Contamination sensitivity and the development of disease-avoidant behaviour

Disgust Processing and Potential Relationships with Behaviors in Autism

PURPOSE OF REVIEW

While there are reports of differences in emotion processing in autism, it is less understood whether the emotion of disgust, in particular, plays a significant role in these effects. Here, we review literature on potential disgust processing differences in autism and its possible associations with autistic traits.

RECENT FINDINGS

In autism, there is evidence for differences in physical disgust processing, pica behaviors, attention away from other's disgust facial expressions, and differences in neural activity related to disgust processing. In typically developing individuals, disgust processing is related to moral processing, but modulated by individual differences in interoception and alexithymia. Autistic individuals may experience atypical disgust, which may lead to difficulty avoiding contaminants and affect socio-emotional processing. In autism, such outcomes may lead to increased occurrences of illness, contribute to gastrointestinal issues, diminish vicarious learning of disgust expression and behaviors, and potentially contribute to differences in processes related to moral reasoning, though further research is needed.

Evaluating nursing opinion and perception of maggot therapy for hard-to-heal wound management

OBJECTIVE

Maggot therapy (MT) or larval debridement therapy is a recognised, effective but underutilised treatment for the management of hard-to-heal wounds and infected ulcers. It is available on NHS prescription in the UK, where wound management is predominantly nurse-led. Anecdotal reports and published literature suggest that nurses may be reluctant to utilise the therapy. The aim of this study was to evaluate the feelings and opinions of nurses regarding the use of MT.

METHOD

The first stage of this mixed-methods study was a focus group held to discuss MT and opinions of specialist nurse clinicians. Next, an anonymised web-based online survey was launched through the Nursing Times journal and distributed through social media targeting all nurses. Finally, in-depth interviews were held with specialist and generalist nurses.

RESULTS

Awareness of MT among all nurses was extremely high. A breakdown of results showed that MT was much more highly regarded by wound specialist nurses than non-wound specialist nurses. The latter exhibited a greater level of reluctance to administer the therapy, with almost one-third of these nurses surveyed saying they found maggots disgusting and that the idea of MT made their skin crawl. In-depth interviews revealed that a lack of knowledge about MT was a prime concern.

CONCLUSION

Wound specialist nurses are more likely to embrace MT than non-wound nurse specialists, who report a varying degree of wariness to MT. Our study highlights a need for better education and training in MT for all nurses, to address issues with acceptance and willingness to treat or help treat patients with hard-to-heal wounds which are suitable for MT.

What Children and Adolescents Know and Need to Learn about Cancer

Despite cancer's devastating effects on health and longevity, and the critical role of health habits formed during childhood and adolescence in its prevention, children's knowledge of contributors to cancer is understudied. In this paper, the first developmental analysis of the literature, we outline relevant theoretical perspectives and three early emerging intuitions about illness evident among preschool children-contagion/germ, contamination, and unhealthy lifestyle theories-and then review research on elementary and secondary school students' awareness of risk factors for cancer in light of these early intuitive theories. Our analysis centers on the 16 studies we could locate, done in seven countries, that allowed calculating the percentages of children of different age groups who mentioned various risk factors in response to open-ended questions or endorsed them in response to structured questions. Awareness of primary known risk factors (led by smoking), lifestyle contributors, and personal factors (genetics and old age) increased with age, while contact myths decreased with age until adolescents began to show awareness of sexual contact as a contributor to certain cancers. In addition, the analysis revealed higher levels of awareness in response to structured questions than in response to open-ended questions; a glaring need for research asking young school-aged children about key risk factors and exploring not only their knowledge but their causal understanding; a need for attention to sociocultural influences; and connections between preschool children's intuitive theories of disease and older children's patterns of belief about cancer that can help guide school-based cancer education.

The essence of crime: Contagious transmission from those who have committed moral transgressions

Across four studies, we investigated the relationship between moral contagion and disgust. Study 1 established that the contamination effect is unique to transgressions that fall within the moral domain. Study 2 replicated this effect and further showed that the underlying mechanism is intimately related to disgust, as disgust was found to uniquely mediate the relationship between moral transgressions and contamination responses. In Study 3, disgust was again found to mediate this relationship. In addition, the results of Study 3 show that the moral contagion effect was not dependent upon the presence of a core disgust cue within the transgression. In Study 4, we investigated whether or not moral contagion leads to behavioural avoidance. Results show that behavioural avoidance only occurred when the moral transgression contained a core disgust cue. Taken together, the results of our studies show that disgust plays a key role in moral contagion processes. However, the difference in findings between the thought experiments (Studies 1-3) and the behavioural experiment (Study 4) identifies a need for further research to examine the conditions under which moral contagion leads to behavioural avoidance.

Trust and doubt: An examination of children's decision to believe what they are told about food

The domain of food is one that is highly relevant and vital to the everyday lives of children. However, children's reasoning about this domain is poorly understood within the field of developmental psychology. Because children's learning about food, including its evaluative components (e.g., health, taste) is so heavily dependent on information conveyed by other people, a major developmental challenge that children face is determining who to distrust regarding food. In three studies, this investigation examined how 3- and 4-year-olds and adults (N=312) use different cues to determine when to ignore informant information (i.e., distrust what an informant tells them by choosing an alternative) in food- and non-food-specific scenarios. The results of Study 1 indicated that by age 4 years, children are less trusting of inaccurate sources of information compared with sources that have not demonstrated previous inaccuracy. Study 2 revealed that these results are applicable across the domain of objects. The results of Study 3 indicated that by age 4, children trust benevolent sources more often than malevolent ones. Thus, when reasoning about the evaluative components of food, by age 4, children appraise other people's untrustworthiness by paying attention to their inaccuracy and malevolence.

Behavioral avoidance of contagion in childhood

Although there is a large literature on children's reasoning about contagion, there has been no empirical research on children's avoidance of contagious individuals. This study is the first to investigate whether children avoid sick individuals. Participants (4- to 7-year-old children) were invited to play with two confederates-one of whom was "sick." Afterward, their knowledge of contagion was assessed. Overall, children avoided proximity to and contact with the sick confederate and her toys, but only 6- and 7-year-olds performed above chance. The best predictor of avoidance behavior was not age but rather children's ability to make predictions about illness outcomes. This provides the first evidence of behavioral avoidance of contagious illness in childhood and suggests that causal knowledge underlies avoidance behavior.

Contamination Appraisals, Pollution Beliefs, and the Role of Cultural Inheritance in Shaping Disease Avoidance Behavior

Despite the upsurge of research on disgust, the implications of this research for the investigation of cultural pollution beliefs has yet to be adequately explored. In particular, the sensitivity of both disgust and pollution to a common set of elicitors (e.g., bodily emissions, disease, and death) suggests a common psychological basis, though several obstacles have prevented an integrative account, including methodological differences between the relevant disciplines. Employing a conciliatory framework that embraces both naturalistic (evolutionary) and humanistic levels of explanation, this article examines the dynamic reciprocal process by which contamination/contagion appraisals in individuals serve to shape-and are in turn shaped by-culture-specific pollution beliefs. This complex interrelationship is illustrated by examining ancient Near Eastern and modern ethnographic documentation of pollution beliefs, highlighting the underappreciated function of these pollution beliefs as folk theories for the spread of infectious disease. By evaluating how pollution beliefs (as also modern germ theory) shape contamination appraisals in individuals, it will be argued that cultural inheritance has played a much larger role in guiding disease avoidance behavior than has been previously recognized.

Parasites and human evolution

Our understanding of human evolutionary and population history can be advanced by ecological and evolutionary studies of our parasites. Many parasites flourish only in the presence of very specific human behaviors and in specific habitats, are wholly dependent on us, and have evolved with us for thousands or millions of years. Therefore, by asking when and how we first acquired those parasites, under which environmental and cultural conditions we are the most susceptible, and how the parasites have evolved and adapted to us and we in response to them, we can gain considerable insight into our own evolutionary history. As examples, the tapeworm life cycle is dependent on our consumption of meat, the divergence of body and head lice may have been subsequent to the development of clothing, and malaria hyperendemicity may be associated with agriculture. Thus, the evolutionary and population histories of these parasites are likely intertwined with critical aspects of human biology and culture. Here I review the mechanics of these and multiple other parasite proxies for human evolutionary history and discuss how they currently complement our fossil, archeological, molecular, linguistic, historical, and ethnographic records. I also highlight potential future applications of this promising model for the field of evolutionary anthropology.

Evolution, development, and the emergence of disgust

Evolutionary developmental psychology typically utilizes an evolutionary lens to explain various phenomena that occur throughout development. In this paper, I argue that the converse is also important: Developmental evidence can inform evolutionary theory. In particular, knowledge about the developmental origins of a psychological trait can be used to evaluate theoretical claims about its evolved function. I use the emotion of disgust as a case study to illustrate this approach. Disgust is commonly thought to be a behavioral adaptation for avoiding the ingestion of pathogens. Given this claim, disgust should be expected to develop at a time when humans are especially vulnerable to the dangers of ingesting pathogens, during the immediate post-weaning period from about 3 to 5 years of age. Despite a strong selective pressure at this point in development, research has suggested that the emotion of disgust and the recognition of the "disgust face" do not reliably emerge until later in ontogeny, at 5 years of age or after. Given the late developmental appearance of disgust, I re-evaluate claims about its adaptive role.

Evolution, development, and the emergence of disgust

Evolutionary developmental psychology typically utilizes an evolutionary lens to explain various phenomena that occur throughout development. In this paper, I argue that the converse is also important: Developmental evidence can inform evolutionary theory. In particular, knowledge about the developmental origins of a psychological trait can be used to evaluate theoretical claims about its evolved function. I use the emotion of disgust as a case study to illustrate this approach. Disgust is commonly thought to be a behavioral adaptation for avoiding the ingestion of pathogens. Given this claim, disgust should be expected to develop at a time when humans are especially vulnerable to the dangers of ingesting pathogens, during the immediate post-weaning period from about 3 to 5 years of age. Despite a strong selective pressure at this point in development, research has suggested that the emotion of disgust and the recognition of the "disgust face" do not reliably emerge until later in ontogeny, at 5 years of age or after. Given the late developmental appearance of disgust, I re-evaluate claims about its adaptive role.

Physiological consequences of the salmon louse (Lepeophtheirus salmonis) on juvenile pink salmon (Oncorhynchus gorbuscha): implications for wild salmon ecology and management, and for salmon aquaculture

Pink salmon, Oncorhynchus gorbuscha, are the most abundant wild salmon species and are thought of as an indicator of ecosystem health. The salmon louse, Lepeophtheirus salmonis, is endemic to pink salmon habitat but these ectoparasites have been implicated in reducing local pink salmon populations in the Broughton Archipelago, British Columbia. This allegation arose largely because juvenile pink salmon migrate past commercial open net salmon farms, which are known to incubate the salmon louse. Juvenile pink salmon are thought to be especially sensitive to this ectoparasite because they enter the sea at such a small size (approx. 0.2 g). Here, we describe how 'no effect' thresholds for salmon louse sublethal impacts on juvenile pink salmon were determined using physiological principles. These data were accepted by environmental managers and are being used to minimize the impact of salmon aquaculture on wild pink salmon populations.

The social life of 'eugh': disgust as assessment in family mealtimes

Disgust is a complex phenomenon that pervades a number of social situations. To date, disgust has primarily been understood as an individually experienced emotion or as a way of defining boundaries between people or objects; the detailed social practices through which disgust is choreographed, however, have yet to be fully explored. The social implications of disgust are particularly apparent when food and eating are involved, as it is in such settings that individuals, objects, and social boundaries coincide. In this paper, I argue that the enactment of disgust is an inherently social event, and that we can evidence it as such through the way in which it is produced and oriented to in everyday interaction. The setting for this paper is family mealtimes, as a situation in which children and parents explore the boundaries of what is, and what is not, disgusting. A large corpus of video and audio recordings of mealtimes in England and Scotland were analysed using a discursive psychological approach, with a focus on explicating the sequential and prosodic features of disgust markers (DMs), such as 'eugh' and 'yuck'. The analysis demonstrates that DMs are typically preceded by a 'noticing' by speakers and that 'eugh' is usually uttered alone and at the start of a turn in talk. It is argued that, regardless of their putative status as emotions or cultural concepts, DMs work as assessments of food and eating practices in everyday interaction. They orient others to a trouble source and attend to people's entitlements to 'know' disgust. The implications for our understanding of disgust as a social psychological concept are further explored.

Proactive strategies to avoid infectious disease

Infectious disease exerts a large selective pressure on all organisms. One response to this has been for animals to evolve energetically costly immune systems to counter infection, while another--the focus of this theme issue--has been the evolution of proactive strategies primarily to avoid infection. These strategies can be grouped into three types, all of which demonstrate varying levels of interaction with the immune system. The first concerns maternal strategies that function to promote the immunocompetence of their offspring. The second type of strategy influences mate selection, guiding the selection of a healthy mate and one who differs maximally from the self in their complement of antigen-coding genes. The third strategy involves two classes of behaviour. One relates to the capacity of the organisms to learn associations between cues indicative of pathogen threat and immune responses. The other relates to prevention and even treatment of infection through behaviours such as avoidance, grooming, quarantine, medicine and care of the sick. In humans, disease avoidance is based upon cognition and especially the emotion of disgust. Human disease avoidance is not without its costs. There is a propensity to reject healthy individuals who just appear sick--stigmatization--and the system may malfunction, resulting in various forms of psychopathology. Pathogen threat also appears to have been a highly significant and unrecognized force in shaping human culture so as to minimize infection threats. This cultural shaping process--moralization--can be co-opted to promote human health.