Behavioral avoidance of contagion in childhood

The social aspects of illness: Children's and parents' explanations of the relation between social categories and illness in a predominantly white U.S. sample

The COVID-19 pandemic in the United States has had a disproportionate impact on Black, low-income, and elderly individuals. We recruited 175 predominantly white children ages 5-12 and their parents (N = 112) and asked which of two individuals (differing in age, gender, race, social class, or personality) was more likely to get sick with either COVID-19 or the common cold and why. Children and parents reported that older adults were more likely to get sick than younger adults, but reported few differences based on gender, race, social class, or personality. Children predominantly used behavioral explanations, but older children used more biological and structural explanations. Thus, children have some understanding of health disparities, and their understanding increases with age.

Age-related disgust responses to signs of disease

Previous studies found similarities in adults' disgust responses to benign (e.g. obesity) and actual disease signs (e.g. influenza). However, limited research has compared visual (i.e. benign and actual) to cognitive (i.e. disease label) disease cues in different age groups. The current study investigated disgust responses across middle childhood (7-9 years), late childhood (10-12 years), adolescence (13-17 years), and adulthood (18+ years). Participants viewed individuals representing a benign visual disease (obese), sick-looking (staphylococcus), sick-label (cold/flu), and healthy condition. Disgust-related outcomes were: (1) avoidance, or contact level with apparel the individual was said to have worn, (2) disgust facial reactions, and (3) a combination of (1) and (2). Avoidance was greater for the sick-looking and sick-label than the healthy and obese conditions. For facial reaction and combination outcomes, middle childhood participants responded with greater disgust to the sick-looking than the healthy condition, while late childhood participants expressed stronger disgust towards the sick-looking and obese conditions than the healthy condition. Adolescents and adults exhibited stronger disgust towards sick-label and sick-looking than obese and healthy conditions. Results suggest visual cues are central to children's disgust responses whereas adolescents and adult responses considered cognitive cues.

Infection detection in faces: Children's development of pathogen avoidance

This study examined the development of children's avoidance and recognition of sickness using face photos from people with natural, acute, contagious illness. In a U.S. sample of fifty-seven 4- to 5-year-olds (46% male, 70% White), fifty-two 8- to 9-year-olds (26% male, 62% White), and 51 adults (59% male, 61% White), children and adults avoided and recognized sick faces (ds ranged from 0.38 to 2.26). Both avoidance and recognition improved with age. Interestingly, 4- to 5-year-olds' avoidance of sick faces positively correlated with their recognition, suggesting stable individual differences in these emerging skills. Together, these findings are consistent with a hypothesized immature but functioning and flexible behavioral immune system emerging early in development. Characterizing children's sickness perception may help design interventions to improve health.

"It kinda has like a mind": Children's and parents' beliefs concerning viral disease transmission for COVID-19 and the common cold

How people reason about disease transmission is central to their commonsense theories, scientific literacy, and adherence to public health guidelines. This study provided an in-depth assessment of U.S. children's (ages 5-12, N = 180) and their parents' (N = 125) understanding of viral transmission of COVID-19 and the common cold, during the first year of the COVID-19 pandemic. The primary aim was to discover children's causal models of viral transmission, by asking them to predict and explain counter-intuitive outcomes (e.g., asymptomatic disease, symptom delay) and processes that cannot be directly observed (e.g., viral replication, how vaccines work). A secondary aim was to explore parental factors that might contribute to children's understanding. Although even the youngest children understood germs as disease-causing and were highly knowledgeable about certain behaviors that transmit or block viral disease (e.g., sneezing, mask-wearing), they generally failed to appreciate the processes that play out over time within the body. Overall, children appeared to rely on two competing mental models of viruses: one in which viruses operate strictly via mechanical processes (movement through space), and one in which viruses are small living creatures, able to grow in size and to move by themselves. These results suggest that distinct causal frameworks co-exist in children's understanding. A challenge for the future is how to teach children about illness as a biological process without also fostering inappropriate animism or anthropomorphism of viruses.

How Children Develop Healthy Behavioral Choices to Promote Illness Prevention

Children’s understanding of contagion has been a fruitful area for studying children’s learning. However, despite a large literature on children’s conceptual understanding of illness, there is very little research on the impact of children’s knowledge about illness transmission on adaptive behavior. This is important because how children behave when faced with a sick individual or a contaminated object is what is most relevant to whether children get sick and pass along that illness to other people. Here, we will bring together various theories of how children learn to behave adaptively when faced with the possibility of getting sick (a) to better illuminate the different ways by which children might acquire health-related behaviors and (b) to help develop recommendations for designing interventions aimed at teaching children about contagion and illness prevention in a way that produces the most adaptive health behaviors.

Food as a key disgust elicitor in infancy and childhood: Previous research and opportunities for future study

Disliked foods may have important value in the study of the development of disgust. The current review draws from literature across disciplines, including theories of disgust and studies of the development of eating behavior and food preferences, to highlight food as an important category of disgust responses across a wide age range, including children as young as 3 years old and adults. Children's disgust responses to certain types of food are considered to be both innate and culturally constrained behaviors, and their perceptions of other people's food choices indicate potential links between foods and cultural groups. We end by discussing several ongoing and future research areas, including connections between disgust responses and food rejection in infancy and children's food rejection behaviors across cultures.

Parent–child interaction during a home STEM activity and children’s handwashing behaviors

We examined correlations between a home-based STEM activity illustrating the importance of soap use during handwashing and children’s (4-to 7-year-olds, N = 81, 42 girls, 39 boys) use of soap when washing their hands. Parents and children either participated in or watched the activity. Children reflected on the activity immediately afterward and a week later. Parent–child interaction during participation related to the frequency of unprompted soap use during handwashing, controlling for performance on other, related cognitive measures. Children whose parents were more goal-directed, and set goals for the interaction, were less likely to use soap spontaneously when handwashing in the subsequent week. The amount of causal knowledge children generated when they reflected on the experience immediately afterward also influenced whether children used soap when washing their hands. Reducing the autonomy children believe they have during a STEM-based activity potentially leads them to not engage in a behavior related to the activity on their own. Overall, these data suggest that parent–child interaction during STEM activities can influence the ways children encode and engage with those activities in their everyday lives. Given that the ways children wash their hands might mitigate the spread of disease, interventions that focus on providing children with the belief that STEM activities are for them might be broadly beneficial to society.

Does disgust-eliciting propaganda shape children's attitudes toward novel immigrant groups?

Propaganda frequently leverages themes of dirtiness and disease to foster negative attitudes toward marginalized social groups. Although history suggests that this tactic is highly successful, empirical evidence is required to evaluate propaganda's potential efficacy. Inspired by previous evidence that children rapidly form attitudes about social groups, we conducted an exploratory investigation into whether 5- to 9-year-olds' (N = 48) judgments of novel foreign groups could be swayed by visually depicting one of these groups as disgusting in poster-sized illustrations. Across a wide battery of tasks, there was no clear indication that children readily internalize messages from propaganda in evaluating members of novel social groups. This finding held regardless of the type of disgustingness that was depicted in the propaganda, and generalized across the age range we investigated. Overall, our results are encouraging in a practical sense, suggesting that children are not easily swayed by negative misrepresentations of immigrants in propaganda.

Effects of sickness manipulation on disgust and pleasantness in interpersonal touch

The theory of the behavioral immune system (BIS) describes a set of behaviors that protect the individual from infectious diseases and that are motivated by disgust and the perceived vulnerability to disease. As interpersonal touch is one of the most common situations of potential transmission of infectious diseases in our everyday life, it seems likely that being touched by an apparently sick individual activates disgust. Our aim was to determine if risk of contamination from interpersonal touch alters the pleasantness of interpersonal touch and modulates facially expressed emotions. In total, 64 participants received interpersonal stroking by either a healthy or by sick-appearing experimenter. Half the strokes were performed at a slow velocity of 3 cm/s and half at a faster velocity of 30 cm/s, to modulate the degree of C-tactile fiber activation in the touch perceiver. While the experimental sickness manipulation did not influence the reported touch pleasantness, there was a tendency for a diminished expression of happiness in the slow stroking condition. In addition, the desire to clean the arm after stroking correlated positively to disgust sensitivity and to germ aversion, which is a subscale of the perceived vulnerability to disease. Contrary to previous studies, participants did not prefer the slow over the fast stroking velocity, irrespective of sickness induction. Our results lead us to assume that disgust in interpersonal touch depends especially on the touch receiver and we speculate that a rather conservative reactivity of the BIS allows for an adaptive behavioral balance in interpersonal relations. This balance may be needed to weight the risks of contamination against the benefits of interpersonal touch for social interaction.

Examining children's questions and parents' responses about COVID-19 pandemic in Turkey

COVID-19 pandemic has had a significant impact on both adults' and children's everyday lives. Conversations about biological processes such as viruses, illness, and health have started to occur more frequently in daily interactions. Although there are many guidelines for parents about how to talk to their children about the coronavirus, only a few studies have examined what children are curious about the coronavirus and how they make sense of the changes in their everyday lives. This study addresses this need by examining children's questions and parents' responses about the COVID-19 Pandemic in the Turkish sociocultural context. Using an online survey, we asked 184 parents of 3- to 12-year-olds to report their children's questions about coronavirus and their answers to these questions. We analyzed children's questions and parents' responses using qualitative and quantitative analyses (Menendez et al., 2021). Children's questions were mainly about the nature of the virus (34%), followed by lifestyle changes (20%). Older children were more likely to ask about school/work and less likely to ask about lifestyle changes than younger children. Parents responded to children's questions by providing realistic explanations (48%) and reassurance (20%). Only 18% of children's questions were explanation-seeking "why" and "how" questions. Parents were more likely to provide explanations if children's questions were explanation-seeking. Family activities such as playing games and cooking were the most common coping strategies reported by parents (69.2%). The findings have important implications for children's learning about the coronavirus and how adults can support children's learning and help them develop coping strategies in different sociocultural contexts.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12144-022-03331-4.

Scientific and Folk Theories of Viral Transmission: A Comparison of COVID-19 and the Common Cold

Disease transmission is a fruitful domain in which to examine how scientific and folk theories interrelate, given laypeople’s access to multiple sources of information to explain events of personal significance. The current paper reports an in-depth survey of U.S. adults’ (N = 238) causal reasoning about two viral illnesses: a novel, deadly disease that has massively disrupted everyone’s lives (COVID-19), and a familiar, innocuous disease that has essentially no serious consequences (the common cold). Participants received a series of closed-ended and open-ended questions probing their reasoning about disease transmission, with a focus on causal mechanisms underlying disease contraction, transmission, treatment, and prevention; non-visible (internal) biological processes; and ontological frameworks regarding what kinds of entities viruses are. We also assessed participants’ attitudes, such as their trust in scientific experts and willingness to be vaccinated. Results indicated complexity in people’s reasoning, consistent with the co-existence of multiple explanatory frameworks. An understanding of viral transmission and viral replication existed alongside folk theories, placeholder beliefs, and lack of differentiation between viral and non-viral disease. For example, roughly 40% of participants who explained illness in terms of the transmission of viruses also endorsed a non-viral folk theory, such as exposure to cold weather or special foods as curative. Additionally, participants made use of competing modes of construal (biological, mechanical, and psychological) when explaining how viruses operate, such as framing the immune system response (biological) as cells trying to fight off the virus (psychological). Indeed, participants who displayed greater knowledge about viral transmission were significantly more likely to anthropomorphize bodily processes. Although comparisons of COVID-19 and the common cold revealed relatively few differences, the latter, more familiar disease elicited consistently lower levels of accuracy and greater reliance on folk theories. Moreover, for COVID-19 in particular, accuracy positively correlated with attitudes (trusting medical scientists and taking the disease more seriously), self-protective behaviors (such as social distancing and mask-wearing), and willingness to be vaccinated. For both diseases, self-assessed knowledge about the disease negatively predicted accuracy. The results are discussed in relation to challenges for formal models of explanatory reasoning.

When do children avoid infection risks: Lessons for schools during the COVID-19 pandemic

The physical closing of schools because of COVID-19 has disrupted both student learning and family logistics. There is significant pressure for in-person learning to remain open for all children. However, as is expected with outbreaks of novel infections, vaccines and other pharmaceutical therapeutics may not be instantly available. This raises serious public health questions about the risks to children and society at large. The best protective measures for keeping young children in school focus on behaviors that limit transmission. It is therefore critical to understand how we can engage children in age-appropriate ways that will best support their ability to adhere to protocols effectively. Here, we synthesize published studies with new results to investigate the earliest ages at which children form an understanding of infection risk and when they can translate that understanding effectively to protective action.

"Touch Me If You Can!": Individual Differences in Disease Avoidance and Social Touch

The threat of diseases varies considerably among individuals, and it has been found to be linked to various proactive or reactive behaviors. In the present studies, we investigated the impact of individual differences in the perceived vulnerability to disease (PVD) on social touch before (Study 1) or during the coronavirus disease 2019 (COVID-19) pandemic (Study 2). We also investigated the influence of personality traits in the covariation between these two dimensions. We found that people who are the most disease-avoidant are also the most reluctant to touching or being touched by others (and this relationship holds when personality traits are taken into account). Interestingly, the association between PVD and social touch increased during the COVID-19 pandemic compared with a few months before. By showing that the fear of contamination has an association with social touch, the findings provide further evidence for the behavioral immune system ( Schaller and Park, 2011), a psychological system acting as a first line of defense against pathogens.

Young children's ability to make predictions about novel illnesses

Understanding disease transmission is a complex problem highlighted by the COVID-19 pandemic. These studies test whether 3- to 6-year-old children in the United States use information about social interactions to predict disease transmission. Before and during COVID-19, children predicted illness would spread through close interactions. Older children outperformed younger children with no associations between task performance and pandemic experience. Children did not predict that being hungry or tired would similarly spread through close interactions. Participants include 196 three- to six-year-olds (53% girls, 47% boys; 68% White, 9% Black, 7% Asian, 6% Hispanic or Latinx), with medium-sized effects (d = .6, η p 2  = .3). These findings suggest that thinking about social interaction supports young children's predictions about illness, with noted limitations regarding children's real-world avoidance of disease-spreading behaviors.

Children With More Uncertainty in Their Intuitive Theories Seek Domain-Relevant Information

How do changes in learners' knowledge influence information seeking? We showed preschoolers (N = 100) uncertain outcomes for events and let them choose which event to resolve. We found that children whose intuitive theories were at immature stages were more likely to seek information to resolve uncertainty about an outcome in the related domains, but children with more mature knowledge were not. This result was replicated in a second experiment but with the nuance that children at intermediate stages of belief development-when the causal outcome would be most ambiguous-were the most motivated to resolve the uncertainty. This effect was not driven by general uncertainty at the framework level but, rather, by the impact that framework knowledge has in accessing uncertainty at the model level. These results are the first to show the relationship between a learning preference and the developmental stage of a child's intuitive theory.

Developmental antecedents of cleansing effects: Evidence against domain-generality

Lee and Schwarz propose grounded procedures of separation as a domain-general mechanism underlying cleansing effects. One strong test of domain generality is to investigate the ontogenetic origins of a process. Here, we argue that the developmental evidence provides weak support for a domain-general grounded procedures account. Instead, it is likely that distinct separation procedures develop uniquely for different content domains.

Social identity and contamination: Young children are more willing to eat native contaminated foods

Ingesting dangerous substances can lead to illness, or even death, meaning that it is critical for humans to learn how to avoid potentially dangerous foods. However, young children are notoriously bad at choosing foods; they are willing to put nonfoods and disgust elicitors into their mouths. Because food choice is inherently social, we hypothesized that social learning and contamination might separately influence children's decisions about whether to eat or avoid a food. Here, we asked how children reason about foods that are contaminated by someone from within versus outside their culture. We presented 3- to 11-year-olds (N = 534) with videos of native and foreign speakers eating snacks. In Studies 1a and 1b, one speaker contaminated her food and the other did not, and we asked children (a) which food they would prefer to eat, (b) how germy each food was, and (c) which food would make them sick. Although children rated the contaminated food as germier regardless of whether it was contaminated by a foreign speaker (Study 1a) or by a native speaker (Study 1b), children were more likely to report that they would avoid eating foreign contaminated food compared with native contaminated food. In Study 2, we used a non-forced-choice method and found converging evidence that children attend to both culture and contamination when making food choices but that with age they place more weight on contamination status.

Developing an Understanding of Science

Young children are adept at several types of scientific reasoning, yet older children and adults have difficulty mastering formal scientific ideas and practices. Why do “little scientists” often become scientifically illiterate adults? We address this question by examining the role of intuition in learning science, both as a body of knowledge and as a method of inquiry. Intuition supports children's understanding of everyday phenomena but conflicts with their ability to learn physical and biological concepts that defy firsthand observation, such as molecules, forces, genes, and germs. Likewise, intuition supports children's causal learning but provides little guidance on how to navigate higher-order constraints on scientific induction, such as the control of variables or the coordination of theory and data. We characterize the foundations of children's intuitive understanding of the natural world, as well as the conceptual scaffolds needed to bridge these intuitions with formal science.

Using Storybooks to Teach Children About Illness Transmission and Promote Adaptive Health Behavior - A Pilot Study

Although there is a large and growing literature on children’s developing concepts of illness transmission, little is known about how children develop contagion knowledge before formal schooling begins and how these informal learning experiences can impact children’s health behaviors. Here, we asked two important questions: first, do children’s informal learning experiences, such as their experiences reading storybooks, regularly contain causal information about illness transmission; and second, what is the impact of this type of experience on children’s developing knowledge and behavior? In Study 1, we examined whether children’s commercial books about illness regularly contain contagion-relevant causal information. In Study 2, we ran a pilot study examining whether providing children with causal information about illness transmission in a storybook can influence their knowledge and subsequent behavior when presented with a contaminated object. The results from Study 1 suggest that very few (15%) children’s books about illness feature biological causal mechanisms for illness transmission. However, results from Study 2 suggest that storybooks containing contagion-relevant explanations about illness transmission may encourage learning and avoidance of contaminated objects. Altogether, these results provide preliminary data suggesting that future research should focus on engaging children in learning about contagion and encouraging adaptive health behaviors.

In sickness and in filth: Developing a disdain for dirty people

Cleanliness is universally valued, and people who are dirty are routinely marginalized. In this research, we measured the roots of negative attitudes toward physically unclean individuals and examined the differences that exist in these attitudes between childhood and adulthood. We presented 5- to 9-year-old children and adults (total N = 260) with paired photographs of a dirty person and a clean person, and we measured biases with a selective trust task and an explicit evaluation task. In Study 1, where images of adults were evaluated, both children and adults demonstrated clear biases, but adults were more likely to selectively trust the clean informant. Study 2 instead used images of children and included several additional tasks measuring implicit attitudes (e.g., an implicit association task) and overt behaviors (a resource distribution task) and also manipulated the cause of dirtiness to include illness, enjoyment of filth, and accidental spillage. Children and adults again revealed strong biases regardless of the cause of dirtiness, but only children exhibited a bias on the explicit evaluation task. Study 3 replicated these findings in India, a country that has historically endorsed strong purity norms. Overall, this research indicates that dirty people are targets of discrimination from early in development, that this is not merely a Western phenomenon, and that this pervasive bias is most strongly directed at individuals of similar ages.

Are unpopular children more likely to get sick? Longitudinal links between popularity and infectious diseases in early childhood

Social stress and inflammatory processes are strong regulators of one another. Considerable evidence shows that social threats trigger inflammatory responses that increase infection susceptibility in both humans and animals, while infectious disease triggers inflammation that in turn regulates social behaviours. However, no previous study has examined whether young children’s popularity and their rate of infectious disease are associated. We investigated the longitudinal bidirectional links between children’s popularity status as perceived by peers, and parent reports of a variety of infectious diseases that are common in early childhood (i.e. common cold as well as eye, ear, throat, lung and gastric infections). We used data from the ‘Matter of the First Friendship Study’ (MOFF), a longitudinal prospective multi-informant study, following 579 Norwegian pre-schoolers (292 girls, median age at baseline = six years) with annual assessments over a period of three years. Social network analysis was used to estimate each child’s level of popularity. Cross-lagged autoregressive analyses revealed negative dose–response relations between children’s popularity scores and subsequent infection (b = –0.18, CI = –0.29, –0.06, and b = –0.13, CI = –0.23, –0.03). In conclusion, the results suggest that children who are unpopular in early childhood are at increased risk of contracting infection the following year.

Disgust Proneness and Personal Space in Children

Individuals vary in their personal space (PS) size as reflected by the preferred distance to another person during social interactions. A previous study with adults showed that pathogen-relevant disgust proneness (DP) predicted PS magnitude. The present study investigated whether this association between DP and PS already exists in 8- to 12-year-old children (144 girls, 101 boys). The children answered a disgust questionnaire with the two trait dimensions "core disgust (contact with spoiled food and poor hygiene) and "death-relevant disgust" (imagined contact with dead and dying organisms). PS magnitude was assessed with a paper-pencil measure (drawing a PS bubble; Experiment 1) or with the stop-distance task (preferred distance to an approaching woman or man; Experiment 2). In both experiments, only death-related disgust predicted PS magnitude and only if the approaching person was male. The current study questions the relevance of pathogen-related disgust in children for regulating interpersonal distance.