A selection from Stockholm University publication database

• A graspable olfactory display for virtual reality

  2023. Simon Niedenthal (et al.). International journal of human-computer studies 169

  Article

  The sense of smell, olfaction, is seldom engaged in digital interactive systems, but, supported by the proper technology, olfaction might open up new interaction domains. Human olfactory experience involves active exploration, directed sniffing and nuanced judgements about odour identity, concentrations, and blends, yet to date most compact olfactory displays do not directly support these experiences. We describe the development and validation of a compact, low-cost olfactory display fitted to the hand controller of the HTC Vive Virtual Reality (VR) system that employs stepless valves to enable control of scent magnitude and blending (Fig. 1). Our olfactory display allows for concealed (i.e., unknown to the user) combinations of odours with virtual objects and contexts, making it well suited to applications involving interactions with odorous objects in virtual space for recreational, educational, scientific, or therapeutic functions. Through a user study and gas sensor analysis, we have been able to demonstrate that our device presents clear and consistent scent output, is intuitive from a user perspective, and supports gameplay interactions. We present results from a smell training game in a virtual wine tasting cellar in which the initial task of identifying wine aroma components is followed by evaluating more complex blends, allowing the player to “level up” as they proceed to higher degrees of connoisseurship. Novice users were able to quickly adapt to the display, and we found that the device affords sniffing and other gestures that add verisimilitude to olfactory experience in virtual environments. Test-retest reliability was high when participants performed the task two times with the same odours. In sum, the results suggest our olfactory display may facilitate use in game settings and other olfactory interactions.

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• A parosmia severity index based on word-classification predicts olfactory abilities and impairment

  2023. Thomas Hörberg (et al.). European Archives of Oto-Rhino-Laryngology 280 (8), 3695-3706

  Article

  Parosmia is an olfactory disorder that involves distortions of specific odors that may co-occur with anosmia, loss of smell of other odors. Little is known about which odors frequently trigger parosmia, and measures of parosmia severity are lacking. Here, we present an approach to understand and diagnose parosmia that is based on semantic properties (e.g., valence) of words describing odor sources (“fish”, “coffee”, etc.). Using a data-driven method based on natural language data, we identified 38 odor descriptors. Descriptors were evenly dispersed across an olfactory-semantic space, which was based on key odor dimensions. Parosmia patients (n = 48) classified the corresponding odors in terms of whether they trigger parosmic or anosmic sensations. We investigated whether these classifications are related to semantic properties of the descriptors. Parosmic sensations were most often reported for words describing unpleasant odors of inedibles that are highly associated to olfaction (e.g., “excrement”). Based on PCA modeling, we derived the Parosmia Severity Index—a measure of parosmia severity that can be determined solely from our non-olfactory behavioral task. This index predicts olfactory-perceptual abilities, self-reported olfactory impairment, and depression. We thus provide a novel approach for investigating parosmia and establishing its severity that does not require odor exposure. Our work may enhance our understanding of how parosmia changes over time and how it is expressed differently across individuals.

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• Body odor disgust sensitivity (BODS) is related to extreme odor valence perception

  2023. Marta Zakrzewska, Marco Tullio Liuzza, Jonas K. Olofsson. PLOS ONE 18 (4)

  Article

  Odors are important disease cues, and disgust sensitivity to body odors reflects individual differences in disease avoidance. The body odor disgust sensitivity (BODS) scale provides a rapid and valid assessment of individual differences. Nevertheless, little is known about how individual differences in BODS might correlate with overall odor perception or how it is related to other differences in emotional reactivity (e.g., affect intensity). We investigated how BODS relates to perceptual ratings of pleasant and unpleasant odors. We aggregated data from 4 experiments (total N = 190) that were conducted in our laboratory, and where valence and intensity ratings were collected. Unpleasant odors were body-like (e.g., sweat-like valeric acid), which may provide disease cues. The pleasant odors were, in contrast, often found in soap and cleaning products (e.g., lilac, lemon). Across experiments, we show that individuals with higher BODS levels perceived smells as more highly valenced overall: unpleasant smells were rated as more unpleasant, and pleasant smells were rated as more pleasant. These results suggest that body odor disgust sensitivity is associated with a broader pattern of affect intensity which causes stronger emotional responses to both negative and positive odors. In contrast, BODS levels were not associated with odor intensity perception. Furthermore, disgust sensitivity to odors coming from external sources (e.g., someone else's sweat) was the best predictor of odor valence ratings. The effects were modest in size. The results validate the BODS scale as it is explicitly associated with experimental ratings of odor valence.

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• Body odour disgust sensitivity is associated with xenophobia: evidence from nine countries across five continents

  2023. Marta Z. Zakrzewska (et al.). Royal Society Open Science 10 (4)

  Article

  Body odour disgust sensitivity (BODS) reflects a behavioural disposition to avoid pathogens, and it may also involve social attitudes. Among participants in the USA, high levels of BODS were associated with stronger xenophobia towards a fictitious refugee group. To test the generalizability of this finding, we analysed data from nine countries across five continents (N = 6836). Using structural equation modelling, we found support for our pre-registered hypotheses: higher BODS levels were associated with more xenophobic attitudes; this relationship was partially explained by perceived dissimilarities of the refugees' norms regarding hygiene and food preparation, and general attitudes toward immigration. Our results support a theoretical notion of how pathogen avoidance is associated with social attitudes: ‘traditional norms’ often involve behaviours that limit inter-group contact, social mobility and situations that might lead to pathogen exposure. Our results also indicate that the positive relationship between BODS and xenophobia is robust across cultures.

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• Odor identification errors reveal cognitive aspects of age-associated smell loss

  2023. Rohan Raj (et al.). Cognition 236

  Article

  Human olfaction can be extraordinarily sensitive, and its most common assessment method is odor identification (OID), where everyday odors are matched to word labels in a multiple-choice format. However, many older persons are unable to identify familiar odors, a deficit that is associated with the risk of future dementia and mortality. The underlying processes subserving OID in older adults are poorly understood. Here, we analyzed error patterns in OID to test whether errors could be explained by perceptual and/or semantic similarities among the response alternatives. We investigated the OID response patterns in a large, population-based sample of older adults in Sweden (n = 2479; age 60–100 years). Olfaction was assessed by a ‘Sniffin ́ TOM OID test with 16 odors; each trial involved matching a target odor to a correct label among three distractors. We analyzed the pattern of misidentifications, and the results showed that some distractors were more frequently selected than others, suggesting cognitive or perceptual factors may be present. Relatedly, we conducted a large online survey of older adults (n = 959, age 60–90 years) who were asked to imagine and rate the perceptual similarity of the target odors and the three corresponding distractors (e.g. “How similar are these smells: apple and mint?”). We then used data from the Swedish web corpus and the Word2Vec neural network algorithm to quantify the semantic association strength between the labels of each target odor and its three distractors. These data sources were used to predict odor identification errors. We found that the error patterns were partly explained by both the semantic similarity between target-distractor pairs, and the imagined perceptual similarity of the target-distractor pair. Both factors had, however, a diminished prediction in older ages, as responses became gradually less systematic. In sum, our results suggest that OID tests not only reflect olfactory perception, but also likely involve the mental processing of odor-semantic associations. This may be the reason why these tests are useful in predicting dementia onset. Our insights into olfactory-language interactions could be harnessed to develop new olfactory tests that are tailored for specific clinical purposes.

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• Semantic processing in children with Cochlear Implants: A review of current N400 studies and recommendations for future research

  2023. Petter Kallioinen, Jonas K. Olofsson, Cecilia Nakeva von Mentzer. Biological Psychology 182

  Article

  Deaf and hard of hearing children with cochlear implants (CI) often display impaired spoken language skills. While a large number of studies investigated brain responses to sounds in this population, relatively few focused on semantic processing. Here we summarize and discuss findings in four studies of the N400, a cortical response that reflects semantic processing, in children with CI. A study with auditory target stimuli found N400 effects at delayed latencies at 12 months after implantation, but at 18 and 24 months after implantation effects had typical latencies. In studies with visual target stimuli N400 effects were larger than or similar to controls in children with CI, despite lower semantic abilities. We propose that in children with CI, the observed large N400 effect reflects a stronger reliance on top-down predictions, relative to bottom-up language processing. Recent behavioral studies of children and adults with CI suggest that top-down processing is a common compensatory strategy, but with distinct limitations such as being effortful. A majority of the studies have small sample sizes (N < 20), and only responses to image targets were studied repeatedly in similar paradigms. This precludes strong conclusions. We give suggestions for future research and ways to overcome the scarcity of participants, including extending research to children with conventional hearing aids, an understudied group.

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• The Psychological Science Accelerator’s COVID-19 rapid-response dataset

  2023. Erin M. Buchanan (et al.). Scientific Data 10

  Article

  In response to the COVID-19 pandemic, the Psychological Science Accelerator coordinated three large-scale psychological studies to examine the effects of loss-gain framing, cognitive reappraisals, and autonomy framing manipulations on behavioral intentions and affective measures. The data collected (April to October 2020) included specific measures for each experimental study, a general questionnaire examining health prevention behaviors and COVID-19 experience, geographical and cultural context characterization, and demographic information for each participant. Each participant started the study with the same general questions and then was randomized to complete either one longer experiment or two shorter experiments. Data were provided by 73,223 participants with varying completion rates. Participants completed the survey from 111 geopolitical regions in 44 unique languages/dialects. The anonymized dataset described here is provided in both raw and processed formats to facilitate re-use and further analyses. The dataset offers secondary analytic opportunities to explore coping, framing, and self-determination across a diverse, global sample obtained at the onset of the COVID-19 pandemic, which can be merged with other time-sampled or geographic data. 

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• A global experiment on motivating social distancing during the COVID-19 pandemic

  2022. Thuy-vy Nguyen (et al.). Proceedings of the National Academy of Sciences of the United States of America 119 (22)

  Article

  Finding communication strategies that effectively motivate social distancing continues to be a global public health priority during the COVID-19 pandemic. This cross-country, preregistered experiment (n = 25,718 from 89 countries) tested hypotheses concerning generalizable positive and negative outcomes of social distancing messages that promoted personal agency and reflective choices (i.e., an autonomy-supportive message) or were restrictive and shaming (i.e., a controlling message) compared with no message at all. Results partially supported experimental hypotheses in that the controlling message increased controlled motivation (a poorly internalized form of motivation relying on shame, guilt, and fear of social consequences) relative to no message. On the other hand, the autonomy-supportive message lowered feelings of defiance compared with the controlling message, but the controlling message did not differ from receiving no message at all. Unexpectedly, messages did not influence autonomous motivation (a highly internalized form of motivation relying on one’s core values) or behavioral intentions. Results supported hypothesized associations between people’s existing autonomous and controlled motivations and self-reported behavioral intentions to engage in social distancing. Controlled motivation was associated with more defiance and less long-term behavioral intention to engage in social distancing, whereas autonomous motivation was associated with less defiance and more short- and long-term intentions to social distance. Overall, this work highlights the potential harm of using shaming and pressuring language in public health communication, with implications for the current and future global health challenges.

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• Cerebrovascular damage in subjective cognitive decline: A systematic review and meta-analysis

  2022. Helda Pitti (et al.). Ageing Research Reviews 82

  Article

  Background: Subjective cognitive decline (SCD) has been postulated as an early marker of Alzheimer’s Disease (AD) but it can also be associated to other non-AD pathologies such as Vascular Dementia (VaD). Nevertheless, there is scarce data about SCD as a potential harbinger of cerebrovascular pathology. Thus, we conducted a systematic review and meta-analysis on the association between SCD and cerebrovascular damage measured by neuroimaging markers.

  Method: This study was performed following the PRISMA guidelines. The search was conducted in 3 databases (PubMed, Scopus and Web of Science) from origin to December 8th, 2021. Primary studies including cognitively unimpaired adults with SCD and neuroimaging markers of cerebrovascular damage (i.e., white matter signal abnormalities, WMSA) were selected. Qualitative synthesis and meta-analysis of studies with a case-control design was performed.

  Results: Of 241 articles identified, 21 research articles were selected. Eight case-control studies were included for the meta-analysis. A significant overall effect-size was observed for the mean WMSA burden in SCD relative to controls, where the WMSA burden was higher in SCD.

  Conclusion: Our findings show the potential usefulness of SCD as a harbinger of cerebrovascular disease in cognitively healthy individuals. Further research is needed in order to elucidate the role of SCD as a preclinical marker of vascular cognitive impairment.

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• Hippocampal subfield volumes and olfactory performance: Emerging longitudinal associations over a 5-year interval

  2022. Georgios Menelaou, Jonas Persson, Jonas K. Olofsson. Neuropsychologia 176

  Article

  Olfaction, the sense of smell, provides important behavioral functions in many species. The hippocampus (HC) is critical for identifying odors, and hippocampal volume is associated with odor identification ability. Impaired odor identification is often reported in old age and might provide an early marker of cognitive decline and dementia. Here, we explored cross-sectional (n = 225) and longitudinal (n = 118) associations between odor identification ability and hippocampal subfield volumes in a sample of middle-aged and older persons (25-80 years). In older participants, longitudinally decreasing volumes of the hippocampal tail, subiculum, CA4 and the dentate gyrus correlated with changes in odor identification. None of these correlations were observed in younger participants, but there was a significant correlation between longitudinal volume reduction in the tail subfield of the hippocampus and odor identification change across all participants. There were no significant cross-sectional associations between hippocampal subfields and odor identification. These exploratory results provide new information regarding precisely where and when declining HC subfield volumes might be associated with odor identification.

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• In COVID-19 Health Messaging, Loss Framing Increases Anxiety with Little-to-No Concomitant Benefits: Experimental Evidence from 84 Countries

  2022. Charles A. Dorison (et al.). Affective Science 3 (3), 577-602

  Article

  The COVID-19 pandemic (and its aftermath) highlights a critical need to communicate health information effectively to the global public. Given that subtle differences in information framing can have meaningful effects on behavior, behavioral science research highlights a pressing question: Is it more effective to frame COVID-19 health messages in terms of potential losses (e.g., “If you do not practice these steps, you can endanger yourself and others”) or potential gains (e.g., “If you practice these steps, you can protect yourself and others”)? Collecting data in 48 languages from 15,929 participants in 84 countries, we experimentally tested the effects of message framing on COVID-19-related judgments, intentions, and feelings. Loss- (vs. gain-) framed messages increased self-reported anxiety among participants cross-nationally with little-to-no impact on policy attitudes, behavioral intentions, or information seeking relevant to pandemic risks. These results were consistent across 84 countries, three variations of the message framing wording, and 560 data processing and analytic choices. Thus, results provide an empirical answer to a global communication question and highlight the emotional toll of loss-framed messages. Critically, this work demonstrates the importance of considering unintended affective consequences when evaluating nudge-style interventions.

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• Olfactory distortions in the general population

  2022. Jonas K. Olofsson, Fredrik Ekesten, Steven Nordin. Scientific Reports 12 (1)

  Article

  Parosmia, distorted smell sensations, is a common consequence of respiratory virus infections. The phenomenon is not well understood in terms of its impact and long-term outcomes. We examined self-reported experiences of parosmia in a population-based sample from the Betula study that was conducted in Umea in northern Sweden (baseline data collected in 1998-2000). We used a baseline sample of 2168 individuals aged 35-90 years and with no cognitive impairment at baseline. We investigated the prevalence of parosmia experiences and, using regression analyses, its relationship to other olfactory and cognitive variables and quality of life. Benefitting from the longitudinal study design, we also assessed the persistence of parosmia over 5 and 10 years prospectively. Parosmia experiences were prevalent in 4.8% of the population and it often co-occurred with phantosmia (olfactory hallucinations), but was not associated with lower self-rated overall quality of life or poor performance on olfactory or cognitive tests. For some individuals, parosmia was retained 5 years (17.0%) or even 10 years later (10.3%). Thus, parosmia experiences are commonly reported in the population, and can be persistent for some individuals, but might be mostly benign in nature. Our work complements research on clinical-level parosmia, which is typically more severe, and recent parosmia reports during the COVID-19 pandemic, where long-term outcomes are still unknown.

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• Perceptual odor qualities predict successful odor identification in old age 

  2022. Robert Lindroos (et al.). Chemical Senses 47

  Article

  Odor identification is a common assessment of olfaction, and it is affected in a large number of diseases. Identification abilities decline with age, but little is known about whether there are perceptual odor features that can be used to predict identification. Here, we analyzed data from a large, population-based sample of 2,479 adults, aged 60 years or above, from the Swedish National study on Aging and Care in Kungsholmen. Participants performed both free and cued odor identification tests. In a separate experiment, we assessed perceived pleasantness, familiarity, intensity, and edibility of all odors in the first sample, and examined how odor identification performance is associated with these variables. The analysis showed that high-intensity odors are easier to identify than low-intensity odors overall, but also that they are more susceptible to the negative repercussions of old age. This result indicates that sensory decline is a major aspect of age-dependent odor identification impairment, and suggests a framework where identification likelihood is proportional to the perceived intensity of the odor. Additional analyses further showed that high-performing individuals can discriminate target odors from distractors along the pleasantness and edibility dimensions and that unpleasant and inedible odors show smaller age-related differences in identification. Altogether, these results may guide further development and optimization of brief and efficient odor identification tests as well as influence the design of odorous products targeted toward older consumers. 

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• Subjective Impairments in Olfaction and Cognition Predict Dissociated Behavioral Outcomes 

  2022. Nira Cedres (et al.). The journals of gerontology. Series B, Psychological sciences and social sciences 78 (1), 1-9

  Article

  Background: Self-rated subjective cognitive decline (SCD) and subjective olfactory impairment (SOI) are associated with objective cognitive decline and dementia. However, their relationship and co-occurrence is unknown. We aimed to (a) describe the occurrence of SOI, SCD and their overlap in the general population; (b) compare SOI and SCD in terms of longitudinal associations with corresponding objective olfactory and cognitive measures; and (c) describe how SOI and SCD may lead to distinct sensory and cognitive outcomes.

  Methods: Cognitively unimpaired individuals from the third wave of the Swedish population-based Betula study (n = 784, aged 35–90 years; 51% females) were split into self-rated SOI, SCD, overlapping SCD + SOI, and controls. Between-subject and within-subject repeated-measures MANCOVA were used to compare the groups regarding odor identification, cognition, age, sex, and education. Spearman correlation was used to assess the different patterns of association between olfaction and cognition across groups.

  Results: SOI was present in 21.1%, whereas SCD was present in 9.9% of participants. According to a chi-square analysis, the SCD + SOI overlap (2.7%) is on a level that could be expected if the phenomena were independent. Odor identification in SOI showed decline at the 10-year follow-up (n = 284) and was positively associated with cognition. The SOI and SCD groups showed distinct cognitive-olfactory profiles at follow-up.

  Conclusions: SOI occur independently of SCD in the population, and these risk factors are associated with different cognitive and olfactory outcomes. The biological causes underlying SOI and SCD, as well as the risk for future cognitive impairment, need further investigation.

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• The Semantic Organization of the English Odor Vocabulary

  2022. Thomas Hörberg, Maria Larsson, Jonas K. Olofsson. Cognitive science 46 (11)

  Article

  The vocabulary for describing odors in English natural language is not well understood, as prior studies of odor descriptions have often relied on preselected descriptors and odor ratings. Here, we present a data-driven approach that automatically identifies English odor descriptors based on their degree of olfactory association, and derive their semantic organization from their distributions in natural texts, using a distributional-semantic language model. We identify 243 descriptors that are much more strongly associated with olfaction than English words in general. We then derive the semantic organization of these olfactory descriptors, and find that it is captured by four clusters that we name Offensive, Malodorous, Fragrant, and Edible. The semantic space derived from our model primarily differentiates descriptors in terms of pleasantness and edibility along which our four clusters are positioned, and is similar to a space derived from perceptual data. The semantic organization of odor vocabulary can thus be mapped using natural language data (e.g., online text), without the limitations of odor-perceptual data and preselected descriptors. Our method may thus facilitate research on olfaction, a sensory system known to often elude verbal description. 

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• A Review of the Effects of Valenced Odors on Face Perception and Evaluation

  2021. Elmeri Syrjänen (et al.). i-Perception 12 (2), 1-19

  Article

  How do valenced odors affect the perception and evaluation of facial expressions? We reviewed 25 studies published from 1989 to 2020 on cross-modal behavioral effects of odors on the perception of faces. The results indicate that odors may influence facial evaluations and classifications in several ways. Faces are rated as more arousing during simultaneous odor exposure, and the rated valence of faces is affected in the direction of the odor valence. For facial classification tasks, in general, valenced odors, whether pleasant or unpleasant, decrease facial emotion classification speed. The evidence for valence congruency effects was inconsistent. Some studies found that exposure to a valenced odor facilitates the processing of a similarly valenced facial expression. The results for facial evaluation were mirrored in classical conditioning studies, as faces conditioned with valenced odors were rated in the direction of the odor valence. However, the evidence of odor effects was inconsistent when the task was to classify faces. Furthermore, using a z-curve analysis, we found clear evidence for publication bias. Our recommendations for future research include greater consideration of individual differences in sensation and cognition, individual differences (e.g., differences in odor sensitivity related to age, gender, or culture), establishing standardized experimental assessments and stimuli, larger study samples, and embracing open research practices.

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• Olfactory Language

  2021. Jonas K. Olofsson, Stephen Pierzchajlo. Trends in cognitive sciences 25 (6), 419-420

  Article

  The sense of smell, olfaction, is currently in the spotlight. Although often a neglected sense, smell loss and smell distortions due to coronavirus disease 2019 (COVID-19) has increased public awareness of olfaction and its role in health, well-being, and nutrition. In this unusual context, Majid provides a timely, well written, and thought-provoking review of olfaction and its cognitive aspects. Majid focuses on how smells are expressed in languages around the world, yet the review covers a vast literature that includes also experimental, cognitive, and biological fields. The thrust of the argument is directed against a perceived dogma; that ‘there is no language of smell and humans are bad at naming odors’. Majid argues that this dogma is refuted by cross-cultural research and concludes that ‘rather than focusing on constrained experimental tasks’, olfactory language should be studied in terms of ‘how people across the globe use, manipulate and talk about odors in their day-to-day contexts’. Later, we show how empirical and theoretical considerations lead us to partly different conclusions. Empirically, we believe that odor naming remains poorer than naming in other senses and that careful laboratory experiments will remain critical for understanding olfactory-based language and cognition. Toward this goal, we emphasize the distinction between multisensory and unisensory olfaction, which is not highlighted in Majid's review but which we believe is of theoretical importance.

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• To which world regions does the valence–dominance model of social perception apply?

  2021. Benedict C. Jones (et al.). Nature Human Behaviour 5 (1), 159-169

  Article

  Over the past 10 years, Oosterhof and Todorov’s valence–dominance model has emerged as the most prominent account of how people evaluate faces on social dimensions. In this model, two dimensions (valence and dominance) underpin social judgements of faces. Because this model has primarily been developed and tested in Western regions, it is unclear whether these findings apply to other regions. We addressed this question by replicating Oosterhof and Todorov’s methodology across 11 world regions, 41 countries and 11,570 participants. When we used Oosterhof and Todorov’s original analysis strategy, the valence–dominance model generalized across regions. When we used an alternative methodology to allow for correlated dimensions, we observed much less generalization. Collectively, these results suggest that, while the valence–dominance model generalizes very well across regions when dimensions are forced to be orthogonal, regional differences are revealed when we use different extraction methods and correlate and rotate the dimension reduction solution.

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• A Method for Computerized Olfactory Assessment and Training Outside of Laboratory or Clinical Settings

  2021. Simon Niedenthal (et al.). i-Perception 12 (3), 1-12

  Article

  There are currently few ways to reliably and objectively assess olfaction outside of the research laboratory or clinic. The COVID-19 pandemic has highlighted the need for remote olfactory assessment; in particular, smell training at home is a promising method for olfactory rehabilitation, but further methodological advances might enhance its effectiveness and range of use. Here, we present Exerscent, a portable, low-cost olfactory display designed primarily for uses outside of the laboratory and that can be operated with a personal computer. Exerscent includes Radio Frequency Identification (RFID) tags that are attached to odor stimuli and read with a MFRC522 module RFID reader/antenna that encodes the odor in order to provide adaptive challenges for the user (e.g., an odor identification task). Hardware parts are commercially available or 3D printed. Instructions and code for building the Exerscent are freely available online (https://osf.io/kwftm/). As a proof of concept, we present a case study in which a participant trained daily to identify 54 odors, improving from 81% to 96% accuracy over 16 consecutive days. In addition, results from a laboratory experiment with 11 volunteers indicated a very high level of perceived usability and engagement. Exerscent may be used for olfactory skills development (e.g., perfumery, enology), and rehabilitation purposes (e.g., postviral olfactory loss), but it also allows for other forms of technological interactions such as olfactory-based recreational interactions.

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• A multi-country test of brief reappraisal interventions on emotions during the COVID-19 pandemic

  2021. Ke Wang (et al.). Nature Human Behaviour 5 (8), 1089-1110

  Article

  The COVID-19 pandemic has increased negative emotions and decreased positive emotions globally. Left unchecked, these emotional changes might have a wide array of adverse impacts. To reduce negative emotions and increase positive emotions, we tested the effectiveness of reappraisal, an emotion-regulation strategy that modifies how one thinks about a situation. Participants from 87 countries and regions (n = 21,644) were randomly assigned to one of two brief reappraisal interventions (reconstrual or repurposing) or one of two control conditions (active or passive). Results revealed that both reappraisal interventions (vesus both control conditions) consistently reduced negative emotions and increased positive emotions across different measures. Reconstrual and repurposing interventions had similar effects. Importantly, planned exploratory analyses indicated that reappraisal interventions did not reduce intentions to practice preventive health behaviours. The findings demonstrate the viability of creating scalable, low-cost interventions for use around the world.

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• Duality of Smell

  2021. Robert Pellegrino (et al.). Chemical Senses 46, 1-11

  Article

  Olfactory research in humans has largely focused on odors perceived via sniffing, orthonasal olfaction, whereas odors perceived from the mouth, retronasal olfaction, are less well understood. Prior work on retronasally presented odors involves animal models and focus mainly on odor sensitivity, but little is known about retronasal olfactory perception and cognition in humans. In this study, we compared orthonasal and retronasal odor presentation routes to investigate differences in odor descriptions and evaluations. Thirty-six individuals participated in a within-subjects study using twelve odors (varying in pleasantness and edibility) in perceptual and semantic tasks. Orthonasal presentation was associated with a better ability to identify odors, and with more concrete (and source-based) language. Exploratory analyses revealed that whereas orthonasal odors were described with words that had visual associations, retronasal odors were described with words that had interoceptive associations. Interestingly, these route-dependent differences in descriptor usage were not explained by differences in sensitivity and intensity, suggesting instead a cognitive and linguistic processing difference between odors presented orthonasally and retronasally. Our results indicate that olfaction is, in fact, a dual sense, in which the routes change the perception of an odor.

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• Human hippocampal connectivity is stronger in olfaction than other sensory systems

  2021. Guangyu Zhou (et al.). Progress in Neurobiology 201

  Article

  During mammalian evolution, primate neocortex expanded, shifting hippocampal functional networks away from primary sensory cortices, towards association cortices. Reflecting this rerouting, human resting hippocampal functional networks preferentially include higher association cortices, while those in rodents retained primary sensory cortices. Research on human visual, auditory and somatosensory systems shows evidence of this rerouting. Olfaction, however, is unique among sensory systems in its relative structural conservation throughout mammalian evolution, and it is unknown whether human primary olfactory cortex was subject to the same rerouting. We combined functional neuroimaging and intracranial electrophysiology to directly compare hippocampal functional networks across human sensory systems. We show that human primary olfactory cortex—including the anterior olfactory nucleus, olfactory tubercle and piriform cortex—has stronger functional connectivity with hippocampal networks at rest, compared to other sensory systems. This suggests that unlike other sensory systems, olfactory-hippocampal connectivity may have been retained in mammalian evolution. We further show that olfactory-hippocampal connectivity oscillates with nasal breathing. Our findings suggest olfaction might provide insight into how memory and cognition depend on hippocampal interactions.

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• Joint trajectories of episodic memory and odor identification in older adults

  2021. Christina S. Dintica (et al.). Aging 13 (13), 17080-17096

  Article

  Emerging evidence suggests that olfactory function is closely linked to memory function. The aims of this study were to assess whether olfactory and episodic memory functions follow similar age-related decline trajectories, to identify different patterns of decline, as well as predictors of the patterns. 1023 participants from the Memory and Aging Project were followed for up to 8 years with annual episodic memory and odor identification assessments. Trajectories were modelled using growth mixture models. Multivariate logistic regression was used to identify pattern predictors. Three patterns of joint trajectories were identified; Class 1- stable average performance in both functions (n=690, 67.4%); Class 2- stable average episodic memory and declining odor identification (n=231, 22.6%); and Class 3- decline in both functions (n=102, 10.0%). Class predictors included age, sex, APOE epsilon 4 status, cognitive activity level and BMI. Participants in Class 3 were most likely to develop dementia. Episodic memory and olfactory function show similar trajectories in aging. Such classification can contribute to a better understanding of the factors related to cognitive decline and dementia.

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• Olfaction and Aging

  2021. Jonas K. Olofsson (et al.). i-Perception 12 (3), 1-24

  Article

  Olfaction, the sense of smell, is characterized by a notable age-dependency such that aging individuals are more likely to have poor olfactory abilities. These impairments are considered to be mostly irreversible and as having potentially profound effects on quality of life and food behavior, as well as constituting warning signs of mortality, cognitive dysfunction, and dementia. Here, we review the current state of research on aging and olfaction, focusing on five topics which we regard to be of particular relevance for the field: nutrition and health, cognition and dementia, mortality, environment and genetics, and training-based enhancement. Under each of these headlines, we provide a state-of-the-art overview and discuss gaps in our knowledge which might be filled by further research. Understanding how olfactory abilities are diminished in aging, and how they may be alleviated or recovered, involves a set of challenging tasks for researchers in the years to come.

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• Recent Smell Loss Is the Best Predictor of COVID-19 Among Individuals With Recent Respiratory Symptoms

  2021. Richard C. Gerkin (et al.). Chemical Senses 46, 1-12

  Article

  In a preregistered, cross-sectional study, we investigated whether olfactory loss is a reliable predictor of COVID-19 using a crowdsourced questionnaire in 23 languages to assess symptoms in individuals self-reporting recent respiratory illness. We quantified changes in chemosensory abilities during the course of the respiratory illness using 0–100 visual analog scales (VAS) for participants reporting a positive (C19+; n = 4148) or negative (C19−; n = 546) COVID-19 laboratory test outcome. Logistic regression models identified univariate and multivariate predictors of COVID-19 status and post-COVID-19 olfactory recovery. Both C19+ and C19− groups exhibited smell loss, but it was significantly larger in C19+ participants (mean ± SD, C19+: −82.5 ± 27.2 points; C19−: −59.8 ± 37.7). Smell loss during illness was the best predictor of COVID-19 in both univariate and multivariate models (ROC AUC = 0.72). Additional variables provide negligible model improvement. VAS ratings of smell loss were more predictive than binary chemosensory yes/no-questions or other cardinal symptoms (e.g., fever). Olfactory recovery within 40 days of respiratory symptom onset was reported for ~50% of participants and was best predicted by time since respiratory symptom onset. We find that quantified smell loss is the best predictor of COVID-19 amongst those with symptoms of respiratory illness. To aid clinicians and contact tracers in identifying individuals with a high likelihood of having COVID-19, we propose a novel 0–10 scale to screen for recent olfactory loss, the ODoR-19. We find that numeric ratings ≤2 indicate high odds of symptomatic COVID-19 (4 < OR < 10). Once independently validated, this tool could be deployed when viral lab tests are impractical or unavailable.

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Show all publications by Jonas Olofsson at Stockholm University