Individual differences in bitter taste preferences are associated with antisocial personality traits

Exploring the association between self-compassion, mindfulness and mindful eating with eating behaviours amongst patients with obesity

Background: People who have obesity often experience problematic eating behaviours, contributing towards their excessive weight gain. Aims: Understanding problematic eating behaviours and their association to self-compassion, mindfulness and mindful eating is important for the development of future interventions that improve weight-loss and weight-regulation. Methods: One hundred and one participants attending their first session of a 6-session dietetic programme within a Tier 3 medical weight management service in the West Midlands, UK were recruited to complete questionnaires on self-compassion, mindfulness, mindful eating and eating behaviours, such as, emotional, restrained, external, fat and sugar consumption and grazing. Results: The findings suggested all three constructs, self-compassion, mindfulness and mindful eating were significantly and negatively associated with grazing and emotional eating, but mindful eating was the only construct that also displayed a significant and negative association with other eating behaviours that are often barriers to successful weight regulation, such as external eating and fat consumption. Further investigation suggested mindful eating had an indirect effect on fat consumption and grazing via external eating. Conclusion: Whilst, self-compassion, mindfulness and mindful eating displayed a negative relationship with grazing and emotional eating, mindful eating also displayed a negative relationship with fat consumption and external eating. Possible explanations and directions for future work are discussed with an emphasis on the need for more empirical work.

Salivary microbial profiles associate with responsiveness to warning oral sensations and dietary intakes

Oral microbiota-host interactions are gaining recognition as potential factors contributing to interindividual variations in taste perception. However, whether such possible links imply specific bacterial co-occurrence networks remains unknown. To address this issue, we used 16 s rRNA gene sequencing to profile the salivary microbiota of 100 healthy individuals (52 % women; 18-30 y/o), who provided hedonic and psychophysical responses to 5 liquid and 5 solid commercially-available foods, each chosen to elicit a target sensation (sweet, sour, bitter, salty, pungent). The same cohort also completed several psychometric measures and a 4-day food diary. Unsupervised data-driven clustering of genus-level Aitchison distances supported the existence of two salivary microbial profiles (CL-1, CL-2). While CL-1 (n = 57; 49.1 % women) exhibited higher α-diversity metrics and was enriched in microbial genera assigned to the class Clostridia (e.g., Lachnospiraceae_[G-3]), CL-2 (n = 43; 55.8 % women) harbored greater amounts of taxa with potential cariogenic effects (e.g., genus Lactobacillus) and significantly lower abundances of inferred MetaCyc pathways related to the metabolic fate of acetate. Intriguingly, CL-2 showed enhanced responsiveness to warning oral sensations (bitter, sour, astringent) and a higher propensity to crave sweet foods or engage in prosocial behaviors. Further, the same cluster reported habitually consuming more simple carbohydrates and fewer beneficial nutrients (vegetable proteins, monounsaturated fatty acids). In summary, while the mediating role of participants' baseline diet on findings can not be definitively excluded, this work provides evidence suggesting that microbe-microbe and microbe-taste interactions may exert an influence on dietary habits and motivates further research to uncover a potential "core" taste-related salivary microbiota.

Feeling up or feeling down: Verticality preferences in personality, pathology, and well-being

Theories of mental functioning have suggested its metaphoric basis. Drawing from theories of this type as well as from recent extensions of such theories to the personality processing realm, participants in three studies (total N = 452) were asked to indicate their relative preferences for the spatial concepts of up versus down, given that verticality metaphors are frequently used to conceptualize states related to emotion and well-being. Up-preferring individuals were more extraverted and approach-motivated (Study 1), whereas down-preferring individuals were more depressed (Studies 1 and 2). Higher levels of vertical preference were also predictive of affective well-being in a daily diary protocol (Study 3) and these relationships operated in both between-person and within-person terms. Metaphors, which liken the intangible to the tangible, may play a significant role in shaping experience and verticality metaphors, in particular, appear to provide insights into the processes that that support happiness versus its absence.

Motives Linking Subclinical Psychopathy and Benign Masochism to Recreational Drug use

As the use of some psychoactive substances continues to be a global health risk, it is important to understand why people use them. We compared the predictive power of psychopathy and masochism with regard to lifetime recreational drug use and tested the underlying motives in a sample of 415 US-based adults. Psychopathy predicted use of illicit drugs, cannabis, and nicotine, while masochism predicted cannabis, alcohol, and caffeine use. Both traits were related to most motives, but the motives differentially predicted substance use. Expansion motivation was the sole motive for illicit drug use, whereas cannabis was predicted mainly by expansion and enhancement. Alcohol, nicotine, and caffeine were used to escape daily worries, and alcohol was further used for social reasons. Benign masochism is a newly identified predictor of popular drug use. Future research could investigate masochism and expansion motivation as predictors of potentially harmful substance use.

Dark personalities and general masochistic tendencies: Their relationships to giving and receiving sexualized pain

Recent research has shown that a tendency to harm others goes hand in hand with a tendency to harm oneself. The present two studies further supported the notion that the joy of harming others and oneself has a common core by showing positive relationships between dark personality traits (particularly psychopathy) and sexual masochistic preferences and between general masochistic tendencies and sexual sadistic preferences. Despite the overlap between dark personality traits and general masochistic tendencies, they independently predicted the engagement in sexual sadomasochism. These relationships statistically held when controlling for the impact of basic personality (Study 1). Study 2 found that self-enhancement, openness to change, and low conservation values serve as motivators for a person's attraction to sexual sadomasochism and shed some light on the differences between sexual sadomasochism and the Dark Tetrad. Overall, people who score relatively high on dark personalities and masochism are particularly predisposed to engage in sexual sadomasochism, in both the dominant and the submissive roles.

Evaluation of Behavior and Affective State of Different-Parity Sows with Strong/Weak Pupil Light Reflex

The stall-housing system is commonly used in the modern swine industry in many countries; however, long-term space restrictions can cause affective and physiological abnormalities in sows. The pupil light reflex (PLR) can reflect the psychological and neurological changes in animals, and confined sows show higher pupillary rigidity. However, the PLR differs between same-parity sows, suggesting differences in behaviors and affective states between parity groups. We subjected confined Yorkshire × Landrace sows of parity 0, 2, and 5 to a PLR test and accordingly assigned them to the weak PLR (WR) group (n = 20) or the strong PLR (SR) group (n = 22). We then observed the sows’ behaviors and performed a sucrose/quinine response test and novel object test (NOT) to assess the differences in their affective states. The standing and lateral lying behaviors of the sows were less frequent in WR than in SR (p < 0.05), whereas ventral lying and sitting behaviors was more frequent in WR than in SR (p < 0.05). No changes in chewing behaviors and sucrose/quinine responses were observed (p > 0.05); however, the numbers and duration of novel object contact were lower and the novel object response latency time was longer in WR than in SR (p < 0.05). Regarding parity, standing and lateral lying behaviors were less frequent and ventral lying and sitting behaviors were more frequent at parity 5 than at parity 0 (p < 0.05). Bar-biting, rooting, trough-biting, and sucrose response score were lower at parity 5 than at parity 0 (p < 0.05), and vacuum chewing behavior and quinine response score were higher in sows of parity 5 than in those of parity 0 (p < 0.05). NOT showed that the number of contacts and contact duration in sows decreased with increasing parity (p < 0.05), and the response latency time was longer in sows of parity 5 than in those of lower parity (p < 0.05). In conclusion, the behavioral expression and responses of confined sows to novel objects differed between PLRs. The evaluation of the affective state of sows also revealed marked differences with increasing parity. Thus, confined sows with WR and high parity apparently suffer from more severe psychological problems, and PLR may be a potent indicator for evaluating the affective state of confined sows.

What is the link between personality and food behavior?

A number of personality characteristics have been linked to various aspects of taste (gustation), trigeminal, and olfactory perception. In particular, personality traits have been linked to olfactory sensory thresholds and olfactory identification abilities, as well as to the sensory-discriminative aspects of taste/flavour perception. To date, much of the research in this area has focused on Sensation Seeking (including Experience Seeking, and Openness to Novel Experiences), with the latter being linked to a preference for spicy, and possibly also crunchy, sour, and bitter foods/drinks. Novelty-seeking has also been linked to a preference for salty foods, while anxious individuals appear to enjoy a much narrower range of foods. A bidirectional link has also been documented between taste and mood. Certain of the personality-based differences in taste/flavour perception and food behaviour have been linked to differences in circulating levels of neurotransmitters and hormones in both normal and clinical populations. Taken together, therefore, the evidence that has been published to date supports a number of intriguing connections between personality traits and taste perception/food behaviour.

Political taste: Exploring how perception of bitter substances may reveal risk tolerance and political preferences

Risk is endemic to the political arena and influences citizen engagement. We explore this connection by suggesting that risk-taking may be biologically instantiated in sensory systems. With specific attention to gender and gender identity, we investigate the connections between self-reported bitter taste reception, risk tolerance, and both of their associations with political participation. In three U.S. samples collected in 2019 and 2020, participants were asked to rate their preferences from lists of foods as well as whether they detected the taste of the substance N-Propylthiouracil (PROP) and, if so, the strength of the taste. In this registered report, we find that self-reported bitter taste preference, but not PROP detection, is positively associated with higher levels of risk tolerance as well as political participation. The pattern with gender and gender identity is mixed across our samples, but interestingly, we find that sex-atypical gender identity positively predicts political participation.

The relation between narcissism and aggression: A meta-analysis

OBJECTIVE

Narcissism is a complex, hierarchical construct that can be studied at the one, two, or three factor levels with different components within each level having their own unique nomological networks. The manner in which narcissism-both broadly and narrowly construed-is linked to aggression is important to understand given longstanding clinical and empirical observations of a link between the two and the critical implications of aggression.

METHODS

The current preregistered meta-analysis (k = 118) took a novel methodological approach in exploring the association between the three levels of narcissism (i.e., global construct level, dual-dimension level, trifurcated level) and three indices of aggression (i.e., general, proactive, reactive).

RESULTS

Results revealed that the global construct of narcissism shows a moderate positive association with different indices of aggression. Vulnerable narcissism associated strongly and positively with reactive aggression and general aggression. At the trifurcated level, interpersonal antagonism associated positively with all indices of aggression, agentic extraversion associated negatively with all indices of aggression, and narcissistic neuroticism associates positively with general and reactive aggression.

CONCLUSION

The study highlighted the importance of studying narcissism, and potentially other personality profiles, at a finer-grained level to better understand crucial psychological processes associated with the construct of interest.

Eating and wheel running across the estrous cycle in rat lines selectively bred on a taste phenotype

The Occidental Low- and High-Saccharin-Consuming rats (respectively, LoS and HiS) have been selectively bred for decades to study the relationship between taste and behaviors in and beyond the ingestive domain. Whether the saccharin phenotype is associated with behavioral periodicities tied to reproductive status is not known. Here we describe for the first time variation across the estrous cycle in chow intake and wheel running by LoS and HiS rats. This study also shed light on why rats, humans, and some other mammals eat less and become more active as fertility increases. Wheel running increases when eating is reduced through restricted chow access, more so in LoS rats than in HiS rats (Dess et al., 2000). If the decrease in food intake from diestrus through estrus causes the increase in running (Eat Less → Run More hypothesis, ELRM), then the running peak should follow the eating nadir and be greater in LoS rats. Bayesian cyclic regression showed that estrous cycles were shorter in LoS rats than in HiS rats; implications are discussed. Contrary to ELRM, the running peak did not follow the eating nadir, and cycle amplitude did not distinguish LoS rats from HiS rats. These results indirectly support the No Time To Eat hypothesis (Fessler, 2003), according to which the periovulatory eating nadir and running peak reflect fitness-enhancing consequences of shifts away from eating and toward mating as fertility increases.

The Association Between Personality Traits and Dietary Choices: A Systematic Review

Increasing evidence shows how diet may play a role in improving health including mental health. Of note, personality may influence the type of diet and consequently the prognosis of medical and psychiatric conditions. The purpose of the present systematic review is to summarize the available data regarding the influence of personality on dietary habits affecting health outcomes. A search in the main databases was conducted matching the terms "personality," "personality traits" with "food choices," "food preferences," "diet," and "dietary habits." A total of 1856 articles were screened, and 24 articles were finally included. Exclusion criteria consisted of studies on animals or children, studies about eating disorders, types of diet not clearly associated with health outcomes, and studies for marketing reasons. Several studies showed that personality traits can influence both dietary choices and the type of diet, including the preference for healthy or unhealthy food. Unfavorable personality traits such as neuroticism and alexithymia (the inability to identify and describe emotions) were associated with unhealthy diet habits such as low consumption of fruit and vegetables, and the increased consumption of sugar and saturated fats. Personality seems to play a role in food selection and in the propensity to change diet. The interpretation of these results should be weighted by the different cultural contexts in which the studies were conducted and the extreme heterogeneity of tools used to assess personality and food preferences. Future research should clarify how personality can affect diet in specific populations such as patients with severe psychiatric disorders.

CAST auf Deutsch

Zusammenfassung. Sadismus ist ein Prädiktor für dysfunktionales Sozialverhalten und erfuhr als Konstrukt viel Aufmerksamkeit im klinischen Kontext. Zunehmend interessieren sich Forscher aber auch für die Rolle des subklinischen Alltagssadismus in anderen Kontexten, wie beispielswiese Mobbing oder disinhibierte Kommunikation in den Neuen Medien. Im Deutschen gab es bisher jedoch kein geeignetes Maß für Alltagssadismus. Um diese Lücke zu schließen, validieren wir eine deutsche Übersetzung des Comprehensive Assessment of Sadistic Tendencies (CAST, Buckels & Paulhus, 2014 ). Wir diskutieren verschiedene englischsprachige Alternativen und begründen unsere Wahl des CAST. Wir präsentieren die Ergebnisse einer webbasierten Validierungsstudie ( N = 419 ). Hierbei prüfen wir die Faktorstruktur der übersetzten Skala und vergleichen die Konstruktvalidität mit dem englischen Original mittels rAlerting-CV ( Westen & Rosenthal, 2003 ). Als Resultat stellen wir neben der originalgetreuen Version (CAST-D, 18 Items, Cronbachs α = .84) eine Kurzversion (CAST-D-K, 9 Items, Cronbachs α = .76) vor.

The Taste of Emotion: Metaphoric Association Between Taste Words and Emotion/Emotion-Laden Words

According to the Conceptual Metaphor Theory, abstract concepts can be metaphorically associated with more concrete, physically embodied concepts, such as gustatory experience. Studies on taste-emotion metaphoric association reported that people associate love with sweet, jealousy with sour and bitter, and sadness with bitter. However, few studies have systematically examined the metaphoric association between taste and words referred to emotion (e.g., "sad") or emotion-laden concepts (e.g., "funeral"). In the current four studies (total N = 357), we examined this metaphoric association by having participants come up with a taste word when reading an emotion and emotion-laden word (Study 1-explicit association of taste words-to-emotion/emotion-laden words), come up with an emotion word when reading taste words (Study 2-explicit association of emotion words-to-taste words), rate the association between taste words and basic or non-basic emotion words (Study 3), and rate the association between taste words and a more expanded pool of emotion/emotion-laden words (Study 4). Results showed that sweet was mostly associated with positive emotion and emotion-laden words, whereas bitter, followed by sour and spicy, was mostly associated with negative emotion and emotion-laden words. The bidirectionality of taste-emotion metaphoric association was supported by our dataset. The implications of these findings on the Conceptual Metaphor Theory and embodied cognition are discussed.

Sweet taste experience improves prosocial intentions and attractiveness ratings

Taste-related terms such as bitter or sweet are often used to describe people's behavior. For example, sweetness metaphors are often used when giving nicknames for romantic partners or when characterizing a friendly person. Previous studies have suggested that sweet taste may be linked to prosocial behavior. Examining a total of 517 participants, we here demonstrate that experiencing sweet taste also seems to have an impact on subsequent attractiveness ratings of faces. Participants were asked to rate pictures of young people and of art. Before this task, they were primed either with sweet candies or with salty snacks. Results revealed that sweet taste increased subsequent attractiveness ratings of faces. In addition, results confirmed earlier findings that sweet taste affected prosocial behavior. Our results suggest that sweetness seems to be more than a mere linguistic metaphor; it influences prosocial behavior as well as attractiveness ratings of faces. We discuss the results with recent findings of physical-to-psychological links to certain figures in speech.

According, against, and above dietary norms: a key to understanding the relationship between personality style and taste preferences

BACKGROUND

Understanding individual food preferences is critical for creating tailored strategies that promote healthy individual eating behaviors. Individual sensory liking appears to be an essential determinant of dietary intake. Taste preferences influence satisfaction and satiety, and may consequently influence weight status and psychological adjustment. The purpose of this study was to identify the association between taste preferences (sweet, salty, sweet & fatty, salty & fatty) and personality features.

METHODS

The Millon Clinical Multiaxial Inventory-III (MCMI-III) was used for the assessment of personality traits and PrefQuest (PQ) was used for measuring recalled food preferences. A total of 137 participants were included in the study. The relationship between compulsive and antisocial features and taste preferences was assessed by hierarchical multiple linear regression, while controlling for age, gender, BMI, marital status, and educational level.

RESULTS

The antisocial personality traits were a negative explanatory variable for sweet & fatty taste preference, R 2 = .15, t(132) =  - 2.40, p = .018, 95% [-.57, -.06] and salty & fatty taste preference, R 2 = .16, t(133) =  - 2.38, p = .019, 95% [-.07, -.01], while controlling for anthropological factors. In addition, men showed a higher preference than women for sweet & fatty food, such as chocolate or desserts, r sp  = .19, p = .021, and for the salty & fatty food, r sp  = .30, p < .001. BMI was not found to moderate the relationship between personality and taste preference. No significant association was found between compulsive personality traits and food preference, as assessed by sensory liking.

CONCLUSIONS

The findings can bring a much better understanding of the relationship between the compulsive or antisocial personality and taste preferences. In addition, it may help build psychotherapeutic and nutritional strategies that promote healthy eating behaviors, tailored to a particular personality style.

Parametric Characterization of a Taste Phenotype in Rats Selectively Bred for High Versus Low Saccharin Intake

Taste signals food quality and reflects energy status and associated processes. Occidental high- and low-saccharin consuming rats (HiS, LoS) have been selectively bred for nearly 60 generations on intake of 0.1% saccharin in a 23-h two-bottle test, as a tool for studying individual differences in taste and its correlates in the domains of feeding, defensive, and social behavior. The saccharin phenotype itself has not been well characterized until now. The present series of parametric studies examined suprathreshold saccharin concentration-intake functions (Experiment 1), saccharin preference threshold (Experiments 2A and 2B), and intra- and inter-sweetener carryforward effects (Experiments 2B, 3A–3D). Results indicate high stability in line differences in behavior toward saccharin and also line-specific mutability of intake of saccharin and certain other sweeteners. Methodological and conceptual implications are discussed.

Common, nonsexual masochistic preferences are positively associated with antisocial personality traits

Objective

Based on prior research linking masochism and antisocial behavior to sensation seeking, we hypothesized that masochistic and antisocial preferences are positively correlated. Besides sensation seeking, we tested whether disgust sensitivity (due to its inhibitory function) and shared social values (e.g., stimulation) accounted for the masochistic‐antisocial link. We additionally examined the link in relation to broad personality factors.

Method

Six online and laboratory studies (N = 2,999) with US‐American and European samples.

Results

We consistently found positive correlations between masochistic enjoyment (e.g., enjoying the burn of spicy food, disgusting jokes, pounding heart, painful massage) and antisocial traits such as subclinical psychopathy, everyday sadism, and low Honesty‐Humility. We observed behavioral correlations in that experienced pleasure of a painful event was positively related to causing another person to feel pain. Shared sensation seeking, low disgust sensitivity, and endorsement of social values such as social power, hedonism, and a stimulating life partially accounted for the masochistic‐antisocial link.

Conclusion

The extent to which a person enjoys threatening stimuli on the self is reliably related to how much a person enjoys and evokes others' suffering. Future research could explore the common core that underlies common masochistic and antisocial preferences beyond the mediators tested here.

Personality traits and preferences for specialty coffee: Results from a coffee shop field experiment

The market for specialty coffee is growing as consumer preferences for high quality coffee become more complex. Identifying the sources of heterogeneity in consumer preferences for specialty coffee is essential to optimizing producer marketing strategies to ensure they both fully capitalize on and satisfy consumer demand. One source of increasing interest is consumer personality profiles, specifically those categorized by the Big Six personality traits. We use the Midlife Development Inventory to investigate the effect of consumer personality traits on willingness to pay for coffee produced by farmer cooperatives. Results from a field experiment using a Becker-DeGroot-Marschak mechanism indicate that, on average, consumers are willing to pay a $1.31 premium for a cup of pour over coffee that was produced by a cooperative member farmer. Consumers exhibiting the extraversion and conscientiousness traits were, on average, willing to pay an even higher premium while those with higher levels of agency had a lower willingness to pay. Results further highlight that sociodemographic characteristics do not always drive consumer purchase decisions and, in the absence of significant sociodemographic influence, intrinsic consumer characteristics like personality traits can better explain preferences.

Consumers' Perceptions and Preferences for Bitterness in Vegetable Foods: The Case of Extra-Virgin Olive Oil and Brassicaceae-A Narrative Review

The presence of some healthy phytochemicals in food can be paired with high bitterness, and consumers have a widespread avoidance toward bitter-tasting food. This causes a gap between preferences and healthy needs of consumers. Therefore, this review collected insights from literature belonging to different discipline domains in order to have a broad view of the current state-of-the-art about biochemical aspects and consumers’ perceptions and preferences toward foods with an enhanced bitter taste. In detail, we focused on two core products of the Mediterranean diet: Extra-virgin olive oil (EVOO) and Brassicaceae, both characterized by specific phytochemicals having strong healthy properties and bitter-pungent taste. Results suggested that, although bitter taste is a general driver of dislike, some exceptions can be represented by: niches of consumers (e.g., innovators and organic buyers), foods consumed with specific purposes (e.g., coffee, chocolate, and alcoholic beverages). The level of bitterness perceived by the consumers can be modulated through exposure, information on benefits, and elements within the environment (e.g., music). Thus, these insights can be used to develop specific campaigns aimed at promoting bitter (healthy) food, considering also the key role that could be played by food pairings.

Dispositional Properties of Metaphor

Abstract. Metaphors often characterize prosocial actions and people as sweet. Three studies sought to explore whether conceptual metaphors of this type can provide insights into the prosocial trait of agreeableness and into daily life prosociality. Study 1 (n = 698) examined relationships between agreeableness and food taste preferences. Studies 2 (n = 66) and 3 (n = 132) utilized daily diary protocols. In Study 1, more agreeable people liked sweet foods to a greater extent. In Study 2, greater sweet food preferences predicted a stronger positive relationship between daily prosocial behaviors and positive affect, a pattern consistent with prosocial motivation. Finally, Study 3 found that daily prosocial feelings and behaviors varied positively with sweet food consumption in a manner that could not be ascribed to positive affect or self-control. Altogether, the findings encourage further efforts to extend conceptual metaphor theory to the domain of personality processes, in part by building on balance-related ideas.

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.

Sweetener Intake by Rats Selectively Bred for Differential Saccharin Intake: Sucralose, Stevia, and Acesulfame Potassium

Behavioral responses to sweeteners have been used to study the evolution, mechanisms, and functions of taste. Occidental low and high saccharin consuming rats (respectively, LoS and HiS) have been selectively outbred on the basis of saccharin intake and are a valuable tool for studying variation among individuals in sweetener intake and its correlates. Relative to HiS rats, LoS rats consume smaller amounts of all nutritive and nonnutritive sweeteners tested to date, except aspartame. The lines also differ in intake of the commercial product Splenda; the roles of sucralose and saccharides in the difference are unclear. The present study extends prior work by examining intake of custom mixtures of sucralose, maltodextrin, and sugars and Splenda by LoS and HiS rats (Experiment 1A-1D), stevia and a constituent compound (rebaudioside A; Experiment 2A-2E), and acesulfame potassium tested at several concentrations or with 4 other sweeteners at one concentration each (Experiment 3A-3B). Results indicate that aversive side tastes limit intake of Splenda, stevia, and acesulfame potassium, more so among LoS rats than among HiS rats. In addition, regression analyses involving 5 sweeteners support the idea that both sweetness and bitterness are needed to account for intake of nonnutritive sweeteners, more so among LoS rats. These findings contribute to well developed and emerging literatures on sweetness and domain-general processes related to gustation.

Is the Association Between Sweet and Bitter Perception due to Genetic Variation?

Perceived intensities of sweetness and bitterness are correlated with one another and each is influenced by genetics. The extent to which these correlations share common genetic variation, however, remains unclear. In a mainly adolescent sample ( n = 1901, mean age 16.2 years), including 243 monozygotic (MZ) and 452 dizygotic (DZ) twin pairs, we estimated the covariance among the perceived intensities of 4 bitter compounds (6- n -propylthiouracil [PROP], sucrose octa-acetate, quinine, caffeine) and 4 sweeteners (the weighted mean ratings of glucose, fructose, neohesperidine dihydrochalcone, aspartame) with multivariate genetic modeling. The sweetness factor was moderately correlated with sucrose octa-acetate, quinine, and caffeine ( rp = 0.35-0.40). This was mainly due to a shared genetic factor ( rg = 0.46-0.51) that accounted for 17-37% of the variance in the 3 bitter compounds' ratings and 8% of the variance in general sweetness ratings. In contrast, an association between sweetness and PROP only became evident after adjusting for the TAS2R38 diplotype ( rp increased from 0.18 to 0.32) with the PROP genetic factor accounting for 6% of variance in sweetness. These genetic associations were not inflated by scale use bias, as the cross-trait correlations for both MZ and DZ twins were weak. There was also little evidence for mediation by cognition or behavioral factors. This suggests an overlap of genetic variance between perceptions of sweetness and bitterness from a variety of stimuli, which includes PROP when considering the TAS2R38 diplotype. The most likely sources of shared variation are within genes encoding post-receptor transduction mechanisms common to the various taste G protein-coupled receptors.