Nature and human well-being: The olfactory pathway

The world is undergoing massive atmospheric and ecological change, driving unprecedented challenges to human well-being. Olfaction is a key sensory system through which these impacts occur. The sense of smell influences quality of and satisfaction with life, emotion, emotion regulation, cognitive function, social interactions, dietary choices, stress, and depressive symptoms. Exposures via the olfactory pathway can also lead to (anti-)inflammatory outcomes. Increased understanding is needed regarding the ways in which odorants generated by nature (i.e., natural olfactory environments) affect human well-being. With perspectives from a range of health, social, and natural sciences, we provide an overview of this unique sensory system, four consensus statements regarding olfaction and the environment, and a conceptual framework that integrates the olfactory pathway into an understanding of the effects of natural environments on human well-being. We then discuss how this framework can contribute to better accounting of the impacts of policy and land-use decision-making on natural olfactory environments and, in turn, on planetary health.

Can metaphors help us better remember wines? The effect of wine evaluation style on short-term recognition of red wines

People are generally poor at remembering complex food stimuli, such as wine. While writing a description has been shown to improve memory performance, talking about wine is generally a difficult task for novices. However, giving novices a framework in which to evaluate the wine may help with the memory process. Using a short-term recognition task, this experiment compared different forms of wine evaluation on the to-be-remembered wine sample, using either 1) a classic smell and taste evaluation, 2) a multisensory metaphor selection task with visual, auditory, and tactile metaphors, or 3) a control condition with no writing. Results from 153 participants revealed that recognition performance between the three groups was not significantly different. Secondary analysis revealed that recognition accuracy was correlated with wine liking for the control group, suggesting that in the absence of explicitly evaluating the wine, participants relied on wine liking as a cue for memory. Implications for theory development and applications in wine education are discussed.

Comparable responses to a wide range of olfactory stimulation in women and men

The evidence for differences between women and men in terms of olfactory abilities is contradictory. We analyzed women and men's performance and reactions to a wider range of odour exposure outcomes than usually studied, to assess possible differences and similarities between sexes. Measures of sensitivity and sensory decision rule were established in 37 women and 39 men. Perceptual, cognitive, symptom-related and autonomic nervous system (skin conductance level and heart-rate variability) reactions were also assessed during extended ambient odour exposure, as well as participants' self-rated chemical intolerance. Bayesian analyses consistently revealed greater support for sex-related similarities than differences, suggesting that women and men perform and react comparably not only in terms of basic olfactory measures, but also to environmental odour exposure mimicking everyday situations.

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 Dysfunction in Aging African American and Caucasian Men With HIV: A Pilot Study

ABSTRACT

As people age with HIV, olfactory dysfunctions may become more pronounced, especially for African Americans who are predisposed to declines in olfaction. In this cross-sectional study, 34 middle-age and older African American and 17 Caucasian men living with HIV were administered two objective olfactory measures (UPSIT). In the Smell Threshold Test, compared to the HIV-negative age norms, adults living with HIV were significantly less able to detect a lower threshold smell. In the University of Pennsylvania Smell Identification Test, compared to the HIV-negative age norms, adults living with HIV were significantly less able to correctly identify odors; furthermore, using such norms, African Americans with HIV were less likely to correctly identify odors compared to Caucasians with HIV. Since the literature indicates that African Americans have a stronger attraction for salty and sweet foods, such olfactory dysfunction may contribute to poor eating habits, potentially predisposing this population to additional health problems.

Correlation between olfactory function, age, sex, and cognitive reserve index in the Italian population

Purpose

Loss of smell decreases the quality of life and contributes to the failure in recognizing hazardous substances. Given the relevance of olfaction in daily life, it is important to recognize an undiagnosed olfactory dysfunction to prevent these possible complications. Up to now, the prevalence of smell disorders in Italy is unknown due to a lack of epidemiological studies. Hence, the primary aim of this study was to evaluate the prevalence of olfactory dysfunction in a sample of Italian adults.

Methods

Six hundred and thirty-three participants (347 woman and 286 men; mean age 44.9 years, SD 17.3, age range 18–86) were recruited from 10 distinct Italian regions. Participants were recruited using a convenience sapling and were divided into six different age groups: 18–29 years (N = 157), 30–39 years (N = 129), 40–49 years (N = 99), 50–59 years (N = 106), > 60 years (N = 142). Olfactory function, cognitive abilities, cognitive reserve, and depression were assessed, respectively, with: Sniffin’ Sticks 16-item Odor Identification Test, Montreal Cognitive Assessment, Cognitive Reserve Index, and the Beck Depression Inventory. Additionally, socio-demographic data, medical history, and health-related lifestyle information were collected.

Results

About 27% of participants showed an odor identification score < 12 indicating hyposmia. Multiple regression analysis revealed that OI was significantly correlated with age, sex, and cognitive reserve index, and young women with high cognitive reserve index showing the highest olfactory scores.

Conclusion

This study provides data on the prevalence of olfactory dysfunction in different Italian regions.

The role of fragrance and self-esteem in perception of body odors and impressions of others

Human sweat odor serves as social communication signal for a person’s traits and emotional states. This study explored whether body odors can also communicate information about one’s self-esteem, and the role of applied fragrance in this relationship. Female participants were asked to rate self-esteem and attractiveness of different male contestants of a dating show, while being exposed to male participant’s body odors differing in self-esteem. High self-esteem sweat was rated more pleasant and less intense than low self-esteem sweat. However, there was no difference in perceived self-esteem and attractiveness of male contestants in videos, hence explicit differences in body odor did not transfer to judgments of related person characteristics. When the body odor was fragranced using a fragranced body spray, male contestants were rated as having higher self-esteem and being more attractive. The finding that body odors from male participants differing in self-esteem are rated differently and can be discriminated suggests self-esteem has distinct perceivable olfactory features, but the remaining findings imply that only fragrance affect the psychological impression someone makes. These findings are discussed in the context of the role of body odor and fragrance in human perception and social communication.

The Sound of Smell: Associating Odor Valence With Disgust Sounds

Olfaction has recently been highlighted as a sense poorly connected with language. Odor is difficult to verbalize, and it has few qualities that afford mimicry by vision or sound. At the same time, emotion is thought to be the most salient dimension of an odor, and it could therefore be an olfactory dimension more easily communicated. We investigated whether sounds imitative of an innate disgust response can be associated with unpleasant odors. In two experiments, participants were asked to make a forced choice between a pseudoword including a disgust sound and a neutral pseudoword, for pleasant and unpleasant odors. Overall, participants chose more disgust pseudowords than neutral pseudowords for unpleasant odors, but this was not the case for pleasant odors. This effect was not driven by a general association between unpleasant sounds and unpleasant odors, but specifically the sounds [x/χ] and [f], thought to reflect physical responses to disgusting odors, as seen in the Polish fu! or the English ugh!. In line with growing evidence that language can encode odor, we provide the first experimental evidence for an association between the sound of a word and odor valence.

Exposure to Particulate Matter Air Pollution and Anosmia

IMPORTANCE

Anosmia, the loss of the sense of smell, has profound implications for patient safety, well-being, and quality of life, and it is a predictor of patient frailty and mortality. Exposure to air pollution may be an olfactory insult that contributes to the development of anosmia.

OBJECTIVE

To investigate the association between long-term exposure to particulate matter (PM) with an aerodynamic diameter of no more than 2.5 μm (PM2.5) with anosmia.

DESIGN, SETTING, AND PARTICIPANTS

This case-control study examined individuals who presented from January 1, 2013, through December 31, 2016, at an academic medical center in Baltimore, Maryland. Case participants were diagnosed with anosmia by board-certified otolaryngologists. Control participants were selected using the nearest neighbor matching strategy for age, sex, race/ethnicity, and date of diagnosis. Data analysis was conducted from September 2020 to March 2021.

EXPOSURES

Ambient PM2.5 levels.

MAIN OUTCOMES AND MEASURES

Novel method to quantify ambient PM2.5 exposure levels in patients diagnosed with anosmia compared with matched control participants.

RESULTS

A total of 2690 patients were identified with a mean (SD) age of 55.3 (16.6) years. The case group included 538 patients with anosmia (20%), and the control group included 2152 matched control participants (80%). Most of the individuals in the case and control groups were women, White patients, had overweight (BMI 25 to <30), and did not smoke (women: 339 [63.0%] and 1355 [63.0%]; White patients: 318 [59.1%] and 1343 [62.4%]; had overweight: 179 [33.3%] and 653 [30.3%]; and did not smoke: 328 [61.0%] and 1248 [58.0%]). Mean (SD) exposure to PM2.5 was significantly higher in patients with anosmia compared with healthy control participants at 12-, 24-, 36-, 60-month time points: 10.2 (1.6) μg/m3 vs 9.9 (1.9) μg/m3; 10.5 (1.7) μg/m3 vs 10.2 (1.9) μg/m3; 10.8 (1.8) μg/m3 vs 10.4 (2.0) μg/m3; and 11.0 (1.8) μg/m3 vs 10.7 (2.1) μg/m3, respectively. There was an association between elevated PM2.5 exposure level and odds of anosmia in multivariate analyses that adjusted for age, sex, race/ethnicity, body mass index, alcohol or tobacco use, and medical comorbidities (12 mo: odds ratio [OR], 1.73; 95% CI, 1.28-2.33; 24 mo: OR, 1.72; 95% CI, 1.30-2.29; 36 mo: OR, 1.69; 95% CI, 1.30-2.19; and 60 mo: OR, 1.59; 95% CI, 1.22-2.08). The association between long-term exposure to PM2.5 and the odds of developing anosmia was nonlinear, as indicated by spline analysis. For example, for 12 months of exposure to PM2.5, the odds of developing anosmia at 6.0 µg/m3 was OR 0.79 (95% CI, 0.64-0.97); at 10.0 µg/m3, OR 1.42 (95% CI, 1.10-1.82); at 15.0 µg/m3, OR 2.03 (95% CI, 1.15-3.58).

CONCLUSIONS AND RELEVANCE

In this study, long-term airborne exposure to PM2.5 was associated with anosmia. Ambient PM2.5 represents a potentially ubiquitous and modifiable risk factor for the loss of sense of smell.

Human Olfaction at the Intersection of Language, Culture, and Biology

The human sense of smell can accomplish astonishing feats, yet there remains a prevailing belief that olfactory language is deficient. Numerous studies with English speakers support this view: there are few terms for odors, odor talk is infrequent, and naming odors is difficult. However, this is not true across the world. Many languages have sizeable smell lexicons - smell is even grammaticalized. In addition, for some cultures smell talk is more frequent and odor naming easier. This linguistic variation is as yet unexplained but could be the result of ecological, cultural, or genetic factors or a combination thereof. Different ways of talking about smells may shape aspects of olfactory cognition too. Critically, this variation sheds new light on this important sensory modality.

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

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

Contribution of ambient noise and hyperbaric atmosphere to olfactory and gustatory function

Introduction

Taste and smell are important for occupational performance and quality of life. Previous studies suggested that the function of these senses might be influenced by ambient pressure and noise. This knowledge would be helpful for divers, submarine crews, or mine workers. The present study aimed to investigate the effects of noise and hyperbaric pressure on olfactory and gustatory functions.

Methods

This prospective controlled study included 16 healthy male divers. Inside a hyperbaric chamber, participants performed olfactory and gustatory function tests at sea level pressure and at 2 bar pressure. The olfaction threshold, and the discrimination and identification of odorants were measured with validated ´Sniffin sticks´. Taste identification and the gustation threshold scores were examined with validated filter paper strips. Tests were performed under two conditions: noise reduction (silence) and white noise stimulation presented at 70 dB sound pressure level.

Results

The results showed that normobaric and hyperbaric ambient pressures did not significantly affect olfactory or gustatory function. Moreover, noise had no relevant impact on taste or odor sensation. The odor identification score was not influenced in hyperbaric conditions, and the odor threshold score was not influenced by ambient noise or both barometric conditions. The only taste modality affected by hyperbaric conditions was the sensitivity to salty taste, but it was not significant.

Conclusion

We concluded that hyperbaric and noisy environments have no influence on gustatory and olfactory function. From a practical point of view, the influence of pressure in moderate hyperbaric occupations should be negligible.

Sequence Variants in TAAR5 and Other Loci Affect Human Odor Perception and Naming

Olfactory receptor (OR) genes in humans form a special class characterized by unusually high DNA sequence diversity, which should give rise to differences in perception and behavior. In the largest genome-wide association study to date based on olfactory testing, we investigated odor perception and naming with smell tasks performed by 9,122 Icelanders, with replication in a separate sample of 2,204 individuals. We discovered an association between a low-frequency missense variant in TAAR5 and reduced intensity rating of fish odor containing trimethylamine (p.Ser95Pro, p_combined = 5.6 × 10^-15). We demonstrate that TAAR5 genotype affects aversion to fish odor, reflected by linguistic descriptions of the odor and pleasantness ratings. We also discovered common sequence variants in two canonical olfactory receptor loci that associate with increased intensity and naming of licorice odor (trans-anethole: lead variant p.Lys233Asn in OR6C70, p_combined = 8.8 × 10^-16 and p_combined = 1.4 × 10^-9) and enhanced naming of cinnamon (trans-cinnamaldehyde; intergenic variant rs317787-T, p_combined = 5.0 × 10^-17). Together, our results show that TAAR5 genotype variation influences human odor responses and highlight that sequence diversity in canonical OR genes can lead to enhanced olfactory ability, in contrast to the view that greater tolerance for mutations in the human OR repertoire leads to diminished function.

Sensory Processing in the Autism Spectrum: The Role of Attention to Detail and Somatic Trait Anxiety in the Olfactory Perception of the General Population

Autism Spectrum Disorders, as well as autism traits (AT), have been associated with altered sensory processing. However, the role of AT in olfactory processing is still unclear. We analyzed the impact of AT and trait anxiety (TANX), relevant in the context of autism and olfactory perception, in the olfactory abilities of a nonclinical adult sample. Participants (N = 116) completed the Autism-Spectrum Quotient (AQ), the State-Trait Inventory for Cognitive and Somatic Anxiety (STICSA) and the Sniffin' Sticks Extended Test to measure AT, TANX and olfactory abilities, respectively. A hierarchical multiple regression analysis suggested that women and higher scores on the Attention to Detail subscale of AQ were associated with better odor discrimination, and higher somatic TANX was related to poorer odor discrimination.

Insights into smell and taste sensitivity in normal weight and overweight-obese adolescents

Research examining connections between BMI and smell and taste sensitivity in adolescents has been minimal, methodologically inconsistent, and inconclusive. We sought to address this issue with an exploratory study of smell and taste sensitivity in overweight-obese (high BMI) and normal BMI male and female adolescents (ages 12-16 years), using previously validated chemosensory testing measures (Sniffin' Sticks, Taste Strips, 6-n-propylthiouracil: PROP), and taking pubertal stage into account. Puberty was evaluated with the validated Pubertal Development Scale and participants were then classified as either "early" or "late" pubertal stage. We used the phenylethyl alcohol (PEA) version of the Sniffin' Sticks olfactory threshold test and found that high BMI adolescents had significantly greater olfactory sensitivity than normal BMI adolescents. This observation contradicts previous results in overweight adults tested with the n-butanol version of Sniffin' Sticks. We also found that participants in early puberty had significantly higher olfactory sensitivity than participants in late puberty. No significant findings for taste sensitivity were obtained, though there is a suggestion that puberty may affect salty taste thresholds. Our results illuminate a potentially important difference in sensitivity to pure olfactory versus olfactory-trigeminal stimuli as a function of BMI, which the PEA and n-butanol versions of the Sniffin' Sticks respectively assess; and for the first time demonstrate variation in chemosensory acuity in relation to pubertal stage. These findings have implications for eating behavior during adolescence.

Expertise Shapes Multimodal Imagery for Wine

Although taste and smell seem hard to imagine, some people nevertheless report vivid imagery in these sensory modalities. We investigate whether experts are better able to imagine smells and tastes because they have learned the ability, or whether they are better imaginers in the first place, and so become experts. To test this, we first compared a group of wine experts to yoked novices using a battery of questionnaires. We show for the first time that experts report greater vividness of wine imagery, with no difference in vividness across sensory modalities. In contrast, novices had more vivid color imagery than taste or odor imagery for wines. Experts and novices did not differ on other vividness of imagery measures, suggesting a domain-specific effect of expertise. Critically, in a second study, we followed a group of students commencing a wine course and a group of matched control participants. Students and controls did not differ before the course, but after the wine course students reported more vivid wine imagery. We provide evidence that expertise improves imagery, exemplifying the extent of plasticity of cognition underlying the chemical senses.

Olfactory screening of Parkinson's Disease patients and healthy subjects in China and Germany: A study of cross-cultural adaptation of the Sniffin' Sticks 12-identification test

BACKGROUND

Olfactory testing is a useful tool in the differential diagnosis of Parkinson's Disease (PD). Although fast and easy to use, the high intercultural variability of odor detection limits the world-wide use of the most common test sets.

OBJECTIVE

The aim of this study was to test one of the most commonly used olfactory tests (Sniffin' Sticks 12-identification test) in an adapted version for a Chinese population of healthy subjects and PD patients.

METHODS

For this purpose, cohorts of 39 Chinese and 41 German PD patients as well as 70 Chinese and 100 German healthy subjects have been examined both with the original and the adapted version of the Sniffin' Sticks test, the latter being designed according to the regional culture.

RESULTS

The adapted Chinese version of the Sniffin' Sticks 12 identification test proved to discriminate Chinese PD patients from controls with a high specificity but relatively low sensitivity. Yet not all odor exchanges would have been necessary as the original odors including liquorice and coffee showed an equally high identification rate in the Chinese and German cohorts.

CONCLUSIONS

The results showed that the newly adapted test could be used as a screening test for PD related olfactory dysfunction in a Chinese population. However further investigation will be necessary to optimize the selection of odors for the Chinese version of the test.

Linguistic features of fragrances: The role of grammatical gender and gender associations

Odors are often difficult to identify and name, which leaves them vulnerable to the influence of language. The present study tests the boundaries of the effect of language on odor cognition by examining the effect of grammatical gender. We presented participants with male and female fragrances paired with descriptions of masculine or feminine grammatical gender. In Experiment 1 we found that memory for fragrances was enhanced when the grammatical gender of a fragrance description matched the gender of the fragrance. In Experiment 2 we found memory for fragrances was affected by both grammatical gender and gender associations in fragrance descriptions - recognition memory for odors was higher when the gender was incongruent. In sum, we demonstrated that even subtle aspects of language can affect odor cognition.

Can the Identification of Odorants Within a Mixture Be Trained?

Identifying odors within mixtures is a difficult task: humans are able to recognize only up to 4 odors within a mixture. We wanted to test the effects of olfactory training on this ability. We used 7 odorants to create 35 olfactory stimuli of 1, 2, 3, 4, or 5 odorants. The task consisted of identifying the odorants present within the mixture. We trained novices on this task for 5 days: they came to the laboratory to perform the task once a day before coming back for the final testing. Then, we compared them to sommeliers, thus olfaction experts, and untrained novices. Results showed that sommeliers outperformed the other groups with mixtures of up to 4 odorants but not with mixtures of 5 odorants. The short olfactory training allowed trained participants to perform as well as sommeliers when it came to identifying single odorants but was not enough to improve their performance when stimuli were mixtures of 2 or more odorants. This study supports the idea that the number of odors we can recognize within a mixture is limited but suggests training can improve the performance: a short olfactory training is enough to enhance the ability to identify single odorants, whereas expertise refines identification ability of mixtures of up to 4 odorants.

Psycholinguistic variables matter in odor naming

People from Western societies generally find it difficult to name odors. In trying to explain this, the olfactory literature has proposed several theories that focus heavily on properties of the odor itself but rarely discuss properties of the label used to describe it. However, recent studies show speakers of languages with dedicated smell lexicons can name odors with relative ease. Has the role of the lexicon been overlooked in the olfactory literature? Word production studies show properties of the label, such as word frequency and semantic context, influence naming; but this field of research focuses heavily on the visual domain. The current study combines methods from both fields to investigate word production for olfaction in two experiments. In the first experiment, participants named odors whose veridical labels were either high-frequency or low-frequency words in Dutch, and we found that odors with high-frequency labels were named correctly more often. In the second experiment, edibility was used for manipulating semantic context in search of a semantic interference effect, presenting the odors in blocks of edible and inedible odor source objects to half of the participants. While no evidence was found for a semantic interference effect, an effect of word frequency was again present. Our results demonstrate psycholinguistic variables—such as word frequency—are relevant for olfactory naming, and may, in part, explain why it is difficult to name odors in certain languages. Olfactory researchers cannot afford to ignore properties of an odor’s label.

Respiration Modulates Olfactory Memory Consolidation in Humans

In mammals respiratory-locked hippocampal rhythms are implicated in the scaffolding and transfer of information between sensory and memory networks. These oscillations are entrained by nasal respiration and driven by the olfactory bulb. They then travel to the piriform cortex where they propagate further downstream to the hippocampus and modulate neural processes critical for memory formation. In humans, bypassing nasal airflow through mouth-breathing abolishes these rhythms and impacts encoding as well as recognition processes thereby reducing memory performance. It has been hypothesized that similar behavior should be observed for the consolidation process, the stage between encoding and recognition, were memory is reactivated and strengthened. However, direct evidence for such an effect is lacking in human and nonhuman animals. Here we tested this hypothesis by examining the effect of respiration on consolidation of episodic odor memory. In two separate sessions, female and male participants encoded odors followed by a 1 h awake resting consolidation phase where they either breathed solely through their nose or mouth. Immediately after the consolidation phase, memory for odors was tested. Recognition memory significantly increased during nasal respiration compared with mouth respiration during consolidation. These results provide the first evidence that respiration directly impacts consolidation of episodic events, and lends further support to the notion that core cognitive functions are modulated by the respiratory cycle.SIGNIFICANCE STATEMENT Memories pass through three main stages in their development: encoding, consolidation, and retrieval. Growing evidence from animal and human studies suggests that respiration plays an important role in the behavioral and neural mechanisms associated with encoding and recognition. Specifically nasal, but not mouth, respiration entrains neural oscillations that enhance encoding and recognition processes. We demonstrate that respiration also affects the consolidation stage. Breathing through the nose compared with the mouth during consolidation enhances recognition memory. This demonstrates, first, that nasal respiration is important during the critical period were memories are reactivated and strengthened. Second, it suggests that the neural mechanisms responsible may emerge from nasal respiration.

Individual Differences in the Perception of Color Solutions

The color of food is important for flavor perception and food selection. The aim of the present study was to evaluate the visual color perception of liquid samples among Finnish adult consumers by their background variables. Participants (n = 205) ranked six different colored solutions just by looking according to four attributes: from most to least pleasant, healthy, sweet and sour. The color sample rated most frequently as the most pleasant was red (37%), the most healthy white (57%), the most sweet red and orange (34% both) and the most sour yellow (54%). Ratings of certain colors differed between gender, age, body mass index (BMI) and education groups. Females regarded the red color as the sweetest more often than males (p = 0.013) while overweight subjects rated the orange as the sweetest more often than normal weight subjects (p = 0.029). Personal characteristics may be associated with some differences in color associations.