The face never lies: facial expressions and mimicry modulate playful interactions in wild geladas

Play fighting, the most common form of social play in mammals, is a fertile field to investigate the use of visual signals in animals’ communication systems. Visual signals can be exclusively emitted during play (e.g. play faces, PF, context-dependent signals), or they can be released under several behavioural domains (e.g. lip-smacking, LS, context-independent signals). Rapid facial mimicry (RFM) is the involuntary rapid facial congruent response produced after perceiving others’ facial expressions. RFM leads to behavioural and emotional synchronisation that often translates into the most balanced and longest playful interactions. Here, we investigate the role of playful communicative signals in geladas (Theropithecus gelada). We analysed the role of PF and LS produced by wild immature geladas during play fighting. We found that PFs, but not LS, were particularly frequent during the riskiest interactions such as those including individuals from different groups. Furthermore, we found that RFM (PF→PF) was highest when playful offensive patterns were not biased towards one of the players and when the session was punctuated by LS. Under this perspective, the presence of context-independent signals such as LS may be useful in creating an affiliative mood that enhances communication and facilitates most cooperative interactions. Indeed, we found that sessions punctuated by the highest frequency of RFM and LS were also the longest ones. Whether the complementary use of PF and LS is strategically guided by the audience or is the result of the emotional arousal experienced by players remains to be investigated. Significance Statement Facial expressions and their rapid replication by an observer are fundamental communicative tools during social contacts in human and non-human animals. Play fighting is one of the most complex forms of social interactions that can easily lead to misunderstanding if not modulated through an accurate use of social signals. Wild immature geladas are able to manage their play sessions thus limiting the risk of aggressive escalation. While playing with unfamiliar subjects belonging to other groups, they make use of a high number of play faces. Moreover, geladas frequently replicate others’ play faces and emit facial expressions of positive intent (i.e. lip-smacking) when engaging in well-balanced long play sessions. In this perspective, this “playful facial chattering” creates an affiliative mood that enhances communication and facilitates most cooperative interactions.

Playing together, laughing together: Rapid facial mimicry and social sensitivity in lowland gorillas

In non-human animals, the phenomenon of Rapid Facial Mimicry (RFM) - the automatic, involuntary and rapid (< 1 sec) replication of others’ facial expressions—has been mainly investigated in the playful domain. In immature lowland gorillas Gorilla gorilla gorilla both Play Face (PF) and Full Play Face (FPF) are rapidly mimicked between the players. This makes the species suitable to test hypotheses on the factors influencing RFM during play. The observations on three captive groups of lowland gorillas (N = 27) revealed that contrary to expectations, the closeness of social bond negatively influenced the occurrence of RFM but it did not affect either RFM latency or its overlapping index. RFM was affected by the degree of symmetry of play fighting: the more balanced the session, the higher the occurrence of RFM. Players of the same sex class responded faster than players of different sex. These findings suggest that RFM may help synchronizing behaviours of playmates matching in size (same-sex) and promote symmetric playful interactions. “Laughing together” (measured by the RFM overlapping index) lasted longer when the responder perfectly mirrored the partner expression (PF→PF; FPF→FPF). If PF and FPF convey information on the different play roughness degree, through “laughing together” the players could coordinate their actions and share positive moods and playful intensity. If the perfect congruency in the motor resonance, also known as social sensitivity, can foster a possible emotional dialogue between gorillas remains to be investigated.

Integrating Rough-and-Tumble Play in Martial Arts: A Practitioner’s Model

This paper introduces a model that explains psychosocial development by embedding the developmental concept of rough-and-tumble play (RTP) into the contextual settings of martial arts (MA). Current sport-for-change literature relies on theories that address contextual factors surrounding sport but agrees that sport in itself does not facilitate developmental outcomes. In contemporary times where western societies invest substantial resources in sport programs for their psychosocial contribution, this becomes problematic. If the contextual factors surrounding sport are exclusively what produce developmental outcomes, what is the rationale for investing resources in sport specifically? We challenge this idea and argue that although contextual factors are important to any social phenomena, the developmental outcomes from sport can also be traced to the corporeal domain in sport. To date, we have lacked the theoretical lenses to articulate this. The developmental concept of RTP emphasizes how “play fighting” between consenting parties stimulates psychosocial growth through its demand for self-regulation and control when “play fighting” with peers. In short, RTP demands that individuals maintain a self-regulated mode of fighting and is contingent on a give-and-take relationship to maintain enjoyment. RTP can thus foster empathy and prosocial behavior and has strong social bonding implications. However, such play can also escalate. A fitting setting to be considered as moderated RTP is MA because of its resemblance to RTP, and its inherent philosophical features, which emphasizes self-regulation, empathy, and prosocial behavior. This paper outlines what constitutes high-quality RTP in a MA context and how this relates to developmental outcomes. By doing so, we present a practitioner’s framework in which practitioners, social workers, and physical educators can explain how MA, and not merely contextual factors, contributes toward developmental outcomes. In a time where sport is becoming increasingly politicized and used as a social intervention, it too becomes imperative to account for why sport, and in this case, MA, is suitable to such ends.

Behaviour and animal welfare indicators of broiler chickens housed in an enriched environment

The present study aimed to assess the influence of adding straw bales, step platforms, and laser projectors as environmental enrichment resources on the behaviour and welfare indicators of broiler chickens (Gallus gallus domesticus). A sample of 4,000 day-old male Cobb® 500 birds was used. The experimental treatments consisted of No Environmental Enrichment (NEE)—similar to a conventional environment; and Environmental Enrichment (EE)—environment enriched with straw bales, step platforms, and laser projectors, with four replicates per treatment of 500 animals. Behavioural characteristics (ethological observation through cameras, grab test, and modified touch test) and animal welfare indicators (pododermatitis and dorsal cranial myopathy) were assessed. The birds submitted to the EE treatment exhibited greater exploratory activity and expression of behaviours associated with comfort and welfare, whereas those in the NEE group were less active. Locomotion and play fighting behaviour decreased and behaviours associated with comfort increased as age advanced. The frequencies of interaction with laser spots and birds lying around straw bales were the highest in the 1st week (P<0.01). The behaviours of pecking at straw bales (P<0.0004), using the step platforms (P = 0.0001) and being on top of straw bales (P<0.0002) gradually increased. The chickens accessed the feeding troughs the most in the period of 0800 hours (P<0.0001) and expressed the highest frequencies of behaviours associated with comfort in the 1400 hours and 1700 hours periods. The birds in the EE group were calmer in face of human presence and touch and scored higher in animal welfare indicators. Adding straw bales, step platforms, and laser projectors increased locomotion, reduced expression of fear, and improved animal welfare indicators of broiler chickens.

Visual communication in social play of a hierarchical carnivore species: The case of wild spotted hyenas

Communication relies on signals that can be produced via different sensory modalities to modify receivers’ behaviour. During social interactions, the possibility to perceive subtle visual cues enhances the use of facial expressions to exchange information. One of the most appropriate fields to explore the specific design features of visual signals is play fighting. Here, we explored the production and potential role of Relaxed Open Mouth (ROM) and Head Bobbing (HB) in regulating play fighting of wild spotted hyenas Crocuta crocuta, a highly hierarchical carnivore species. In accordance with the assumptions of the signal optimization theory, wild hyenas produced ROM and HB almost exclusively when the sender was in direct visual contact with the receiver thus suggesting that senders were attentive to the playmates’ face. Contrary to HB, the sequential analysis revealed that ROM often anticipated offensive patterns such as play biting thus supporting the hypothesis that ROM, but not HB, is a metacomunicative signal. Moreover, when the offensive patterns were biased towards one of the two players, the session was punctuated by a higher number of ROMs. Our findings support the general hypothesis that these two visual signals can play different roles in the management of play fighting in this carnivore species. The complementary use of ROM and HB would suggest that spotted hyenas are highly competent and fast in processing facial displays of different nature to correctly “read others’ intentions” and respond with appropriate motor actions to avoid misunderstanding during one of the most multifaceted and risky social interaction.