: PMC7142800 DOI: 10.3390/metabo10030084] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2020] [Revised: 02/22/2020] [Accepted: 02/24/2020] [Indexed: 01/10/2023] Open
Abstract
Chemical communication is common among animals. In humans, the chemical basis of social communication has remained a black box, despite psychological and neural research showing distinctive physiological, behavioral, and neural consequences of body odors emitted during emotional states like fear and happiness. We used a multidisciplinary approach to examine whether molecular cues could be associated with an emotional state in the emitter. Our research revealed that the volatile molecules transmitting different emotions to perceivers also have objectively different chemical properties. Chemical analysis of underarm sweat collected from the same donors in fearful, happy, and emotionally neutral states was conducted using untargeted two-dimensional (GC×GC) coupled with time of flight (ToF) MS-based profiling. Based on the multivariate statistical analyses, we find that the pattern of chemical volatiles (N = 1655 peaks) associated with fearful state is clearly different from that associated with (pleasant) neutral state. Happy sweat is also significantly different from the other states, chemically, but shows a bipolar pattern of overlap with fearful as well as neutral state. Candidate chemical classes associated with emotional and neutral sweat have been identified, specifically, linear aldehydes, ketones, esters, and cyclic molecules (5 rings). This research constitutes a first step toward identifying the chemical fingerprints of emotion.
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Affiliation(s)
- Monique A.M. Smeets
- Unilever R&D Vlaardingen, Olivier van Noortlaan 120, 3133 AT Vlaardingen, The Netherlands; (E.A.E.R.); (D.M.J.); (E.v.V.); (J.H.K.); (C.B.); (I.G.)
- Faculty of Social and Behavioural Sciences, Utrecht University, Heidelberglaan 1, 3584 CS Utrecht, The Netherlands; (M.B.E.); (B.M.); (J.d.G.); (G.R.S.)
| | - Egge A.E. Rosing
- Unilever R&D Vlaardingen, Olivier van Noortlaan 120, 3133 AT Vlaardingen, The Netherlands; (E.A.E.R.); (D.M.J.); (E.v.V.); (J.H.K.); (C.B.); (I.G.)
| | - Doris M. Jacobs
- Unilever R&D Vlaardingen, Olivier van Noortlaan 120, 3133 AT Vlaardingen, The Netherlands; (E.A.E.R.); (D.M.J.); (E.v.V.); (J.H.K.); (C.B.); (I.G.)
| | - Ewoud van Velzen
- Unilever R&D Vlaardingen, Olivier van Noortlaan 120, 3133 AT Vlaardingen, The Netherlands; (E.A.E.R.); (D.M.J.); (E.v.V.); (J.H.K.); (C.B.); (I.G.)
| | - Jean H. Koek
- Unilever R&D Vlaardingen, Olivier van Noortlaan 120, 3133 AT Vlaardingen, The Netherlands; (E.A.E.R.); (D.M.J.); (E.v.V.); (J.H.K.); (C.B.); (I.G.)
| | - Cor Blonk
- Unilever R&D Vlaardingen, Olivier van Noortlaan 120, 3133 AT Vlaardingen, The Netherlands; (E.A.E.R.); (D.M.J.); (E.v.V.); (J.H.K.); (C.B.); (I.G.)
| | - Ilse Gortemaker
- Unilever R&D Vlaardingen, Olivier van Noortlaan 120, 3133 AT Vlaardingen, The Netherlands; (E.A.E.R.); (D.M.J.); (E.v.V.); (J.H.K.); (C.B.); (I.G.)
| | - Marloes B. Eidhof
- Faculty of Social and Behavioural Sciences, Utrecht University, Heidelberglaan 1, 3584 CS Utrecht, The Netherlands; (M.B.E.); (B.M.); (J.d.G.); (G.R.S.)
| | - Benyamin Markovitch
- Faculty of Social and Behavioural Sciences, Utrecht University, Heidelberglaan 1, 3584 CS Utrecht, The Netherlands; (M.B.E.); (B.M.); (J.d.G.); (G.R.S.)
| | - Jasper de Groot
- Faculty of Social and Behavioural Sciences, Utrecht University, Heidelberglaan 1, 3584 CS Utrecht, The Netherlands; (M.B.E.); (B.M.); (J.d.G.); (G.R.S.)
| | - Gün R. Semin
- Faculty of Social and Behavioural Sciences, Utrecht University, Heidelberglaan 1, 3584 CS Utrecht, The Netherlands; (M.B.E.); (B.M.); (J.d.G.); (G.R.S.)
- William James Center for Research, ISPA-Instituto Universitário, 1149-041 Lisboa, Portugal
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Maier A, Heinen-Ludwig L, Güntürkün O, Hurlemann R, Scheele D. Childhood Maltreatment Alters the Neural Processing of Chemosensory Stress Signals. Front Psychiatry 2020; 11:783. [PMID: 32848947 PMCID: PMC7425696 DOI: 10.3389/fpsyt.2020.00783] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Accepted: 07/22/2020] [Indexed: 12/20/2022] Open
Abstract
Accumulating evidence suggests that childhood maltreatment (CM) confers risk for psychopathology later in life by inducing hypervigilance to social threat cues such as fearful faces. However, it remains unclear whether the modulatory impact of CM extents to the olfactory domain of social communication in humans. To address this question, we examined whether CM modulates the neural processing of chemosensory threat signals in sweat and whether CM affects the stress-reducing effects of oxytocin (OXT) in this context. In a randomized, double-blind within-subject functional MRI study design, 58 healthy participants (30 females) received intranasal OXT (40 IU) or placebo (PLC) and completed a forced-choice emotion recognition task with faces of varying emotion intensities (neutral to fearful) while exposed to sweat stimuli and a non-social control odor. Axillary sweat samples were collected from 30 healthy male donors undergoing an acute psychosocial stressor (stress) and ergometer training (sport) as control in a pre-study. CM was assessed by the 25-item Childhood Trauma Questionnaire (CTQ). The final fMRI analysis included 50 healthy participants (26 females). Regression analysis showed a stress-specific association of CTQ scores with amygdala hyperreactivity, hippocampal deactivation, and increased functional connectivity between the amygdala and the hippocampus, medial orbitofrontal cortex, and the anterior cingulate cortex (ACC) under PLC. Furthermore, we observed a positive association of CTQ scores and the dampening effects of OXT on stress-related amygdala responses. Our findings suggest that CM may induce hypervigilance to chemosensory threat cues in a healthy sample due to inefficient frontolimbic inhibition of amygdala activation. Future studies should investigate whether increased recruitment of the intralimbic amygdala-hippocampus complex reflects a compensatory mechanism that prevents the development of psychopathology in those who have experienced CM. Furthermore, the results reveal that the stress-specific effects of OXT in the olfactory domain are more pronounced in participants with increasing levels of CM exposure.
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Affiliation(s)
- Ayline Maier
- Division of Medical Psychology, Department of Psychiatry and Psychotherapy, University Hospital Bonn, Bonn, Germany
| | - Luca Heinen-Ludwig
- Division of Medical Psychology, Department of Psychiatry and Psychotherapy, University Hospital Bonn, Bonn, Germany
| | - Onur Güntürkün
- Department of Psychology, Laboratory for Biological Psychology, Ruhr-University of Bochum, Bochum, Germany
| | - René Hurlemann
- Department of Psychiatry, School of Medicine & Health Sciences, University of Oldenburg, Oldenburg, Germany.,Research Center Neurosensory Science, University of Oldenburg, Oldenburg, Germany
| | - Dirk Scheele
- Division of Medical Psychology, Department of Psychiatry and Psychotherapy, University Hospital Bonn, Bonn, Germany.,Department of Psychiatry, School of Medicine & Health Sciences, University of Oldenburg, Oldenburg, Germany
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41
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Scopa C, Contalbrigo L, Greco A, Lanatà A, Scilingo EP, Baragli P. Emotional Transfer in Human-Horse Interaction: New Perspectives on Equine Assisted Interventions. Animals (Basel) 2019; 9:E1030. [PMID: 31779120 PMCID: PMC6941042 DOI: 10.3390/ani9121030] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Revised: 11/19/2019] [Accepted: 11/22/2019] [Indexed: 12/16/2022] Open
Abstract
Equine assisted interventions (EAIs) include all therapeutic interventions aimed at improving human wellbeing through the involvement of horses. Due to the prominent emotional involvement traditionally characterizing their relation with humans, horses developed sophisticated communicative skills, which fostered their ability to respond to human emotional states. In this review, we hypothesize that the proximate causation of successful interventions could be human-animal mutual coordination, through which the subjects bodily and, most importantly, emotionally come into contact. We propose that detecting emotions of other individuals and developing the capacity to fine-tune one's own emotional states accordingly (emotional transfer mechanism), could represent the key engine triggering the positive effects of EAIs. We provide a comprehensive analysis of horses' socio-emotional competences according to recent literature and we propose a multidisciplinary approach to investigate this inter-specific match. By considering human and horse as a unique coupling system during the interaction, it would be possible to objectively measure the degree of coordination through the analysis of physiological variables of both human and animal. Merging the state of art on human-horse relationship with the application of novel methodologies, could help to improve standardized protocols for animal assisted interventions, with particular regard to the emotional states of subjects involved.
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Affiliation(s)
- Chiara Scopa
- Italian National Reference Centre for Animal Assisted Interventions, Istituto Zooprofilattico Sperimentale delle Venezie, 35020 Legnaro (Padua), Italy;
| | - Laura Contalbrigo
- Italian National Reference Centre for Animal Assisted Interventions, Istituto Zooprofilattico Sperimentale delle Venezie, 35020 Legnaro (Padua), Italy;
| | - Alberto Greco
- Department of Information Engineering, University of Pisa, 56122 Pisa, Italy; (A.G.); (A.L.); (E.P.S.)
- Feel-Ing s.r.l., 56122 Pisa, Italy
| | - Antonio Lanatà
- Department of Information Engineering, University of Pisa, 56122 Pisa, Italy; (A.G.); (A.L.); (E.P.S.)
- Feel-Ing s.r.l., 56122 Pisa, Italy
| | - Enzo Pasquale Scilingo
- Department of Information Engineering, University of Pisa, 56122 Pisa, Italy; (A.G.); (A.L.); (E.P.S.)
- Feel-Ing s.r.l., 56122 Pisa, Italy
| | - Paolo Baragli
- Department of Veterinary Sciences, University of Pisa, 56124 Pisa, Italy;
- Bioengineering and Robotic Research Center “E. Piaggio”, University of Pisa, 56122 Pisa, Italy
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42
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Oren C, Shamay-Tsoory SG. Women's Body Odor during Ovulation Improves Social Perception in Single Men. Chem Senses 2019; 44:653-662. [PMID: 31412102 DOI: 10.1093/chemse/bjz053] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Previous research has shown that men's mating motivation may increase following exposure to women's body odor during ovulation. In the current study, we examined whether exposure to women's fertility odor cues influences social perception among men, while focusing on the role of men's relationship status in moderating this reaction. We collected body odor samples from 43 women during ovulation and during the luteal phase and exposed 85 men to these odor samples while they performed an emotion recognition task and an interpersonal perception task. Single men were better at recognizing emotional facial expressions following exposure to odor cues of high fertility as compared with odor cues of low fertility. No such effect was identified in pair-bonded men. In support of this finding, single men became more accurate on the interpersonal perception task following exposure to odor cues of high fertility, while pair-bonded men became less accurate after such exposure. Collectively, the results suggest that exposure to women's fertility odor cues improves social perception among single men, while it impairs such perception among pair-bonded men. We suggest that these effects may result from increased mating motivation following exposure to odor cues of fertility, which in turn encourages accurate social perception among single men while promoting an avoidant attitude toward social stimuli among pair-bonded men.
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Affiliation(s)
- Chen Oren
- Department of Psychology, University of Haifa, Mount Carmel, Haifa, Israel
| | - Simone G Shamay-Tsoory
- Department of Psychology, University of Haifa, Mount Carmel, Haifa, Israel.,The Integrated Brain and Behavior Research Center (IBBR), University of Haifa, Haifa, Israel
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43
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Ferdenzi C, Razafindrazaka H, Baldovini N, Poupon D, Pierron D, Bensafi M. Influence of gender and culture on the perception of acidic compounds of human body odor. Physiol Behav 2019; 210:112561. [PMID: 31178171 DOI: 10.1016/j.physbeh.2019.112561] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Revised: 04/17/2019] [Accepted: 05/24/2019] [Indexed: 12/26/2022]
Abstract
There is increasing evidence that human body odor is involved in interpersonal communication. However, among the wide variety of substances excreted by the human body that might act as chemosignals, much attention has been granted to androstenes to the detriment of other categories. Here, we focused on the acidic fraction of human body odor. We investigated men and women's perceptual descriptions and detection thresholds of the sexually dimorphic (male) compound 3-hydroxy-3-methylhexanoic acid (HMHA) in two contrasted cultures, France and Madagascar. Perceptual responses to HMHA in both countries were very similar. HMHA proved to be more typical of body odor than another chemically-related major compound of human body odor 3MHA (3-methylhex-2-enoic acid also known as 3M2H). A significant portion of the samples studied (between 8 and 19%) was likely to be anosmic to HMHA (and to 3MHA: 25%). Although differences would be expected between men and women's perceptual responses to HMHA, based on the assumption that this compound would have a function in human partner choice, no sex differences were found for any of the perceptual variables. However, in Malagasy women, perceived intensity of HMHA was higher in participants who were in the fertile phase of the menstrual cycle. Whether HMHA is relevant in the perception of a potential partner thus requires further explorations, with more implicit approaches for example and/or by investigating the repercussions of HMHA specific anosmia on interpersonal relationships.
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Affiliation(s)
- Camille Ferdenzi
- Centre de Recherche en Neurosciences de Lyon, CNRS UMR 5292, INSERM U1028, Université Claude Bernard Lyon 1, Centre Hospitalier Le Vinatier, 95 bd Pinel, 69675 Bron Cedex, France.
| | - Harilanto Razafindrazaka
- Laboratoire d'Anthropologie Moléculaire et Imagerie de Synthèse, CNRS UMR 5288, Université Toulouse 3, 37 Allées Jules Guesde, 31073 Toulouse Cedex 3, France; Aix Marseille Univ, CNRS, EFS, ADES, Marseille, France; Institute for Advanced Study in Toulouse, 21 allée de Brienne, 31015 Cedex 6, Toulouse, France
| | - Nicolas Baldovini
- Institut de Chimie de Nice, CNRS UMR 7272, Université de Nice-Sophia Antipolis, Parc Valrose, 28 avenue Valrose, 06108 Nice Cedex 2, France
| | - Daphnée Poupon
- Centre de Recherche en Neurosciences de Lyon, CNRS UMR 5292, INSERM U1028, Université Claude Bernard Lyon 1, Centre Hospitalier Le Vinatier, 95 bd Pinel, 69675 Bron Cedex, France
| | - Denis Pierron
- Laboratoire d'Anthropologie Moléculaire et Imagerie de Synthèse, CNRS UMR 5288, Université Toulouse 3, 37 Allées Jules Guesde, 31073 Toulouse Cedex 3, France
| | - Moustafa Bensafi
- Centre de Recherche en Neurosciences de Lyon, CNRS UMR 5292, INSERM U1028, Université Claude Bernard Lyon 1, Centre Hospitalier Le Vinatier, 95 bd Pinel, 69675 Bron Cedex, France
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44
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Lanata A, Nardelli M, Valenza G, Baragli P, DrAniello B, Alterisio A, Scandurra A, Semin GR, Scilingo EP. A Case for the Interspecies Transfer of Emotions: A Preliminary Investigation on How Humans Odors Modify Reactions of the Autonomic Nervous System in Horses. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2019; 2018:522-525. [PMID: 30440449 DOI: 10.1109/embc.2018.8512327] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
We examined the Autonomic Nervous System (ANS) activity of horses in response to human body odors (BOs) produced under happy and fear states. The ANS response of horses was analyzed in terms of Heart Rate Variability (HRV) features extracted in the frequency domain. Our results revealed that human BOs induce sympathetic and parasympathetic changes and stimulate horses emotionally, suggesting interspecies transfer of emotions via BOs. These preliminary findings open the way to measure changes in horse's ANS dynamics in response to human internal states via human BOs, and allow us to better understand unexpected animal behavior that could compromise human-horse interaction. Moreover, it becomes possible to design more effective strategies to manage animals across a range of situations in which a strict humananimal interaction is required, such as the well known Animal Assisted Therapy (AAT).
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45
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Quintana P, Nolet K, Baus O, Bouchard S. The Effect of Exposure to Fear-Related Body Odorants on Anxiety and Interpersonal Trust Toward a Virtual Character. Chem Senses 2019; 44:683-692. [DOI: 10.1093/chemse/bjz063] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Abstract
A growing body of literature documents how exposure to another person's fear-related body odorants can increase one's own anxiety and interfere with processing of social information, such as facial expression and impression formation. Building on these results, we aimed to 1) test the hypothesis that exposure to fear-related odorant would affect impression formation through fear contagion and 2) verify whether these effects can be observed in an ecologically valid (i.e., virtual) environment. We proposed that exposure to fear-related odorant would cause receivers to feel more anxious, which in turn would lead them to report less trust toward an unknown virtual character. This study had 2 distinct phases. First, we collected perspiration odorants from the armpits of 12 male senders (i.e., the source of the odorant) during the viewing of either fear or joy inducing film clips. In the second phase, 53 women receivers were exposed to either a fear, joy, or neutral odorant (i.e., between-subjects design) by breathing through a gauze attached to a disposable respirator mask while immersed in a virtual bar. As expected, receivers exposed to fear odorants felt significantly more stressed. Mediation analysis also revealed an indirect effect of exposure on trust through anxiety. More specifically, the more anxious the receiver felt, the less she trusted the virtual character. Our results show for the first time that the impact of exposure to fear-related body odorants on negative interpersonal impression formation is mediated by the anxiety induced in the receiver.
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Affiliation(s)
- Pamela Quintana
- Département de psychoéducation et de psychologie, University of Quebec in Outaouais (UQO), Gatineau, Quebec, Canada
| | - Kévin Nolet
- Département de psychoéducation et de psychologie, University of Quebec in Outaouais (UQO), Gatineau, Quebec, Canada
| | - Oliver Baus
- School of psychology, University of Ottawa, Ontario, Canada
| | - Stéphane Bouchard
- Département de psychoéducation et de psychologie, University of Quebec in Outaouais (UQO), Gatineau, Quebec, Canada
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46
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van Nieuwenburg D, de Groot JHB, Smeets MAM. The Subtle Signaling Strength of Smells: A Masked Odor Enhances Interpersonal Trust. Front Psychol 2019; 10:1890. [PMID: 31481913 PMCID: PMC6710396 DOI: 10.3389/fpsyg.2019.01890] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Accepted: 07/31/2019] [Indexed: 12/22/2022] Open
Abstract
Most everyday smells, from lavender to body odors, are complex odorant mixtures that “host” particular compounds that guide (social) behavior and motivation (biomarkers). A key element of social behavior is interpersonal trust, and building on previous research showing that (i) lavender odor can enhance trust, and that (ii) certain compounds in body odor can reduce stress in mice and humans (called “social buffering”), we examined whether a grassy-smelling compound found in both body odors and lavender, hexanal, would enhance interpersonal trust. Notably, we applied odor masking to explore whether trust could be influenced subconsciously by masked (i.e., undetectable) hexanal. In Study 1 (between-subjects), 90 females played a Trust Game while they either smelled hexanal (0.01% v/v), clove odor (eugenol: 10% v/v), or hexanal masked by clove odor (a mix of the former). As a sign of higher trust, participants gave more money to a trustee while exposed to masked hexanal (vs. the mask: eugenol). In Study 2 (within-subjects, double-blind), another sample of 35 females smelled the same three odors, while they rated the trustworthiness of a spectrum of faces that varied on trustworthiness. Controlling for subjective odor intensity and pleasantness and substantiating that masked hexanal could not be distinguished from the mask, faces were perceived as more trustworthy during exposure to masked hexanal (vs. the mask: eugenol). Whereas non-masked hexanal also increased face trustworthiness ratings, these effects disappeared after controlling for the odor’s subjective intensity and pleasantness. The combined results bring new evidence that trust can be enhanced implicitly via undetected smells.
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Affiliation(s)
- Daan van Nieuwenburg
- Department of Psychology, Faculty of Social and Behavioral Sciences, Utrecht University, Utrecht, Netherlands
| | - Jasper H B de Groot
- Department of Psychology, Faculty of Social and Behavioral Sciences, Utrecht University, Utrecht, Netherlands.,Department of Neurology, University of Pennsylvania, Philadelphia, PA, United States
| | - Monique A M Smeets
- Department of Psychology, Faculty of Social and Behavioral Sciences, Utrecht University, Utrecht, Netherlands
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47
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Singh PB, Young A, Lind S, Leegaard MC, Capuozzo A, Parma V. Smelling Anxiety Chemosignals Impairs Clinical Performance of Dental Students. Chem Senses 2019; 43:411-417. [PMID: 29767685 DOI: 10.1093/chemse/bjy028] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Despite the fact that human body odors can transfer anxiety-related signals, the impact of such signals in real-life situations is scant. In this study, the effects of anxiety chemosignals on the performance of dental students operating on simulation units, wearing T-shirts imbued with human sweat and masked with eugenol were tested. A total of 24 fourth-year dental students (17 F) donated their body odors in two sessions (Anxiety and Rest). Twenty-four normosmic, sex- and age-matched test subjects who were third-year dental students performed 3 dental procedures while smelling masked anxiety body odors, masked rest body odors, or masker alone. The intensity and pleasantness ratings showed that the test subjects could not report perceptual differences between the odor conditions. When exposed to masked anxiety body odors, the test subjects' dental performance was significantly worse than when they were exposed to masked rest body odors and masker alone, indicating that their performance was modulated by exposure to the emotional tone of the odor. These findings call for a careful evaluation of the anxiety-inducing effects of body odors in performance-related tasks and provide the first ecological evaluation of human anxiety chemosignal communication.
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Affiliation(s)
- Preet Bano Singh
- Institute of Clinical Dentistry, Faculty of Dentistry, University of Oslo, Oslo, Norway
| | - Alix Young
- Institute of Clinical Dentistry, Faculty of Dentistry, University of Oslo, Oslo, Norway
| | - Synnøve Lind
- Institute of Clinical Dentistry, Faculty of Dentistry, University of Oslo, Oslo, Norway
| | | | - Alessandra Capuozzo
- Department of Neuroscience Area, International School for Advanced Studies (SISSA), Trieste, Italy
| | - Valentina Parma
- Department of Neuroscience Area, International School for Advanced Studies (SISSA), Trieste, Italy.,Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden.,William James Research Center (WJCR), Instituto Superior de Psicologia Aplicada (ISPA), Lisbon, Portugal
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48
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Ferreira J, Parma V, Alho L, Silva CF, Soares SC. Emotional Body Odors as Context: Effects on Cardiac and Subjective Responses. Chem Senses 2019; 43:347-355. [PMID: 29617740 DOI: 10.1093/chemse/bjy021] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Many studies have indicated that the chemical cues from body odors (BOs) of donors experiencing negative emotions can influence the psychophysiological and behavioral response of the observers. However, these olfactory cues have been used mainly as contextual information for processing visual stimuli. Here, for the first time, we evaluate how emotional BO affects the emotional tone of a subsequent BO message. Axillary sweat samples were taken from 20 donors in 3 separate sessions while they watched fear, disgust, or neutral videos. In a double-blind experiment, we assessed the cardiac and subjective responses from 69 participants who were either exposed to negative emotional or neutral BOs. Our results showed a reduced cardiac parasympathetic activity (HF%)-indicating increased stress-when participants smelled the emotional BOs before the neutral BOs, compared to when they smelled neutral followed by emotional BOs. The intensity of the neutral odor also increased following the exposure to both negative BOs. These findings indicate that BOs contain an emotion-dependent chemical cue that affects the perceiver both at the physiological and subjective levels.
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Affiliation(s)
- Jacqueline Ferreira
- CINTESIS.UA, Department of Education and Psychology, University of Aveiro, Aveiro, Portugal.,Institute for Biomedical Imaging and Life Sciences (IBILI), Faculty of Medicine, University of Coimbra, Coimbra, Portugal
| | - Valentina Parma
- William James Centre for Research (WJCR), Instituto Superior de Psicologia Aplicada (ISPA), Lisbon, Portugal.,International School for Advanced Studies (SISSA), Neuroscience Area, Trieste, Italy.,Department of Clinical Neuroscience, Division for Psychology, Karolinska Institutet, Stockholm, Sweden
| | - Laura Alho
- Lusófona University of Humanities and Technology, Lisbon, Portugal.,Instituto Universitário de Lisboa (ISCTE-IUL), CIS-IUL, Lisbon, Portugal
| | - Carlos F Silva
- CINTESIS.UA, Department of Education and Psychology, University of Aveiro, Aveiro, Portugal
| | - Sandra C Soares
- CINTESIS.UA, Department of Education and Psychology, University of Aveiro, Aveiro, Portugal.,Institute for Biomedical Imaging and Life Sciences (IBILI), Faculty of Medicine, University of Coimbra, Coimbra, Portugal.,Department of Clinical Neuroscience, Division for Psychology, Karolinska Institutet, Stockholm, Sweden
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49
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Body odors (even when masked) make you more emotional: behavioral and neural insights. Sci Rep 2019; 9:5489. [PMID: 30940875 PMCID: PMC6445102 DOI: 10.1038/s41598-019-41937-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2018] [Accepted: 03/18/2019] [Indexed: 12/19/2022] Open
Abstract
Morality evolved within specific social contexts that are argued to shape moral choices. In turn, moral choices are hypothesized to be affected by body odors as they powerfully convey socially-relevant information. We thus investigated the neural underpinnings of the possible body odors effect on the participants’ decisions. In an fMRI study we presented to healthy individuals 64 moral dilemmas divided in incongruent (real) and congruent (fake) moral dilemmas, using different types of harm (intentional: instrumental dilemmas, or inadvertent: accidental dilemmas). Participants were required to choose deontological or utilitarian actions under the exposure to a neutral fragrance (masker) or body odors concealed by the same masker (masked body odor). Smelling the masked body odor while processing incongruent (not congruent) dilemmas activates the supramarginal gyrus, consistent with an increase in prosocial attitude. When processing accidental (not instrumental) dilemmas, smelling the masked body odor activates the angular gyrus, an area associated with the processing of people’s presence, supporting the hypothesis that body odors enhance the saliency of the social context in moral scenarios. These results suggest that masked body odors can influence moral choices by increasing the emotional experience during the decision process, and further explain how sensory unconscious biases affect human behavior.
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Women smelling men's masked body odors show enhanced harm aversion in moral dilemmas. Physiol Behav 2019; 201:212-220. [PMID: 30639588 DOI: 10.1016/j.physbeh.2019.01.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Revised: 01/09/2019] [Accepted: 01/09/2019] [Indexed: 12/18/2022]
Abstract
Among the most unnoticeable stimuli providing social information, body odors are powerful social tools that can modulate behavioral and neural processing. It has recently been shown that body odors can affect moral decision-making, by increasing the activations in neural areas processing social and emotional information during the decision process. The aim of the present study was twofold: 1) to test whether body odors selectively affect decisions to real dilemmatic moral scenario (incongruent) vs. fake (congruent) dilemmas, and 2) to characterize whether the impact of masked body odors is modulated by four conceptual factors: personal force, intentionality, benefit recipient and evitability. Women chose between utilitarian (sacrificing a person's life in order to save other lives) or deontological actions (deciding against the harmful action) in 64 moral dilemmas under the exposure of a neutral fragrance (masker) or a masked male body odor. Our results showed that the masked male body odor did not specifically affect the answers to real and fake dilemmas but instead, its effect is modulating whether the agent harms the victim in a direct or indirect manner (personal force) to save herself or only other people (benefit recipient). In particular, when exposed to the masked body odor participants gave more deontological answers when the harm was indirect and only other people were saved. These data support the hypothesis that body odors induce participants to perceive the individuals described in moral dilemmas as more real, triggering harm avoidance.
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