Observing grooming promotes affiliation in Barbary macaques

Play contagion in African elephants: The closest, the better

Behavioural contagion is an automatic process through which a behaviour performed by an individual (trigger) is reproduced by an observer (responder) without necessarily replicating the exact motor sequence. It has been linked to inter-individual synchronisation and possibly emotional contagion. Play can convey emotions and enhance social bonding, although its contagiousness is understudied. To verify social play contagion presence and modulating factors, we gathered audio-video data on social play, distance and affiliation on a group of savannah African elephants (15 individuals) at Parque de la Naturaleza de Cabarceno (Cantabria, Spain). Social play was contagious as it was more likely started by uninvolved elephants (within 3-min) in Post-Play Condition (PP) - after that other elephants had started playing - than in Matched-control Condition (MC; no previous play). Social play contagion mostly occurred within 30 m - probably due to elephants' limited visual acuity - and it was highest between individuals that affiliated the most, with the distance-affiliation interaction having no effect. The most prominent individuals in the social play network were also the most influential in the play contagion network (Eigenvector-centrality measure). Play contagion was socially modulated, thus suggesting it may extend from motor replication to the replication of the underlying affective state.

Sharing Positive Affective States Amongst Rodents

Group living is thought to benefit from the ability to empathize with others. Much attention has been paid to empathy for the pain of others as an inhibitor of aggression. Empathizing with the positive affect of others has received less attention although it could promote helping by making it vicariously rewarding. Here, we review this latter, nascent literature to show that three components of the ability to empathize with positive emotions are already present in rodents, namely, the ability to perceive, share, and prefer actions that promote positive emotional states of conspecifics. While it has often been argued that empathy evolved as a motivation to care for others, we argue that these tendencies may have selfish benefits that could have stabilized their evolution: approaching others in a positive state can provide information about the source of valuable resources; becoming calmer and optimistic around animals in a calm or positive mood can help adapt to the socially sensed safety level in the environment; and preferring actions also benefiting others can optimize foraging, reduce aggression, and trigger reciprocity. Together, these findings illustrate an emerging field shedding light on the emotional world of rodents and on the biology and evolution of our ability to cooperate in groups.

Island Life: Use of Activity Budgets and Visibility to Evaluate a Multi-Species Within-Zoo Exhibit Move

Modern zoos strive to construct habitats which both enable and encourage animals to engage in species-specific behaviour, without compromising their visibility to visitors. Here, we present the findings of a within-zoo move to a custom-built exhibit (Islands at Chester Zoo, UK) with respect to the behaviour of four mammal species; the Sumatran orangutan (Pongo abelii), crested macaque (Macaca nigra), Malayan tapir (Tapirus indicus) and the Malayan sun bear (Helarctos malayanus). We used full activity budgets along with Compositional Data Analysis (CoDA) to gain insight into how the move to a more naturalistic exhibit influenced behaviour. Engagement in abnormal behaviour remained low during the study period for all four species, suggesting no adverse responses to the change in environment. Following the move, both the non-human primate species spent more time engaged in positive social interactions with conspecifics, highlighting the importance of social support during enclosure moves. Time spent visible to the public was largely unaffected by the enclosure move for the Sumatran orangutan, whilst the movement to a new environment increased visibility for the Malayan sun bear and decreased visibility for the crested macaque and Malayan tapir. We demonstrate the value of monitoring behaviour throughout the translocation of zoo-housed species and outline the positive behavioral impacts of providing individuals with naturalistic, species-appropriate environments.

Visuo-Motor Affective Interplay: Bonding Scenes Promote Implicit Motor Pre-dispositions Associated With Social Grooming-A Pilot Study

Proximity and interpersonal contact are prominent components of social connection. Giving affective touch to others is fundamental for human bonding. This brief report presents preliminary results from a pilot study. It explores if exposure to bonding scenes impacts the activity of specific muscles related to physical interaction. Fingers flexion is a very important component when performing most actions of affectionate contact. We explored the visuo-motor affective interplay by priming participants with bonding scenes and assessing the electromyographic activity of the fingers flexor muscle, in the absence of any overt movements. Photographs of dyads in social interaction and of the same dyads not interacting were employed. We examined the effects upon the electromyographical activity: (i) during the passive exposure to pictures, and (ii) during picture offset and when expecting the signal to perform a fingers flexion task. Interacting dyads compared to matched non-interacting dyads increased electromyographic activity of the fingers flexor muscle in both contexts. Specific capture of visual bonding cues at the level of visual cortex had been described in the literature. Here we showed that the neural processing of visual bonding cues reaches the fingers flexor muscle. Besides, previous visualization of bonding cues enhanced background electromyographic activity during motor preparation to perform the fingers flexion task, which might reflect a sustained leakage of central motor activity downstream leading to increase in firing of the respective motor neurons. These data suggest, at the effector level, an implicit visuo-motor connection in which social interaction cues evoke intrinsic dispositions toward affectionate social behavior.

Testing the contagious nature of allopreening: bystander ravens are affected by conspecifics' affiliative interactions

Emotional contagion refers to the mechanism of aligning with conspecifics' emotional states and is thought to be highly beneficial in social group living. While emotional contagion is well studied in humans, most studies in nonhuman animals fail to clearly distinguish between behavioural and emotional contagion. Furthermore, evidence for positive emotional contagion in nonhuman animals is almost entirely restricted to the context of play. In the present study, we aimed at adding observational evidence of contagion in a positive context, while separating aspects of behavioural and emotional contagion. In a group of nonbreeder common ravens, Corvus corax, we investigated whether witnessing conspecifics in positive social interaction, namely allopreening, would influence a bystander's behavioural and, possibly, emotional state. We recorded behavioural expressions of bystanders in postpreening observation phases and compared them to those in matched-control observation phases. We found effects of witnessing others' allopreening on the bystanders' subsequent affiliative interactions but not on their self-directed behaviours (e.g. autopreening) or agonistic interactions. Specifically, bystanders were more likely to engage in allopreening themselves in the postpreening observation phase than in the matched-control observation phase, which could be explained via behavioural and emotional contagion; however, bystanders also showed elevated levels of nonpreening affiliative interactions and spent more time close to conspecifics after observing others allopreening, which hints towards a more general effect on the bystanders' emotional states. Whether these nonpreening affiliative interactions are indeed an indication of emotional contagion needs to be tested in further studies that measure, and manipulate, emotional states.

Yawn contagion in bonobos: Another group, another story

In primates, yawn contagion (the yawning response elicited by others' yawn) is variably influenced by individual (e.g., sex, age) and social factors (e.g., familiarity) and possibly linked to interindividual synchronization, coordination, and emotional contagion. Two out of three studies on yawn contagion in bonobos (Pan paniscus), found the presence of the phenomenon with mixed results concerning the effect of familiarity and no replication on its modulating factors. To address this puzzling issue, we recorded all occurrences data on yawn contagion in a captive bonobo group (March-June 2021; 18 individuals; La Vallée des Singes, France). Contrary to chimpanzees and humans, the number of triggering yawns increased contagion, possibly owing to a higher stimulus threshold. This aspect may explain the interindividual variability observed in yawn contagion rates. In subjects under weaning, we did not detect yawn contagion and, as it occurs in certain human cohorts, yawn contagion declined with age, possibly due to reduced sensitivity to others. Females responded more than males and elicited more responses from females when showing sexual swelling. As reproductive females are central in bonobo society, our results support the hypothesis that-as in other Hominini-the most influential sex can influence yawn contagion. The relationship quality (measured via grooming/play) did not affect yawn contagion, possibly due to bonobos' xenophilic nature. Overall, this study confirms the presence of yawn contagion in bonobos and introduces new elements on its modulating factors, pointing toward the necessity of cross-group studies.

Watching others in a positive state does not induce optimism bias in common marmosets (Callithrix jacchus), but leads to behaviour indicative of competition

Emotional contagion is suggested to facilitate group life by enhancing synchronized responses to the environment. Cooperative breeders are an example of a social system that requires such intricate coordination between individuals. Therefore, we studied emotional contagion in common marmosets by means of a judgement bias test. Demonstrators were exposed to an emotion manipulation (i.e., positive, negative, control), and observers perceived only the demonstrator's behaviour. We predicted that the positive or negative states of the demonstrator would induce matching states in the observer, indicating emotional contagion. All subjects' emotional states were assessed through behaviour and cognition, the latter by means of a judgement bias test. Behavioural results showed a successful emotion manipulation of demonstrators, with manipulation-congruent expressions (i.e., positive calls in the positive condition, and negative calls and pilo-erect tail in the negative condition). Observers showed no manipulation-congruent expressions, but showed more scratching and arousal after the positive manipulation. Concerning the judgement bias test, we predicted that subjects in a positive state should increase their response to ambiguous cues (i.e., optimism bias), and subjects in a negative state should decrease their response (i.e., pessimism bias). This prediction was not supported as neither demonstrators nor observers showed such bias in either manipulation. Yet, demonstrators showed an increased response to the near-positive cue, and additional analyses showed unexpected responses to the reference cues, as well as a researcher identity effect. We discuss all results combined, including recently raised validation concerns of the judgement bias test, and inherent challenges to empirically studying emotional contagion.

Emotional contagion in nonhuman animals: A review

Emotional contagion, the emotional state‐matching of an individual with another, seems to be crucial for many social species. In recent years evidence on emotional contagion in different animal species has accumulated. However, despite its adaptative advantages and its presumed simplicity, the study and direct demonstration of this phenomenon present more complexities than previously thought. For these reasons, a review of the literature on emotional contagion in nonhuman species is timely to integrate current findings. In this paper thus, we carry out a comprehensive review of the most relevant studies on emotional contagion in animals and discuss the main problems and challenges of the field. We conclude that more research is needed to broaden our understanding of the mechanisms and functions of emotional contagion and the extent to which this process is present in a wide variety of species. Furthermore, the comparative study of emotional contagion would benefit from the use of systematized paradigms including both behavioral and physiological measures and the simultaneous recording of the responses of the interacting individuals to reliably assess an emotional state‐matching between them and reliable controls.

This article is categorized under:

Cognitive Biology > Evolutionary Roots of Cognition

Psychology > Comparative Psychology

Psychology > Emotion and Motivation

Social contagion of affiliation in female macaques

Social contagion of non-interactive behaviour is widespread among animals including humans. It is thought to facilitate behavioural synchronization and consequently group cohesion, coordination and opportunities for social learning. Contagion of interactive behaviour-particularly affiliation-has received much less attention. Here, we investigated in female rhesus macaques (Macaca mulatta) the effect of observing group members groom on a subject's subsequent grooming behaviour and the potential modulation of contagion by relationship quality and social status. We recorded behaviour after subjects witnessed a grooming event and compared it to behaviour in a control condition with the same individuals in proximity but in the absence of a stimulus grooming event. Compared to the control condition, after observing others groom, females engaged in a grooming interaction sooner, and were more likely to be the initiator and to take on the active groomer role. Dominance rank of the focal individual and more weakly also of the stimulus individuals affected the latency to the next grooming interaction of the focal subject. Latency to the next grooming interaction decreased with increasing rank of the subject potentially reflecting lower social constraints faced by high ranking individuals in this highly despotic species. Relationship quality between the subject and the stimulus individuals had no effect on latency to grooming. Collectively, our findings provide evidence for visual contagion of affiliation in rhesus macaques. Future studies should explore the systematic variation in contagion of interactive behaviour in relation to a gradient of social tolerance.

Social and affective touch in primates and its role in the evolution of social cohesion

Primates are long-lived, highly social mammals who maintain long-term social bonds and cohesive social groups through many affiliative mechanisms, foremost among them social touch. From birth through adulthood, social touch - primarily mutual grooming - creates and maintains relationships of trust and reliance, which are the basis for individual physical and emotional well-being and reproductive success. Because social touch helps to establish, maintain, and repair social alliances in primates, it contributes to the emotional stability of individuals and the cohesion of social groups. In these fundamental ways, thus, social touch supports the slow life histories of primates. The reinforcing neurochemistry of social touch insures that it is a pleasurable activity and this, in turn, makes it a behavioral commodity that can be traded between primates for desirable rewards such as protection against future aggression or opportunities to handle infants. Social touch is essential to normal primate development, and individuals deprived of social touch exhibit high levels of anxiety and lower fertility compared to those receiving regular social touch. Understanding the centrality of social touch to primate health and well-being throughout the lifespan provides the foundation for appreciating the importance of social touch in human life.

Prosocial Influence and Opportunistic Conformity in Adolescents and Young Adults

Adolescence is associated with heightened social influence, especially from peers. This can lead to detrimental decision-making in domains such as risky behavior but may also raise opportunities for prosocial behavior. We used an incentivized charitable-donations task to investigate how people revise decisions after learning about the donations of others and how this is affected by age (N = 220; age range = 11-35 years). Our results showed that the probability of social influence decreased with age within this age range. In addition, whereas previous research has suggested that adults are more likely to conform to the behavior of selfish others than to the behavior of prosocial others, here we observed no evidence of such an asymmetry in midadolescents. We discuss possible interpretations of these findings in relation to the social context of the task, the perceived value of money, and social decision-making across development.

Challenges in the comparative study of empathy and related phenomena in animals

The aim of this review is to discuss recent arguments and findings in the comparative study of empathy. Based on a multidisciplinary approach including psychology and ethology, we review the non-human animal literature concerning theoretical frameworks, methodology, and research outcomes. One specific objective is to highlight discrepancies between theory and empirical findings, and to discuss ambiguities present in current data and their interpretation. In particular, we focus on emotional contagion and its experimental investigation, and on consolation and targeted helping as measures for sympathy. Additionally, we address the feasibility of comparing across species with behavioural data alone. One main conclusion of our review is that animal research on empathy still faces the challenge of closing the gap between theoretical concepts and empirical evidence. To advance our knowledge, we propose to focus more on the emotional basis of empathy, rather than on possibly ambiguous behavioural indicators, and we provide suggestions to overcome the limitations of previous research .