Lenka Martinec Nováková

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

Recent research has shown that within-gender variability in olfactory abilities may be linked to sexual orientation, particularly in men, but is better predicted by childhood gender nonconformity. However, whether there could be similar within-gender variability in odor awareness remains unclear. Further, gender differences in olfactory abilities and odor awareness in favor of women have been proposed to be partly related to women’s broader olfactory experience due to their greater engagement in olfaction-related activities. Nevertheless, within-gender variability in odor exposure could also be expected. Therefore, in a sample of 156 men and women (83 non-heterosexual), we aimed to look for between- and within-gender variability in odor awareness and self-reported engagement in specific olfaction-related activities. Secondly, we tested whether interindividual (between- and within-gender) differences in olfactory abilities and odor awareness might be related to experience with odors, assessed in terms of engagement in olfaction-related activities. The results of the present study show that within-gender variability, previously found in some olfactory abilities in men and women, does not seem to extend to odor awareness, and appears to only apply to certain olfaction-related activities. In the total sample, more frequent exposure to a greater variety of potentially intense or novel food odors and flavors in both childhood and adulthood was positively linked to both greater odor awareness and better odor identification. There was also a positive link between female-stereotyped activities in childhood and odor awareness. Our results suggest that long-term everyday experience with odors may be linked to a better ability of odor identification and greater odor awareness, although longitudinal studies are needed to further investigate these associations.

Sex Differences in Olfactory Behavior in Namibian and Czech Children

Sex differences in olfaction are well-established, but explanations for those sex differences remain incomplete. One contributing factor could be individual- or cultural-level differences in exposure to odors. We tested whether frequent engagement with common sources of domestic odors (cooking, domestic animals, siblings) was linked to individual differences in olfactory reactivity and awareness among children in southern Namibia and also compared study populations in southern Namibia and the Czech Republic using the established Children’s Olfactory Behavior in Everyday Life (COBEL) questionnaire. We did not find any effects of engagement with odor sources on olfactory behavior, but our results were consistent with usual olfactory sex differences in that girls scored higher than boys in measures of olfactory reactivity and awareness. Further, among the Czech children (but not among the Namibian children), odor identification abilities were positively linked to COBEL scores. Our data contribute to the literature that finds that sex differences in olfactory awareness are apparent across a diverse range of cultures and age groups.

Positive relationship between odor identification and affective responses of negatively valenced odors.

Hedonic ratings of odors and olfactory preferences are influenced by a number of modulating factors, such as prior experience and knowledge about an odor’s identity. The present study addresses the relationship between knowledge about an odor’s identity due to prior experience, assessed by means of a test of cued odor identification, and odor pleasantness ratings in children who exhibit ongoing olfactory learning. Ninety-one children aged 8–11 years rated the pleasantness of odors in the Sniffin’ Sticks test and, subsequently, took the odor identification test. A positive association between odor identification and pleasantness was found for two unpleasant food odors (garlic and fish): higher pleasantness ratings were exhibited by those participants who correctly identified these odors compared to those who failed to correctly identify them. However, we did not find a similar effect for any of the more pleasant odors. The results of this study suggest that pleasantness ratings of some odors may be modulated by the knowledge of their identity due to prior experience and that this relationship might be more evident in unpleasant odors.

Decoding of Baby Calls: Can Adult Humans Identify the Eliciting Situation from Emotional Vocalizations of Preverbal Infants?

Preverbal infants often vocalize in emotionally loaded situations, yet the communicative potential of these vocalizations is not well understood. The aim of our study was to assess how accurately adult listeners extract information about the eliciting situation from infant preverbal vocalizations. Vocalizations of 19 infants aged 5-10 months were recorded in 3 negative (Pain, Isolation, Demand for Food) and 3 positive (Play, Reunion, After Feeding) situations. The recordings were later rated by 333 adult listeners on the scales of emotional valence and intensity. Subsequently, the listeners assigned the eliciting situations in a forced choice task. Listeners were almost perfectly able to discriminate whether a recording came from a negative or a positive situation. Their discrimination may have been based on perceived valence as they consistently assigned higher valence when listening to positive, and lower valence when listening to negative, recordings. Ability to identify the particular situation within the negative or positive realm was substantially weaker, with only three of the six situations being discriminated above chance. The best discriminated situation, Play, was associated with high perceived intensity. The weak qualitative discrimination of negative situations seemed to be based on graded perception of negative recordings, from the most intense and unpleasant (assigned to Pain) to the least intense and least unpleasant (assigned to Demand for Food). Parenthood and younger age, but not gender of listeners, had weak positive effects on the accuracy of judgments. Our results indicate that adults almost flawlessly distinguish positive and negative infant sounds, but are rather inaccurate regarding identification of the specific needs of the infant and may normally employ other sensory channels to gain this information.

Olfactory processing and odor specificity: a meta-analysis of menstrual cycle variation in olfactory sensitivity

Abstract Cycle-correlated variation in olfactory threshold, with women becoming more sensitive to odors mid-cycle, is somewhat supported by the literature but the evidence is not entirely consistent, with several studies finding no, or mixed, effects. It has been argued that cyclic shifts in olfactory threshold might be limited to odors relevant to the mating context. We aimed to test whether the evidence currently available points in the direction of odor-specific or, rather, general changes in olfactory sensitivity and, if the former is the case, to what group of odorants in particular. We carried out a meta-analysis of relevant studies which together used a variety of different odorants, including some found in food, body odor, and some that occur in neither of these. First we tested whether there appears to be an overall effect when all studies are included. Next, we hypothesised that if cyclic changes in olfactory processing are odor-specific and tuned to biologically relevant odors, we should find changes in detection thresholds only for odorants found in body odor, or for those that are perceptually similar to it. In contrast, if threshold patterns are linked to more general fluctuations in odor processing across the cycle, we would not expect changes in relation to any particular odorant group. The results support the view that there is significant cycle-correlated variation. Thresholds were in general significantly lower in the fertile than the non-fertile phases, with effect sizes consistently in this direction. This same conclusion applied to both ‘food’ and ‘musky’ odorants, despite their different evolutionary significance, and to the androgen steroids (androstadienone, androstenone, and androsterone), but could not be applied to phenyl-ethyl alcohol. The results indicate that olfactory sensitivity may be a non-adaptive by-product of the general physiological fluctuations or differences in neural processing experienced across the cycle to a broad spectrum of odorants, rather than being specifically selected for mate choice-related odors.

Differential Patterns of Food Appreciation during Consumption of a Simple Food in Congenitally Anosmic Individuals: An Explorative Study

Food is evaluated for various attributes. One of the key food evaluation domains is hedonicity. As food is consumed, its hedonic valence decreases (due to prolonged sensory stimulation) and hedonic habituation results. The aim of the present study was to investigate changes in food pleasantness ratings during consumption of a simple food by individuals without olfactory experience with food as compared to normosmics. 15 congenital anosmics and 15 normosmic controls were each presented with ten 10 g banana slices. Each was visually inspected, then smelled and chewed for ten seconds and subsequently rated for hedonicity on a 21-point scale. There was a significant difference in pleasantness ratings between congenital anosmics and controls (F(1, 26) = 6.71, p = .02) with the anosmics exhibiting higher ratings than the controls, a significant main repeated-measures effect on the ratings (F(1.85, 48) = 12.15, p<.001), which showed a decreasing trend over the course of consumption, as well as a significant portion*group interaction (F(1.85, 48) = 3.54, p = .04), with the anosmic participants experiencing a less pronounced decline. The results of the present explorative study suggest that over the course of consumption of a simple food, congenitally anosmic individuals experience differential patterns of appreciation of food as compared to normosmics. In this particular case, the decrease of hedonic valence was less pronounced in congenital anosmics.

Do differences in Toxoplasma prevalence influence global variation in secondary sex ratio? Preliminary ecological regression study

Sex of the fetus is genetically determined such that an equal number of sons and daughters are born in large populations. However, the ratio of female to male births across human populations varies significantly. Many factors have been implicated in this. The theory that natural selection should favour female offspring under suboptimal environmental conditions implies that pathogens may affect secondary sex ratio (ratio of male to female births). Using regression models containing 13 potential confounding factors, we have found that variation of the secondary sex ratio can be predicted by seroprevalence of Toxoplasma across 94 populations distributed across African, American, Asian and European continents. Toxoplasma seroprevalence was the third strongest predictor of secondary sex ratio, β = -0·097, P < 0·01, after son preference, β = 0·261, P < 0·05, and fertility, β = -0·145, P < 0·001. Our preliminary results suggest that Toxoplasma gondii infection could be one of the most important environmental factors influencing the global variation of offspring sex ratio in humans. The effect of latent toxoplasmosis on public health could be much more serious than it is usually supposed to be.

Development of an International Odor Identification Test for Children: The Universal Sniff Test

Objective To assess olfactory function in children and to create and validate an odor identification test to diagnose olfactory dysfunction in children, which we called the Universal Sniff (U‐Sniff) test. Study design This is a multicenter study involving 19 countries. The U‐Sniff test was developed in 3 phases including 1760 children age 5‐7 years. Phase 1: identification of potentially recognizable odors; phase 2: selection of odorants for the odor identification test; and phase 3: evaluation of the test and acquisition of normative data. Test—retest reliability was evaluated in a subgroup of children (n = 27), and the test was validated using children with congenital anosmia (n = 14). Results Twelve odors were familiar to children and, therefore, included in the U‐Sniff test. Children scored a mean ± SD of 9.88 ± 1.80 points out of 12. Normative data was obtained and reported for each country. The U‐Sniff test demonstrated a high test—retest reliability (r27 = 0.83, P < .001) and enabled discrimination between normosmia and children with congenital anosmia with a sensitivity of 100% and specificity of 86%. Conclusions The U‐Sniff is a valid and reliable method of testing olfaction in children and can be used internationally.