Disgust Responses to Bitter Compounds: the Role of Disgust Sensitivity

Long-term behavioural rewriting of maladaptive drinking memories via reconsolidation-update mechanisms

BACKGROUND

Alcohol use disorders can be conceptualised as a learned pattern of maladaptive alcohol-consumption behaviours. The memories encoding these behaviours centrally contribute to long-term excessive alcohol consumption and are therefore an important therapeutic target. The transient period of memory instability sparked during memory reconsolidation offers a therapeutic window to directly rewrite these memories using targeted behavioural interventions. However, clinically-relevant demonstrations of the efficacy of this approach are few. We examined key retrieval parameters for destabilising naturalistic drinking memories and the ability of subsequent counterconditioning to effect long-term reductions in drinking.

METHODS

Hazardous/harmful beer-drinking volunteers (N = 120) were factorially randomised to retrieve (RET) or not retrieve (No RET) alcohol reward memories with (PE) or without (No PE) alcohol reward prediction error. All participants subsequently underwent disgust-based counterconditioning of drinking cues. Acute responses to alcohol were assessed pre- and post-manipulation and drinking levels were assessed up to 9 months.

RESULTS

Greater long-term reductions in drinking were found when counterconditioning was conducted following retrieval (with and without PE), despite a lack of short-term group differences in motivational responding to acute alcohol. Large variability in acute levels of learning during counterconditioning was noted. 'Responsiveness' to counterconditioning predicted subsequent responses to acute alcohol in RET + PE only, consistent with reconsolidation-update mechanisms.

CONCLUSIONS

The longevity of behavioural interventions designed to reduce problematic drinking levels may be enhanced by leveraging reconsolidation-update mechanisms to rewrite maladaptive memory. However, inter-individual variability in levels of corrective learning is likely to determine the efficacy of reconsolidation-updating interventions and should be considered when designing and assessing interventions.

Phenol-Rich Food Acceptability: The Influence of Variations in Sweetness Optima and Sensory-Liking Patterns

The consumption of phenol-rich foods is limited by their prominent bitterness and astringency. This issue has been addressed by adding sweet tastes, which suppress bitterness, but this is not a complete solution since individuals also differ in their preference for sweetness. In this study, we aimed at identifying groups of consumers differing in sweetness optima and sensory-liking patterns. To this end, increasing concentrations of sucrose were added to a chocolate pudding base. This allowed us to (1) investigate if individual differences in sensory responses are associated with different sweet liking optima in a product context, (2) define the psychological and oro-sensory profile of sweet liker phenotypes derived using a product context, and (3) assess if individuals differing in sweet liking optima differ also in consumption and liking of phenol-rich foods and beverages as a function of their sensory properties (e.g., sweeter vs. more bitter and astringent products). Individuals (1208; 58.4% women, 18–69 years) were characterised for demographics, responsiveness to 6-n-propylthiouracil (PROP), personality traits and attitudes toward foods. Three clusters were identified based on correlations between sensory responses (sweetness, bitterness and astringency) and liking of the samples: liking was positively related to sweetness and negatively to bitterness and astringency in High and Moderate Sweet Likers, and the opposite in Inverted U-Shaped. Differences between clusters were found in age, gender and personality. Furthermore, the Inverted-U Shaped cluster was found to have overall healthier food behaviours and preferences, with higher liking and consumption of phenol-rich vegetables and beverages without added sugar. These findings point out the importance of identifying the individual sensory-liking patterns in order to develop more effective strategies to promote the acceptability of healthy phenol-rich foods.

Disgust Propensity and the Bitter Aftertaste Response

Introduction

A high level of disgust propensity (the general tendency to respond with the emotion of disgust to any given situation) is associated with an increased sensitivity to bitter taste. The present study examined the relationship between disgust propensity and the sensitivity to bitter aftertaste.

Methods

A total of 200 women rinsed their mouth with concentrated wormwood tea (Artemisia absinthium). The resulting aftertaste was evaluated (intensity of bitterness and disgust) every 15 s for 10 min. A multiple linear regression analysis was calculated to capture the association between aftertaste ratings and affective variables (e.g., disgust propensity, depression symptoms).

Results

Higher disgust propensity was associated with higher initial disgust ratings and faster reduction of disgust over time. Higher depression scores were associated with a slower disgust reduction.

Conclusion

We demonstrated that affective variables predict the temporal course of the wormwood aftertaste response. Having a higher disgust propensity was associated with a shortened disgust recovery.

Implications

A shortened disgust recovery may be adaptive because it enables faster processing of new disgust stimuli.

Perceptual and cognitive determinants of tactile disgust

Tactile cues are said to be potent elicitors of disgust and reliable markers of disease. Despite this, no previous study had explored what the full range of tactile properties are that cue disgust, nor how interpretation of these sensations influences disgust. To answer these questions, participants were asked to touch nine objects, selected to cover the range of tactile properties, and evaluate their sensory, affective, and risk-based characteristics (primarily how sick they thought the object would make them). Object contact was manipulated in four ways, with participants randomly allocated to corresponding groups-one that could see the objects (i.e., the control) and three that could not (i.e., the blind groups). To manipulate disease risk interpretation of the objects, labelling was used on the blind groups, with one receiving Disgust-Labels, one True-Labels and one no labels. Disgust was strongly associated with sticky and wet textures, and moderately with viscous, cold, and lumpy textures, suggesting adherence-to-skin may predict disgust. The participants in the disgust-labelled condition had the highest disgust ratings, and this was mediated by their increased sickness belief and fear of the objects. Object identification was poor when labels or visual cues were absent. Our findings suggest that tactile disgust may reflect a bottom-up sensory component-skin adhesion-moderated by judgements of disease-related threat.

A Proximal Perspective on Disgust

The functional basis of disgust in disease avoidance is widely accepted; however, there is disagreement over what disgust is. This is a significant problem, as basic questions about disgust require knowing if single/multiple forms/processes exist. We address this issue with a new model with one form of disgust generated by multiple processes: (a) pure disgust experienced during gastrointestinal illness; (b) somatosensory disgust elicited by specific cues that activate the pure disgust state; (c) anticipatory disgust elicited by associations between distance cues for somatosensory disgust and requiring threat evaluation; (d) simulated disgusts elicited by imagining somatosensory and anticipatory disgust and frequently involving other emotions. Different contamination processes interlink (a–d). The implications of our model for fundamental questions about disgust (e.g., emotion status; continuation into animals) are examined.

The Body Odor Disgust Scale (BODS): Development and Validation of a Novel Olfactory Disgust Assessment

Disgust plays a crucial role in the avoidance of pathogen threats. In many species, body odors provide important information related to health and disease, and body odors are potent elicitors of disgust in humans. With this background, valid assessments of body odor disgust sensitivity are warranted. In the present article, we report the development and psychometric validation of the Body Odor Disgust Scale (BODS), a measure suited to assess individual differences in disgust reaction to a variety of body odors. Collected data from 3 studies (total n = 528) show that the scale can be used either as a unidimensional scale or as a scale that reflects two hypothesized factors: sensitivity to one's own body odors versus those of others. Guided by our results, we reduced the scale to 12 items that capture the essence of these 2 factors. The final version of the BODS shows an excellent internal consistency (Cronbach's αs > 0.9). The BODS subscales show convergent validity with other general disgust scales, as well as with other olfactory functions measures and with aspects of personality that are related to pathogen avoidance. A fourth study confirmed the construct validity of the BODS and its measurement invariance to gender. Moreover, we found that, compared with other general disgust scales, the BODS is more strongly related to perceived vulnerability to disease. The BODS is a brief and valid assessment of trait body odor disgust sensitivity.

Affective Evaluation of One's Own and Others' Body Odor: The Role of Disgust Proneness

Disgust is part of a behavioral immune system that helps to detect pathogens. One important input to this system is the sense of smell. We conducted an experiment on body odor perception with 72 participants (35 men, 37 women; mean age = 24 years), who had been divided according to high versus low disgust proneness. All participants were exposed to six samples of axillary sweat from other individuals and to their own sweat. They were asked to identify their own body odor and to rate their affective experience. The participants were not able to identify their own sweat; however, differentiation of self versus others was based on experienced disgust; the sweat of others was perceived as more disgusting. Moreover, disgust-prone participants showed differential affective responses to the two sweat sources and evaluated others' sweat as more negative and arousing. The current study points to the important role of state/trait disgust in the implicit processing of body odor.

Influence of Bitter Taste on Affective Facial Processing: An ERP Study

Previous research showed that a bitter taste in the mouth is able to enhance hostile response tendencies to social rejection. The present event-related potential (ERP) study sought to investigate neuronal components of this effect. We presented 52 participants (39 women and 13 men; mean age = 23.3 years) with images of facial expressions signaling social rejection (angry, disgusted) or no rejection (happy, neural), whereas they either experienced a bitter aftertaste (bitter group [BG]: n = 26) or rinsed their mouth with water (control group [CG]: n = 26). The BG rated the aftertaste as extremely intense and disgusting and showed a decreased parietal P200 to all facial expressions, as well as a lowered parietal P300 to cues of nonrejection. The bitter intervention neither influenced the affective ratings for the images nor self-reported hostility. In conclusion, the ERP findings indicated that bitterness first reduced visual attention to social cues in general (P200) and then specifically to cues of nonrejection (P300). Bitterness was not associated with increased sensitivity to disgust/anger signaled by others neither on a neuronal nor self-report level.

Is Disgust Proneness Associated With Anxiety and Related Disorders? A Qualitative Review and Meta-Analysis of Group Comparison and Correlational Studies

Research suggests that disgust may be linked to the etiology of some anxiety-related disorders. The present investigation reviews this literature and employs separate meta-analyses of clinical group comparison and correlational studies to examine the association between disgust proneness and anxiety-related disorder symptoms. Meta-analysis of 43 group comparison studies revealed those high in anxiety disorder symptoms reported significantly more disgust proneness than those low in anxiety symptoms. Although this effect was not moderated by clinical versus analogue studies or type of disorder, larger group differences were observed for those high in anxiety symptoms associated with contagion concerns compared to those high in anxiety symptoms not associated with contagion concerns. Similarly, meta-analysis of correlational data across 83 samples revealed moderate associations between disgust proneness and anxiety-related disorder symptoms. Moderator analysis revealed that the association between disgust proneness and anxiety-related disorder symptoms was especially robust for anxiety symptoms associated with contagion concerns. After controlling for measures of negative affect, disgust proneness continued to be moderately correlated with anxiety-related disorder symptoms. However, negative affect was no longer significantly associated with symptoms of anxiety-related disorders when controlling for disgust proneness. The implications of these findings are discussed in the context of a novel transdiagnostic model.

Disgust-Related Olfactory Processing: The Role of Gender and Trait Disgust

For the rejection of disgusting and potentially health-threatening food, the sense of smell plays a critical role. We conducted two experiments in order to investigate the role of gender and trait disgust (the temporally stable tendency to experience disgust across different situations) on disgust-related olfactory processing. A total of 40 men and women (Study 1), as well as a group of women divided according to high versus low trait disgust (Study 2, n = 59), were compared with regard to their odor thresholds for carbon disulfide (which smells like spoiled food) and a control stimulus ( n-butanol). The stimuli were rated for experienced arousal, negative valence, and familiarity. In addition, all participants underwent the "Sniffin' Sticks" battery assessing general olfactory performance. We found that women had a lower carbon disulfide threshold and rated this odorant as more unpleasant than men. Trait disgust was neither associated with the detection of the odorant signaling spoilage, nor with general olfactory function. The latter finding questions the role of this personality trait for olfactory-driven food-rejection responses, at least for normosmic individuals.