How pathogen cues shape impressions of foods: the omnivore's dilemma and functionally specialized conditioning

Personality, self-knowledge, and meat reduction intentions

OBJECTIVE

Meat consumption has a host of serious negative consequences for nonhuman animals, underprivileged humans, and the natural environment. Several interventions have been developed to encourage meat reduction but to relatively limited effect. There is also a range of established predictors of meat consumption, but much less is known about the factors that predict intentions to reduce meat consumption. The goal of this study was to determine the roles of personality and self-knowledge in meat reduction intentions.

METHOD

In this set of three preregistered studies, we tested brief interventions to encourage meat reduction intentions and examined personality predictors of intentions to reduce meat consumption.

RESULTS

We found no evidence that brief interventions with or without a self-knowledge component had a meaningful effect on changing meat reduction intentions. However, we found robust evidence for relatively small associations between intending to eat less meat and high Openness to Experience, high Emotionality, and perceiving meat reduction as moral behaviors.

CONCLUSION

Individual differences may be a more influential predictor of meat reduction intentions than brief interventions. Implications for promoting meat reduction are discussed.

Four studies yield limited evidence for prepared (disgust) learning via evaluative conditioning

Prepared learning accounts suggest that specialized learning mechanisms increase the retention of associations linked to ancestrally-prevalent threats. Few studies have investigated specialized aversion learning for pathogen threats. In four pre-registered studies (N's = 515, 495, 164, 175), we employed an evaluative conditioning procedure to test whether foods (versus non-foods) are more readily associated with negative content associated with pathogens than negative content not associated with pathogens. Participants saw negatively valenced (either pathogen-relevant or -irrelevant), neutral or positively-valenced stimuli paired with meats and plants (in Studies 1 and 2) and with meats and abstract shapes (in Studies 3 and 4). They then evaluated each stimulus explicitly via self-reports (Studies 1-4) and implicitly via an Affect Misattribution Procedure (Studies 3 and 4). Linear mixed models revealed general evaluative conditioning effects, but inconsistent evidence for specialized (implicit or explicit) learning for a food-pathogen association. However, results from a mega-analysis across studies revealed stronger conditioning effects for meats paired with pathogen-relevant negative stimuli than pathogen-irrelevant negative stimuli.

WITHDRAWN: Four studies Yield limited evidence for prepared (disgust) learning via evaluative conditioning

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The relationship between meat disgust and meat avoidance-A chicken-and-egg problem

Feelings of disgust toward meat have been researched for at least 30 years, but so far the causal relationship that may link meat disgust and meat consumption has remained elusive. Two possible pathways have been proposed in previous literature: the more common pathway seems to be that meat disgust is developed after a transition to vegetarianism, potentially via the process of moralization and recruitment of (moral) disgust. Other accounts suggest the existence of a second pathway in which disgust initiates the avoidance of meat and this can be explained by existing theories of disgust functioning as a pathogen avoidance mechanism and meat serving as a pathogen cue. However, the evidence base for either relationship remains thin and to our knowledge no research has examined whether temporary meat abstention can lead to increases in meat disgust, as the first pathway suggests. We measured meat disgust and meat intake in n = 40 meat eaters before and after attempting a meat-free diet for 1 month (while taking part in the annual vegan campaign Veganuary). Although most participants lapsed to eating meat during this period, we found that reductions in meat intake during the month were predictive of increases in meat disgust afterwards. This supports the view that meat disgust is expressed as a result of meat avoidance in meat eaters. Implications for theoretical understanding of the relationship between meat disgust and meat avoidance, as well as the development of disgust based interventions are discussed.

Implicit and explicit safety evaluation of foods: The importance of food processing

Identifying beneficial foods in the environment, while avoiding ingesting something toxic, is a crucial task humans face on a daily basis. Here we directly examined adults' implicit and explicit safety evaluations of the same foods presented with different degrees of processing, ranging from unprocessed (raw) to processed (cut or cooked). Moreover, we investigated whether individual characteristics (e.g., Body Mass Index, food neophobia and hunger) modulated their evaluations. We hypothesized that adults would associate the processed form of a food with safety more than its unprocessed form since processing techniques, which are ubiquitously applied in different cultures, often reduce the toxicity of foods, and signal previous human intervention and intended consumption. Adults (N = 109, 43 females) performed an implicit Go/No-Go association task (GNAT) online, assessing the association between safety attributes and food images differing on their degree of processing, both unfamiliar and familiar foods were used. Then each food was explicitly evaluated. Results revealed that individual self-reported characteristics affected both implicit and explicit evaluations. Individuals with excess weight and obesity had a strong and positive implicit association between processed foods and safety attributes, but explicitly rated cooked foods as the least safe overall, this latter result was found in highly neophobic individuals as well. Yet, at the explicit level, when looking at unfamiliar foods only, processed foods were rated safer than unprocessed foods by all participants. Our results are the first evidence that directly highlights the relevance of the degree of processing in food safety evaluation and suggest that thinking of the important tasks humans face regarding food selection enriches our understanding of food behaviors.

Meating Conflict: Toward a Model of Ambivalence-Motivated Reduction of Meat Consumption

An increasing number of people are concerned about eating meat, despite enjoying doing so. In the present research, we examined whether the desire to resolve this ambivalence about eating meat leads to a reduction in meat consumption. Our model of ambivalence-motivated meat reduction proposes that the pervasive nature of evaluative conflict motivates meat avoidance, and we highlight two potential mechanisms involved: the anticipation of ambivalence reduction through behavioral change, and information seeking for contents that facilitate meat reduction. Study 1 drew on a cross-sectional 6-day food diary with 7485 observations in a quota sample to investigate why meat-related ambivalence arises and to demonstrate the correlation of ambivalence with meat reduction. Two experiments investigated the causal direction of this association by showing that ambivalence-induced discomfort motivated participants to eat less meat when they introspected on their preexisting incongruent evaluations (Study 2 and 3), which was mediated by the aforementioned mechanisms involved (Study 3; preregistered). The studies utilized diverse samples from Germany, England, and the US (total N = 1192) and support the proposed model by indicating that behavioral change is an important coping strategy to resolve ambivalent discomfort in the context of meat consumption. Our model of ambivalence-motivated meat reduction contributes to theorizing on the consequences of ambivalence and the psychology of (not) eating meat.

Towards reduced meat consumption: A systematic literature review of intervention effectiveness, 2001-2019

A reduction of meat consumption and shift to plant-based diets, especially in industrialized countries, is acknowledged as crucial for reaching climate targets, addressing public health problems, and protecting animal welfare. While scholarly research distilled drivers of meat consumption and barriers to its reduction, insights into the effectiveness of measures to initiate such a profound change in consumer behaviour are relatively scarce. This paper presents a systematic literature review on consumption-side interventions in the context of meat consumption across scholarly disciplines. Our analysis confirms that existing research predominantly assessed interventions addressing personal factors of behavioural change such as knowledge and emotions. Whether these interventions are effective depends on whether information (i) is provided on health, animal welfare or environmental effects, (ii) is emotionally or cognitively framed, and (iii) is aligned with consumers' information needs. Moreover, linking meat to living animals or to the humanness of animals activates negative emotions and, thus, reduces meat consumption. Further, increasing the visibility and variety of vegetarian dishes in food environments decreases meat-eating. Also, educational courses on how to shop and cook vegetarian food are effective in reducing meat consumption. There is less evidence on the effectiveness of interventions addressing socio-cultural factors such as social norms. Regarding future research directions, existing research mainly investigated the influence of interventions on attitudes and behavioural intentions. Hence, there is still a need for studies to assess more long-term effects of intervention measures on actual meat consumption and their potential to initiate fundamental changes in dietary habits.

Meat disgust is negatively associated with meat intake - Evidence from a cross-sectional and longitudinal study

Meat consumption is increasingly seen as unsustainable, unhealthy, and unethical. Understanding what factors help people reduce their meat intake is urgently needed. One such factor is meat disgust, a feeling reported by many vegetarians, and which could be a promising basis for meat reduction interventions. However, meat disgust and its impact on meat consumption is poorly understood. We examined meat disgust and its role in vegetarianism and reducing meat intake in a cross-sectional and longitudinal online study. We measured self-reported meat consumption, meat disgust (by self-report and Implicit Association Test), meat liking, self-control, and disgust sensitivity in N = 711 adults (57% omnivores, 28% flexitarians, 15% vegetarians) recruited from a community cohort. Results showed that 73% of vegetarians can be classified as 'meat disgusted', and that meat disgust predicted meat intake better than self-control in omnivores and flexitarians at baseline. Following up a sub-sample of participants (N = 197) after six months revealed that changes in meat intake over time were also associated with changes in meat disgust. This is the first study to quantify the impact of meat disgust on (changes in) meat consumption and its prevalence in the vegetarian and the general population. Our findings advance research into meat disgust and encourage the development of disgust-based interventions to reduce meat intake.

The multidimensional nature of food neophobia

People vary in their willingness to try new foods. This variation, which is most frequently measured using the Food Neophobia Scale (FNS; Pliner & Hobden, 1992), has been interpreted as unidimensional. In four studies (N's = 210, 306, 160, and 161), we 1) demonstrate that food neophobia varies across meat and plant dimensions, 2) explore the validity of a measure of meat and plant neophobia, and 3) test whether these food neophobia dimensions predict decisions to eat a novel food item (i.e., a snack bar that contains insects). Mixed-effects model across the four studies indicated that the two dimensions differentially relate to a number of variables, including disgust sensitivity, animal empathy, and masculinity. Women scored higher on meat neophobia than men, but the sexes did not differ on plant neophobia. Only meat neophobia uniquely predicted eating a novel insect-based snack bar. Overall, these results extend knowledge regarding orientations toward novel foods.

Why do people vary in disgust?

People vary in the degree to which they experience disgust toward—and, consequently, avoid—cues to pathogens. Prodigious work has measured this variation and observed that it relates to, among other things, personality, psychopathological tendencies, and moral and political sentiments. Less work has sought to generate hypotheses aimed at explaining why this variation exists in the first place, and even less work has evaluated how well data support these hypotheses. In this paper, we present and review the evidence supporting three such proposals. First, researchers have suggested that variability reflects a general tendency to experience anxiety or emotional distress. Second, researchers have suggested that variability arises from parental modelling, with offspring calibrating their pathogen avoidance based on their parents' reactions to pathogen cues. Third, researchers have suggested that individuals calibrate their disgust sensitivity to the parasite stress of the ecology in which they develop. We conclude that none of these hypotheses is supported by existing data, and we propose directions for future research aimed at better understanding this variation.

This article is part of the Theo Murphy meeting issue ‘Evolution of pathogen and parasite avoidance behaviours’.

PsychoBehavioroimmunology: Connecting the Behavioral Immune System to Its Physiological Foundations

Although infectious disease has posed a significant and persistent threat to human survival and welfare throughout history, only recently have the psychological and behavioral implications of disease threat become a topic of research within the behavioral sciences. This growing body of work has revealed a suite of affective and cognitive processes that motivate the avoidance of disease-causing objects and situations—a cascade of processes loosely conceptualized as a “behavioral immune system (BIS).” Recent BIS research has linked disease threat to a surprisingly broad set of psychological and behavioral phenomena. However, research examining how the BIS is nested within our broader physiology is only beginning to emerge. Here, we review research that has begun to elucidate the physiological foundations of the BIS—at the levels of sensory modalities, cells, and genes. We also discuss the future of this work.

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.