A three-factor benefits framework for understanding consumer preference for scented household products: psychological interactions and implications for future development.

Humans have deliberately scented their environment for purpose or pleasure for millennia. In the contemporary marketplace most consumers prefer and purchase scented versions of common household products. However, the drivers of this consumer preference have not been elucidated. To explain the attraction to scent in household products we propose a novel three-factor framework, comprising functional benefits (malodor mitigation, base odor coverage, freshening), in-use experience benefits (cleanliness, efficacy, pleasure), and emotional benefits (increasing in confidence, mood and nostalgia). To support this framework, we present new data from a market research survey on US consumer purchasing habits and attitudes towards home cleaning, laundry, and air freshening products. Further substantiating our framework, a focused review of olfactory psychological science illustrating the central role of scent in cognition, wellbeing, motivated behavior, and social behavior, as well as sensory marketing research highlights the benefits and implications of scent in consumer household products. Based on our three-factor framework we go on to discuss the potential for scent to influence health and raise issues to consider (such as potential negative responding to fragranced products). We conclude by showcasing new opportunities for future research in olfactory science and on scented household products that can advance the positive impacts of scent.

Your Money or Your Sense of Smell? A Comparative Analysis of the Sensory and Psychological Value of Olfaction.

In public discourse, the sense of smell is typically characterized as the least important of the five senses. However, there are very little empirical data on this topic. Recently, much more attention has been brought to the sense of smell since olfactory dysfunction is a primary and often long-term symptom of COVID-19 infection. It was therefore of interest to expand research on the perceived value of olfaction in the current cultural condition. We developed a survey that directly compared the value of the senses of smell, hearing, and vision with each other and in relation to nine common items representing digital, material, personal, and physical commodities of varying social and emotional meaningfulness (phone, $10,000, favorite social media, online shopping, favorite streaming service, dream vacation, pet, hair, little left toe). In total, four hundred and seven female and male respondents comprising two life-stage groups (college students, general public adults) participated in our online survey study during winter-spring of 2021. The results reveal that the sense of smell was perceived as vastly less important than vision and hearing and much less valuable than various common commodities. We also found that life-stage and gender mediated our findings. For example, one-quarter of the college student respondents would give up their sense of smell in order to keep their phone and nearly half of all women would give up their sense of smell to keep their hair. Our data further illustrate that the senses of vision and hearing are valued relatively similarly. A number of questions arise from the present data and suggestions for ways in which our survey can be expanded and altered to address further research are discussed.

The Circadian Clock, the Brain, and COVID-19: The Cases of Olfaction and the Timing of Sleep.

Daily rhythms of behavior and neurophysiology are integral to the circadian clocks of all animals. Examples of circadian clock regulation in the human brain include daily rhythms in sleep-wake, cognitive function, olfactory sensitivity, and risk for ischemic stroke, all of which overlap with symptoms displayed by many COVID-19 patients. Motivated by the relatively unexplored, yet pervasive, overlap between circadian functions and COVID-19 neurological symptoms, this perspective piece uses daily variations in the sense of smell and the timing of sleep and wakefulness as illustrative examples. We propose that time-stamping clinical data and testing may expand and refine diagnosis and treatment of COVID-19.

Tracking smell loss to identify healthcare workers with SARS-CoV-2 infection.

INTRODUCTION: Healthcare workers (HCW) treating COVID-19 patients are at high risk for infection and may also spread infection through their contact with vulnerable patients. Smell loss has been associated with SARS-CoV-2 infection, but it is unknown whether monitoring for smell loss can be used to identify asymptomatic infection among high risk individuals. In this study we sought to determine if tracking smell sensitivity and loss using an at-home assessment could identify SARS-CoV-2 infection in HCW. METHODS AND FINDINGS: We performed a prospective cohort study tracking 473 HCW across three months to determine if smell loss could predict SARS-CoV-2 infection in this high-risk group. HCW subjects completed a longitudinal, behavioral at-home assessment of olfaction with household items, as well as detailed symptom surveys that included a parosmia screening questionnaire, and real-time quantitative polymerase chain reaction testing to identify SARS-CoV-2 infection. Our main measures were the prevalence of smell loss in SARS-CoV-2-positive HCW versus SARS-CoV-2-negative HCW, and timing of smell loss relative to SARS-CoV-2 test positivity. SARS-CoV-2 was identified in 17 (3.6%) of 473 HCW. HCW with SARS-CoV-2 infection were more likely to report smell loss than SARS-CoV-2-negative HCW on both the at-home assessment and the screening questionnaire (9/17, 53% vs 105/456, 23%, P < .01). 6/9 (67%) of SARS-CoV-2-positive HCW reporting smell loss reported smell loss prior to having a positive SARS-CoV-2 test, and smell loss was reported a median of two days before testing positive. Neurological symptoms were reported more frequently among SARS-CoV-2-positive HCW who reported smell loss compared to those without smell loss (9/9, 100% vs 3/8, 38%, P < .01). CONCLUSIONS: In this prospective study of HCW, self-reported changes in smell using two different measures were predictive of SARS-CoV-2 infection. Smell loss frequently preceded a positive test and was associated with neurological symptoms.

Tracking Smell Loss to Identify Healthcare Workers with SARS-CoV-2 Infection.

BACKGROUND: Healthcare workers (HCW) treating COVID-19 patients are at high risk for infection and may also spread infection through their contact with vulnerable patients. Smell loss has been associated with SARS-CoV-2 infection, but it is unknown whether monitoring for smell loss can be used to identify asymptomatic infection among high risk individuals, like HCW. METHODS: We performed a prospective cohort study, tracking 473 HCW across three months to determine if smell loss could predict SARS-CoV-2 infection in this high-risk group. HCW subjects completed a longitudinal, novel behavioral at-home assessment of smell function with household items, as well as detailed symptom surveys that included a parosmia screening questionnaire, and RT-qPCR testing to identify SARS-CoV-2 infection. RESULTS: SARS-CoV-2 was identified in 17 (3.6%) of 473 HCW. Among the 17 infected HCW, 53% reported smell loss, and were more likely to report smell loss than COVID-negative HCW on both the at-home assessment and the screening questionnaire (P < .01). 67% reported smell loss prior to having a positive SARS-CoV-2 test, and smell loss was reported a median of two days before testing positive. Neurological symptoms were reported more frequently among COVID-positive HCW who reported smell loss (P < .01). CONCLUSIONS: In this prospective study of HCW, self-reported changes in smell using two different measures were predictive of COVID-19 infection. Smell loss frequently preceded a positive test and was associated with neurological symptoms.

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.

Pleasant olfactory cues can reduce cigarette craving.

Cigarette craving is a cardinal feature of smoking, which is the leading preventable cause of death. Despite its clinical relevance, there remains a pressing need to develop new approaches for controlling craving. Although olfactory cues (OCs) are especially well suited to reduce affectively charged cravings, there has been surprisingly little research on the topic. We investigated the strategic use of OCs to reduce cigarette craving. Abstinent smokers (N = 232) initially sampled and rated a series of OCs. Participants then were exposed to in vivo smoking cues, which produced robust cigarette cravings. During peak craving, they were randomly assigned to sniff one of three types of OCs (all of which they had previously sampled) while their craving, and a set of responses thought to be associated with craving, were assessed. OCs that a participant had rated as pleasant reduced craving more than did exposure to odor blank (i.e., neutral) or tobacco-related OCs. This effect persisted over the course of 5 min. In addition, smokers with the most specific autobiographical memory systems were most responsive to the craving-reducing effects of pleasant OCs. About 90% of participants reported they could imagine using a pleasant OC to curb their craving in the natural environment. The present data suggest that OCs show promise for controlling cravings and highlight the need to conduct further research to test whether OCs may prove useful alone or in combination with existing approaches as a smoking cessation intervention. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Exploring the science, safety, and benefits of air care products: perspectives from the inaugural air care summit.

Seventy-one percent of US households purchase air care products. Air care products span a diverse range of forms, including scented aerosol sprays, pump sprays, diffusers, gels, candles, and plug-ins. These products are used to eliminate indoor malodors and to provide pleasant scent experiences. The use of air care products can lead to significant benefits as studies have shown that indoor malodor can cause adverse effects, negatively impacting quality of life, hygiene, and the monetary value of homes and cars, while disproportionately affecting lower income populations. Additionally, studies have also shown that scent can have positive benefits related to mood, stress reduction, and memory enhancement among others. Despite the positive benefits associated with air care products, negative consumer perceptions regarding the safety of air care products can be a barrier to their use. During the inaugural Air Care Summit, held on 18 May 2018 in the Washington, DC, metropolitan area, multidisciplinary experts including industry stakeholders, academics, and scientific and medical experts were invited to share and assess the existing data related to air care products, focusing on ingredient and product safety and the benefits of malodor removal and scent. At the Summit's completion, a panel of independent experts representing the fields of pulmonary medicine, medical and clinical toxicology, pediatric toxicology, basic science toxicology, occupational dermatology and experimental psychology convened to review the data presented, identify potential knowledge gaps, and suggest future research directions to further assess the safety and benefits of air care products.

The Influence of Circadian Timing on Olfactory Sensitivity.

Olfactory sensitivity has traditionally been viewed as a trait that varies according to individual differences but is not expected to change with one's momentary state. Recent research has begun to challenge this position and time of day has been shown to alter detection levels. Links between obesity and the timing of food intake further raise the issue of whether odor detection may vary as a function of circadian processes. To investigate this question, 37 (21 male) adolescents (M age = 13.7 years) took part in a 28-h forced desynchrony (FD) protocol with 17.5 h awake and 10.5 h of sleep, for 7 FD cycles. Odor threshold was measured using Sniffin' Sticks 6 times for each FD cycle (total threshold tests = 42). Circadian phase was determined by intrinsic period derived from dim light melatonin onsets. Odor threshold showed a significant effect of circadian phase, with lowest threshold occurring on average slightly after the onset of melatonin production, or about 1.5○ (approximately 21:08 h). Considerable individual variability was observed, however, peak olfactory acuity never occurred between 80.5○ and 197.5○ (~02:22-10:10 h). These data are the first to show that odor threshold is differentially and consistently influenced by circadian timing, and is not a stable trait. Potential biological relevance for connections between circadian phase and olfactory sensitivity are discussed.

The Role of Odor-Evoked Memory in Psychological and Physiological Health.

This article discusses the special features of odor-evoked memory and the current state-of-the-art in odor-evoked memory research to show how these unique experiences may be able to influence and benefit psychological and physiological health. A review of the literature leads to the conclusion that odors that evoke positive autobiographical memories have the potential to increase positive emotions, decrease negative mood states, disrupt cravings, and reduce physiological indices of stress, including systemic markers of inflammation. Olfactory perception factors and individual difference characteristics that would need to be considered in therapeutic applications of odor-evoked-memory are also discussed. This article illustrates how through the experimentally validated mechanisms of odor-associative learning and the privileged neuroanatomical relationship that exists between olfaction and the neural substrates of emotion, odors can be harnessed to induce emotional and physiological responses that can improve human health and wellbeing.

Birth of a Neurogastronomy Nation: The Inaugural Symposium of the International Society of Neurogastronomy.

A review of the neuroscientific, clinical medicine, culinary, and food technology and agriculture presentations and demonstrations that were featured at the inaugural symposium of the International Society of Neurogastronomy, held at the University of Kentucky on November 7, 2015.

Verbal priming and taste sensitivity make moral transgressions gross.

The aims of the present study were to assess whether: (a) visceral and moral disgust share a common oral origin (taste); (b) moral transgressions that are also viscerally involving are evaluated accordingly as a function of individual differences in taste sensitivity; (c) verbal priming interacts with taste sensitivity to alter how disgust is experienced in moral transgressions; and (d) whether gender moderates these effects. Standard tests of disgust sensitivity, a questionnaire developed for this research assessing different types of moral transgressions (nonvisceral, implied-visceral, visceral) with the terms "angry" and "grossed-out," and a taste sensitivity test of 6-n-propylthiouracil (PROP) were administered to 102 participants. Results confirmed past findings that the more sensitive to PROP a participant was the more disgusted they were by visceral, but not moral, disgust elicitors. Importantly, the findings newly revealed that taste sensitivity had no bearing on evaluations of moral transgressions, regardless of their visceral nature, when "angry" was the emotion primed. However, when "grossed-out" was primed for evaluating moral violations, the more intense PROP tasted to a participant the more "grossed-out" they were by all transgressions. Women were generally more disgust sensitive and morally condemning than men, but disgust test, transgression type, and priming scale modulated these effects. The present findings support the proposition that moral and visceral disgust do not share a common oral origin, but show that linguistic priming can transform a moral transgression into a viscerally repulsive event and that susceptibility to this priming varies as a function of an individual's sensitivity to the origins of visceral disgust-bitter taste.

Stealing is not gross: language distinguishes visceral disgust from moral violations.

The similarity between moral and visceral disgust is a current topic of debate. One method of investigating this issue has been to examine the use of language. Prior work has shown that the words disgust and anger are often used interchangeably to describe offense toward immoral behavior involving harm (autonomy violations), whereas "grossed out" is reserved for viscerally repulsive stimuli. Based on these findings we developed a questionnaire and tested 126 undergraduates for how they used the words disgusted, angry, grossed out, and morally right or morally wrong to rate various responses toward ethics of autonomy social situations. We found that grossed out was least endorsed for these transgressions and that ratings on this measure did not correspond to ratings of moral wrongness. Moreover, individual differences in visceral disgust sensitivity had no association with participants' evaluations or use of any of the descriptors. By contrast, ratings for angry and disgusted were equivalently and highly endorsed for autonomy violations, and the ratings given with these descriptors also corresponded to the ratings given for moral wrongness. These findings add to growing evidence that moral disgust is not visceral (gross) but rather appears to be representative of anger even though autonomy violations are often labeled as "disgusting".

Aromatherapy facts and fictions: a scientific analysis of olfactory effects on mood, physiology and behavior.

A systematic review of scientific experimentation addressing olfactory effects on mood, physiology and behavior was undertaken. From this review, 18 studies meeting stringent empirical criteria were then analyzed in detail and it was found that credible evidence that odors can affect mood, physiology and behavior exists. To explain these effects, pharmacological and psychological mechanisms were explored and a psychological interpretation of the data was found to be more comprehensive. Methodological problems regarding dependent measures and stimuli, which led to inconsistencies in the data were discussed, as were the mediating variables of culture, experience, sex differences, and personality.

Minimal olfactory perception during sleep: why odor alarms will not work for humans.

STUDY OBJECTIVES: To examine olfactory arousal threshold during sleep in comparison to an auditory tone. DESIGN: On night 1, participants rated odor intensity when awake and experienced olfactory stimuli during stage 1 sleep. Night 2 involved stage 2, stage 4, and rapid-eye-movement (REM) sleep trials using the "staircase" threshold-detection method. Electroencephalogram, electrooculogram, electromyogram, electrocardiogram, and respiration were recorded along with behavioral response. An 800-Hz tone was given on trials when odors failed to arouse. SETTING: Participants slept in individual rooms. Stimulus-delivery systems were operated from a separate room, where an experimenter observed physiologic recordings and behavioral responses. PARTICIPANTS: Three healthy men and 3 women aged 20 to 25 years (mean, 22 years). INTERVENTIONS: Two odorants, peppermint and pyridine, at 4 concentrations were presented through nasal cannulas using an air-dilution olfactometer. Tones were played over a speaker. MEASUREMENTS: Behavioral (button press and oral) responses, electroencephalographic activation, and changes in breathing and heart rate were assessed. RESULTS: Participants responded to odors on 92% of stage 1 sleep trials. Peppermint was ineffective in stages 2, 4, and REM sleep. Pyridine produced behavioral threshold on 45% of stage 2 trials, none in stage 4, and one third of REM sleep trials. Tones were effective on at least 75% of trials. Heart rate increased significantly only following behavioral responses to odors or tones across sleep stages. CONCLUSIONS: The data indicate that human olfaction is not reliably capable of alerting a sleeper.

A naturalistic analysis of autobiographical memories triggered by olfactory visual and auditory stimuli.

The emotional and content qualities of autobiographical memories evoked by three memory cue items (campfire, fresh-cut grass, popcorn) presented in olfactory, visual and auditory form were examined using a new repeated measures paradigm. Results revealed that memories recalled by odors were significantly more emotional and evocative than those recalled by the same cue presented visually or auditorily. However, there were no differences in the content features (vividness, specificity) of memories as a function of cue-form. These findings support previous research in both laboratory and naturalistic settings and is the first comparative sensory memory study to include auditory variants of memory cues. The present data contribute to a growing body of evidence indicating that there is a privileged relationship between olfaction and emotion during recollection. Various subject factors such as age, sex and region of residence were also examined and some were found to affect the quality of memories in interaction with the specific memory cue items, indicating that prior experience is a primary influence in autobiographical memory. Questions for future investigation regarding how odor-evoked memories may be different from other memory experiences are suggested.

Neuroimaging evidence for the emotional potency of odor-evoked memory.

To assess past behavioral reports of the emotional distinctiveness of odor-evoked memories, functional magnetic resonance imaging (fMRI) was used to compare regions of activation during recall triggered by olfactory and visual cues that were connected to a personally meaningful memory and a comparable control cue presented in olfactory and visual form. Five healthy right-handed females experienced both behavioral and fMRI memory testing. fMRI analyses indicated significantly greater activation in the amygdala and hippocampal regions during recall to the personally significant odor than any other cue, and behavioral responses confirmed that emotional responses were greatest to the personally meaningful odor. These findings provide convincing neurobiological evidence that the subjective experience of the emotional potency of odor-evoked memory is correlated with specific activation in the amygdala during recall and offers new insights into the affective organization of memory.

The effect of verbal context on olfactory perception.

Three experiments were conducted to examine how verbal context and sensory stimulation interact to influence odor hedonic perception. Eight common odors were presented in their natural and synthetic forms, and verbal labels designating name and source (natural, synthetic) information were either explicitly given, self-generated, falsely provided, or not provided. Results revealed that verbal information about source influenced hedonic ratings whether or not the odorant itself was also present. When odorants were presented without verbal labels, olfactory evaluations were based in sensation. Name and source information contributed different levels of meaning and influence to perceptual evaluations. The findings are discussed with reference to an experiential-collocation model for odor-label interactions and a dual-coding hypothesis for olfactory perception.