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Chemosignals Communicate Human Emotions
Abstract
Can humans communicate emotional states via chemical signals? In the experiment reported here, we addressed this question by examining the function of chemosignals in a framework furnished by embodied social communication theory. Following this theory, we hypothesized that the processes a sender experiences during distinctive emotional states are transmitted to receivers by means of the chemicals that the sender produces, thus establishing a multilevel correspondence between sender and receiver. In a double-blind experiment, we examined facial reactions, sensory-regulation processes, and visual search in response to chemosignals. We demonstrated that fear chemosignals generated a fearful facial expression and sensory acquisition (increased sniff magnitude and eye scanning); in contrast, disgust chemosignals evoked a disgusted facial expression and sensory rejection (decreased sniff magnitude, target-detection sensitivity, and eye scanning). These findings underline the neglected social relevance of chemosignals in regulating communicative correspondence outside of conscious access.
... Data on intraspecific communication between different species of animals (Brennan, 2010;Wyatt, 2010Wyatt, , 2014aWyatt, , 2014b confirm the common observation that animals communicate with each other through body odors. More surprisingly, some experimental studies suggest that also humans may be influenced in their interpersonal relationships and behaviors by the unconscious messages sent through chemosignals enclosed in body odors (de Groot, Smeets, Kaldewaij, Duijndam, & Semin, 2012). ...
... In 16 studies Ferreira, Haegler et al., 2010;Mutic, Parma, Brünner, & Freiherr, 2016;Rocha, Parma, Lundström, & Soares, 2018;Wudarczyk et al., 2015Wudarczyk et al., , 2016Zernecke et al., 2011;Zheng et al., 2018;, homosexual donors were excluded, as female perceives sweat from heterosexual donors differently than homosexual male sweat (Martins et al., 2005). In order to increase sensibility to emotional signals in receivers of the opposite sex (Martins et al., 2005), in 10 studies only heterosexual receivers were selected Ferreira et al., 2018;de Groot et al., 2012;Groot, Smeets, Rowson, et al., 2015 The competition was evaluated only by one study by collecting axillary sweat after an important badminton match (Adolph, Schlösser, Hawighorst, & Pause, 2010). Three studies evaluated the effect on receivers of sexual arousal induced by watching erotic video clips (Iversen et al., 2015;. ...
... Three studies evaluated the effect on receivers of sexual arousal induced by watching erotic video clips (Iversen et al., 2015;. Four studies evaluated disgust evoked in donors by watching disgust-evoking videos (Ferreira et al., 2018;de Groot et al., 2012;Iversen et al., 2015;Zheng et al., 2018). ...
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.
... An accumulating body of research suggests that humans, like other animals, can communicate information by means of olfactory signals. Specifically, scents released by the body have been shown to convey fitness-relevant information about a person's physical health, fertility, and genetic relatedness, as well as emotional states such as fear (de Groot, Smeets, Kaldewaij, Duijndam, & Semin, 2012;Pankevich, Baum, & Cherry, 2004;Ziegler, Kentenich, & Uchanska-Ziegler, 2005). The release of chemosignals during emotional experiences can function as an additional channel of communication along with other modalities (e.g., visual, auditory) and prompt nearby perceivers to respond in adaptive ways (de Groot et al., 2012). ...
... Specifically, scents released by the body have been shown to convey fitness-relevant information about a person's physical health, fertility, and genetic relatedness, as well as emotional states such as fear (de Groot, Smeets, Kaldewaij, Duijndam, & Semin, 2012;Pankevich, Baum, & Cherry, 2004;Ziegler, Kentenich, & Uchanska-Ziegler, 2005). The release of chemosignals during emotional experiences can function as an additional channel of communication along with other modalities (e.g., visual, auditory) and prompt nearby perceivers to respond in adaptive ways (de Groot et al., 2012). For example, fearful or anxious experiences cause people to release body sweat that activates threat management responses in others (e.g., a stronger startle response, heightened vigilance), enabling conspecifics to respond to potential threats in ways that improve their likelihood of survival (de Groot et al., 2012). ...
... The release of chemosignals during emotional experiences can function as an additional channel of communication along with other modalities (e.g., visual, auditory) and prompt nearby perceivers to respond in adaptive ways (de Groot et al., 2012). For example, fearful or anxious experiences cause people to release body sweat that activates threat management responses in others (e.g., a stronger startle response, heightened vigilance), enabling conspecifics to respond to potential threats in ways that improve their likelihood of survival (de Groot et al., 2012). ...
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.
... The experimental paradigms used a number of dependent measures depending on the type of emotional condition under which the donor produced the armpit odor and the predicted neural, cognitive, and behavioral consequences for the recipient. For example, in the case of fear odor one general question has been its consequences for increased vigilance (e.g., [24,25]), which has been measured by the caution manifested in a word choice task [24], the accuracy on an easy visual search task [25], the speed with which facial expressions were classified [26]. Another frequently used indicator of armpit sweat effects is facial muscle activity measurement (electromyography) indicative of facial emotion expressions [1,8,[26][27][28]. ...
... The experimental paradigms used a number of dependent measures depending on the type of emotional condition under which the donor produced the armpit odor and the predicted neural, cognitive, and behavioral consequences for the recipient. For example, in the case of fear odor one general question has been its consequences for increased vigilance (e.g., [24,25]), which has been measured by the caution manifested in a word choice task [24], the accuracy on an easy visual search task [25], the speed with which facial expressions were classified [26]. Another frequently used indicator of armpit sweat effects is facial muscle activity measurement (electromyography) indicative of facial emotion expressions [1,8,[26][27][28]. ...
... A total of 144 sweat pads were collected from the left and right underarm of 24 non-smoking Caucasian men (Mage = 22.42, SD = 3.54; range [19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34] during the three conditions Fear, Happy, and Neutral. ...
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.
... prior research, which did not record sniffs: de Lange et al., 2012;Holland et al., 2005), to be able to observe changes in participants' olfactory intake patterns as a function of odor and context. Prior research has shown that expressing fear (Susskind et al., 2008) and smelling fear odor (de Groot et al., 2012) increases sensory intake volume through the nose; yet, the present research filled a knowledge gap by showing that an immersive context and congruent laundry odor "turned on" the odor intake apparatus, by increasing sniff volume and speed. Hence, this is the first study to show that not only motivated cleaning behavior, but also the olfactomotor system is tuned differently to the same odors in a different context. ...
... Sniffing responses/breathing were monitored for two reasons: (i) To ensure participants' took in the odors, and (ii) to explore whether different conditions (odor, test context) would induce different patterns of air intake (cf. de Groot,Smeets, Kaldewaij, Duijndam, & Semin, 2012). Continuous tracking of nasal air pressure (with changes reflecting sniffing/breathing) was achieved with high temporal resolution(Johnson, Russell, Khan, & Sobel, 2006) using a silicon nasal cannula (SleepSense) that was inserted ~0.5 cm into the participant's nose. ...
... Because of this, prestimulus baseline breathing (-30 to 0 s) could be neatly separated from post-stimulus sniffing responses (0 to 15 s). Offline, data were low pass FIR-filtered (16 Hz) using custom-developed software (Sniff Analyzer, Utrecht University, Utrecht), and inhalations were identified based on any negative air pressure ≥ 0.4 s in length, and any negative air pressure ≥ 10% of the largest post-stimulus pressure per subject, per condition(de Groot et al., 2012). Inhalations overlapping with odor onset were considered invalid, except when ≥ 80% of its area under the curve laid preor post-stimulus, in which case the inhalation was classified as pre-stimulus or post-stimulus, respectively. ...
Extending traditional research methods for studying effects of odor on behavior, this study
applied Virtual Reality (VR) to create a real-world, immersive context that was compared to a traditional sterile, non-immersive lab setting. Using precise odor administration with
olfactometry, participants were exposed to three odors (cleaning-related pleasant smell, cleaning-unrelated pleasant smell: vanillin, and odorless air). Our aim was to tease apart whether participants’ motivation to clean was driven by cleaning associations and/or odor pleasantness, and how context would accentuate these effects. The results indeed showed that, in VR only, the cleaning-related smell elicited faster and more energetic cleaning behavior on a custom-designed cleaning task, and faster and more voluminous olfactory sampling compared to controls (vanillin, air). These effects were not driven by odor valence, given the general absence of significant differences between the pleasant control odor vanillin and odorless air. In sum, combining rigorous experimental control with high ecological validity, this research shows the context-dependency of (congruent) odors affecting motivated behavior in an immersive context only.
... Various levels of social information can be conveyed through body odors, including individuality (Hold and Schleidt, 1977;Mallet and Schaal, 1998;Platek et al., 2001;Lenochova and Havlicek, 2008), self (Hold and Schleidt, 1977;Lord and Kasprzak, 1989;Mallet and Schaal, 1998;Platek et al., 2001), kin (Porter and Moore, 1981;Porter et al., 1983Porter et al., , 1985Porter et al., , 1986Porter, 1998;Schaal and Marlier, 1998;Weisfeld et al., 2003;Lundström et al., 2009;Schäfer et al., 2020), age (Haze et al., 2001;Yamazaki et al., 2010;Mitro et al., 2012), sex (Russell, 1976;Doty et al., 1978;Schleidt, 1980), andpersonality (McBurney et al., 1976;Sorokowska et al., 2012Sorokowska et al., , 2016Sorokowska, 2013a,b). Body odor can also inform about transient states such as illness (Moshkin et al., 2012;Olsson et al., 2014;Newman and Buesching, 2019), and emotions (e.g., Haviland-Jones, 1999, 2000;Prehn et al., 2006;de Groot et al., 2012de Groot et al., , 2020Zheng et al., 2018; for reviews, see Pause, 2012;Calvi et al., 2020;Kontaris et al., 2020). Beyond the mere consideration of the ability of olfaction to cue different levels of social information, several questions emerge on the potential interactions between the sensory channels processing this social information. ...
... In fact, a number of studies have reported such increase in sensory vigilance following exposure to axillary stress odor (e.g., Prehn et al., 2006;de Groot et al., 2012;de Groot et al., 2015b). This phenomenon might partly account for the readiness to associate face and chemosensory stimuli in a non-emotionally specific manner in some studies (e.g., de Groot et al., 2015bde Groot et al., , 2018Rocha et al., 2018), even though the reasons for unsystematic increase of sensory vigilance are actually unclear. ...
... Even though it stands to reason that emotional chemosensory cues do communicate information, these outcomes led to question the actual signaling value of emotional body odors (de Groot et al., 2015b). For instance, with regards to fear odor, an outstanding issue is whether the odor emulated the precise emotional state of the sender in the receiver (de Groot et al., 2012), or alternatively whether it generated a non-specific state of high arousal and negative valence unrelated to fear, upon which the fear emotion category is attributed depending on contextual factors (Hess and Fischer, 2013;Barrett, 2017). The former view relates to a widespread conception in psychology considering that emotions are psychologically and biologically basic, discrete, and shared within and across cultures (Ekman and Friesen, 1971;Ekman, 1992a;Scollon et al., 2004;Izard, 2007;Ekman and Cordaro, 2011). ...
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.
... The detection of stimuli containing either social or nonsocial odours requires processing within the primary level of the olfactory system (de Groot et al. 2012;Tirindelli et al. 2009). One useful index of this detection is the use of olfactory threshold sensitivity tests. ...
... Researchers induce donors to feel anxious using methods such as administering academic exams (Prehn et al. 2006) and asking participants to undertake 'high ropes' courses (Albrecht et al. 2011). The effect that the presented chemosignals have upon the participant receiver may then be assessed through the coding of fearful facial expressions (de Groot et al. 2012) and subjective emotion measures (Albrecht et al. 2011). In these laboratory studies, the odour is explicitly presented to the receiver and detection of the odour is as controlled as possible. ...
... The mediation model findings can be interpreted to suggest that the magnitude of emotional contagion between dyads may be associated with individuals' odour function, which supports and extends the literature. Research has demonstrated that emotions can transfer between individuals by means of olfactory-detected chemosignals (e.g. de Groot et al. 2012). Nevertheless, whereas previous work has focused on the transfer of specific emotions (e.g. ...
Introduction
Research has provided evidence for the transfer of single emotions including anger, anxiety and happiness through olfactory chemosignals, yet no work has examined the role of odour function in the aggregation of more complex emotional states or in the emotional contagion process. The aim of the present study was to ascertain whether an individual’s tendency to experience emotional aggregation was affected by objective measures of their olfactory function and subjective self-assessments of the importance of their own olfactory system.
Methods
In this study (N = 70), participant pairs were first assessed individually for olfactory threshold and odour identification, then completed the Importance of Olfaction Questionnaire. Each pair subsequently took part in two collaborative tasks. Individual emotion measures were taken before, during and after the completion of the two tasks.
Results
Multilevel structural equation modelling revealed that individuals’ within-dyad positive emotional agreement scores were associated with both their ‘importance of olfaction’ scores and their olfactory function. A significant association was also found between olfactory performance and the Importance of Olfaction scores.
Conclusions
These results provide evidence that the subjective importance an individual assigns to their sense of smell can predict their susceptibility to experience emotional aggregation during active, collaborative tasks.
Implications
The findings suggest that individuals’ tendency and capability to detect and respond to emotional chemosignals, a process required for olfactory-facilitated emotional contagion, may be affected by individual differences in olfactory function and subjective attitudes toward olfaction.
... In particular, exposure to fear chemosignals (i.e., sweat collected during fearinducing conditions) activates facial muscles associated with facial expressions of fear (medial frontalis and corrugator supercilii; de Groot et al. 2014;Kamiloğlu et al. 2018). These muscles are associated with increased sensory acquisition (Susskind et al. 2008), manifested in a widening of the eye aperture, speeding up of ocular movement, and increasing inhalation volume (de Groot et al. 2012). Moreover, fear-related chemosignals also facilitate the processing of emotional faces (e.g., Kamiloğlu et al. 2018;Silva et al. 2020;Wudarczyk et al. 2016;Zhou and Chen 2009), trigger withdrawal behaviors (enhance the startle reflex; Prehn et al. 2006), reduce cardiac parasympathetic activity (Rocha et al. 2018), and activate brain areas associated with threat processing (e.g., amygdala; Mujica-Parodi et al. 2009). ...
... Moreover, fear-related chemosignals also facilitate the processing of emotional faces (e.g., Kamiloğlu et al. 2018;Silva et al. 2020;Wudarczyk et al. 2016;Zhou and Chen 2009), trigger withdrawal behaviors (enhance the startle reflex; Prehn et al. 2006), reduce cardiac parasympathetic activity (Rocha et al. 2018), and activate brain areas associated with threat processing (e.g., amygdala; Mujica-Parodi et al. 2009). Thus, fear chemosignals appear to act as an "alarm" signal, increasing sensory acquisition, and preparing its receivers to deal with potential threats (e.g., de Groot et al. 2012;Parma et al. 2017). ...
... This "mutual warning-like phenomenon" seems not to be driven by a higher number of threatening events that are avoided but rather by the fact that individuals exposed to the danger signal respond faster to threatening events than those who did not receive it (for a similar argument in animal research see, for instance, Martín et al. 2006). Thus, in addition to previous research pointing fear chemosignals as an alarm cue that increases sensory acquisition in its recipients (e.g., de Groot et al. 2012de Groot et al. , 2014de Groot et al. , 2018, our results suggest a practical advantage of being exposed to fear chemosignals in coping with danger events (i.e., faster threat avoidance reactions). ...
It has been shown that the presence of conspecifics modulates human’s 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 modulates 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. The present 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 its receiver to a readiness state that allows faster reactions to threat-related events.
... Nevertheless, valuable studies have been performed in this context. Jasper et al. [2] conducted a study with the aim of investigating how people communicate with their body secretions. They collected sweat from a group of healthy males who were attending emotional videos. ...
... Social olfactory stimuli (sweat) were collected from fourteen healthy heterosexual Caucasian males 1 who provided informed consent similar to the female participants. All sweat donors were non-smokers who had been asked to avoid odorous food, alcohol, deodorants, scented products, strenuous activity and sexual activity [2], [10]. In order to induce emotions, sweat donors watched video clips containing disgusting and neutral scenes. ...
... In humans, the ability to identify olfactory threat cues in the environment and respond to them in an adaptive manner is well developed (20). Olfaction plays a key role in the modulation of behavior and interpersonal relationships (21), with accumulating evidence indicating social chemosignaling in humans (20,(22)(23)(24). Human social chemosignals have been shown to convey information with respect to kin recognition (20), motherinfant bonding (25), disease detection (26), aggression (24) and emotional states (23). ...
... Olfaction plays a key role in the modulation of behavior and interpersonal relationships (21), with accumulating evidence indicating social chemosignaling in humans (20,(22)(23)(24). Human social chemosignals have been shown to convey information with respect to kin recognition (20), motherinfant bonding (25), disease detection (26), aggression (24) and emotional states (23). A recent line of research demonstrates that chemosensory communication of threat cues in axillary sweat modulates cross-modal emotion perception of ambiguous threatening facial stimuli and produces widespread neural threat responses in the amygdala, ACC, hippocampus, the prefrontal cortex, and fusiform face area (FFA) (27)(28)(29)(30). ...
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.
... F(1, 53.3) = 4.24; p =.044; 95% CI [−.012; −2.88*10 −4 ]), indicating that the activation of the medial frontalis diverges between sweat conditions over time for the two sweat applications (see Fig. 4). These results are in accordance with previous studies (e.g., de Groot et al., 2012de Groot et al., , 2014de Groot et al., , 2015Kamiloğlu et al., 2018), showing that the exposure to sweat produced under fear states results in higher activation (compared with the exposure to neutral sweat) of the medial frontalis, one of the facial muscles involved in fear facial expression (see Fridlund & Cacioppo, 1986). ...
... A final consideration that might prove relevant and perhaps limit the scope of our conclusions is that our senders and receivers were males and females, respectively. Although this procedure is common to most studies (e.g., de Groot et al., 2012de Groot et al., , 2014de Groot et al., , 2015Kamiloğlu et al., 2018), it is nonetheless a variable that needs to be addressed. ...
A growing body of research has shown that human apocrine sweat carries information about the emotional state of its donor. Exposure to sweat produced in a fear-inducing context, triggers in its receivers a simulacrum of this emotional state, as evidenced by increased medial frontalis and corrugator supercilii (facial electromyography; fEMG) activity-two facial muscles involved in the display of fear facial expressions. However, despite the increased interest in the effects of emotional sweat, little is known about the proprieties of these chemical sweat samples. The goal of this study was to examine if a second application of the same sweat sample would yield reliable results. Specifically, we assessed whether sweat samples collected, from Portuguese males (N = 8) in fear (vs. neutral) inducing contexts, produce similar fEMG activations (i.e., in the medial frontalis and corrugator supercilii) in female receivers (N = 60) across two independent applications (the first with Dutch and the second with Portuguese receivers). Our findings showed that exposure to fear (vs. neutral) sweat resulted in higher activation of both muscles compared to neutral odors, revealing a similar data pattern across both applications underlining the feasibility of re-using emotional sweat samples. The implications of these findings for properties of these sweat volatiles are discussed.
... The human sense of smell drives overall attractiveness judgments (Thornhill et al., 2003) and provides signals of genetic incompatibility of partners (Wedekind & Füri, 1997;Wedekind et al., 1995), which further highlights the importance of chemosignalling in human mate choice. Beyond mating, the human nose uses body odor as a premise for social judgments, particularly in the recognition of individuals in terms of personal identity (Penn et al., 2006), fear (Albrecht et al., 2010;Chen, 2006;de Groot et al., 2012;Prehn et al., 2006;Zernecke et al., 2011;Zhou & Chen, 2009), happiness (Chen & Haviland-Jones, 2000; de Groot al., 2015), and reactions to disgust (de Groot et al., 2012). Furthermore, people can use olfactory cues to relatively accurately attribute biological qualities such as sex (Hold & Schleidt, 2010;Schleidt, 1980), and psychological traits such as neuroticism and dominance (Sorokowska et al., 2012;Sorokowska, 2013a, b). ...
... The human sense of smell drives overall attractiveness judgments (Thornhill et al., 2003) and provides signals of genetic incompatibility of partners (Wedekind & Füri, 1997;Wedekind et al., 1995), which further highlights the importance of chemosignalling in human mate choice. Beyond mating, the human nose uses body odor as a premise for social judgments, particularly in the recognition of individuals in terms of personal identity (Penn et al., 2006), fear (Albrecht et al., 2010;Chen, 2006;de Groot et al., 2012;Prehn et al., 2006;Zernecke et al., 2011;Zhou & Chen, 2009), happiness (Chen & Haviland-Jones, 2000; de Groot al., 2015), and reactions to disgust (de Groot et al., 2012). Furthermore, people can use olfactory cues to relatively accurately attribute biological qualities such as sex (Hold & Schleidt, 2010;Schleidt, 1980), and psychological traits such as neuroticism and dominance (Sorokowska et al., 2012;Sorokowska, 2013a, b). ...
Social perception is a multimodal process involving vision and audition as central input sources for human social cognitive processes. However, it remains unclear how profoundly deaf people assess others in the context of mating and social interaction. The current study explored the relative importance of different sensory modalities (vision, smell, and touch) in assessments of opposite- and same-sex strangers. We focused on potential sensory compensation processes in mate selection (i.e., increased importance of the intact senses in forming impressions of an opposite-sex stranger as a potential partner). A total of 74 deaf individuals and 100 normally hearing controls were included in the study sample. We found diminished importance of vision and smell in deaf participants compared with controls for opposite- and same-sex strangers, and increased importance of touch for the assessment of same-sex strangers. The results suggested that deaf people rely less on visual and olfactory cues in mating and social assessments, highlighting a possible role of sign language in shaping interpersonal tactile experience in non-romantic relationships.
... Another set of variables that have previously been linked to both competition outcomes and body odour are affective states. Body odour can contain cues to affective states such as happiness [98], disgust [99], fear [100], anxiety [90], stress [91], but also aggression [38] and contexts such as competition [37]. This is why we investigated possible mediating effects of changes in hormone levels and affective states. ...
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’.
... Interestingly, this notion is also supported by the recent observations that pheromones act as both interspecific and intraspecific signaling molecules 12 . In humans, social communication probably occurs through secretions other than urine, for example, sweat whose pheromonal cues are probably detected by the olfactory system [22][23][24][25] . It is noteworthy that women's tears contain a chemosignal that, when smelled by men, decreases the sexual arousal and the salivary testosterone level and attenuates the hypothalamic activation following sexual stimulation 26 . ...
Tears contain pheromones that trigger specific behavioral responses. In the mouse, male tear fluid is involved in long and short-term effects such as the receptive behavior and pregnancy block in females and the aggression in males. In contrast, pup tears exert an inhibitory effect on male mating behavior, also promoting sexual rejection in females. In the rat, a male lacrimal protein acts as an intraspecific and heterospecific signal enhancing sexual behavior in females and evoking avoidance behavior in mouse. However, behavioral effects of female tears on male behavior have yet to be described. Here, we report that female lacrimal fluid of different mouse strains contains a relatively small and involatile factor that abolishes inter-male aggression switching it into a copulatory behavior. The production of this molecule by the lacrimal glands is not affected by the estrous cycle but it is sensitive to ovariectomy, thus suggesting a control mediated by hormones. Moreover, this lacrimal anti-aggression pheromone modulates the activity of the lateral habenula, a brain area responsible for the valence of the aggressive interactions.
... En relación con ello, se suele hablar de una "memoria olfativa" vinculada con la capacidad especial de los humanos para detectar similitudes o diferencias entre un olor presente y olores pasados (es decir, solemos saber si un olor es nuevo o si lo hemos percibido anteriormente). Diferentes estudios empíricos demuestran que la información olfativa se conecta directamente con áreas del cerebro que procesan las emociones (DE GROOT et al., 2012), la memoria (YESHURUN et al., 2009;MORGADO, 2012), la motivación, el placer o regulan la atracción entre los sexos (MORGADO, 2012). En relación con ello, se considera que, desde el punto de vista evolutivo, el olfato, al igual que los demás sentidos, está estrechamente relacionado con la mejora en las respuestas reflejas y la capacidad adaptativa al entorno. ...
En este texto, reflexionamos sobre Fraseología y experiencia senso-rial, a partir de uno de los sentidos menos estudiados y valorados: el olfato. Nos sumamos, así, a una especie de "revolución sensorial", tomando prestadas las palabras de Howes (2013a), por la que los sentidos se han convertido en objeto de interés de diferentes ciencias. Este ámbito de investigación se caracteriza por su complejidad e interdisciplinariedad: los sentidos nos posibilitan percibir el mundo físico, inferirlo e interpre-tarlo y, en consecuencia, repercuten en diferentes esferas de nuestra vida, intercalándose en cualquier interacción entre la realidad externa y nuestro mundo interior, y viceversa. En consecuencia, en este estudio pueden ser consideradas cuestiones psicológicas, biológicas, antropológicas, sociológicas, filosóficas e, incluso, históricas. La citada revolución sensorial ha llegado, quizás de forma algo tardía, a la Lingüística, como así lo demuestra la publicación de diferentes trabajos en los que se considera la relación entre lengua, sentido y cultura (MAJID y LEVINSON, 2011; DIGONNET, 2016 y 2018, SPEED et al., 2019) 1. En estos estudios, se busca, entre otros objetivos, averiguar cómo los sen-1 Los índices temáticos de revistas como Trends in Cognitive Sciences o Senses & Society dan una buena muestra de ello..
... Importantly, the absence of statistically significant difference in perception does not preclude other type of effects. For instance, it has been shown that differences between body odors are not necessarily observed at the level of conscious perception (Lundström and Olsson, 2005;de Groot et al., 2012) but can be seen in physiological measures such as electromyographical recordings of the facial muscles relating to different emotions. ...
Animal studies suggest that ill-health can be detected by way of body odor which, in turn, can be important information for the receiver to avoid potential infectious transmission from the sick individual. There are also a number of human observational studies that indicate that different types of disease are associated with more or less aversive smells. Recent studies have indicated that the body odor from otherwise healthy human individuals smell more aversive within a few hours as a function of a systemic inflammation of bacterial type induced by experimental exposure to an endotoxin (lipopolysaccharide). To investigate if naturally occurring immune activation also gives rise to perceivable olfactory changes, we collected body odor samples during five 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 than the body odor from the same individuals when healthy, these effects were not statistically significant. Moreover, three questionnaires, Perceived Vulnerability to Disease, Disgust Scale, and Health Anxiety, were administered to the raters of the body odor 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 a sickness response.
... [36] Chemosignals communicate human emotions. [37] A putative human pheromone, androstadienone, increases cooperation between men. [38] This is important because it means that the contemporary debates about how to make psychology more rigorous and reproducible can readily inform the ways we could transform the study of human chemical communication ( §5- §8). ...
Despite the lack of evidence that the ‘putative human pheromones' androstadienone and estratetraenol ever were pheromones, almost 60 studies have claimed ‘significant' results. These are quite possibly false positives and can be best seen as potential examples of the ‘reproducibility crisis', sadly common in the rest of the life and biomedical sciences, which has many instances of whole fields based on false positives. Experiments on the effects of olfactory cues on human behaviour are also at risk of false positives because they look for subtle effects but use small sample sizes. Research on human chemical communication, much of it falling within psychology, would benefit from vigorously adopting the proposals made by psychologists to enable better, more reliable science, with an emphasis on enhancing reproducibility. A key change is the adoption of study pre-registration and/or Registered Reports which will also reduce publication bias. As we are mammals, and chemical communication is important to other mammals, it is likely that chemical cues are important in our behaviour and that humans may have pheromones, but new approaches will be needed to reliably demonstrate them.
This article is part of the Theo Murphy meeting issue ‘Olfactory communication in humans’.
... Furthermore, the inability to perceive body odour precludes anosmic patients a wide variety of social-relevant information, such as emotional conditions of others, e.g. fear [6][7][8][9] and happiness [10]. Body odour constitutes an individual and sex-specific fingerprint [11][12][13] that enables women to recognize a partner or a close friend [14]. ...
Olfactory perception has implications for human chemosensory communication and in a broader context, it affects well-being. However, most of the studies investigating the consequences of olfactory loss have recruited patients who have already been categorized as having a dysfunctional sense of smell and sought help in an ENT clinic. We revisit these findings by distinguishing subjects with olfactory impairment from a group of subjects who all declared a normal sense of smell when enrolling for this study. In the initial sample of 203 individuals, we found 59 to have impaired olfaction and four with marginal olfactory performance, not useful in daily life. Interestingly, we found a significant between-group difference in cognitive functioning, further supporting the notion of the relationship between cognition and olfactory performance. However, their chemosensory communication and well-being appeared not to be different from subjects with normosmia. Impaired olfactory function certainly has a severe impact on daily life but more so in individuals who are bothered with it and decide to seek treatment. The limited-to-no olfactory perception in the fraction of subjects who neither complain about it nor seek help in ENT clinics does not seem to have a major effect on their social, cognitive, emotional and health functioning.
This article is part of the Theo Murphy meeting issue ‘Olfactory communication in humans’.
... Pierwszą, najważniejszą zasadą jest to, by zwierzę było uśmiercane w specjalnym, przeznaczonym do tego pomieszczeniu, tak by inne zwierzęta tego nie widziały. Wiadomo że zwierzęta [50], a także ludzie [15], są w stanie wyczuć zapach emocji, przede wszystkim tych towarzyszących stresowi (strach, lęk). Tu pojawia się kluczowy problem, ponieważ aby zwierzę nie czuło lęku przed śmiercią (by było nieświadome, co zaraz się stanie), należałoby usunąć "zapach śmierci" [52], co w rzeźni jest praktycznie niemożliwe. ...
Knowledge of the behaviour of a species makes it possible to ensure the well-being of animals raised in farm conditions, because when we know the behavioural standard we can guarantee that at least the animals’ minimum needs will be met. Observation of animal behaviour is the first element in assessing their physical and psychological comfort. The main objective is to maximize production while at the same time maintaining animal welfare. However, this is often difficult and economic considerations come into conflict with the comfort and needs of the animals. The elements of knowledge of behaviour, in addition to ethology, i.e. the science dealing with animal behaviour, also include zoosemiotics and cognitive science, which explain of the occurrence of specific behaviours in terms of biology and physiology.
... The capacity to register these invisible, far-reaching, and long-lasting chemical warning cues would have increased our ancestors' survival chances. Indeed, the smell of fear has been shown to instigate adaptive processes: a fearful facial expression (raised eyebrows, opened nose) and increased sensory intake (eyes and nose) to better detect threat (de Groot et al., 2012); yet, typically this phenomenon has not been examined beyond WEIRD samples, with one East Asian exception (de Groot et al., 2018). Quintana and colleagues (2019) further assessed the breadth of chemical communication in a controlled yet ecologically valid Virtual Reality environment. ...
Communication constitutes the core of human life. A large portion of our everyday social interactions is nonverbal. Of the sensory modalities we use for nonverbal 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 nonverbally and subconsciously affect our social lives across contexts.
Part of a special issue, see: https://www.frontiersin.org/research-topics/11360/advances-and-obstacles-in-contemporary-nonverbal-communication-research#articles
... Researchers have examined whether humans can communicate emotions such as fear or anxiety (see de Groot and Smeets 2017 for a recent review), happiness (e.g., Zhou and Chen 2009;de Groot et al. 2015), disgust (e.g., Zheng et al. 2018), aggression (e.g., Mutic et al. 2017) and competition (Adolph et al. 2010). Individuals exposed to emotional body odors (EBOs) exhibit behavioral effects, such as increased startle response (Prehn et al. 2006;Adolph et al. 2013), biased identifications or judgments (Zernecke et al. 2011;Dalton et al. 2013;Wudarczyk et al. 2016), higher risk taking behavior (Haegler et al. 2010), generation of emotional facial expressions (de Groot et al. 2012(de Groot et al. , 2015Kamiloğlu et al. 2018) or lower practice performance (Singh et al. 2018). ...
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.
... Whereas active delivery is the best-studied component of chemical communication in strepsirrhines, it is the leaststudied component in humans. Signal delivery in humans is generally seen as passive or reflexive, unconsciously changing with an individual's emotional state [135,136]). With few exceptions (e.g. ...
The study of human chemical communication benefits from comparative perspectives that relate humans, conceptually and empirically, to other primates. All major primate groups rely on intraspecific chemosignals, but strepsirrhines present the greatest diversity and specialization, providing a rich framework for examining design, delivery and perception. Strepsirrhines actively scent mark, possess a functional vomeronasal organ, investigate scents via olfactory and gustatory means, and are exquisitely sensitive to chemically encoded messages. Variation in delivery, scent mixing and multimodality alters signal detection, longevity and intended audience. Based on an integrative, 19-species review, the main scent source used (excretory versus glandular) differentiates nocturnal from diurnal or cathemeral species, reflecting differing socioecological demands and evolutionary trajectories. Condition-dependent signals reflect immutable (species, sex, identity, genetic diversity, immunity and kinship) and transient (health, social status, reproductive state and breeding history) traits, consistent with socio-reproductive functions. Sex reversals in glandular elaboration, marking rates or chemical richness in female-dominant species implicate sexual selection of olfactory ornaments in both sexes. Whereas some compounds may be endogenously produced and modified (e.g. via hormones), microbial analyses of different odorants support the fermentation hypothesis of bacterial contribution. The intimate contexts of information transfer and varied functions provide important parallels applicable to olfactory communication in humans.
This article is part of the Theo Murphy meeting issue ‘Olfactory communication in humans’.
... de Groot et al. 2012). ...
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.
... Overall, such results suggest that several cues (e.g., individuality, gender, age, kin, physiological stage, health, psychological state, immunogenetic type, and diet) can be nested in the complex body odor of a particular person and that the perception of these different cues can be assessed under specific test conditions (cf. de Groot, Smeets, Kaldewaij, Duijndam, & Semin, 2012;Havlíček, Fialová, & Roberts, 2017;Miller & Maner, 2010;Penn et al., 2006;Schaal, 1988;Schaal & Porter, 1991). Thus, in the present case, it is possible that the physiological/psychological state of postpartum women similarly affected their body odors in a way that rendered them olfactorily similar to the infants. ...
Little is known about the effects of olfaction on visual processing during infancy. We investigated whether and how an infant's own mother's body odor or another mother's body odor affects 4-month-old infants’ looking at their mother's face when it is paired with a stranger's face. In Experiment 1, infants were exposed to their mother's body odor or to a control odor, while in Experiment 2, infants were exposed to a stranger mother's body odor while their visual preferences were recorded. Results revealed that infants looked more at the stranger's female face in presence of the control odor but that they looked more at their mother's face in the context of any mother's body odors. This effect was due to a reduction of looking at the stranger's face. These findings suggest that infants react similarly to the body odor of any mother and add to the growing body of evidence indicating that olfactory stimulation represents a pervasive aspect of
infant multisensory perception.
... Bodziec w postaci filmu wydaje się być bardzo nienaturalny, dlatego w niniejszym badaniu zaproponowano obserwację bezpośrednią. Badania pokazują, iż oprócz standardowych kanałów przekazywania informacji emocjonalnej między ludźmi, takich jak informacja wzrokowa czy werbalna, istnieją też mniej zbadane kanały -między innymi sygnały chemiczne(de Groot, Smeets, Kaldewaij, Duijndam, Semin, 2012). Można więc założyć, że umieszczenie obserwatora i demonstratora w jednym pomieszczeniu podczas procedury obserwacyjnego uczenia się strachu zwiększy jej efektywność.Efektywność obserwacyjnego uczenia się strachu u Olssona mierzona była poprzez analizę odpowiedzi skórno-galwanicznej na prezentowane bodźce warunkowe. ...
... nakrčený nos, povytažený horní ret a zúžené zorné pole -nižší míra rozhlížení se). 12 Navíc se ukázalo, že při současné prezentaci tělesné vůně a fotografií snižovala tělesná vůně nemocných hodnocení atraktivity tváří. 13 ...
Behaviorální imunitní systém představuje vedle tělesného imunitního systému další obranný nástroj organismu. Jeho hlavní funkcí je detekce a vyhnutí se potenciálně ohrožujícím podnětům, jež mohou vést k přenosu patogenů. Včasná vyhýbavá reakce organismu významně snižuje energii, jež by jinak byla vydána na metabolicky náročné reakce tělesného imunitního systému po infekci patogenem. Cílem tohoto souborného článku je představit jednotlivé složky behaviorálního imunitního systému, jenž v první řadě zahrnuje percepci ohrožujících podnětů na základě jednotlivých smyslových modalit (vizuální, akustická, čichová, taktilní a jejich integrace). Dále se jedná o afektivní složku, a to zejména emoci znechucení, kterou zde dále dělíme na patogenní, sexuální a morální. Další části zahrnují kognitivní složku, která umožňuje uvědomovat si a hodnotit míru nebezpečnosti podnětu, a exekutivní složku včetně vyhýbavého chování.
Součástí práce je také krátké představení základních metod měření behaviorálního imunitního systému pomocí dotazníků, vizuálních stimulů či měření fyziologických reakcí. Fungování behaviorálního imunitního systému je možné vysvětlit pomocí "teorie zvládání chyb" (error management theory), podle níž systém funguje ve prospěch energeticky méně náročných chyb. Kvůli vysoké citlivosti behaviorálního imunitního systému se snižuje množství falešně negativních chyb, ale naopak se zvyšuje náchylnost vůči falešně pozitivním chybám. V důsledku generalizace pak tyto reakce mohou mít zásadní sociální implikace, jako je vliv na společenskost, ageismus, xenofobii a konformitu vůči normám. V neposlední řadě poukážeme na možnou souvislost mezi behaviorálním imunitním systémem a vznikem některých psychiatrických poruch, jako je obsedantně-kompulzivní porucha. Systém je funkčně flexibilní dle možné zranitelnosti jedince a aktuální situace, proto se stručně věnujeme i jevům souvisejícím s aktivací behaviorálního imunitního systému objevujícím se v současné situaci pandemie COVID-19.
... Women rate liking someone's body odor (BO) as the most important physical factor driving sexual attraction and mate choice, while men report that smell is as equally important as physical appearance, demonstrating the influence of BOs in the early stages of a romantic relationship [1,2]. In established relationships, humans may utilize chemosignal cues from their partner's BO to detect emotional states and subsequently respond effectively, guiding relationship-maintaining behaviors [3,4]. However, research is lacking in the area of relationship breakdown [5], which refers to the dissolution of a romantic relationship. ...
Anecdotal reports indicate that women dislike their partner’s body odor (BO) during the breakdown of a relationship; however, whether disliking a partner’s BO is associated with intentions to break up has not been empirically tested. Therefore, the aim of the current study was to investigate, for the first time, whether disliking one’s partner’s BOs is associated with experiencing lower commitment to a romantic relationship. Eighty participants (48 partnered, 32 single and previously partnered) completed self-report questionnaires about their current or previous romantic relationship and the amount of exposure to—and hedonic ratings of—their current or former partner’s BOs. Olfactory function was also tested, and participants smelled and rated various pieces of clothing imbued with a stranger’s BO. The results demonstrated that for participants who had experienced a breakup, historically higher levels of relationship commitment were associated with higher hedonic ratings of a previous partner’s BOs, regardless of the type of BOs. For participants currently in a relationship, lower relationship commitment was associated with higher breakup intentions in response to smelling their partner’s BOs. These preliminary results contribute evidence for the positive association between exposure to a partner’s BOs and favorable hedonic appraisals of BOs; however, further research needs to be conducted in this area to investigate nuances. Lower levels of exposure to one’s partner’s BOs may be more indicative of relationship commitment than exposure to hedonically unpleasant BOs of one’s partner. The findings are discussed with reference to their implications for interventions in relationship breakdown.
... They can distinguish between good and bad smells and exhibit an aversion to smells they dislike (wrinkling nose, pouting) (Soussignan, 1997;Bensafi et al., 2002). Moreover, fear chemosignals generate a fearful facial expression and sensory acquisition (an increased sniff magnitude and eye scanning), whereas disgust chemosignals evoke a disgusted facial expression and sensory rejection (decreased sniff magnitude, detection sensitivity, and eye scanning) (Zhou and Chen, 2009;de Groot et al., 2012). A comparison between two odors from neutral odor and unpleasant odor was used in the present study. ...
Objectives
The aim of this study was to determine whether behavioral responses elicited by olfactory stimulation are a predictor of conscious behavioral response and prognosis of patients with disorders of consciousness (DOC).
Methods
Twenty-three DOC patients (8 unresponsive wakefulness syndrome [UWS]; 15 minimally conscious state [MCS]) were recruited for this study in which 1-Octen-3-ol (familiar neutral odor) and pyridine were used to test odor behavioral responses, and water was used as an odorless stimulus. One rater presented the three odors in front of each patient’s nose randomly, and another one videotaped all behavioral responses (e.g., pouting, wrinkling nose, slightly shaking head, frowning, etc.). Two independent raters, blind to the stimuli and the patient’s diagnosis, gave the behavioral results according to the recorded videos. One-, 3-, and 6-month follow-up evaluations were conducted to obtain a good prognostic value.
Results
All MCS patients showed behavioral responses to the 1-Octen-3-ol stimulus; nine MCS and one UWS showed olfactory emotional responses to the pyridine, and two MCS showed olfactory emotional responses to the water stimulus. The incidence of behavioral response was significantly higher using 1-Octen-3-ol than it was for water by McNemar test ( p < 0.001), significantly higher using pyridine than it was for water ( p < 0.01). The χ ² test results indicated that there were significant differences between MCS and UWS to 1-Octen-3-ol ( p < 0.001). For MCS patients, the incidence of behavioral response was no different between using 1-Octen-3-ol and pyridine ( p > 0.05). There was no significant relationship between the olfactory behavioral response and the improvement of consciousness based on the χ ² test analysis ( p > 0.05).
Conclusion
Olfactory stimuli, especially for the familiar neutral odor, might be effective for eliciting a conscious behavioral response and estimating the clinical diagnosis of DOC patients.
Clinical Trial Registration
[ https://clinicaltrials.gov/ct2/show/NCT03732092 ], [identifier NCT03732092].
... We live in a world full of odors -at least a trillion that our noses can distinguish (Bushdid et al., 2014) and that have significant impact on our life and emotions. Amazingly, our noses are also developed to smell feeling-related chemicals (fear, joy, sexual arousal) of other people, and therefore, we, like other creatures, 'talk' to each other through chemical signals (de Groot et al., 2012). ...
In humans, finding a partner is quite a difficult task because there are many criteria that one needs to consider. However, in comparison to many animals, when choosing a partner, we easily discriminate between ourselves and members of other species through various communication systems. On the contrary, many fly species (Diptera) are morphologically similar and overlap in their geographical distributions and eco-logical habitats. Sexual interactions of most drosophilid flies occur on their hosts. Therefore, flies rely on olfactory sex pheromones, as well as on non-pheromonal chemicals such as host volatiles – which guide and restrict the search for conspecifics within limited locations – as honest signals for pre-mating reproductive isolation. A subtle divergence in the perception of these signals can lead to accumulated changes among populations of the same species, and ultimately to a reduction in gene flow and reproductive isolation. In recent years, we have seen an increased interest in how olfactory systems diverge to drive host adaptation and speciation. In this review, we discuss the evolutionary changes of the neural circuits that underlie mate recognition. We shed light onto sex pheromone communication systems, the construction of ol-factory nervous systems, and the role of host specialization in reproductive isolation. Finally, leveraging the incipient speciation of Drosophila mojavensis Patterson popula-tions, we highlight the underlying sensory mechanisms of the reproductive isolation barriers. In the end, we propose future research topics of the evolutionary neuroecol-ogy field of sexual communication.
... Some of these findings are also consistent with reports in humans [8], as human body odour, too, carries information about one's emotional state [5][6][7]12,[24][25][26][27]. Humans are able to recognise emotions such as happiness [12,28,29] or fear [27,29,30] from the body odour of conspecifics. ...
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.
... Despite this lack of research, the fact that the human olfactory bulb projects monosynaptically to the MeA (Allison, 1954) implicates this subregion in a significant olfactory role which remains to be disambiguated. Odors trigger innate responses in humans (Yeshurun and Sobel, 2010), and humans engage in olfactory-guided social behaviors (Classen, 1992;Ober et al., 1997;Wysocki and Preti, 2004;Wyart et al., 2007;Samuelsen and Meredith, 2009;de Groot et al., 2012;Frumin et al., 2015), despite the lack of an accessory olfactory system (Mast and Samuelsen, 2009;Savic et al., 2009). The neural bases of these behaviors have yet to be identified. ...
Three subregions of the amygdala receive monosynaptic projections from the olfactory bulb, making them part of the primary olfactory cortex. These primary olfactory areas are located at the anterior-medial aspect of the amygdala and include the medial amygdala (MeA), cortical amygdala (CoA), and the periamygdaloid complex (PAC). The vast majority of research on the amygdala has focused on the larger basolateral and basomedial subregions, which are known to be involved in implicit learning, threat responses, and emotion. Fewer studies have focused on the MeA, CoA, and PAC, with most conducted in rodents. Therefore, our understanding of the functions of these amygdala subregions is limited, particularly in humans. Here, we first conducted a review of existing literature on the MeA, CoA, and PAC. We then used resting-state fMRI and unbiased k-means clustering techniques to show that the anatomical boundaries of human MeA, CoA, and PAC accurately parcellate based on their whole-brain resting connectivity patterns alone, suggesting that their functional networks are distinct, relative both to each other and to the amygdala subregions that do not receive input from the olfactory bulb. Finally, considering that distinct functional networks are suggestive of distinct functions, we examined the whole-brain resting network of each subregion and speculated on potential roles that each region may play in olfactory processing. Based on these analyses, we speculate that the MeA could potentially be involved in the generation of rapid motor responses to olfactory stimuli (including fight/flight), particularly in approach/avoid contexts. The CoA could potentially be involved in olfactory-related reward processing, including learning and memory of approach/avoid responses. The PAC could potentially be involved in the multisensory integration of olfactory information with other sensory systems. These speculations can be used to form the basis of future studies aimed at clarifying the olfactory functions of these under-studied primary olfactory areas.
... During sleep, if a fear inducing odor was given to rats, this adversely affected memory consolidation [71]. Humans therefore probably also communicate emotion through chemosensory signaling [72]. ...
... Previous studies have also emphasized a relationship between the ability to identify odors and the social life of individuals (Boesveldt et al., 2017). In particular, it has been found that body odor can convey the age, health, and emotional state of individuals (de Groot et al., 2012;Mitro et al., 2012;Olsson et al., 2014). Furthermore, most social interactions involve the act of eating and drinking, the pleasure of which can be seriously impaired and limited by a reduced olfactory function, leading individuals to limit their social interactions (Murphy, 2008;Boesveldt et al., 2017). ...
Objective : This cross-sectional study evaluates the impact of active or non-active lifestyle in terms of physical, cognitive and social activity on the olfactory function in Elderly Subjects (ES) and aims at looking for a correlation between the time devoted to life activities and the score obtained during the olfactory tests by each individual.
Methods : One hundred and twenty-two elderly volunteers were recruited in Sardinia (Italy) and divided into active ES ( n = 60; 17 men, 43 women; age 67.8 ± 1.12 years) and inactive ES ( n = 62; 21 men, 41 women, age 71.1 ± 1.14 years) based on their daily physical activities. The olfactory function was evaluated using the “ Sniffin’s Sticks ” battery test, while the assessment of daily activities was made by means of personal interviews.
Results : A significant effect of active or inactive lifestyle was found on the olfactory function of ES ( F (1,120) > 10.16; p < 0.005). A positive correlation was found between the olfactory scores and the number of hours per week dedicated to physical activities (Pearson’s r > 0.32, p ≤ 0.014) in both active and inactive ES.
Conclusions : High levels of exercise and non-exercise physical activity are strongly associated with the olfactory function and, consequently, with the quality of life of the elderly. Given the limited physical exercise of elderly people, they can benefit from a more active lifestyle by increasing non-exercise physical activities.
... Additionally, the literature on emotional, social, and behavioural contagion (Levy & Nail, 1993) further indicates how, under certain circumstances, affective states, cognitions, and behaviours can spread across individuals and groups (Hatfield, Cacioppo, & Rapson, 1994). Experimental evidence also suggests that behavioural mimicry and emotional contagion might be heightened in stressful situations (Gump & Kulik, 1997), and that the physiological markers of stress might be transmitted between individuals (de Groot, Smeets, Kaldewaij, Duijndam, & Semin, 2012;Dimitroff et al., 2017;Engert, Plessow, Miller, Kirschbaum, & Singer, 2014) Outside of the literature on evacuation and emotional contagion, the study by Drury et al. (2016) of the 2010 Chile earthquake and tsunami found a strong link between reports of observing social and emotional support in others and providing support oneself. A meta-analysis has recently confirmed that witnessing prosocial acts consistently inspires others to act kindly as well (Jung, Seo, Han, Henderson, & Patall, 2020). ...
Intrusive memories represent a hallmark symptom of post-traumatic stress disorder (PTSD). Cognitive theories of PTSD hypothesize that intrusive memories result from disruptions in information processing during traumatic memory encoding. The affective, cognitive, and behavioural reactions taking place during trauma have been termed peritraumatic reactions. These include reactions such as peritraumatic dissociation and tonic immobility. Experimental evidence has supported the theoretical claims concerning the role of peritraumatic reactions in the development of intrusive memories. This literature, however, presents a number of limitations. First, it relies on a conceptualisation of peritraumatic reactions based largely on quantitative measures with a large degree of conceptual overlap. Secondly, the identification of peritraumatic reactions has relied on clinical expertise, theory, and animal models, rather than on systematic investigations of survivors’ lived experience. Finally, studies on peritraumatic reactions and intrusive memories, have generally assessed peritraumatic reactions for the entire trauma rather than for the specific moments experienced as intrusive memories. This thesis set out to address these limitations. Firstly, I investigated the factorial structure of the six most widely used peritraumatic measures. This led to the identification of a psychometrically validated model comprising five distinct peritraumatic reactions. Secondly, I explored using a largely inductive analytical framework the lived experienced of peritraumatic reactions spontaneously reported in interviews. Finally, building on these findings, I confirmed the theory-informed claims that the specific moments of a trauma experienced as intrusive memories would be characterised by higher levels of peritraumatic reactions compared to moments from the same trauma that did not intrude. All research was conducted among earthquake survivors. The current findings hold various implications for the conceptualisation of peritraumatic reactions and intrusive memories. Additionally, they have a number of practical implications for the prevention and management of intrusive memories as well as for the wellbeing of disaster survivors more generally.
... For instance, according to Olsson et al. (2014), human body odour contains an early chemosensory cue of sickness (see also Moshkin et al., 2012). Meanwhile, different chemosensory signals have been associated with different emotions such as fear and anxiety (de Groot et al., 2012). A person's body odour can also be influenced by aspects of their diet (Fialová et al., 2013;Havlicek & Lenochova, 2006), while single men have also been shown to have stronger body odour than partnered men, attributable to their higher levels of testosterone (Mahmut & Stevenson, 2019). ...
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.
... Pregnant pauses and eye contact are widely recognized social phenomena, but the source of their magnified meaning is difficult to trace and objectify. Vibes might describe subconscious neural processing of subtle paraverbal cues or chemical signals (de Groot et al., 2012). However, given their uncertain origin, these meaningful gestures lack an objective material basis upon which they can be judged in the real world today. ...
IntroductionAdvocates of affirmative consent argue that such policies can change sexual mores rooted in entitled masculinity while shifting the burden of preventing sexual assault from women to men. Yet there is little research to date on the implementation of affirmative consent or analysis of whether the policy’s demands are feasible in contemporary college sexual culture. We compare undergraduate students’ descriptions of sexual norms and behaviors on one college campus to the norms and logics implicit in the school’s affirmative consent sexual assault policy.Methods
Thirty-three undergraduate students from a mid-sized public university participated in one of eight same or mixed-gender, semi-structured focus groups in 2018.ResultsAffirmative consent assumes that sexual situations are a clearly definable category of activity, whereas student accounts suggest that sexual and non-sexual situations bleed into one another, making it difficult for students to establish consent via clear communication before sexual encounters begin. Students convey sexual interest through an accumulation of gestures exchanged over time, leading us to propose a cumulative model of consent. Students also report deliberately using ambiguous communication in sexual situations because it confers several social benefits, despite the risk of miscommunication.Conclusions
Student sexual behavior and affirmative consent policies are at odds because they are logically incompatible, and because student sexual culture is influenced by factors other than rape avoidance.Policy ImplicationsPolicies intended to curb sexual assault on campus should be written with normative student sexual behavior in mind and should offer clear guidelines for implementation in the real world.
... When an event is interpreted as threatening by an individual, it provokes behavioral responses such as facial expressions and physiological responses that generate body odors. Those responses may have a distinctive quality indicating VOCs olfactory roles that can exist and be associated with human emotions [41,42]. ...
Academic stress is an emotion that students experience during their time at the university, sometimes causing physical and mental health effects. Because of the COVID-19 pandemic, universities worldwide have left the classroom to provide the method of teaching virtually, generating challenges, adaptations, and more stress in students. In this pilot study, a methodology for academic stress detection in engineering students at the University of Pamplona (Colombia) is proposed by developing and implementing an artificial electronic nose system and the galvanic skin response. For the study, the student’s stress state and characteristics were taken into account to make the data analysis where a set of measurements were acquired when the students were presenting a virtual exam. Likewise, for the non-stress state, a set of measurements were obtained in a relaxation state after the exam date.
To carry out the pre-processing and data processing from the measurements obtained previously by both systems, a set of algorithms developed in Python software were used to perform the data analysis. Linear Discriminant Analysis (LDA), K-Nearest Neighbors (K-NN), and Support Vector Machine (SVM) classification methods were applied for the data classification, where a 96% success rate of classification was obtained with the E-nose, and 100% classification was achieved by using the Galvanic Skin Response.
... Olfaction is the oldest sensory function of human beings and is essential to human survival (1). The olfactory system not only enables humans to perceive their environment, but also plays an important role in social interaction (2)(3)(4) and food intake (5). Therefore, decreased olfactory function can lead to a decline in quality of life (6,7), and even depression (8,9). ...
Background:
Olfactory dysfunction significantly reduces quality of life, with a prevalence as high as 20% in the general adult population. Odor identification (OI) tests are culturally dependent and widely used in clinical and epidemiological evaluations of olfaction. We aimed to develop a Chinese odor identification test (COIT) based on the Sniffin' Sticks identification test.
Methods:
Patients (n=60) with olfactory disorders and healthy controls (n=404) were recruited in the Smell and Taste Center of a tertiary-care university hospital. Unfamiliar odors in the Sniffin' Sticks identification test were replaced to create a 16-item COIT, which was validated with a simplified Chinese version of the Cross-culture Smell Identification Test (CC-SIT) and Sniffin' Sticks. A test-retest reliability of COIT was also conducted.
Results:
Six odors with a correct recognition rate <75% were replaced with familiar odors for Chinese. The COIT score significantly correlated with both Sniffin' Sticks (r=0.755 P<0.0001) and CC-SIT score (r=0.7462 P<0.0001). Based on the testing results of an additional 120 subjects, we concluded that scores of 12-16, 7-11, and 0-6 corresponded to normosmia, hyposmia, and anosmia, respectively. The 3-month test-retest-reliability coefficient was as high as 0.83.
Conclusions:
The COIT is an effective tool for assessing olfactory function in the Chinese population.
... Researchers have examined whether humans can communicate emotions such as fear or anxiety (see de Groot and Smeets 2017 for a recent review), happiness (e.g., Zhou and Chen 2009;de Groot et al. 2015), disgust (e.g., Zheng et al. 2018), aggression (e.g., Mutic et al. 2017) and competition (Adolph et al. 2010). Individuals exposed to emotional body odors (EBOs) exhibit behavioral effects, such as increased startle response (Prehn et al. 2006;Adolph et al. 2013), biased identifications or judgments (Zernecke et al. 2011;Dalton et al. 2013;Wudarczyk et al. 2016), higher risk taking behavior (Haegler et al. 2010), generation of emotional facial expressions (de Groot et al. 2012(de Groot et al. , 2015Kamiloğlu et al. 2018) or lower practice performance (Singh et al. 2018). ...
Background:
Though aberrant face processing is a hallmark of autistic spectrum disorder (ASD), findings on accompanying brain activity are divergent. Therefore, we conducted an activation likelihood estimation (ALE) meta-analysis of studies examining brain activity during face processing.
Methods:
We searched PubMed and PsycINFO using combinations of terms as 'fMRI', 'Autism Spectrum Disorder', 'Face Perception'. Eligible studies reported on DSM-diagnosed ASD individuals, compared to controls (HC), using face stimuli presented in fMRI and reporting whole-brain analysis coordinates. We compared two approaches: 'convergence of differences' (primary analysis) using study-level coordinates from ASD vs. HC contrasts, and 'differences in convergence' (secondary) pooling coordinates within each group separately, and contrasting the resultant ALE maps.
Results:
Thirty-five studies (655 ASD and 668 HC) were included. Primary analysis identified a cluster in amygdala/parahippocampus where HC showed greater convergence of activation. Secondary analysis yielded no significant results.
Conclusions:
Results suggest that ASD dysfunction in face processing relies on structures involved in emotional processing rather than perception. We also demonstrate that the two ALE methodologies lead to divergent results.
... Cette expérimentation justifie une théorie selon laquelle le sens olfactif déclencherait une émotion dite pré-conceptuelle, ne transitant pas par le néocortex (Herz et al., 2004). D'autres expérimentations ont été faites sur un lien direct entre l'odeur et l'émotion (De Groot et al., 2012). ...
L’objet de cette thèse était d’étudier le rôle de l’émotion dans un processus de conception sensorielle. Une première expérimentation a permis de mettre en place une mesure émotionnelle du toucher lors de l’exploration tactile de surfaces. Une seconde expérimentation a permis de mettre en place une mesure émotionnelle visuelle lors de la visualisation d’images IAPS. Ces mesures ont permis d’objectiver la mesure émotionnelle des matériaux et des images en se basant sur deux indicateurs émotionnels, i) la valeur émotionnelle collectée lors de tests déclaratifs et ii) le coefficient de dilatation de la pupille (Bertheaux et al., 2020a).Le processus décisionnaire lors d’un acte d’achat repose sur l’estimation de valeurs utilitaires et hédoniques. Une autre contribution présentée dans ce document réside dans une nouvelle approche du modèle de préférence qui considère les données provenant de l’axe « Sensations » et de l’axe « Emotions ». Par ailleurs, un opérateur d’agrégation permet d’attribuer un score d’acceptabilité aux différentes configurationsdu produit étudié. Ce modèle multidimensionnel de préférence permet de représenter le ressenti émotionnel du panel relatif aux produits (Bertheaux et al., 2018, 2019).Une autre approche a permis de prédire les réactions émotionnelles lors de l’examen d’images de chaises dans un contexte d’achat en ligne. Dans ce cas le modèle multidimensionnel de préférence est utilisé pour estimer une valence basée sur l’évaluation de six descripteurs d’apparence. Une régression non linéaire via un modèle neuronal a montré que la valence « estimée » obtenue par le modèle multidimensionnel de préférence était corrélée à la valence exprimée par le panel (Bertheaux et al., 2020b).
Olfaction could influence how people respond to threats or select a partner. To investigate, researchers need to design experiments that can capture its effects. Olfaction could influence how people respond to threats or select a partner. To investigate, researchers need to design experiments that can capture its effects.
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 – i.e., disgust. We compared the time that three different emotional facial expressions (i.e., fear, disgust, and neutral) took to reach visual awareness, during a breaking continuous flash suppression paradigm, across three 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 to 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.
Altered social cognition is a core feature of Autism Spectrum Disorders (ASD). These impairments have been explained as the consequence of compromised social motivational mechanisms that limit social interest and activate a cascade of social deficits. Following this rational, we argue that approaches capable of surpassing ASD usual restraints (e.g., deficits in verbal abilities), and able to assign social meaning, could be more effective at responding to these difficulties. In this framework, we propose that olfaction, as well as cross-modal integration strategies involving both visual and olfactory domains, may have such potential. In fact, most of socioemotional processing deficits in ASD have been shown in an uni-modal perspective, mainly with visual stimuli. However, the social environment involves other modalities and is typically multisensorial. Given the potential of olfaction as a gateway for socioemotional information in ASD, we argue in favor of studying olfactory perception, as well as visuo-olfactory integration, given the potential of these approaches to drive effective interventions and give the access to a meaningful social world in ASD.
It is well accepted that emotional intensity scales with stimulus strength. Here, we used physiological and neuroimaging techniques to ask whether human body odor – which can convey salient social information – also induces dose-dependent effects on behavior, physiology, and neural responses. To test this, we first collected sweat from 36 males classified as low, medium, and high fear responders. Next, in a double-blind, within-subjects fMRI design, 31 females were exposed to three doses of fear-associated human chemosignals (vs. neutral sweat) while viewing face morphs varying between expressions of fear and disgust. Behaviorally we found that all doses of fear sweat volatiles biased subjects towards perceiving fear in ambiguous morphs, a dose-invariant effect generally repeated across physiological and neural measures. Bayesian dose-response analysis indicated moderate evidence for the null (except left amygdala), tentatively suggesting that the human olfactory system above all engages an all-or-none mechanism for tagging fear above a minimal threshold.
Autism Spectrum Disorders, as well as autism traits (AT), have been associated with altered sensory processing. However, the role of AT in olfactory processing is still unclear. We analyzed the impact of AT and trait anxiety (TANX), relevant in the context of autism and olfactory perception, in the olfactory abilities of a nonclinical adult sample. Participants (N = 116) completed the Autism-Spectrum Quotient (AQ), the State-Trait Inventory for Cognitive and Somatic Anxiety (STICSA) and the Sniffin’ Sticks Extended Test to measure AT, TANX and olfactory abilities, respectively. A hierarchical multiple regression analysis suggested that women and higher scores on the Attention to Detail subscale of AQ were associated with better odor discrimination, and higher somatic TANX was related to poorer odor discrimination.
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.
The existence of pheromones in humans is controversial, partly because of definitional difficulties and partly because of the question of possible chemical substances. The synthetic compound Methyl dihydrojasmonate (Hedione) is potent to bind to vomeronasal-type 1 receptors (VN1R1s) and activate limbic areas of the brain in a sex-specific manner. However, one of the most important definitional points for a human pheromone effect has not yet been investigated, i.e., whether smelling Hedione, a model of pheromone, has a behavioral effect.
We tested in females whether Hedione leads to altered perception of male social stimuli. Each of the included women were sensitive to Hedione and were tested around the time of ovulation in three consecutive sessions, during each they were exposed to either Hedione or Phenylethyl alcohol or Odorless air. We measured the speed of male face recognition (implicit priming task) and collected ratings of facial attractiveness and likeability of men (explicit task).
Only about half of the women tested were sensitive to Hedione. Those women did not show any effect of Hedione exposure in the implicit priming task and moderate, but non-significant effects in the explicit task. We therefore assume that Hedione is not a potent model of pheromone in humans and this observation may be due to the fact that the artificially produced substance is not suited for signaling the proximity of other humans. Furthermore, the high rate of Hedione-specific anosmia leads to the hypothesis that a substantial proportion of individuals has a poor V1NR1 receptor expression.
The incorporation of emotions in educational and cultural spaces is increasingly important in our society. The main objective is to review studies on emotional pedagogy both in school and in the museum and its importance in the education of blind pupils, providing elements for good practice. In the methodology used, a systematic review has been carried out with a selection of 410 articles examined up to 52 articles from 2003 to 2020. The search was conducted using 10 databases: Circ, Miar, Eric, Science Direct, 1Findr, Dialnet, Scopus, Google Scholar, Teacher Reference Center, and Wos. Among the results, we identified the importance of defining emotional training programs for teachers and museum didactic teams. They should be geared toward improving professional practices and cooperation between the museum and the school. In the conclusions obtained, it is fundamental to incorporate emotional literacy in inclusive education from the first stages of development, to promote creativity and emotional management, to exemplify the figure of the neuro-educator and his role in improving didactics both in schools and in the museum, favoring inclusion, promoting kinesthetic and corporal stimulation, both in the school and in the museum, it is a joint work between teachers and museum staff.
The quality of life can be impacted by the smell as well as taste syndromes. As far as the smell and taste senses are concerned, they have dispensed three major roles—cautioning of imminent risk, communication with different people, and significance during eating as well as drinking. These responsibilities show the issues of individuals who are experiencing smell and taste syndromes. As is the norm, the significance of something is only appreciated once it is absent. Thus, it is only after one loses the smell and taste senses that their importance is acknowledged. Decreased olfactory abilities have been found to be an indicator of low levels of life expectancy. Odor together with taste senses is vital in every human being’s daily life. Indeed, apart from the reasons establishing a swift response, the sensor also record in the individual’s memory. It activates personal feelings as well as experiences. As a result, one is left to happen what would happen if people were able to taste food without being required to put the food in the mouth or even sending smell as well as taste to a given location and then stimulate the perception of the users accordingly. In this part of the paper, a novel opportunity for nonverbal communication is suggested. Among others, it could comprise of a social media platform that would have the capability to share experiences with different smells as well as different tastes.
recently, we have begun to explore . . . [the] process of emotional contagion / people's conscious analyses give them a great deal of information about their social encounters / [people] can also focus their attention on their moment-to-moment emotional reactions to others, during their social encounters / this stream of reactions comes to them via their fleeting observations of others' faces, voices, postures, and instrumental behaviors / further, as they nonconsciously and automatically mimic their companions' fleeting expressions of emotion, people also may come to feel as their partners feel / by attending to the stream of tiny moment-to-moment reactions, people can gain a great deal of information on their own and their partners' emotional landscapes
begin by defining emotion and emotional contagion and discussing several mechanisms that we believe might account for this phenomenon / review the evidence from a variety of disciplines that "primitive emotional contagion" exists / examine the role of individual differences in emotional contagion / outline some of the broad research questions researchers might profitably investigate (PsycINFO Database Record (c) 2012 APA, all rights reserved)
The hypothesis of this experiment was that humans in an anxious state compared with a nonanxious state are able to increase anxiety levels in other humans via their body odors. Specifically, we hypothesized that male chemosensory anxiety signals compared with neutral chemosignals increase state anxiety of female subjects. Thirteen male subjects participated in 2 different sweat donation sessions: chemosignals were collected during participation in a high rope course (anxiety condition) and in an ergometer workout (neutral condition). State and trait anxiety were evaluated in 20 female odor recipients using Spielberger's state-trait anxiety inventory in a double-blind design. Comparison of state anxiety of odor donors between control and anxiety condition differed significantly indicating that our model of anxiety induction successfully led to the expected change in emotion. Comparison of state anxiety of odor recipients showed a trend toward higher state anxiety in the anxiety condition compared with the neutral condition after 5 min of odor exposure. After 20 min of odor exposure, state anxiety of female subjects was significantly higher during the perception of sweat collected during the anxiety condition in comparison with the perception of sweat collected during the neutral condition. This experiment gives evidence that male anxiety chemosignals compared with neutral chemosignals are capable of inducing an increased state anxiety in female subjects.
Alarm substances are airborne chemical signals, released by an individual into the environment, which communicate emotional stress between conspecifics. Here we tested whether humans, like other mammals, are able to detect emotional stress in others by chemosensory cues. Sweat samples collected from individuals undergoing an acute emotional stressor, with exercise as a control, were pooled and presented to a separate group of participants (blind to condition) during four experiments. In an fMRI experiment and its replication, we showed that scanned participants showed amygdala activation in response to samples obtained from donors undergoing an emotional, but not physical, stressor. An odor-discrimination experiment suggested the effect was primarily due to emotional, and not odor, differences between the two stimuli. A fourth experiment investigated behavioral effects, demonstrating that stress samples sharpened emotion-perception of ambiguous facial stimuli. Together, our findings suggest human chemosensory signaling of emotional stress, with neurobiological and behavioral effects.
In recent years, considerable progress has been achieved in the comprehension of the profound effects of pheromones on reproductive physiology and behavior. Pheromones have been classified as molecules released by individuals and responsible for the elicitation of specific behavioral expressions in members of the same species. These signaling molecules, often chemically unrelated, are contained in body fluids like urine, sweat, specialized exocrine glands, and mucous secretions of genitals. The standard view of pheromone sensing was based on the assumption that most mammals have two separated olfactory systems with different functional roles: the main olfactory system for recognizing conventional odorant molecules and the vomeronasal system specifically dedicated to the detection of pheromones. However, recent studies have reexamined this traditional interpretation showing that both the main olfactory and the vomeronasal systems are actively involved in pheromonal communication. The current knowledge on the behavioral, physiological, and molecular aspects of pheromone detection in mammals is discussed in this review.
The communication of stress/anxiety between conspecifics through chemosensory signals has been documented in many vertebrates and invertebrates. Here, we investigate how chemosensory anxiety signals conveyed by the sweat of humans (N = 49) awaiting an academic examination are processed by the human brain, as compared to chemosensory control signals obtained from the same sweat donors in a sport condition. The chemosensory stimuli were pooled according to the donation condition and administered to 28 participants (14 males) synchronously to breathing via an olfactometer. The stimuli were perceived with a low intensity and accordingly only about half of the odor presentations were detected by the participants. The fMRI results (event-related design) show that chemosensory anxiety signals activate brain areas involved in the processing of social emotional stimuli (fusiform gyrus), and in the regulation of empathic feelings (insula, precuneus, cingulate cortex). In addition, neuronal activity within attentional (thalamus, dorsomedial prefrontal cortex) and emotional (cerebellum, vermis) control systems were observed. The chemosensory perception of human anxiety seems to automatically recruit empathy-related resources. Even though the participants could not attentively differentiate the chemosensory stimuli, emotional contagion seems to be effectively mediated by the olfactory system.
Body odor sampling is an essential tool in human chemical ecology research. However, methodologies of individual studies vary widely in terms of sampling material, length of sampling, and sample processing. Although these differences might have a critical impact on results obtained, almost no studies test validity of current methods. Here, we focused on the effect of freezing samples between collection and use in experiments involving body odor perception. In 2 experiments, we tested whether axillary odors were perceived differently by raters when presented fresh or having been frozen and whether several freeze-thaw cycles affected sample quality. In the first experiment, samples were frozen for 2 weeks, 1 month, or 4 months. We found no differences in ratings of pleasantness, attractiveness, or masculinity between fresh and frozen samples. Similarly, almost no differences between repeatedly thawed and fresh samples were found. We found some variations in intensity; however, this was unrelated to length of storage. The second experiment tested differences between fresh samples and those frozen for 6 months. Again no differences in subjective ratings were observed. These results suggest that freezing has no significant effect on perceived odor hedonicity and that samples can be reliably used after storage for relatively long periods.
EEG and behavioural evidence suggests that air-borne chemicals can affect the nervous system without being consciously detected. EEG and behaviour, however, do not specify which brain structures are involved in chemical sensing that occurs below a threshold of conscious detection. Here we used functional MRI to localize brain activation induced by high and low concentrations of the air-borne compound oestra-1,3,5(10),16-tetraen-3yl acetate. Following presentations of both concentrations, eight of eight subjects reported verbally that they could not detect any odour (P = 0.004). Forced choice detection performed during the presentations revealed above-chance detection of the high concentration, but no better than chance detection of the low concentration compound. Both concentrations induced significant brain activation, primarily in the anterior medial thalamus and inferior frontal gyrus. Activation in the inferior frontal gyrus during the high concentration condition was significantly greater in the right than in the left hemisphere (P = 0.03). A trend towards greater thalamic activation was observed for the high concentration than the low concentration compound (P = 0.08). These findings localize human brain activation that was induced by an undetectable air-borne chemical (the low concentration compound).
Nonhuman animals communicate their emotional states through changes in body odor. The study reported here suggests that this may be the same for humans. We collected underarm odors on gauze pads from 25 young women and men on two different occasions. On one occasion the donors were induced to feel happy by viewing an excerpt from a funny movie whereas on the other, separated by a day, they were induced to feel afraid by watching an excerpt from a frightening movie. One week later, 40 women and 37 men were asked to smell several different bottles, some of which contained underarm odor pads collected during the happy movie, some contained underarm odor pads collected during the frightening movie, whereas others contained unused pads (control odor). Each odor was identified on two separate tasks that involved identifying the odor from among three odors and identifying it again from among six odors. Data were the number of women and men who identified an odor correctly on both tasks. When asked to select which bottles contained "the odor of people when they are happy," women chose the correct bottles for both tasks significantly more often than chance. Men chose the bottle which contained the body odors collected when women (but not men) viewed the happy movie more often than would be expected by chance. When asked to select which bottles contained "the odor of people when they are afraid," women and men both chose the bottle that contained the body odors collected when men (but not women) viewed the frightening movie more often than would be expected by chance. The finding suggests that there is information in human body odors indicative of emotional state. This finding introduces new complexity in how humans perceive and interact.
After the classic serial/parallel dichotomy of visual search mechanisms has been increasingly doubted, we investigated what search mechanisms are used between the two poles termed "pop-out" and "strictly serial search" in an overt feature search paradigm. Since reaction time slopes do not contain sufficient information for this purpose, we developed a novel technique for analyzing reaction times. Individual reaction times are modeled as sums of the durations of successive search steps. Model parameters are task characteristics (similarity, number and arrangement of target and distractors) and processing characteristics of the participant (e.g., attention dwell and shift durations). In Experiment 1, several model variants were fitted numerically to empirical reaction times. The best fitting model suggested that more than one item can be processed in a single fixation, movement of attention is abrupt and not continuous, and even in pop out search, attention is often explicitly moved to the target. In Experiment 2, we measured the central model parameter, the so-called range of attention, more directly and thereby validated the model. The model provides an explanation for the strong variation in the slope of reaction time functions, which is not based on an explicit distinction between parallel and serial search processes.
Chemosensory communication of anxiety is a common phenomenon in vertebrates and improves perceptual and responsive behaviour in the perceiver in order to optimize ontogenetic survival. A few rating studies reported a similar phenomenon in humans. Here, we investigated whether subliminal face perception changes in the context of chemosensory anxiety signals. Axillary sweat samples were taken from 12 males while they were waiting for an academic examination and while exercising ergometric training some days later. 16 subjects (eight females) participated in an emotional priming study, using happy, fearful and sad facial expressions as primes (11.7 ms) and neutral faces as targets (47 ms). The pooled chemosensory samples were presented before and during picture presentation (920 ms). In the context of chemosensory stimuli derived from sweat samples taken during the sport condition, subjects judged the targets significantly more positive when they were primed by a happy face than when they were primed by the negative facial expressions (P = 0.02). In the context of the chemosensory anxiety signals, the priming effect of the happy faces was diminished in females (P = 0.02), but not in males. It is discussed whether, in socially relevant ambiguous perceptual conditions, chemosensory signals have a processing advantage and dominate visual signals or whether fear signals in general have a stronger behavioural impact than positive signals.
In this review, we use data obtained primarily from humans to argue that sniffs are not merely a stimulus carrier but are rather a central component of the olfactory percept. We argue that sniffs 1) are necessary for the olfactory percept, 2) affect odorant intensity perception and identity perception, 3) drive activity in olfactory cortex, 4) are rapidly modulated in an odorant-dependent fashion by a dedicated olfactomotor system, and 5) are sufficient to generate an olfactory percept of some sort even in the absence of odor.
Visual and auditory stimuli of high social and ecological importance are processed in the brain by specialized neuronal networks.
To date, this has not been demonstrated for olfactory stimuli. By means of positron emission tomography, we sought to elucidate
the neuronal substrates behind body odor perception to answer the question of whether the central processing of body odors
differs from perceptually similar nonbody odors. Body odors were processed by a network that was distinctly separate from
common odors, indicating a separation in the processing of odors based on their source. Smelling a friend's body odor activated
regions previously seen for familiar stimuli, whereas smelling a stranger activated amygdala and insular regions akin to what
has previously been demonstrated for fearful stimuli. The results provide evidence that social olfactory stimuli of high ecological
relevance are processed by specialized neuronal networks similar to what has previously been demonstrated for auditory and
visual stimuli.
It has been proposed that facial expression production originates in sensory regulation. Here we demonstrate that facial expressions of fear are configured to enhance sensory acquisition. A statistical model of expression appearance revealed that fear and disgust expressions have opposite shape and surface reflectance features. We hypothesized that this reflects a fundamental antagonism serving to augment versus diminish sensory exposure. In keeping with this hypothesis, when subjects posed expressions of fear, they had a subjectively larger visual field, faster eye movements during target localization and an increase in nasal volume and air velocity during inspiration. The opposite pattern was found for disgust. Fear may therefore work to enhance perception, whereas disgust dampens it. These convergent results provide support for the Darwinian hypothesis that facial expressions are not arbitrary configurations for social communication, but rather, expressions may have originated in altering the sensory interface with the physical world.
Mammalian pheromones, audiomones, visuomones, and snarks-Richard Doty argues that they all belong in the same category: objects of imagination. For more than 50 years, researchers-including many prominent scientists-have identified pheromones as the triggers for a wide range of mammalian behaviors and endocrine responses. In this provocative book, renowned olfaction expert Richard L. Doty rejects this idea and states bluntly that, in contrast to insects, mammals do not have pheromones. Doty systematically debunks the claims and conclusions of studies that purport to reveal the existence of mammalian pheromones. He demonstrates that there is no generally accepted scientific definition of what constitutes a mammalian pheromone and that attempts to divide stimuli and complex behaviors into pheromonal and nonpheromonal categories have primarily failed. Doty's controversial assertion belies a continued fascination with the pheromone concept, numerous claims of its chemical isolation, and what he sees as the wasted expenditure of hundreds of millions of dollars by industry and government. The Great Pheromone Myth directly challenges ideas about the role chemicals play in mammalian behavior and reproductive processes. It is a must-have reference for biologists, psychologists, neuroscientists, and readers interested in animal behavior, ecology, and evolution. © 2010 by The Johns Hopkins University Press. All rights reserved.
Research on emotion has undergone explosive growth during the past few decades, marked by new theories (e.g., evolutionary analyses; Tooby & Cosmides, 1990), methods (e.g., anatomically-based systems for coding facial expressive behavior, see Cohn this volume), and findings (see Cacioppo & Gardner, 1999). Some of the research in this area has been correlational, focusing on factors that naturally co-vary with emotional processes, such as chronological age, physical health, or social status. However, experimental research also has flourished, focusing on emotional processes in the context of relatively well-controlled laboratory environments. Our chapter on the use of emotion-eliciting films, like many of the contributions to the Handbook of Emotion Elicitation and Assessment, lies squarely within this second, experimental tradition.
Emotions have ubiquitous effects in human affairs. Vivian Gornick, in Fierce Attachments,^ recounts a typ-ical exchange with her mother. Gor-nick always begins these encounters with high hopes. "Somehow," de-spite her best intentions, the conver-sations always spiral downward: Today is promising, tremendously prom-ising I go to meet my mother. I'm flying. Flying! I want to give her some of this shiningness bursting in me, siphon into her my immense happiness at being alive. Just because she is my oldest inti-mate and at this moment I love every-body, even her. "Oh, Ma! What a day I've had," I say. "Tell me," she says. "Do you have the rent this month?" "Ma, listen ..." I say. "That review you wrote for the Times," she says. "Ifs for sure they'll pay you?" "Ma, stop it. Let me tell you what I've been feeling," I say. "Why aren't you wearing something warmer?" she cries. "It's nearly winter." The space inside begins to shimmer. The walls collapse inward. I feel breath-less. Swallow slowly, I say to myself, slowly. To my mother I say, "You do know how to say the right thing at the right time. Ifs remarkable, this gift of yours. It quite takes my breath away." But she doesn't get it. She doesn't loiow I'm being ironic. Nor does she Elaine Hatfield is a Professor of Psychology and Richard L. Rapson is a Professor of History at the Uni-versity of Hawaii. John T. Ca-cioppo is a Professor of Psychology at the Ohio State University. Ad-dress correspondence to Elaine Hatfield, 2430 Campus Rd., Honolulu, HI 96822; BITNET: psych@uhunix; INTERNET: psych@uhunix.uhcc.hawaii.edu. know she's wiping me out. She doesn't know I take her anxiety personally, feel annihilated by her depression. How can she know this? She doesn't even know I'm there. Were I to tell her that it's death to me, her not knowing I'm there, she would stare at me out of her eyes crowd-ing up with puzzled desolation, this young girl of seventy-seven, and she would cry angrily, "You don't under-stand! You have never understood!" (pp. 103-104)
The aim of this paper is to identify the functions of social cognition in a communication context. It is argued that social cognition is for the regulation of adaptive action and makes use of external devices (e.g. language) to implement action. First, the complexity of communication as a social achievement is discussed to prepare the ground for examining the link between language, cognition and communication. The implementational devices (language) of social cognition are addressed next. On the basis of these considerations a message-modulation model is proposed to conceptualize the interplay between language, cognition, motivation and communication. The application of this model to research on the transmission and maintenance of stereotypes illustrates the types of open research issues and directions that may be possible routes for future work. Copyright
The communication of chemosensory alarm signals is well explored in mammals. In humans the effects of anxiety substances might seem to be less important due to their high-developed visual system, and their sophisticated ability to communicate via speech and body language. Nevertheless, an increasing number of studies suggest an effect of chemosignals of anxiety on human physiology and behavior. In the present study two kinds of human sweat were collected from 21 males during a bicycle workout and a visit of a high rope course, and were then applied to 15 different healthy male participants during an emotion evaluation task. Participants were instructed to rate emotional male faces of different morphing levels (neutral-happy) by using a visual analog scale under exposure of three different samples (exercise sweat, anxiety sweat, and control material). Our study revealed that men rated happy faces as less happy under the influence of anxiety sweat compared to the exercise and the control conditions; significant differences were demonstrated only for ambiguous emotional faces. In conclusion, chemosignals of anxiety comprised in human sweat are communicated between males; they diminish the evaluation of ambiguous happy male facial expressions in men and thereby influence the perception of emotional faces.
I argue that the psychological and neural mechanisms that constitute an embodied grounding of communication rely on a unique knowledge system. The unique features of this knowledge system are that it is specialized for social cognition and is grounded on processes that give privileged and immediate mutual access by coupling two agents. It is only through jointly recruited processes that it is possible for two agents to be coupled and put on the same footing. In other words, such mechanisms must facilitate obtaining a state of equivalence between two parties: What counts for one member must also count for the other. I refer to this process as synchronization. Synchronization gives simultaneous partial mutual access to internal states, thereby establishing a type of knowledge that is different from knowledge about manipulable objects, spatial orientation, or numerosities. I regard a jointly and simultaneously recruited process by means of which correspondence is established at neural, perceptual, affective, and behavioral levels between producer and perceiver as synchronization. Moreover, I posit that synchronization precedes communication by means of language both evolutionarily and ontogenetically. It is a process that occurs without the presence of explicit communicative intent. I review research on synchronization, focusing first on neurophysiological evidence obtained with nonhuman primates and humans. I turn to some developmental evidence obtained in infant studies and related comparative evidence with nonhuman primates. I provide an overview of the voluminous behavioral evidence, which has a long history in social psychology. I circumscribe what synchronization as a core knowledge system entails. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
Detection Theory is an introduction to one of the most important tools for analysis of data where choices must be made and performance is not perfect. Originally developed for evaluation of electronic detection, detection theory was adopted by psychologists as a way to understand sensory decision making, then embraced by students of human memory. It has since been utilized in areas as diverse as animal behavior and X-ray diagnosis. This book covers the basic principles of detection theory, with separate initial chapters on measuring detection and evaluating decision criteria. Some other features include: complete tools for application, including flowcharts, tables, pointers, and software;. student-friendly language;. complete coverage of content area, including both one-dimensional and multidimensional models;. separate, systematic coverage of sensitivity and response bias measurement;. integrated treatment of threshold and nonparametric approaches;. an organized, tutorial level introduction to multidimensional detection theory;. popular discrimination paradigms presented as applications of multidimensional detection theory; and. a new chapter on ideal observers and an updated chapter on adaptive threshold measurement. This up-to-date summary of signal detection theory is both a self-contained reference work for users and a readable text for graduate students and other researchers learning the material either in courses or on their own. © 2005 by Lawrence Erlbaum Associates, Inc. All rights reserved.
The human axillae have a characteristic odour that is comprised of or generated from a mixture of C6–C11 normal, branched, hydroxy- and unsaturated acids (and other compounds). We used ethyl esters of one of these acids and a palette of fragrance compounds (tested individually) to evaluate the effectiveness of these chemicals to reduce the overall olfactory impact of a model of human stress-related odour (SRO) by cross-adaptation (adaptation to one odorant can reduce sensitivity to other odorants). Sensory volunteers provided hedonic and intensity ratings of the SRO and of each of the potential cross-adapting agents prior to 2.5 min of induced olfactory adaptation to each agent. Across adaptation, possible cross-adaptation was evaluated by intermittent evaluations of the perceived intensity of the SRO. We determined that some potential cross-adapting agents did reduce the impact of the SRO; however, the same chemicals were not necessarily effective for male and female SRO. Indeed, the list of effective chemicals depended upon the gender of the donor of the SRO and the gender of the sensory volunteer, suggesting a gender-specific response to both the SRO-stimuli used and the fragrance chemicals used to cross-adapt it. Copyright © 2009 John Wiley & Sons, Ltd.
Guidelines are proposed for the collection, analysis, and description of electromyographic (EMG) data. The guidelines cover technological issues in EMG recording, social aspects of EMG experimentation, and limits to inferences that can be drawn in EMG research. An atlas is proposed for facial EMG electrode placements, and standard EMG terminology is suggested.
It is generally assumed that disgust is accompanied by increased activation of the parasympathetic nervous system (PNS). However, empirical support for the role of PNS in disgust is scarce. This study tested whether (i) activation of the PNS is indeed involved in disgust and (ii) disgust-induced autonomic activation is especially pronounced in individuals with high disgust propensity or enhanced disgust sensitivity. Participants (N=60) viewed a 5 min disgust-inducing video clip. Participants showed increased parasympathetic activity of both the cardiac and the digestive components of the autonomic nervous system (ANS), together with increased sympathetic activation of the cardiac system. ANS responses were independent of subjective disgust and individuals' habitual disgust propensity or sensitivity. Results support the hypothesis that PNS activation is involved in disgust. The absence of a relationship between subjective and physiological indices of disgust indicates that both types of responses reflect independent phenomena.
An important aspect of cognitive functioning is decision-making, which depends on the correct interpretation of emotional processes. High trait anxiety has been associated with increased risk taking behavior in decision-making tasks. An interesting fact is that anxiety and anxiety-related chemosignals as well as decision-making share similar regions of neuronal activation. In order to ascertain if chemosensory anxiety signals have similar effects on risk taking behavior of healthy participants as high trait anxiety we used a novel computerized decision-making task, called Haegler's Risk Game (HRG). This task measures risk taking behavior based on contingencies and can be played repeatedly without a learning effect. To obtain chemosensory signals the sweat of 21 male donors was collected in a high rope course (anxiety condition). For the chemosensory control condition sweat was collected during an ergometer workout (exercise condition). In a double-blind study, 30 healthy recipients (16 females) had to play HRG while being exposed to sweat samples or empty control samples (control condition) in three sessions of randomized order. Comparison of the risk taking behavior of the three conditions showed significantly higher risk taking behavior in participants for the most risky choices during the anxiety condition compared to the control conditions. Additionally, recipients showed significantly higher latency before making their decision in the most risky choices during the anxiety condition. This experiment gives evidence that chemosensory anxiety signals are communicated between humans thereby increasing participants' risk taking behavior.
The present study aimed to investigate whether withdrawal related behavior is activated in the context of chemosensory anxiety signals. Moreover, it was examined whether chemosensory perception of social stress is modulated by the degree of social anxiety. Axillary sweat was collected from students, awaiting an oral examination at the university (anxiety condition) and from the same students in a sport control condition. The chemosensory stimuli were presented to 32 participants (16 socially anxious) via an olfactometer during inhalation (duration=3 s). 102 dB white noise bursts served as startle probes. During a single session only male or female axillary sweat was presented, therefore, all participants were tested in two separate sessions. Even though the chemosensory stimuli were perceived at the perceptual threshold level, participants could identify (forced choice) the emotion of the donors in the anxiety condition. In the context of chemosensory anxiety signals the acoustic startle reflex was significantly augmented as compared to startle responses obtained in the context of sport sweat (p=0.002). This effect was more pronounced in socially anxious than in non-anxious participants. It is concluded that human motor systems automatically adapt to chemosensory stress signals. This adaptation is neither dependent on the gender of the odor donor nor on the gender of the perceiver, but is intensified in socially anxious participants.
Integrating emotional cues from different senses is critical for adaptive behavior. Much of the evidence on cross-modal perception of emotions has come from studies of vision and audition. This research has shown that an emotion signaled by one sense modulates how the same emotion is perceived in another sense, especially when the input to the latter sense is ambiguous. We tested whether olfaction causes similar sensory modulation of emotion perception. In two experiments, the chemosignal of fearful sweat biased women toward interpreting ambiguous expressions as more fearful, but had no effect when the facial emotion was more discernible. Our findings provide direct behavioral evidence that social chemosignals can communicate emotions and demonstrate that fear-related chemosignals modulate humans' visual emotion perception in an emotion-specific way--an effect that has been hitherto unsuspected.