Engagement in Olfaction-Related Activities is Associated with the Ability of Odor Identification and Odor Awareness

The Impact of Body Odors on Sexual Attraction and Partner Selection: A Review of Cisgender Homosexual Men and Women

This study examined the role of odors in sexual attraction and partner selection among non-heterosexual individuals. We searched using MESH terms in databases including PubMed, Embase, Scopus, Web of Science, Cochrane Central Register of Controlled Trials, CINAHL, and Clinical Trials. We focused on experimental or quasi-experimental studies where olfactory cues were used in partner selection. The studies had to identify participants' sexual orientation and include heterosexuals for comparison. Seven studies, published between 2005 and 2014, involving 345 participants (Mean age, 27.09 years), met the criteria. Results suggest that sexual orientation affects both preference for and production of human body odors and that human body odors appear to provide cues about the sex and sexual orientation of potential partners. Most participants were male, limiting conclusions about the role of pheromones in attraction among non-heterosexual women.

Odor awareness modulates the association between perceived stress and chemosensory anhedonia in women

Chronic stress alters reward sensitivity and contributes to anhedonia. Chemosensation is dominated by a hedonic dimension, but little is known about the association between chronic perceived stress and hedonic chemosensation in non-clinical populations. In the current study, 325 participants (201 females) completed a questionnaire-based survey measuring their chronic perceived stress (Perceived Stress Scale; PSS), chemosensory pleasure (Chemosensory Pleasure Scale; CPS), and olfactory metacognitive abilities (odor awareness, affective impact of odor, importance of olfaction). For females, higher PSS scores significantly predicted lower CPS scores, which is mediated by the positive odor awareness. Moreover, negative odor awareness was identified as a moderator underlying the relationship between PSS and CPS scores in females  but not in males. For females, higher PSS predicted lower CPS for those with lower, but not for those with higher levels of negative odor awareness. These results show that the link between chronic perceived stress and chemosensory anhedonia is pronounced in females, with olfactory perception playing a key role. The current study provides insights into the understanding of stress-related anhedonia and into the development of effective treatments.

Olfactory performance and odor liking are negatively associated with food neophobia in children aged between 3 and 9 years

BACKGROUND

Child food neophobia, i.e., rejection or avoidance of novel foods at a young age, is a prevalent nutrition problem that affects the quality of children's diet and impedes the development of healthy food preferences. Sensory sensitivity can relate to the degree of food neophobia, but previous studies rarely focused on the olfactory component of this problem in children.

OBJECTIVE

We aimed to thoroughly examine the relationship between various aspects of olfactory sensitivity and food neophobia in children.

METHODS

246 children aged between three and nine years took part in a food neophobia assessment as well as in a comprehensive, psychophysical olfactory testing.

RESULTS

We found that certain smell perception aspects such as lower odor liking, poorer odor identification ability as well as lower sensitivity to an unknown non-food odor all significantly predicted higher food neophobia in children. Among individual characteristics of either a child or a caregiver, only the child's age significantly and positively predicted food neophobia. The exploratory model looking into the role of family environment factors predicting self-reported food neophobia in children revealed that food neophobia was associated with lower control given to a child in this child's feeding process, as well as with a more frequent use of food as a reward in feeding.

CONCLUSIONS

We suggest that suppressed olfactory perception and performance can play a unique role in child nutritional difficulties. The study inspires further considerations of olfaction-engaging interventions to counteract food-neophobia in children.

Small effects of olfactory identification and discrimination on global cognitive and executive performance over 1 year in aging people without a history of age-related cognitive impairment

Olfactory and cognitive performance share neural correlates profoundly affected by physiological aging. However, whether odor identification and discrimination scores predict global cognitive status and executive function in healthy older people with intact cognition is unclear. Therefore, in the present study, we set out to elucidate these links in a convenience sample of 204 independently living, cognitively intact healthy Czech adults aged 77.4 ± 8.7 (61-97 years) over two waves of data collection (one-year interval). We used the Czech versions of the Montreal Cognitive Assessment (MoCA) to evaluate global cognition, and the Prague Stroop Test (PST), Trail Making Test (TMT), and several verbal fluency (VF) tests to assess executive function. As a subsidiary aim, we aimed to examine the contribution of olfactory performance towards achieving a MoCA score above vs. below the published cut-off value. We found that the MoCA scores exhibited moderate associations with both odor identification and discrimination. Furthermore, odor identification significantly predicted PST C and C/D scores. Odor discrimination significantly predicted PST C/D, TMT B/A, and standardized composite VF scores. Our findings demonstrate that olfaction, on the one hand, and global cognition and executive function, on the other, are related even in healthy older people.

Children's odor pleasantness ratings may not differ according to pubertal status: Preliminary results from a sample of 11-14-year-old Czech children

Puberty tends to be viewed as a "turning point" in hedonic perception of body odor (BO)-related smells. The pubertal stage, a potential proxy for the underlying physiological changes, may contribute to variation in odor hedonic perception. Other potential modulators of odor hedonics are general semantic knowledge about odors (which also tends to be subsumed under the term "age") and perceived odor intensity. The present cross-sectional study examined differences in hedonic odor perception across puberty in 205 Czech children aged 11-14 (89 boys). We investigated whether children differ in the hedonic appraisal of BO-related (16-androstenes and castoreum control), but also food and non-food odors according to their pubertal (penis/breast and pubic hair) development and general semantic knowledge about odors (operationalized as odor identification), controlling for age and perceived odor intensity. As a subsidiary aim, we examined variation in odor identification. We asked the children to self-stage themselves using drawings depicting Tanner's penis/breast and pubic hair stages of pubertal development, estimated their general semantic knowledge about odors with a Sniffin' Sticks identification test, and obtained their pleasantness and intensity ratings of body odor-related, food, a non-food smells. We found that the participants' ratings of the 16-androstenes and those of the perceptually similar odor of castoreum differed according to perceived intensity and, in the latter case, in boys vs. girls as well, but there were no influences of pubertal status or odor identification on the perceived pleasantness. Similarly, hedonic appraisal of non-food (but not food) odors was only influenced by perceived intensity. Regarding odor identification, differences between boys and girls were limited to younger children and did not become more marked throughout puberty. Perceived pleasantness of odors, irrespective of whether they are associated with body smells, food, or other, does not appear to vary across puberty, and boys and girls seem to achieve similar levels of semantic odor knowledge as they grow up.

The relationship of personality, alexithymia, anxiety symptoms, and odor awareness: a mediation analysis

OBJECTIVE

Personality, emotions, and olfaction exhibit partial anatomical overlap in the limbic system structure, establishing potential mechanisms between personality, affective disorders, and olfactory-related aspects. Thus, this study aims to investigate the associations among the Big Five personality traits, alexithymia, anxiety symptoms, and odor awareness.

METHODS

A total of 863 college participants were recruited for this study. All participants completed the Chinese Big Five Personality Inventory-15, the Odor Awareness Scale (OAS), the Toronto Alexithymia Scale-20, and the Generalized Anxiety Disorder Screener-7. Structural equation modeling was employed to examine the hypothesized mediated model.

RESULTS

The findings revealed the majority of significant intercorrelations among the dimensions of the Big Five personality traits, alexithymia, anxiety symptoms, and OAS (|r| = 0.072-0.567, p < 0.05). Alexithymia and anxiety symptoms exhibited a serial mediation effect between neuroticism and OAS (95%CI[0.001, 0.014]), conscientiousness and OAS (95%CI[-0.008, -0.001]), and extraversion and OAS (95%CI[-0.006, -0.001]). Anxiety symptoms mediated the relationship between agreeableness and OAS (95%CI[-0.023, -0.001]) and between openness and OAS (95%CI [0.004, 0.024]).

CONCLUSION

The mediating roles of alexithymia and anxiety symptoms between the Big Five personality traits and odor awareness support the idea of a certain level of association among personality, emotions, and olfaction, with the underlying role of the limbic system structure. This enhances our understanding of personality, emotions, and olfaction and provides insights for future intervention measures for affective disorders and olfactory dysfunctions.

Low odor awareness predicts reduced olfactory abilities in women with depressive symptoms, but not with anxiety symptoms

BACKGROUND

Olfactory disorders and affective symptoms are tightly related. However, the factors underlying this association are not yet understood. One candidate factor is "odor awareness": the degree of attention individuals pays to the odors. However, the association between odor awareness and olfactory abilities in individuals with affective symptoms has not been clarified yet.

METHOD

The present study examined whether odor awareness may moderate (a) the relation between olfactory dysfunctions and depressive and anxiety symptoms; (b) the relation between the perceptual ratings of the odors and depressive and anxiety symptoms in a sample of healthy women (n = 214). Self-report measures of depression and anxiety were collected, whereas the Sniffin' Stick test was employed to measure olfactory abilities.

RESULTS

Linear regression analysis revealed that individuals with higher depressive symptoms presented lower olfactory abilities and that odor awareness was a significant moderator of the association between depressive symptoms and olfactory abilities. Anxiety symptoms were not related to any of the olfactory abilities considered, and this relationship did not change according to odor awareness. The familiarity rating of the odor was significantly predicted by odor awareness. These results were confirmed by Bayesian statistics.

LIMITATIONS

The sample was composed only of women.

CONCLUSIONS

In a healthy population of women, only the presence of depressive symptoms is related to reduced olfactory performance. Odor awareness may be implicated in the development and maintenance of olfactory dysfunction; hence it could be used as a useful target for specific treatments in clinical settings.

Factor structure and psychometric properties of the Chinese version of the Odor Awareness Scale

Background

The Odor Awareness Scale (OAS) is a questionnaire that assesses individual differences in awareness of odors in the surrounding environment, which has been shown to be associated with affective symptoms in recent researches. To further research, A Chinese version of the OAS needs to be introduced.

Objective

To investigate the factor structure and validate the psychometric properties of the OAS.

Methods

A total of 978 participants from college were randomly allocated into two groups for exploratory factor analysis (EFA) and confirmatory factor analysis (CFA), respectively. Additionally, the study entailed item analysis and scrutinized internal consistency reliability, test-retest reliability, and concurrent validity. Test-retest reliability was assessed by having 214 participants complete the OAS twice at a one-week interval. Concurrent validity was measured using the Body Odor Sniffing Questionnaire (BOSQ), the Generalized Anxiety Disorder Scale (GAD-7), and the Toronto Alexithymia Scale (TAS-20).

Results

EFA identified three factors that best fit the data: odor sensitivity, odor impact, and odor attention. CFA validated a second-order factor model, yielding good fit indices: χ 2 / Df = 2.326, RMSEA = 0.052, CFI = 0.911, TLI = 0.900, SRMR = 0.053. The final version of the OAS comprised 27 items and exhibited a commendable internal consistency reliability (Cronbach's α = 0.913), and a good test-retest reliability, as evidenced by the high Pearson correlation coefficient (r = 0.940) and intraclass correlation coefficient (ICC = 0.940). The OAS was significantly correlated with BOSQ (r = 0.416), GAD-7 (r = 0.155), and TAS-20 (r = -0.081).

Conclusion

The Chinese version of the OAS demonstrated robust reliability and validity, rendering it a valuable instrument for evaluating odor awareness in the Chinese population.

Olfactory abstraction: a communicative and metacognitive account

The usual puzzle raised about olfaction is that of a deficit of abstraction: smells, by contrast notably with colours, do not easily lend themselves to abstract categories and labels. Some studies have argued that the puzzle is culturally restricted and that abstraction is more common outside urban Western societies. Here, I argue that the puzzle is misconstrued and should be reversed: given that odours are constantly changing and that their commonalities are difficult for humans to identify, what is surprising is not that abstract terms are rare, but that they should be used at all for olfaction. Given the nature of the olfactory environment and our cognitive equipment, concrete labels referring to sources seem most adaptive. To explain the use and presence of abstract terms, we need to examine their social and communicative benefits. Here these benefits are spelt out as securing a higher agreement among individuals varying in their olfactory experiences as well as the labels they use, as well as feeling a heightened sense of confidence in one's naming capacities. This article is part of the theme issue 'Concepts in interaction: social engagement and inner experiences'.

Children’s Personal Significance of Olfaction — the ChiPSO Questionnaire

Introduction

The human sense of smell has different functions which can be categorized as “food,” “social,” and “environment.” Different questionnaires about the importance of olfaction in adults are available, but little attention has been paid to children and adolescents. Therefore, we aimed to develop a questionnaire about children’s personal significance of olfaction (ChiPSO).

Methods

The questionnaire was developed in two steps. The first questionnaire included 33 statements about the importance of olfactory information in daily life — covering three subscales “food,” “environment,” and “social” administered to 191 participants (mean age: 14.4 ± 1.7 years). The five best fitting items of each subscale were chosen for the final 15-item questionnaire. In the second part, we administered the developed questionnaire to 208 children and adolescents (mean age: 11.5 ± 3.5 years) who additionally underwent olfactory testing to investigate the association between olfactory function and questionnaire results. Participants were separated in two age groups: (i) 6–11 years (children), (ii) 12–17 years (adolescents).

Results

A significant influence of age on the total ChiPSO score and all three subscales with adolescents scoring higher than children was found. Additionally, there was a significant influence of sex in adolescents on total ChiPSO score and subscales “social” and “food” with girls scoring higher than boys.

Conclusion

We report an association between questionnaires results and olfactory performance. Additionally, olfactory information seems to be more important to adolescents compared to children and girls compared to boys.

Implications

The ChiPSO questionnaire is a practical tool to evaluate the importance of olfactory information in children and adolescents aged 6–17 years.

Odor perception of aromatherapy essential oils with different chemical types: Influence of gender and two cultural characteristics

Olfactory perception, and especially affective responses of odors, is highly flexible, but some mechanisms involved in this flexibility remain to be elucidated. This study investigated the odor perceptions of several essential oils used in aromatherapy with emotion regulation functions among college students. The influences of people's characteristics including gender, hometown region, and fragrance usage habit on odor perception were further discussed. Odor perception of nine essential oils, which can be divided into the ester-alcohol type (e.g., lavender oil) and terpene type (e.g., lemon oil) were evaluated under three odor concentrations. The results indicated that chemical type, but not concentration, significantly influenced the odor perception and there was no interaction between the two factors in this study. The arousal and emotional perception scores of odors with terpene-type oil were significantly higher than odors with ester-alcohol type. In terms of people's characteristics, participants from the southern Yangtze river gave a higher familiarity rating to almost all of these odors. The habits of fragrance usage also significantly influenced some of the odors' subjective intensity and emotional perception ratings. However, there were no significant gender differences in most of the odor perceptions. In addition, familiarity and pleasantness were positively correlated, and emotional perception and subjective intensity also showed a weak correlation. These results suggested that users' cultural characteristics could be considered to be important factors that affect the essential oil's odor perception in aromatherapy.

Olfactory metacognition and memory in individuals with different subjective odor imagery abilities

Imagery vividness is one of the key indicators to evaluate the ability to generate mental images. There is large inter-individual variability in olfactory imagery (OI) abilities, however, little is known about the underlying factors for individual OI abilities. Using a word cueing imagery paradigm and the trial-by-trial imagery vividness rating method, participants with high or low OI abilities (differentiated by the Vividness of Olfactory Imagery Questionnaire) completed two OI tasks with either shorter (2 s) or longer (8 s) image generation time. Participants' olfactory function, olfactory-related working memory and episodic recognition memory were measured using validated methods. Moreover, olfactory metacognition was assessed using the Odor Awareness Scale (OAS) and the Importance of Olfaction Questionnaire (IOQ). Compared to participants with high OI abilities, those with low OI abilities reported less vivid odor images during OI tasks. For participants with low OI abilities, the imagery vividness significantly improved as the image generation time increased. There was no difference regarding olfactory perception or olfactory-related memory performances between the high and the low OI ability groups. However, participants with higher OI abilities had significant higher scores on the OAS and the IOQ, indicating a superior olfactory-related metacognition. These results provide evidences supporting the underlying factors that related to variances of subjective ability of generating vivid odor mental images.

Olfactory meta-cognition in individuals with depressive and anxiety symptoms: The differential role of common and social odors

BACKGROUND

Diminished olfactory functioning has been reported in depression, whereas evidence in anxiety disorders is still controversial. Olfactory meta-cognitive abilities (i.e., olfactory awareness, imagery and reactivity, and the importance of odors) are essential in shaping olfaction. Few studies examined these meta-cognitive abilities in relation to depressive, anxiety, and social anxiety symptoms, and none of them considered the awareness of social odors (i.e., body odors).

METHODS

This pre-registered study examined the relationship between olfactory meta-cognitive abilities and symptoms of depression, general anxiety, and social anxiety in 429 individuals. Self-report measures of symptoms of depression, general anxiety, and social anxiety, along with self-report olfactory meta-cognitive scales, were collected using an online survey.

RESULTS

Linear regression analyses revealed that olfactory awareness and importance of common odors were significantly directly predicted by symptoms of general anxiety, while affective importance to odors was negatively predicted by symptoms of depression. Regarding social odors, higher symptoms of depression and lower symptoms of social anxiety predicted increased awareness.

LIMITATIONS

Higher prevalence of women and narrow age range of the participants. Depressive and anxiety symptoms were assessed only with self-report questionnaires.

CONCLUSIONS

Symptoms of anxiety seem to be associated with higher levels of common odor awareness, corroborating the importance of olfactory functions in anxiety. In addition, results on social odors seem to reflect dysfunctional social behaviour that characterized symptoms of depression and social anxiety. Hence, the assessment of meta-cognitive abilities may represent a useful tool in the prevention and assessment of depressive, anxiety, and social anxiety symptoms.

Human odor exploration behavior is influenced by olfactory function and interest in the sense of smell

Olfaction plays an important role in social interaction. This study examined the influence of chemosensory and cognitive abilities on conscious odor sniffing behaviors in humans. Participants (N = 349) were surveyed using a questionnaire for the frequency of behaviors in terms of odor exploration from intrinsic and external sources. Chemosensory functions (e.g., odor identification, trigeminal sensitivity, taste functions, and nasal patency), self-reported olfactory function, and the subjective importance of olfaction were assessed. Hierarchical regression analyses demonstrate a strong impact of olfactory importance on odor exploration behavior. Both female gender and chemosensory function (odor identification ability and trigeminal sensitivity) had a positive impact on odor exploration behavior from individuals' own body and from external sources. Moreover, participants with dysosmia compared to those with normosmia showed less frequent odor exploration behaviors, while their behaviors were partly predicted by nasal patency. In conclusion, conscious olfactory exploration behaviors reflect the interest in the sense of smell and is strongly modulated by chemosensory function. In turn, individuals with lower olfactory sensitivity invest less in olfactory explorations.

The social odor scale: Development and initial validation of a new scale for the assessment of social odor awareness

The degree of attention individuals pay to olfactory cues (called odor awareness) influences the role of odors in everyday life. Particularly, odors produced by the human body (i.e., social odors) are able to carry a wide variety of information and to elicit a broad spectrum of emotional reactions, making them essential in interpersonal relationships. Hence, despite the assessment of awareness toward social odors is crucial, a proper tool is still lacking. Here, we designed and initially validated the Social Odor Scale (SOS), a 12-item scale designed to measure the individual differences in awareness towards different social odors. In Study 1, an exploratory factor analysis (EFA; KMO test: MSA = 0.78; Bartlett's test: χ2(78) = 631.34, p < 0.001; Chi-squared test: χ2(42) = 71.84, p = 0.003) suggests that the three factors structure was the model that best fit with the Italian version of the scale. The confirmatory factor analysis (CFA) supports a second-order model with one higher-order factor representing social odor awareness in general and three lower-order factors representing familiar, romantic partner, and stranger social odors. The final version of the scale presented a good fit (RMSEA = 0.012, SRMR = 0.069, CFI = 0.998, TLI = 0.997). In Study 2, CFA was performed in the German version of the scale confirming the validity of scale structure. Study 3 and 4 revealed that SOS total score and its subscales were positively correlated with other validated olfactory scales, but not with olfactory abilities. Moreover, SOS was found to be related to the gender of the participants: women reported to be more aware to social odors and, specifically, to familiar social odors than men. Overall, the results indicated that SOS is a valid and reliable instrument to assess awareness toward social odors in everyday life.

Olfaction-Related Factors Affecting Chemosensory Dream Content in a Sleep Laboratory

Mental activity in sleep often involves visual and auditory content. Chemosensory (olfactory and gustatory) experiences are less common and underexplored. The aim of the study was to identify olfaction-related factors that may affect the occurrence of chemosensory dream content. Specifically, we investigated the effects of all-night exposure to an ambient odour, participants' appraisal of their current olfactory environment, their general propensity to notice odours and act on them (i.e., odour awareness), and their olfactory acuity. Sixty pre-screened healthy young adults underwent olfactory assessment, completed a measure of odour awareness, and spent three nights in weekly intervals in a sleep laboratory. The purpose of the first visit was to adapt to the experimental setting. On the second visit, half of them were exposed to the smell of vanillin or thioglycolic acid and the other half to an odourless control condition. On the third visit, they received control or stimulation in a balanced order. On each visit, data were collected twice: once from the first rapid eye movement (REM) stage that occurred after 3 a.m., and then shortly before getting up, usually from a non-REM stage. Participants were asked to report the presence of sensory dream content and to assess their current olfactory environment. Neither exposure, nor participants' assessments of the ambient odour, or olfactory acuity affected reports of chemosensory dream content but they were more frequent in individuals with greater odour awareness. This finding may have implications for treatment when such experiences become unwanted or bothersome.

Odours count: human olfactory ecology appears to be helpful in the improvement of the sense of smell

Odours modify human behaviour. Research in this field develops rapidly, providing more and more exciting discoveries. In this context, our daily odorous environment has been surprisingly poorly explored. The aim of our study was to quantify olfactory perception and preliminarily identify factors affecting the frequency of odorous experiences. We were also interested in knowing whether human olfactory ecology relates with olfactory performance. In this study, patients with olfactory deficits (n = 62) and healthy controls (n = 97) had their olfactory threshold and odour identification abilities measured before and after a two-week intervention comprising counting of conscious perception of odours naturally occurring in the environment. In both groups, we observed enhanced olfactory performance after the intervention suggesting that (1) the conscious focus on odours may change its perception, and that (2) social and physical environment can effectively stimulate the human olfactory system, presumably supporting the improvement of olfactory sensitivity.

Students' school-level symptoms mediate the relationship between a school's observed moisture problems and students' subjective perceptions of indoor air quality

Moisture damage can influence the subjective assessment of indoor air quality (subjective IAQ) in various ways. We studied whether the frequency of symptoms reported across students at school level mediates the relationship between observed mold and dampness in a school building and students' subjective IAQ. To answer this research question, we tested a multilevel path model. The analyzed data were created by merging two nationwide data sets: (a) survey data from students, including information on subjective IAQ (N = 24,786 students); (b) data from schools, including information on mold and dampness in a school building (N = 222). After the background variables were adjusted, schools' observed mold and dampness were directly and significantly related to poor subjective IAQ (standardized beta (β)= 0.22, P = .002). In addition, in schools with mold and dampness, students reported significantly more symptoms (β = 0.22, P = .023) than in schools without; the higher the prevalence of symptoms at school level, the worse the students' subjective IAQ (β = 0.60, P < .001). This indirect path was significant (P = .023). In total, schools' observed mold and dampness and student-reported symptoms explained 52% of the between-school variance in subjective IAQ.

Human olfactory communication: current challenges and future prospects

Although anthropologists frequently report the centrality of odours in the daily lives and cultural beliefs of many small-scale communities, Western scholars have historically considered the sense of smell as minimally involved in human communication. Here, we suggest that the origin and persistence of this latter view might be a consequence of the fact that most research is conducted on participants from Western societies who, collectively, were rather old (adults), deodorized and desensitized (ODD) to various aspects of olfactory perception. The view is rapidly changing, however, and this themed issue provides a timely overview of the current state-of-the-art on human chemocommunication. Based on evolutionary models of communication, the papers cover both general mechanisms of odour production by 'senders' and odour perception by 'receivers'. Focus on specific functional contexts includes reciprocal impact of odours between infants and mothers, the role of odour in mate choice and how odours communicate emotion and disease. Finally, a position paper outlines pitfalls and opportunities for the future, against the context of the replication crisis in psychology. We believe a more nuanced view of human chemical communication is within our grasp if we can continue to develop inter-disciplinary insights and expand research activities beyond ODD people. This article is part of the Theo Murphy meeting issue 'Olfactory communication in humans'.

Global Study of Social Odor Awareness

Olfaction plays an important role in human social communication, including multiple domains in which people often rely on their sense of smell in the social context. The importance of the sense of smell and its role can however vary inter-individually and culturally. Despite the growing body of literature on differences in olfactory performance or hedonic preferences across the globe, the aspects of a given culture as well as culturally universal individual differences affecting odor awareness in human social life remain unknown. Here, we conducted a large-scale analysis of data collected from 10 794 participants from 52 study sites from 44 countries all over the world. The aim of our research was to explore the potential individual and country-level correlates of odor awareness in the social context. The results show that the individual characteristics were more strongly related than country-level factors to self-reported odor awareness in different social contexts. A model including individual-level predictors (gender, age, material situation, education, and preferred social distance) provided a relatively good fit to the data, but adding country-level predictors (Human Development Index, population density, and average temperature) did not improve model parameters. Although there were some cross-cultural differences in social odor awareness, the main differentiating role was played by the individual differences. This suggests that people living in different cultures and different climate conditions may still share some similar patterns of odor awareness if they share other individual-level characteristics.

Sex Differences in Human Olfaction: A Meta-Analysis

Although the view that women's olfactory abilities outperform men's is taken for granted, some studies involving large samples suggested that male and female olfactory abilities are actually similar. To address this discrepancy, we conducted a meta-analysis of existing studies on olfaction, targeting possible sex differences. The analyzed sample comprised n = 8 848 (5 065 women and 3 783 men) for olfactory threshold (as measured with the Sniffin Sticks Test; SST), n = 8 067 (4 496 women and 3 571 men) for discrimination (SST), n = 13 670 (7 501 women and 6 169 men) for identification (SST), and a total sample of n = 7 154 (3 866 women and 3 288 men) for works using University of Pennsylvania Smell Identification Test (UPSIT). We conducted separate meta-analyses for each aspect of olfaction: identification, discrimination and threshold. The results of our meta-analysis indicate that women generally outperform men in olfactory abilities. What is more, they do so in every aspect of olfaction analyzed in the current study. However, the effect sizes were weak and ranged between g = 0.08 and g = 0.30. We discuss our findings in the context of factors that potentially shape sex differences in olfaction. Nevertheless, although our findings seem to confirm the "common knowledge" on female olfactory superiority, it needs to be emphasized that the effect sizes we observed were notably small.

Both anxiety and joint laxity determine the olfactory features in panic disorder

Previous research showed a high sensitivity in sensorial modalities in panic disorder (PD). This disorder has been consistently associated to the joint hypermobility syndrome (JHS). In non-clinical samples, this collagen alteration has been also related to an enhanced sensitivity in some sensorial modalities. The main aim of this study is to explore the olfactory functioning in PD in relation to JHS. Sixty patients with PD and sixty healthy controls performed the Sniffin' Sticks Test (SST) (threshold subtest), and completed the Affective Impact of Odors scale (AIO), the Relational Scale of Olfaction (EROL), and the Odor Awareness Scale (OAS). Clinical symptom rating scales and JHS assessment were also obtained. PD patients showed enhanced odor acuity, greater reactivity to smells and also increased odor awareness compared to the healthy controls. Within the patients group, those suffering from JHS displayed higher functioning in all olfactory domains compared to the non-JHS ones. The JHS and anxiety measures emerged as predictor variables of the olfactory function. The present findings highlight the importance of the olfactory function in PD and underline that both, JHS and anxiety, determine the olfactory characteristics in this disorder.

Effects of diversity in olfactory environment on children's sense of smell

Diversity in children's everyday olfactory environment may affect the development of their olfactory abilities and odor awareness. To test this, we collected data on olfactory abilities using the Sniffin' Sticks and odor awareness with Children's Olfactory Behaviors in Everyday Life Questionnaire in 153 preschool children and retested them one and a half year later. Parents completed an inventory on children's exposure to a variety of odors and on their own odor awareness using the Odor Awareness Scale. We controlled for the effects of age and verbal fluency on the children's performance. We found that the children's odor identification and discrimination scores differed as a function of parental odor awareness. Although these effects were rather small, they were commensurate in size with those of gender and age. To the best of our knowledge, this study is the first to present evidence that diversity in children's olfactory environment affects variation in their olfactory abilities and odor awareness. We suggest that future studies consider the long-term impact of perceptual learning out of the laboratory and its consequences for olfactory development.

Gender differences in influences of temperament on olfactory reactivity and awareness

Children's olfactory performance is associated with temperament but whether there is a link with olfactory reactivity and awareness is not known. In adults negative affectivity is linked to reactivity to environmental odours but it is not clear whether these associations extend to children. We aimed to investigate the effect of temperamental factors on olfactory reactivity and awareness. In so doing, we controlled for the effect of parenting styles on temperamental assessment and of verbal fluency on children's olfactory reactivity and awareness. We hypothesised that children with a high degree of negative affectivity would show greater olfactory reactivity and awareness. 129 children (62 boys, mean age 6.83 ± 0.40 years) were interviewed about their olfactory reactivity and awareness in everyday life using the established Children's Olfactory Behavior in Everyday Life questionnaire (COBEL). Parents assessed their child's temperament using the 94-item short form of the Children's Behavior Questionnaire. We found that the relationship between negative affectivity and total COBEL scores varied between the genders: there was a positive, medium to large effect in boys and a negative, small one in girls. Future studies could include behavioural observations of temperament and olfactory reactivity and awareness.

Child Odors and Parenting: A Survey Examination of the Role of Odor in Child-Rearing

Parental caregiving is critical for the survival of our young and continuation of our species. In humans, visual and auditory signals from offspring have been shown to be potent facilitators of parenting. However, whether odors emitted by our young also influence human parenting remains unclear. To explore this, we conducted a series of questionnaire surveys targeting parents with children under 6 years old. First, we collected episodes on experiencing odors/sniffing various parts of a child’s body (n = 507). The prevalence of experiencing events described in those episodes was examined in a separate survey (n = 384). Based on those results, the Child Odor in Parenting scale (COPs) was developed, and subsequently used in the main survey (n = 888). We found COPs to have adequate content validity, concurrent validity, and reliability. Responses to the COPs demonstrated that parents, especially mothers with infants, are aware of odors from their offspring, and actively seek them in daily child-rearing. The factor structure and content of the COPs items indicated that child odors have both affective and instrumental roles. Affective experiences induce loving feeling and affectionate sniffing, while instrumental experiences pertain to specific hygienic needs. The head was the most frequent source of affective experiences, and the child’s bottom of instrumental. Each was experienced by more than 90% of the mothers with a child below 1 year of age. Affective experiences significantly declined as the child grew older, possibly associated with the decline of physical proximity between parents and child. This age-related decline was not prominent for instrumental experiences, except for the bottom, which significantly declined after 3 years of age. The present findings suggest that child odors play roles in human parenting, and that their nature and significance change during the course of a child’s development.

Possible relation between olfaction and anxiety in healthy subjects

AIMS

While olfaction is a sense closely associated with the limbic system and emotions, the relation between emotional status and olfactory functioning has not been well documented. This study aimed to examine the possible effect of anxiety on olfaction in healthy subjects.

METHODS

We investigated the effect of state and trait anxiety on the detection and recognition thresholds for five different odors in 124 healthy subjects (62 men and 62 women, mean age = 27.2 years) using a T&T olfactometer.

RESULTS

While the influences of age, socioeconomic status, IQ, and smoking history on olfaction were not significant, women had a lower recognition threshold for the odor of sweet fruit and a higher detection threshold for that of rotten food as compared with men. Both state and trait anxiety ratings were significantly associated with reduced olfactory ability, especially for identification of rose odor.

CONCLUSIONS

These findings suggest that emotional status affects olfactory functioning in healthy subjects. Our findings may also partly explain the mild olfactory impairment reported in clinical conditions, such as anxiety disorders.