Infectious disease dynamics are deeply intertwined with social structures, behaviors, and information systems. This narrative review examines how social factors conceptualized through the integrated lens of "social contagion" within a syndemic framework shape infectious disease patterns from January 2000 to January 2024. Literature was retrieved from PubMed, Scopus, Web of Science, and Google Scholar using targeted combinations of terms related to social determinants, networks, communication, and digital epidemiology. Foundational pre-2000 works were consulted for theoretical grounding. Studies were selected based on their relevance to understanding how social processes influence infectious disease dynamics. The selection process prioritized high-impact empirical studies, meta-analyses, and seminal theoretical works that collectively informed the four thematic areas presented. As this is a narrative review, no statistical analyses were performed. The synthesis approach followed established guidelines for narrative reviews. Four major themes emerged from the synthesis of identified literature: (1) structural and commercial determinants socioeconomic inequality, racism, and commercial practices produce environments where infectious and non-communicable diseases interact synergistically; (2) network effects household, occupational, and mobility patterns shape transmission pathways and superspreading events; (3) belief systems misinformation, behavioral contagion, and varying levels of institutional trust influence vaccine uptake and protective behaviors; and (4) diagnosis and intervention digital epidemiology and agent-based models offer tools for integrating social data into disease surveillance and response. Infectious diseases are fundamentally biosocial phenomena. Effective control requires moving beyond biomedical models toward approaches centered on social epidemiology, equity, and trust-building. Future research must employ transdisciplinary collaboration to better measure and model the complex interactions that constitute social contagion.

Prenatal behavioral contagion through maternal yawning and fetal resonance.

Behavioral contagion is defined as the tendency of individuals to conform with others' behavior after observing them. Despite the important role that behavioral contagion plays in societies, its brain mechanism is still not fully understood. In this study, we hypothesized that the brain functional network rearranges its regional associations in a way to achieve a more stable state after behavioral contagion. Therefore, the stability of the brain network before and after observing others' choices (preferences) was assessed using structural balance theory (SBT) on the fMRI data. For this purpose, we developed a version of the dictator game as a task, and recorded participants' brain responses using fMRI. The participants were classified into Contagion and No-Contagion groups based on significant changes in their preferences after observing others' choices. In both groups, changes in SBT parameters of the brain functional network were statistically compared before and after the observation. The results indicated that behavioral contagion is accompanied with a rearrangement of the links in the network to transform imbalanced triads into balanced triads. This process lowers the balance energy of the brain functional network and pushes it to a more stable state. Interestingly, for the No-Contagion group, no significant changes in stability (balance energy level) of the brain functional network was observed. Based on these findings, we believe that if the brain network goes to a more stable state by changing the topology of negative links (anti-correlated regional associations) after observation of others' preference, the contagion may occur.

Modeling the dynamical process of behavioral contagion in human crowds during evacuation

Adaptive network dynamics and behavioral contagion in multi-state drug use propagation

ABSTRACTBehavioral contagion is spread across animal species and is thought to promote social cohesion and group synchronization. While yawn contagion has been extensively studied, scratch contagion remains comparatively under‐researched, particularly in wild populations. We investigated whether yawn and scratch contagion occurred in a wild group of Ecuadorian white‐fronted capuchins (Cebus aequatorialis, N = 16) at La Hesperia Cloud Forest Reserve in Ecuador. We assessed whether scratching or yawning were more likely to occur after observing a conspecific (i.e., the trigger) scratching or yawning (i.e., triggering event) compared to a control condition. We further examined whether this effect was modulated by the (a) individual characteristics of the trigger and the partner (sex, age category, and social centrality), and (c) dyadic‐level variables (sex and age similarity, social bond strength). Our results showed that the probability of scratching was significantly higher in individuals that observed the triggering event, as compared to individuals that did not observe it. However, scratch contagion was not modulated by any of the individual or dyadic predictors included in our models. No yawning events were recorded during the study period. Our findings contribute to understanding scratch contagion in wild primates and underscore the need for further exploration of social factors influencing behavioral contagion.

Human social interaction relies fundamentally on the ability to express and perceive affective states through action. According to Daniel Stern’s concept of Vitality Forms (VFs), actions convey affective qualities, such as gentleness or rudeness, shaping how people behave beyond their action goal. While previous research has shown that VFs expressed by agents can influence observers’ perception and their motor responses, evidence from real, face-to-face social interactions remains limited. The present study addresses this gap by examining how affective contagion mediated by VFs operates during an authentic social exchange. Specifically, this work aims to: 1) identify the kinematic parameters that are influenced by others during a real game interaction; 2) determine whether this contagion effect is conscious or automatic; 3) examine whether this effect is associated with participants’ empathy abilities. In this view, pairs of participants engaged in a tic-tac-toe game, with one player acting as an insider instructed to consistently display either gentle or rude behavior through their action execution. Across 18 matches, the action of both players were recorded to assess whether and how the VFs of the inside player modulated the participant’s motor response in terms of kinematics. At regular intervals, participants reported their own affective state and their perception of the insider’s affect using Likert scales. Moreover, to assess individual empathic abilities, the Empathy Quotient questionnaire was administered. The findings revealed three principal results. First, participants’ actions were significantly modulated by the VFs of the inside player across multiple kinematic parameters (i.e., velocity, acceleration etc.), indicating a clear motor contagion effect. Second, although participants accurately perceived changes in the insider’s attitude, they did not report corresponding changes in their affective state, suggesting that VFs contagion occurs implicitly and without conscious awareness. Third, the magnitude of this motor contagion was positively correlated with empathic abilities of participants.

Witnessing robot mistreatment: A dual-path model of behavioral contagion and empathy in customer observers

While enforcing egalitarian social norms is critical for human society, punishing social norm violators often incurs a cost to the self. This cost looms even larger when one can benefit from an unequal distribution of resources, a phenomenon known as advantageous inequity—for example, receiving a higher salary than a colleague with the identical role. In the Ultimatum Game, a classic testbed for fairness norm enforcement, individuals rarely reject (or punish) such unequal proposed divisions of resources because doing so entails a sacrifice of one’s own benefit. Recent work has demonstrated that observing and implementing another’s punitive responses to unfairness can efficiently alter the punitive preferences of an observer. It remains an open question, however, whether such contagion is powerful enough to impart advantageous inequity aversion to individuals—that is, can observing another’s preferences to punish inequity result in increased enforcement of equality norms, even in the difficult case of Advantageous inequity? Using a variant of the Ultimatum Game in which participants are tasked with responding to fairness violations on behalf of another ‘Teacher’—whose aversion to advantageous (versus disadvantageous) inequity was systematically manipulated—we probe whether individuals subsequently increase their punishment unfairly after experiencing fairness violations on their own behalf. In two experiments, we found individuals can acquire aversion to advantageous inequity through observing (and implementing) the Teacher’s preferences. Computationally, these learning effects were best characterized by a model which learns the latent structure of the Teacher’s preferences, rather than a simple Reinforcement Learning account. In summary, our study is the first to demonstrate that people can swiftly and readily acquire another’s preferences for advantageous inequity, suggesting in turn that behavioral contagion may be one promising mechanism through which social norm enforcement—which people rarely implement in the case of advantageous inequality—can be enhanced.

While enforcing egalitarian social norms is critical for human society, punishing social norm violators often incurs a cost to the self. This cost looms even larger when one can benefit from an unequal distribution of resources, a phenomenon known as advantageous inequity-for example, receiving a higher salary than a colleague with the identical role. In the Ultimatum Game, a classic testbed for fairness norm enforcement, individuals rarely reject (or punish) such unequal proposed divisions of resources because doing so entails a sacrifice of one's own benefit. Recent work has demonstrated that observing and implementing another's punitive responses to unfairness can efficiently alter the punitive preferences of an observer. It remains an open question, however, whether such contagion is powerful enough to impart advantageous inequity aversion to individuals-that is, can observing another's preferences to punish inequity result in increased enforcement of equality norms, even in the difficult case of Advantageous inequity? Using a variant of the Ultimatum Game in which participants are tasked with responding to fairness violations on behalf of another 'Teacher'-whose aversion to advantageous (versus disadvantageous) inequity was systematically manipulated-we probe whether individuals subsequently increase their punishment unfairly after experiencing fairness violations on their own behalf. In two experiments, we found individuals can acquire aversion to advantageous inequity through observing (and implementing) the Teacher's preferences. Computationally, these learning effects were best characterized by a model which learns the latent structure of the Teacher's preferences, rather than a simple Reinforcement Learning account. In summary, our study is the first to demonstrate that people can swiftly and readily acquire another's preferences for advantageous inequity, suggesting in turn that behavioral contagion may be one promising mechanism through which social norm enforcement-which people rarely implement in the case of advantageous inequality-can be enhanced.

This paper provides a comprehensive review of herding behavior in financial markets, with a specific focus on the social factors that influence such collective decision-making. Herding occurs when investors mimic the actions of others rather than relying on their own analysis or private information. While traditional models emphasize informational cascades or rational herding, growing evidence highlights the role of social dynamics such as peer pressure, conformity, media influence, reputation concerns, and behavioral contagion. Drawing from a broad range of empirical studies and theoretical frameworks, this review explores the manifestations of herding across different investor groups, market conditions, and geographical regions. Particular attention is paid to the contrast between developed and emerging markets, and between individual and institutional investors. The study reveals that social herding is not only a reflection of bounded rationality but also a socially reinforced behavior that undermines market efficiency and can contribute to volatility and systemic risk. The paper concludes by identifying gaps in the current literature and proposing directions for future research, especially in the context of digital trading environments and algorithmic decision-making.

This case study examines the phenomenon of dimensional-slips, i. e., anomalous distortions or perceptions of spacetime that may involve transcendental content or themes. Our investigation specifically centers on “Nell,” a known ‘haunted’ woman who documented four experiences of perceived physical transports to other realms. Using a mixed-methods approach, we employed AI-assisted content analyses with secondary evaluations by subject matter experts to assess Nell’s experiences through the competing theoretical lenses of kundalini awakenings, physical mediumship, bilocation-related phenomena, and electromagnetic field (EMF) effects. Findings indicated strong alignment with EMF-related activity and, to some extent, bilocation phenomena, as compared to the other hypotheses explored here. Post-hoc accounts of different dimensional-slips experienced by Nell’s family members in the same geographic vicinity further hinted at the probable influences of environmental variables or behavioral contagion. Finally, we build on key literature cited in the study to introduce a continuum model of bilocation, integrating concepts from psychology, neuro­science, and parapsychology. There was no conclusive evidence that Nell physically moved anywhere, so our findings arguably point to the interplay among boundary-thinness, altered states, and environmental factors in her anomalous cognitions. These results underscore the need for further multidisciplinary inquiries into dimensional-slip narratives and their implications for consciousness studies. Future research should therefore incorporate controlled experiments and broader case studies to refine theoretical models of these extraordinary experiences.

The basic forms of motor and possibly emotion replication include behavioral contagion and rapid motor mimicry (RMM). RMM—mainly demonstrated during play—occurs when an individual perceives and rapidly (< 1 s) replicates the exact motor sequence of another individual. We collected data on an African Savanna Elephant (Loxodonta africana; N = 15) group housed at the Parque de la Naturaleza de Cabárceno (Spain) on play target movements of both trunk and head. We demonstrated the presence of RMM. Elephants that were more prone in mimicking others’ target movements were also more prone to play after observing others playing. RMM—as behavioral contagion—can enhance action coordination between players. As RMM was associated with more offensive play patterns than unreplicated target movements, RMM may allow competitive play sessions to occur, possibly replacing agonistic interactions. Neither individual (age, sex) nor social (affiliation levels) factors modulated the RMM. These findings can be related to the elephant high tolerance levels and the wide presence of play across age (including adults) and sex. Concluding, African elephants have the potential to share their affective states (emotional contagion) via RMM which is relevant to the investigation of the evolution of empathy in mammals including humans.

This research examines the mechanisms through which toxic leadership behaviors cascade through organizations, influencing employee conduct and ultimately affecting customer service outcomes. Drawing on established theories including Social Learning Theory, Trickle-Down Effect, and Service Climate Theory, this paper synthesizes empirical evidence demonstrating that employees systematically mirror the negative behaviors modeled by organizational leaders. Through a comprehensive analysis of psychological processes such as behavioral contagion, moral disengagement, and displaced aggression, we delineate precise pathways through which toxic leadership transmits from management to frontline employees, creating systemic dysfunction that undermines service quality. The findings establish a causal relationship between leadership conduct, organizational culture, service climate, and customer experience metrics. Statistical correlations and case-based evidence indicate significant implications for stakeholder relationships, brand perception, and financial performance. We conclude with evidence-based recommendations for breaking cycles of toxicity through structural interventions, leadership development program and culture transformation initiatives that foster accountability and empathy at all organizational levels.

The spread of behavior in collective evasion of mobile animal groups can be predicted by reconstructing quantitative interaction networks. Based on the assumption of time scale separation between a fast contagion process and a slower movement response, the underlying interaction networks have been previously assumed to be static, determined by the spatial structure at the onset of the collective escape response. This idealization does not account for the temporal evolution of the spatial network structure, which may have a major impact on the behavioral contagion dynamics. Here, we propose a spatially explicit, agent-based model for the coupling between behavioral contagion and the network dynamics originating from the spreading movement response. We explore the impact of movement parameters (startle speed, initial directionality, and directional noise) on average cascade size. By conducting numerical simulations for different density levels, we show that increasing escape speed suppresses the cascade size in most cases, that the cascade size depends strongly on the movement direction of the initially startled individual, and that large variability in the direction of individual escape movements (rotational noise) will typically promote the spread of behavioral contagion through spatial groups. Our work highlights the importance of accounting for movement dynamics in behavioral contagion, and facilitates our understanding of rapid coordinated response and collective information processing in animal groups. Published by the American Physical Society 2025

When we see someone yawning, we often feel compelled to yawn ourselves -a phenomenon known as behavioral contagion in psychology.While one person's yawn acts as an activator that triggers yawns in others, we sometimes suppress the urge to yawn in situations like meetings, representing an inhibitor of this behavior.We formulated this yawning contagion as a reaction-diffusion phenomenon in an activator-inhibitor system and confirmed the emergence of Turing patterns.Our findings provide a theoretical framework for understanding and potentially controlling the spread of social behaviors in human populations.

Behavioral copying is a key process in group actions, but it is challenging for individuals with autism spectrum disorder (ASD). We investigated behavioral contagion, or instinctual replication of behaviors, in Krushinky-Molodkina (KM) rats (n = 16), a new potential rodent model for ASD, compared to control Wistar rats (n = 15). A randomly chosen healthy Wistar male ("demonstrator rat") was introduced to the homecage of experimental rats ("observers") 10-14 days before the experiments to become a member of the group. For the implementation of the behavioral contagion experiment, we used the IntelliCage system, where rats can live in a group of 5-6 rats and their water visits can be automatically scored. During the experiment, the demonstrator was taken out of IntelliCage for a pre-test water deprivation and then placed back for the behavioral contagion test. As a result, a drinking behavior of the water-deprived demonstrator rat prompted water-seeking and drinking behaviors in the whole group. Unlike the Wistar controls, KM observers showed fewer visits to the drinking bottles, particularly lacking inspection visits (i.e., visits without drinking). The control group, in contrast, exhibited a dynamic, cascade-like visiting of the water corners. The proportion of activated observers in KM rats was significantly lower, as compared to Wistar ones, and they did not mimic other observer rats. KM rats, therefore, displayed an attenuated pattern of behavioral contagion, highlighting social deficits in this strain. This study suggests that measuring group dynamics of behavioral contagion in an automated, non-invasive setup offers valuable insights into social behavior in rodents.

Behavioral contagion is widespread in primates, with yawn contagion (YC) being a well-known example. Often associated with ingroup dynamics and synchronization, the possible functions and evolutionary pathways of YC remain subjects of active debate. Among nonhuman animals, geladas (Theropithecus gelada) are the only species known to occasionally emit a distinct vocalization while yawning. Yet, the role of different sensory modalities in YC remains poorly understood. Due to their social and communicative complexity, geladas serve as an excellent model for investigating the effects of multimodality and social factors on behavioral contagion. Here we studied a large zoo-housed colony of geladas (103 subjects, 1422 yawns) and confirm the previous evidence for visual and auditory YC. Hearing, seeing, or hearing and seeing yawns significantly triggered contagious yawning at comparable levels. Additionally, we found no evidence of laterality influencing responses based on the side of detection. While the social bond, measured via grooming, between the trigger and receiver did not correlate with YC, a consistent sex effect emerged. Females responded more frequently to female than to male yawns and were more likely to match modality (i.e., vocalized vs. nonvocalized) and mirror morphology of other females' yawns. Effective female-female communication and affiliation are crucial for maintaining cohesion and fostering strong intra-unit relationships among geladas. Our results underscore the importance of different sensory components in the distribution of YC, particularly for species living in complex social systems. These findings raise further questions about the functional and emotional significance of yawning and potential inter-sexual differences, suggesting that the phenomenon is more complex than previously thought.

Behavioral contagion is thought to play a significant role in social synchronization and coordination across animal taxa. While there is extensive evidence of behavioral contagion in Haplorrhines (i.e. monkeys and apes), limited research exists in Strepsirrhines (i.e. lemurs). Here, we aimed to investigate the presence of contagious yawning and scratching in two captive groups of black-and-white ruffed lemurs (Varecia variegata) (N = 4) and red ruffed lemurs (Varecia rubra) (N = 4), and further test whether behavioral contagion is modulated by the model’s social integration in the group. We conducted all occurrence sampling to examine whether individuals observing a yawning or scratching event (i.e. trigger event) were more likely to yawn or scratch in the following 2 min, as compared to individuals who did not observe it. We ran generalized linear mixed models and found that the likelihood of yawning and scratching was higher for subjects observing the trigger event than for subjects who did not observe the event, although the model’s social integration had no modulating effect on the probability of showing behavioral contagion. Our findings represent the first evidence of behavioral contagion in this genus and contribute to shed light on the distribution and the possible adaptive function of this phenomenon in primates.

Social contagions in business resilience: Evidence from the U.S. restaurant industry in the COVID-19 pandemic