Publications by authors named "Monique A M Smeets"

45 Publications

From musk to body odor: Decoding olfaction through genetic variation.

PLoS Genet 2022 02 3;18(2):e1009564. Epub 2022 Feb 3.

CAS Key Laboratory of Computational Biology, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China.

The olfactory system combines input from multiple receptor types to represent odor information, but there are few explicit examples relating olfactory receptor (OR) activity patterns to odor perception. To uncover these relationships, we performed genome-wide scans on odor-perception phenotypes for ten odors in 1000 Han Chinese and validated results for six of these odors in an ethnically diverse population (n = 364). In both populations, consistent with previous studies, we replicated three previously reported associations (β-ionone/OR5A1, androstenone/OR7D4, cis-3-hexen-1-ol/OR2J3 LD-band), but not for odors containing aldehydes, suggesting that olfactory phenotype/genotype studies are robust across populations. Two novel associations between an OR and odor perception contribute to our understanding of olfactory coding. First, we found a SNP in OR51B2 that associated with trans-3-methyl-2-hexenoic acid, a key component of human underarm odor. Second, we found two linked SNPs associated with the musk Galaxolide in a novel musk receptor, OR4D6, which is also the first human OR shown to drive specific anosmia to a musk compound. We noticed that SNPs detected for odor intensity were enriched with amino acid substitutions, implying functional changes of odor receptors. Furthermore, we also found that the derived alleles of the SNPs tend to be associated with reduced odor intensity, supporting the hypothesis that the primate olfactory gene repertoire has degenerated over time. This study provides information about coding for human body odor, and gives us insight into broader mechanisms of olfactory coding, such as how differential OR activation can converge on a similar percept.
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http://dx.doi.org/10.1371/journal.pgen.1009564DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8812863PMC
February 2022

Situating desire: Situational cues affect desire for food through eating simulations.

Appetite 2022 01 6;168:105679. Epub 2021 Sep 6.

Wageningen Food and Biobased Research, the Netherlands. Electronic address:

How do situations influence food desire? Although eating typically occurs in rich background situations, research on food desire often focuses on the properties of foods and consumers, rather than on the situations in which eating takes place. Here, we take a grounded cognition perspective and suggest that a situation that is congruent with consuming a food increases simulations of eating it, which, in turn, affect desire, and the expected and actual liking of the food. We tested this idea in four pre-registered experiments (N = 524). Participants processed an image of a food presented in a congruent situation, an incongruent situation, or no background situation. Compared to the incongruent situation, the congruent situation increased expected liking of the food and desire, and this was partially or fully mediated by eating simulations. The congruent situation also increased salivation, a physiological indicator of preparing to eat. However, there was only weak and indirect evidence for congruence effects on actual liking of the food when tasted. These findings show that situational cues can affect desire for food through eating simulations. Thus, background situations play an important but understudied role in human food desires. We address implications for research using food images, and for applications to promote healthy and sustainable eating behaviour.
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http://dx.doi.org/10.1016/j.appet.2021.105679DOI Listing
January 2022

More Data, Please: Machine Learning to Advance the Multidisciplinary Science of Human Sociochemistry.

Front Psychol 2020 22;11:581701. Epub 2020 Oct 22.

Faculty of Social and Behavioural Sciences, Utrecht University, Utrecht, Netherlands.

Communication constitutes the core of human life. A large portion of our everyday social interactions is non-verbal. Of the sensory modalities we use for non-verbal communication, olfaction (i.e., the sense of smell) is often considered the most enigmatic medium. Outside of our awareness, smells provide information about our identity, emotions, gender, mate compatibility, illness, and potentially more. Yet, body odors are astonishingly complex, with their composition being influenced by various factors. Is there a chemical basis of olfactory communication? Can we identify molecules predictive of psychological states and traits? We propose that answering these questions requires integrating two disciplines: psychology and chemistry. This new field, coined , faces new challenges emerging from the sheer amount of factors causing variability in of body odorants on the one hand (e.g., diet, hygiene, skin bacteria, hormones, genes), and variability in states and traits on the other (e.g., genes, culture, hormones, internal state, context). In past research, the reality of these high-dimensional data has been reduced in an attempt to isolate unidimensional factors in small, homogenous samples under tightly controlled settings. Here, we propose big data approaches to establish novel links between chemical and psychological data on a large scale from heterogeneous samples in ecologically valid settings. This approach would increase our grip on the way chemical signals non-verbally and subconsciously affect our social lives across contexts.
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http://dx.doi.org/10.3389/fpsyg.2020.581701DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7642605PMC
October 2020

Chemical Fingerprints of Emotional Body Odor.

Metabolites 2020 Feb 28;10(3). Epub 2020 Feb 28.

Faculty of Social and Behavioural Sciences, Utrecht University, Heidelberglaan 1, 3584 CS Utrecht, The Netherlands.

Chemical communication is common among animals. In humans, the chemical basis of social communication has remained a black box, despite psychological and neural research showing distinctive physiological, behavioral, and neural consequences of body odors emitted during emotional states like fear and happiness. We used a multidisciplinary approach to examine whether molecular cues could be associated with an emotional state in the emitter. Our research revealed that the volatile molecules transmitting different emotions to perceivers also have objectively different chemical properties. Chemical analysis of underarm sweat collected from the same donors in fearful, happy, and emotionally neutral states was conducted using untargeted two-dimensional (GC×GC) coupled with time of flight (ToF) MS-based profiling. Based on the multivariate statistical analyses, we find that the pattern of chemical volatiles (N = 1655 peaks) associated with fearful state is clearly different from that associated with (pleasant) neutral state. Happy sweat is also significantly different from the other states, chemically, but shows a bipolar pattern of overlap with fearful as well as neutral state. Candidate chemical classes associated with emotional and neutral sweat have been identified, specifically, linear aldehydes, ketones, esters, and cyclic molecules (5 rings). This research constitutes a first step toward identifying the chemical fingerprints of emotion.
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http://dx.doi.org/10.3390/metabo10030084DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7142800PMC
February 2020

From sterile labs to rich VR: Immersive multisensory context critical for odors to induce motivated cleaning behavior.

Behav Res Methods 2020 08;52(4):1657-1670

Department of Psychology, Utrecht University, PO Box 80140, 3508 TC, Utrecht, the Netherlands.

Extending traditional research methods for studying the effects of odor on behavior, this study applied virtual reality (VR) to create a real-world, immersive context that was compared with 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 with 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.
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http://dx.doi.org/10.3758/s13428-019-01341-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7406481PMC
August 2020

Placebo Effects in the Neuroendocrine System: Conditioning of the Oxytocin Responses.

Psychosom Med 2020 01;82(1):47-56

From the Health, Medical and Neuropsychology Unit (Skvortsova, Veldhuijzen, Pacheco-Lopez, van Middendorp, Evers), Faculty of Social and Behavioural Sciences, Leiden University; Leiden Institute for Brain and Cognition (Skvortsova, Veldhuijzen, Pacheco-Lopez, Bakermans-Kranenburg, Wilderjans, van Middendorp, Evers), Leiden, the Netherlands; Department of Health Sciences (Pacheco-Lopez), Metropolitan Autonomous University, Campus Lerma, Lerma, Edo. Mex., Mexico; Leiden Consortium on Individual Development (Bakermans-Kranenburg), Leiden University, Leiden; Department of Psychology, Education and Child Studies (van IJzendoorn), Erasmus University Rotterdam, Rotterdam, the Netherlands; Primary Care Unit (van IJzendoorn), School of Clinical Medicine, University of Cambridge, Cambridge, United Kingdom; Department of Social, Health, and Organizational Psychology (Smeets), Utrecht University, Utrecht; Methodology and Statistics Research Unit (Wilderjans), Institute of Psychology, Faculty of Social and Behavioural Sciences, Leiden University, Leiden, the Netherlands; Research Group of Quantitative Psychology and Individual Differences (Wilderjans), University of Leuven - KU Leuven, Leuven, Belgium; Department of Anaesthesiology (Dahan), Leiden University Medical Center, Leiden, the Netherlands; Health Psychology (van den Bergh), University of Leuven - KU Leuven, Leuven, Belgium; Departments of Public Health and Primary Care (Chavannes) and Psychiatry (van der Wee, Evers), Leiden University Medical Center, Leiden, the Netherlands; and Department of Psychiatry (Grewen), University of North Carolina, Charlotte, North Carolina.

Objective: There is evidence that placebo effects may influence hormone secretion. However, few studies have examined placebo effects in the endocrine system, including oxytocin placebo effects. We studied whether it is possible to trigger oxytocin placebo effects using a classical conditioning paradigm.

Methods: Ninety-nine women were assigned to a conditioned, control, or drug control group. In the two-phase conditioning paradigm, participants in the conditioned and drug control groups received an oxytocin nasal spray combined with a distinctive smell (conditioned stimulus [CS]) for three acquisition days, whereas the control group received placebo spray. Subsequently, the conditioned and control groups received placebo spray with the CS and the drug control group received oxytocin spray for three evocation days. Salivary oxytocin was measured several times during each day. Pain sensitivity and facial evaluation tests previously used in oxytocin research were also administered.

Results: On evocation day 1, in the conditioned group, oxytocin significantly increased from baseline to 5 minutes after CS (B[slope] = 19.55, SE = 5.88, p < .001) and remained increased from 5 to 20 (B = -10.42, SE = 5.81, p = .071) and 50 minutes (B = -0.70, SE = 3.37, p = .84). On evocation day 2, a trend for increase in oxytocin was found at 5 minutes (B = 15.22, SE = 8.14, p = .062). No placebo effect was found on evocation day 3 (B = 3.57, SE = 3.26, p = .28). Neither exogenous nor conditioned oxytocin affected pain or facial tasks.

Conclusions: Results indicate that oxytocin release can be conditioned and that this response extinguishes over time. Triggering hormonal release by placebo manipulation offers various clinical possibilities, such as enhancing effects of pharmacological treatments or reducing dosages of medications.

Trial Registration: The study was registered as a clinical trial on www.trialregister.nl (number NTR5596).
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http://dx.doi.org/10.1097/PSY.0000000000000759DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6946094PMC
January 2020

The Subtle Signaling Strength of Smells: A Masked Odor Enhances Interpersonal Trust.

Front Psychol 2019 20;10:1890. Epub 2019 Aug 20.

Department of Psychology, Faculty of Social and Behavioral Sciences, Utrecht University, Utrecht, Netherlands.

Most everyday smells, from lavender to body odors, are complex odorant mixtures that "host" particular compounds that guide (social) behavior and motivation (biomarkers). A key element of social behavior is interpersonal trust, and building on previous research showing that (i) lavender odor can enhance trust, and that (ii) certain compounds in body odor can reduce stress in mice and humans (called "social buffering"), we examined whether a grassy-smelling compound found in both body odors and lavender, hexanal, would enhance interpersonal trust. Notably, we applied odor masking to explore whether trust could be influenced by masked (i.e., undetectable) hexanal. In Study 1 (between-subjects), 90 females played a Trust Game while they either smelled hexanal (0.01% v/v), clove odor (eugenol: 10% v/v), or hexanal masked by clove odor (a mix of the former). As a sign of higher trust, participants gave more money to a trustee while exposed to masked hexanal (vs. the mask: eugenol). In Study 2 (within-subjects, double-blind), another sample of 35 females smelled the same three odors, while they rated the trustworthiness of a spectrum of faces that varied on trustworthiness. Controlling for subjective odor intensity and pleasantness and substantiating that masked hexanal could not be distinguished from the mask, faces were perceived as more trustworthy during exposure to masked hexanal (vs. the mask: eugenol). Whereas non-masked hexanal increased face trustworthiness ratings, these effects disappeared after controlling for the odor's subjective intensity and pleasantness. The combined results bring new evidence that trust can be enhanced implicitly via undetected smells.
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http://dx.doi.org/10.3389/fpsyg.2019.01890DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6710396PMC
August 2019

Human chemosignals modulate emotional perception of biological motion in a sex-specific manner.

Psychoneuroendocrinology 2019 02 28;100:246-253. Epub 2018 Oct 28.

State Key Laboratory of Brain and Cognitive Science, CAS Center for Excellence in Brain Science and Intelligence Technology, Institute of Psychology, Chinese Academy of Sciences, Beijing, 100101, China; Department of Psychology, University of Chinese Academy of Sciences, Beijing, 100049, China. Electronic address:

Androsta-4,16,-dien-3-one and estra-1,3,5(10),16-tetraen-3-ol have previously been shown to communicate opposite sex information that is differently effective to the two sex groups. The current study critically examines if the two human steroids could facilitate interactions with potential mates rather than competitors by acting on the recipients' emotional perception in a sex-appropriate manner. Using dynamic point-light displays that portray the gaits of walkers whose emotional states are digitally morphed along the valence and the arousal axes, we show that smelling androstadienone subconsciously biases heterosexual women, but not men, towards perceiving the male, but not female, walkers as happier and more relaxed. By contrast, smelling estratetraenol subconsciously biases heterosexual men, but not women, towards perceiving the female, but not male, walkers as happier and more relaxed. These findings indicate that androstadienone and estratetraenol prime the identification of emotionally receptive states for the potential mates with whom they are associated, in manners contingent upon not only the recipients' own sex but also their sex perception of other individuals that ensure sex-appropriate behavior.
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http://dx.doi.org/10.1016/j.psyneuen.2018.10.014DOI Listing
February 2019

Beyond the west: Chemosignaling of emotions transcends ethno-cultural boundaries.

Psychoneuroendocrinology 2018 12 7;98:177-185. Epub 2018 Aug 7.

Department of Social, Health, & Organizational Psychology, Utrecht University, Heidelberglaan 1, 3584 CS, Utrecht, the Netherlands; Unilever R&D, Olivier van Noortlaan 120, 3133 AT, Vlaardingen, the Netherlands.

Accumulating evidence has pointed to a human capacity to communicate emotions to others via sweat. So far, these studies have relied exclusively on Western Caucasian samples. Our aim was to test whether the chemosensory communication of emotions extended beyond ethno-cultural boundaries, from Western Caucasians (N = 48) to East Asians (N = 48). To test this, we used well-validated materials and procedures, a double-blind design, a pre-registered analysis plan, and a combination of facial electromyography (EMG) and continuous flash suppression techniques to measure unconscious emotions. Our results show that East Asian (and Western Caucasian) female receivers exposed to the sweat (body odor) of fearful, happy, and neutral Western Caucasian male senders emulate these respective states based on body odors, outside of awareness. More specifically, East Asian (and Western Caucasian) receivers demonstrated significantly different patterns of facial muscle activity when being exposed to fear odor, happy odor, and neutral odor. Furthermore, fear odor decreased the suppression time of all faces on an interocular suppression task (IST), indicating subconscious vigilance, whereas happy odor increased the detection speed of happy faces. These combined findings suggest that the ability to perceive emotional signals from body odor may be a universal phenomenon.
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http://dx.doi.org/10.1016/j.psyneuen.2018.08.005DOI Listing
December 2018

Fear Odor Facilitates the Detection of Fear Expressions Over Other Negative Expressions.

Chem Senses 2018 07;43(6):419-426

Department of Social, Health and Organizational Psychology, Faculty of Social and Behavioral Sciences, Utrecht University, Utrecht, The Netherlands.

In a double-blind experiment, participants were exposed to facial images of anger, disgust, fear, and neutral expressions under 2 body odor conditions: fear and neutral sweat. They had to indicate the valence of the gradually emerging facial image. Two alternative hypotheses were tested, namely a "general negative evaluative state" hypothesis and a "discrete emotion" hypothesis. These hypotheses suggest 2 distinctive data patterns for muscle activation and classification speed of facial expressions. The pattern of results that would support a "discrete emotions perspective" would be expected to reveal significantly increased activity in the medial frontalis (eyebrow raiser) and corrugator supercilii (frown) muscles associated with fear, and significantly decreased reaction times (RTs) to "only" fear faces in the fear odor condition. Conversely, a pattern of results characterized by only a significantly increased corrugator supercilii activity together with decreased RTs for fear, disgust, and anger faces in the fear odor condition would support an interpretation in line with a general negative evaluative state perspective. The data support the discrete emotion account for facial affect perception primed with fear odor. This study provides a first demonstration of perception of discrete negative facial expressions using olfactory priming.
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http://dx.doi.org/10.1093/chemse/bjy029DOI Listing
July 2018

Relationships between body image, sexual satisfaction, and relationship quality in romantic couples.

J Fam Psychol 2018 06 8;32(4):466-474. Epub 2018 Mar 8.

Department of Clinical Psychology, Utrecht University.

Previous studies found important associations between body image, sexual satisfaction, and perceived romantic relationship quality, but mainly focused on one individual's perceptions rather than both partners. To take the interdependency of romantic partners into account, the present study examined these associations in romantic couples with a dyadic approach. In a cross-sectional design, 151 Dutch heterosexual couples completed an online survey measuring body image, sexual satisfaction, and perceived relationship quality. Hypotheses were tested using the actor-partner interdependence model (APIM) and an APIM extended with a mediator (APIMeM), with couple members' body image as predictors, couple members' sexual satisfaction as mediators, and couple members' relationship quality as outcomes. Results indicated that within individuals, a more positive body image was linked to higher perceived romantic relationship quality through greater sexual satisfaction. No gender differences were found, implying that body image and sexual satisfaction are equally strongly associated with perceived relationship quality in women and men. Results revealed no associations of an individual's body image and sexual satisfaction with the partner's perceived relationship quality. These findings implicate that interventions focusing on developing and maintaining a positive body image may be helpful in building on a more satisfying sex life and higher perceived relationship quality. (PsycINFO Database Record
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http://dx.doi.org/10.1037/fam0000407DOI Listing
June 2018

Human Fear Chemosignaling: Evidence from a Meta-Analysis.

Chem Senses 2017 Oct;42(8):663-673

Department of Social, Health, & Organizational Psychology, Utrecht University, PO Box 80140, 3508 TC Utrecht, The Netherlands.

Alarm pheromones are widely used in the animal kingdom. Notably, there are 26 published studies (N = 1652) highlighting a human capacity to communicate fear, stress, and anxiety via body odor from one person (66% males) to another (69% females). The question is whether the findings of this literature reflect a true effect, and what the average effect size is. These questions were answered by combining traditional meta-analysis with novel meta-analytical tools, p-curve analysis and p-uniform-techniques that could indicate whether findings are likely to reflect a true effect based on the distribution of P-values. A traditional random-effects meta-analysis yielded a small-to-moderate effect size (Hedges' g: 0.36, 95% CI: 0.31-0.41), p-curve analysis showed evidence diagnostic of a true effect (ps < 0.0001), and there was no evidence for publication bias. This meta-analysis did not assess the internal validity of the current studies; yet, the combined results illustrate the statistical robustness of a field in human olfaction dealing with the human capacity to communicate certain emotions (fear, stress, anxiety) via body odor.
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http://dx.doi.org/10.1093/chemse/bjx049DOI Listing
October 2017

On the Communicative Function of Body Odors.

Perspect Psychol Sci 2017 03;12(2):306-324

1 Faculty of Social and Behavioral Sciences, Utrecht University, The Netherlands.

Humans use multiple senses to navigate the social world, and the sense of smell is arguably the most underestimated one. An intriguing aspect of the sense of smell is its social communicative function. Research has shown that human odors convey information about a range of states (e.g., emotions, sickness) and traits (e.g., individuality, gender). Yet, what underlies the communicability of these states and traits via smell? We fill this explanatory gap with a framework that highlights the dynamic and flexible aspects of human olfactory communication. In particular, we explain how chemical profiles, associative learning (i.e., the systematic co-occurrence of chemical profiles with state- or trait-related information), and top-down contextual influences could interact to shape human odor perception. Our model not only helps to integrate past research on human olfactory communication but it also opens new avenues for future research on this fascinating, yet to date poorly understood, field.
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http://dx.doi.org/10.1177/1745691616676599DOI Listing
March 2017

A sniff of happiness.

Psychol Sci 2015 Jun 13;26(6):684-700. Epub 2015 Apr 13.

Faculty of Social and Behavioral Sciences, Utrecht University Department of Psychology, Koç University Instituto Superior de Psicologia Aplicada, Lisbon, Portugal

It is well known that feelings of happiness transfer between individuals through mimicry induced by vision and hearing. The evidence is inconclusive, however, as to whether happiness can be communicated through the sense of smell via chemosignals. As chemosignals are a known medium for transferring negative emotions from a sender to a receiver, we examined whether chemosignals are also involved in the transmission of positive emotions. Positive emotions are important for overall well-being and yet relatively neglected in research on chemosignaling, arguably because of the stronger survival benefits linked with negative emotions. We observed that exposure to body odor collected from senders of chemosignals in a happy state induced a facial expression and perceptual-processing style indicative of happiness in the receivers of those signals. Our findings suggest that not only negative affect but also a positive state (happiness) can be transferred by means of odors.
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http://dx.doi.org/10.1177/0956797614566318DOI Listing
June 2015

Positive Body Image and Sexual Functioning in Dutch Female University Students: The Role of Adult Romantic Attachment.

Arch Sex Behav 2016 07 17;45(5):1217-26. Epub 2015 Mar 17.

Division of Clinical and Health Psychology, Department of Behavioral Sciences, Utrecht University, Heidelberglaan 1, 3508 TC, Utrecht, The Netherlands.

This study focused on links between romantic attachment, positive body image, and sexual functioning. Dutch female university students (N = 399) completed an online survey that included self-report items about body appreciation, sexual functioning, and romantic attachment. A proposed conceptual model was tested using structural equation modeling and a good fit to the data was found. Results revealed that attachment avoidance in a romantic context was negatively related to sexual arousal, vaginal lubrication, the ability to reach orgasm, and sexual satisfaction. Attachment anxiety was negatively related to body appreciation which, in turn, was positively related to sexual desire and arousal. Findings indicated that romantic attachment is meaningfully linked to body appreciation and sexual functioning. Therefore, the concept of adult attachment may be a useful tool for the treatment of sexual problems of young women.
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http://dx.doi.org/10.1007/s10508-015-0511-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4863903PMC
July 2016

Rapid stress system drives chemical transfer of fear from sender to receiver.

PLoS One 2015 27;10(2):e0118211. Epub 2015 Feb 27.

Department of Social and Organizational Psychology, Faculty of Social and Behavioral Sciences, Utrecht University, Utrecht, the Netherlands; Department of Psychology, Koç University, Istanbul, Turkey; Instituto Superior de Psicologia Aplicada (ISPA), Instituto Universitário, Lisbon, Portugal.

Humans can register another person's fear not only with their eyes and ears, but also with their nose. Previous research has demonstrated that exposure to body odors from fearful individuals elicited implicit fear in others. The odor of fearful individuals appears to have a distinctive signature that can be produced relatively rapidly, driven by a physiological mechanism that has remained unexplored in earlier research. The apocrine sweat glands in the armpit that are responsible for chemosignal production contain receptors for adrenalin. We therefore expected that the release of adrenalin through activation of the rapid stress response system (i.e., the sympathetic-adrenal medullary system) is what drives the release of fear sweat, as opposed to activation of the slower stress response system (i.e., hypothalamus-pituitary-adrenal axis). To test this assumption, sweat was sampled while eight participants prepared for a speech. Participants had higher heart rates and produced more armpit sweat in the fast stress condition, compared to baseline and the slow stress condition. Importantly, exposure to sweat from participants in the fast stress condition induced in receivers (N = 31) a simulacrum of the state of the sender, evidenced by the emergence of a fearful facial expression (facial electromyography) and vigilant behavior (i.e., faster classification of emotional facial expressions).
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0118211PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4344325PMC
January 2016

Does the experience of ownership over a rubber hand change body size perception in anorexia nervosa patients?

Neuropsychologia 2014 Sep 19;62:26-37. Epub 2014 Jul 19.

Experimental Psychology/Helmholtz Institute, Utrecht University, P.O. Box 80140, 3508TC Utrecht, The Netherlands; Department of Neurology, University Medical Centre Utrecht, P.O. Box 85500, 3508GA Utrecht, The Netherlands. Electronic address:

Anorexia nervosa (AN) patients show disturbances in body size experience. Here, malleability of body representation was assessed by inducing the Rubber Hand Illusion (RHI). Specifically the impact of the illusion on body size estimation was investigated. Thirty AN patients and thirty healthy females participated. The RHI was induced synchronously (experimental condition) and asynchronously (control condition) Both before and after induction of the RHI participants were asked to estimate the size of their own and the rubber hand. The results showed that AN patients had a stronger experience of ownership over the rubber hand than healthy females in the experimental, but not the control condition. AN patients and HC did not differ on proprioceptive drift. Before induction of the illusion AN patients overestimated hand width. After induction of the illusion (experimental as well as control condition) AN patients no longer overestimated the width of their hand. Healthy females correctly estimated hand size both before and after induction of the RHI. In conclusion, stronger experience of ownership over the rubber hand in the AN group implies a more malleable body representation in AN patients compared to healthy females. Changed hand size estimation in the AN group appears to be unrelated to the RHI, as it occurred under both experimental and control conditions of the illusion. Alternative interpretations are discussed.
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http://dx.doi.org/10.1016/j.neuropsychologia.2014.07.003DOI Listing
September 2014

Chemical communication of fear: A case of male-female asymmetry.

J Exp Psychol Gen 2014 Aug 3;143(4):1515-25. Epub 2014 Mar 3.

Faculty of Social and Behavioral Sciences, Utrecht University.

Previous research has documented sex differences in nonverbal communication. What has remained unknown is whether similar sex differences would exist with regard to olfactory communication via chemosignals, a relatively neglected nonverbal communication medium. Because women generally have a better sense of smell and greater sensitivity to emotional signals, we hypothesized that compared with male participants and relative to a neutral control condition, female participants would emulate the fearful state of the sender producing the chemosignals. Facial electromyography was used in a double-blind experiment to measure in the receiver a partial reproduction of the state of the sender, controlling for the moderating influence of the sex of the sender and receiver. The results indicated that only female participants emulated the fearful state of the sender. The present study revealed a boundary condition for effective chemosignaling by reporting behavioral evidence of sexual asymmetry in olfactory communication via chemosignals.
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http://dx.doi.org/10.1037/a0035950DOI Listing
August 2014

The effects of odor and body posture on perceived duration.

Front Neurorobot 2014 6;8. Epub 2014 Feb 6.

Department of Psychology, Faculty of Social and Behavioral Sciences, University of Utrecht Utrecht, Netherlands ; Department of Psychology, Koç University Istanbul, Turkey ; Department of Psychology, Instituto Superior de Psicologia Aplicada Lisbon, Portugal.

This study reports an examination of the internal clock model, according to which subjective time duration is influenced by attention and arousal state. In a time production task, we examine the hypothesis that an arousing odor and an upright body posture affect perceived duration. The experimental task was performed while participants were exposed to an odor and either sitting upright (arousing condition) or lying down in a relaxing chair (relaxing condition). They were allocated to one of three experimental odor conditions: rosemary (arousing condition), peppermint (relaxing condition), and no odor (control condition). The predicted effects of the odors were not borne out by the results. Self-reported arousal (SRA) and pleasure (PL) states were measured before, during (after each body posture condition) and postexperimentally. Heart rate (HR) and skin conductance were measured before and during the experiment. As expected, odor had an effect on perceived duration. When participants were exposed to rosemary odor, they produced significantly shorter time intervals than in the no odor condition. This effect, however, could not be explained by increased arousal. There was no effect of body posture on perceived duration, even though body posture did induce arousal. The results do not support the proposed arousal mechanism of the internal clock model.
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http://dx.doi.org/10.3389/fnbot.2014.00006DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3915145PMC
February 2014

Walking through apertures: do you know what you are doing during body-scaled action?

Perception 2013 ;42(5):583-5

Faculty of Social and Behavioral Sciences, Experimental Psychology, Utrecht University, Helmholtz Institute, PO Box 80140, 3508 TC Utrecht, The Netherlands.

We investigated whether body-scaled action is influenced by awareness of task performance. Participants walked through apertures varying in size. Awareness of performing the action was manipulated by asking half of the participants to concurrently perform a haptic memory task. Distracted participants showed a smaller maximum amount of shoulder rotation at A/S(crit). Walking through apertures thus seems a rather automatic/uniform process regarding action planning, but being distracted from performing the action appears to influence how the action is performed, and may increase its efficiency.
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http://dx.doi.org/10.1068/p7484DOI Listing
September 2013

I can see, hear, and smell your fear: comparing olfactory and audiovisual media in fear communication.

J Exp Psychol Gen 2014 Apr 15;143(2):825-34. Epub 2013 Jul 15.

Faculty of Social and Behavioral Sciences, Utrecht University.

Recent evidence suggests that humans can become fearful after exposure to olfactory fear signals, yet these studies have reported the effects of fear chemosignals without examining emotion-relevant input from traditional communication modalities (i.e., vision, audition). The question that we pursued here was therefore: How significant is an olfactory fear signal in the broader context of audiovisual input that either confirms or contradicts olfactory information? To test this, we manipulated olfactory (fear, no fear) and audiovisual (fear, no fear) information and demonstrated that olfactory fear signals were as potent as audiovisual fear signals in eliciting a fearful facial expression. Irrespective of confirmatory or contradictory audiovisual information, olfactory fear signals produced by senders induced fear in receivers outside of conscious access. These findings run counter to traditional views that emotions are communicated exclusively via visual and linguistic channels.
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http://dx.doi.org/10.1037/a0033731DOI Listing
April 2014

Too fat to fit through the door: first evidence for disturbed body-scaled action in anorexia nervosa during locomotion.

PLoS One 2013 29;8(5):e64602. Epub 2013 May 29.

Experimental Psychology/Helmholtz Institute, Utrecht University, Utrecht, The Netherlands.

To date, research on the disturbed experience of body size in Anorexia Nervosa (AN) mainly focused on the conscious perceptual level (i.e. body image). Here we investigated whether these disturbances extend to body schema: an unconscious, action-related representation of the body. AN patients (n = 19) and healthy controls (HC; n = 20) were compared on body-scaled action. Participants walked through door-like openings varying in width while performing a diversion task. AN patients and HC differed in the largest opening width for which they started rotating their shoulders to fit through. AN patients started rotating for openings 40% wider than their own shoulders, while HC started rotating for apertures only 25% wider than their shoulders. The results imply abnormalities in AN even at the level of the unconscious, action oriented body schema. Body representation disturbances in AN are thus more pervasive than previously assumed: They do not only affect (conscious) cognition and perception, but (unconscious) actions as well.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0064602PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3667140PMC
January 2014

Chemosignals communicate human emotions.

Psychol Sci 2012 27;23(11):1417-24. Epub 2012 Sep 27.

Faculty of Social and Behavioral Sciences, Utrecht University, The Netherlands.

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.
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http://dx.doi.org/10.1177/0956797612445317DOI Listing
November 2013

Body satisfaction and sexual health in Dutch female university students.

J Sex Res 2013 10;50(8):786-94. Epub 2012 Sep 10.

a Department of Psychology, Division of Clinical Psychology and Health Psychology , Utrecht University.

Studies in the field of body image have primarily addressed its negative aspects, such as body dissatisfaction. The present study focused instead on women who are satisfied with their bodies and on how body satisfaction relates to sexual health. A sample of 319 Dutch female university students completed an online survey that included items about body image evaluation, body image investment, overweight preoccupation, body image affect during sexual activity, sexual frequency, sexual functioning, and sexual self-esteem. We found that the level of body dissatisfaction was minimal in our sample. The majority reported neutral or mildly positive body evaluations, and in 30% of the sample these evaluations were clearly positive. Comparisons between women who reported positive versus neutral body evaluations showed that the body-satisfied women had lower body mass indexes (BMIs) and reported less body image investment, less overweight preoccupation, and less body self-consciousness during sexual activity. With regard to sexual health, they reported higher sexual self-esteem and better sexual functioning. Furthermore, we found that body image self-consciousness was negatively associated with sexual functioning, sexual self-esteem, and frequency of sexual activity with a partner. Body satisfaction did not account for a portion of the relationship of body self-consciousness during sexual activity with sexual health.
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http://dx.doi.org/10.1080/00224499.2012.684250DOI Listing
July 2014

Time-course of eye movement-related decrease in vividness and emotionality of unpleasant autobiographical memories.

Memory 2012 9;20(4):346-57. Epub 2012 Mar 9.

Clinical & Health Psychology, Utrecht University, Utrecht, The Netherlands.

The time-course of changes in vividness and emotionality of unpleasant autobiographical memories associated with making eye movements (eye movement desensitisation and reprocessing, EMDR) was investigated. Participants retrieved unpleasant autobiographical memories and rated their vividness and emotionality prior to and following 96 seconds of making eye movements (EM) or keeping eyes stationary (ES); at 2, 4, 6, and 10 seconds into the intervention; then followed by regular larger intervals throughout the 96-second intervention. Results revealed a significant drop compared to the ES group in emotionality after 74 seconds compared to a significant drop in vividness at only 2 seconds into the intervention. These results support that emotionality becomes reduced only after vividness has dropped. The results are discussed in light of working memory theory and visual imagery theory, following which the regular refreshment of the visual memory needed to maintain it in working memory is interfered with by eye movements that also tax working memory, which affects vividness first.
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http://dx.doi.org/10.1080/09658211.2012.665462DOI Listing
August 2012

Stimulus sets can induce shifts in descriptor meanings in product evaluation tasks.

Acta Psychol (Amst) 2011 Sep 14;138(1):237-43. Epub 2011 Jul 14.

Department of Industrial Design, Delft University of Technology, The Netherlands.

The meaning of adjectives is often ambiguous and may be susceptible to contextual changes. Nonetheless, response scales with adjectives are often employed in product evaluation research. Because context-dependent changes in descriptor meanings may threaten the validity of research outcomes, the present study tried to demonstrate empirically whether such shifts may occur. The variation between stimuli in two stimulus sets (either 10 cups or 10 drinks) created two experimental contexts that were expected to activate different descriptor meanings in a product evaluation task. A single ballot with 7 descriptors was used in both conditions. In a subsequent property verification task, participants were presented with adjective-noun word pairs exemplifying the different descriptor meanings. Responses for adjective-noun pairs whose meanings had been primed were faster and more accurate than for non-primed pairs. These findings suggest that between-participants comparisons over conditions with different stimulus sets may not be valid, due to differences in interpretations of descriptor meanings.
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http://dx.doi.org/10.1016/j.actpsy.2011.06.009DOI Listing
September 2011

Proust revisited: odours as triggers of aversive memories.

Cogn Emot 2012 1;26(1):83-92. Epub 2011 Jun 1.

Clinical and Health Psychology, Utrecht University, Utrecht, The Netherlands.

According to the Proust phenomenon, olfactory memory triggers are more evocative than other-modality triggers resulting in more emotional and detailed memories. An experimental paradigm was used to investigate this in aversive memories, similar to those experienced by patients with posttraumatic stress disorder. Seventy healthy participants watched an aversive film, while simultaneously being exposed to olfactory, auditory and visual triggers, which were matched on intensity, valence, arousal and salience. During a second session one week later, participants were randomly exposed to one of the three triggers, and asked to think back about the film and to rate the resulting memory. Results revealed that odour-evoked memories of aversive events were more detailed, unpleasant and arousing than memories evoked by auditory, but not visual, triggers.
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http://dx.doi.org/10.1080/02699931.2011.555475DOI Listing
April 2012

Odors eliciting fear: a conditioning approach to Idiopathic Environmental Intolerances.

J Behav Ther Exp Psychiatry 2011 Jun 21;42(2):240-9. Epub 2010 Dec 21.

Department of Clinical & Health Psychology, Utrecht University, P.O. Box 80140, 3508 TC Utrecht, The Netherlands.

Patients suffering from Idiopathic Environmental Intolerances (IEI) report health symptoms, referable to multiple organ systems, which are triggered by harmless odors and therefore medically unexplainable. In line with previous research that predominantly points towards psychological explanations, the present study tests the hypothesis that IEI symptoms result from learning via classical conditioning of odors to fear. A differential conditioning paradigm was employed. Hedonically different odors were compared on ease of fear acquisition. Conditioned stimuli (CSs) were Dimethyl Sulfide (unpleasant) and peach (pleasant). The unconditioned stimulus (US) was an electrical shock. During acquisition one odor (CS+) was followed by shock, while the other odor (CS-) was not. Next, fear extinction was tested by presenting both CS+ and CS- without US. Electrodermal response, odor evaluation, and sniffing behavior were monitored. Results showed successful fear conditioning irrespective of hedonic character as evidenced by electrodermal response. Acquired fear did not extinguish. There was no evidence of evaluative conditioning taking place, as CS evaluation did not change during fear acquisition. Early avoidance of the CS+, as deduced from odor inhalation measures, was demonstrated, but did not sustain during the entire acquisition phase. This study suggests that a fear conditioning account of IEI is only partially satisfactory.
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http://dx.doi.org/10.1016/j.jbtep.2010.12.007DOI Listing
June 2011

Effects of Pleasant Ambient Fragrances on Dental Fear: Comparing Apples and Oranges.

Chemosens Percept 2010 Dec 17;3(3-4):182-189. Epub 2010 Aug 17.

Previous studies showed that orange odor reduces the anticipatory anxiety and improves the mood of patients waiting for scheduled appointments in small dental practices. We replicated these previous studies in the setting of three large dental clinics. In addition, we investigated whether another pleasant fruity smell (apple odor) is similarly associated with reduced anxiety. We included 219 patients (117 males, 102 females) between the ages of 18 and 81 in this study. While they were waiting for dental treatment, the participants were either exposed to the ambient odor of orange (N = 81) or apple (N = 69), or they received no stimulation. State anxiety, mood, and perceived level of pain of the participants were assessed using questionnaires. Statistical analysis showed no significant difference between the responses of patients in each of the three experimental groups. We therefore conclude that orange and apple odors have no effect on the anticipatory anxiety or mood of patients waiting for scheduled appointments in large dental clinics.
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http://dx.doi.org/10.1007/s12078-010-9078-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2975911PMC
December 2010
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