Le bâillement, du réflexe à la pathologie
Le bâillement : de l'éthologie à la médecine clinique
Le bâillement : phylogenèse, éthologie, nosogénie
 Le bâillement : un comportement universel
La parakinésie brachiale oscitante
Yawning: its cycle, its role
Warum gähnen wir ?
 
Fetal yawning assessed by 3D and 4D sonography
Le bâillement foetal
Le bâillement, du réflexe à la pathologie
Le bâillement : de l'éthologie à la médecine clinique
Le bâillement : phylogenèse, éthologie, nosogénie
 Le bâillement : un comportement universel
La parakinésie brachiale oscitante
Yawning: its cycle, its role
Warum gähnen wir ?
 
Fetal yawning assessed by 3D and 4D sonography
Le bâillement foetal
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mise à jour du
31 août 2013
Primates
2014;55(1):113-118
 Response facilitation in the four great apes:
is there a role for empathy?
 
Federica Amici, Filippo Aureli,Josep Call
Department of Comparative and Developmental Psychology, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany

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 Tous les articles sur la contagion du bâillement
All articles about contagious yawning
 
Abstract
 
Contagious yawning is a form of response facilitation found in humans and other primates in which observing a model yawning enhances the chance that the observer will also yawn. Because contagious yawning seems to be more easily triggered when models are conspecifics or have a strong social bond with the observer, it has been proposed that contagious yawning is linked to empathy. A possible way to test this hypothesis is to analyze whether individuals' responses differ when they observe models yawning or performing different involuntary (i.e., nose wiping, scratching) and voluntary (i.e., hand closing, wrist shaking) actions that are not linked to empathy. In this study, we tested the four great ape species with two different setups by exposing them to a human experimenter repeatedly performing these actions online, and video-recorded conspecifics repeatedly performing these actions on a screen. We examined which behaviors were subject to response facilitation, whether response facilitation was triggered by both human models and video-recorded conspecifics, and whether all species showed evidence of response facilitation. Our results showed that chimpanzees yawned significantly more when and shortly after watching videos of conspecifics (but not humans) yawning than in control conditions, and they did not do so as a response to increased levels of anxiety. For all other behaviors, no species produced more target actions when being exposed to either model than under control conditions. Moreover, the individuals that were more "reactive" when watching yawning videos were not more reactive when exposed to other actions. Since, at least in chimpanzees, (1) subjects only showed response facilitation when they were exposed to yawning and (2) only if models were conspecifics, it appears that contagious yawning is triggered by unique mechanisms and might be linked to empathy.
 
La réplication, alias contagion, du bâillement est un réponse comportementale mimétique observée chez les humains et d'autres primates. L'observation du bâillement d'un congénère augmente la chance que l'observateur se mette également à bâiller.
 
La réplication du bâillement semble être plus facilement déclenchée entre congénères, en particulier entre ceux partageant un lien social fort. Il en a été déduit la proposition que la réplication du bâillement est liée à l'empathie.
 
Une façon de tester cette hypothèse est d'analyser si les réponses des sujets diffèrent quand ils observent des bâillements ou d'autres comportements qu'ils soient involontaires (essuyage du nez, grattage) ou volontaires (fermeture de la main, serrer le poignet), ces actions n'étant pas liées à l'empathie.
 
Dans cette étude, les auteurs ont testé quatre espèces de grands singes dans deux situations différentes: soit en les exposant à un expérimentateur humain exécutant à plusieurs reprises ces actions successivement, soit en leur présentant, sur un écran, leurs congénères qui avaient été enregistrés en video, effectuant à plusieurs reprises ces actions.
 
Les auteurs ont examiné ces comportements "à la réponse induite facilitée" et comparé si le déclenchement diffèrent suivant que le comportement est réalisé par des humains ou par leurs congénères (vidéo enregistrés) et si toutes les espèces ont montré des réponses comparables.
 
Leurs résultats ont montré que les chimpanzés bâillaient beaucoup plus quand ils regardent leurs congénères bâiller et peu de temps après, mais pas en regardant les bâillements humains. Ces bâillements ne correspondent pas à une réponse par augmentation des niveaux d'anxiété comprartivement aux conditions de contrôle.Aucun autre comportement, avec examen en siutuations contrôles, n'ait reproduit par aucune espèce.
 
Ceux qui étaient les plus sensibles à la réplication des bâillements n'ont pas montré de sensiblité particulière à mimer d'autres comportements. Chez le chimpanzé, en particulier, le fait que la réplication soit nettement facilitée par l'observation d'un congénère, il semble que la réplication du bâillement soit déclenchée par des mécanismes uniques et qu'ils pourraient être liés à l'empathie.
 
Introduction
 
Response facilitation happens when observing a model performing an action increases the likelihood that the observer will also perform the same action (Byrne 1994). Although some authors prefer to refer to contagion when the target action is reflexive or involuntary, as in yawning (Zentall 2003), the more general term ''response facilitation'' is usually preferred, as for most actions it is not possible to exactly know whether the target action is reflexive or has been learned (e.g., Hoppitt et al. 2007). There are many examples of response facilitation across animal taxa. Synchronous courtship behavior and synchronized predator evasion in flocks and herds have been explained in terms of response facilitation (Armstrong 1951; Nuechterlein and Storer 1982). More recently, response facilitation has also been postulated as a more likely mechanism than imitation and social learning in some situations (e.g., Hoppitt et al. 2007). One of the most basic examples of response facilitation is yawning. In 40&endash;60 % of adult humans, yawning is easily triggered by seeing, reading or thinking about another individual yawning (Provine 1986, 2005; Platek et al. 2003). On the basis of experimental evidence, several authors have proposed that contagious yawning is linked to the ability to share others' emotions and engage in successful social interactions; in other words, it is linked to empathy (Preston and de Waal 2002; Platek et al. 2003; Singer 2006; Senju et al. 2007; but see Provine 1986; Nahab et al. 2009). In particular, both empathy and contagious yawning may rely on a perception&endash;action mechanism in which perceiving one behavior would lead the subject to activate shared representations and involuntarily re-enact the observed behavior (Platek et al. 2003). For example, humans showing higher levels of response facilitation to yawning stimuli also score higher in questionnaires evaluating empathy, self-recognition, and theory of mind (Platek et al. 2003). Moreover, presumed emotional closeness between individuals best predicts yawning contagion in humans (Norscia and Palagi 2011).
 
Yawning is common across vertebrates, and yawning contagion has been shown in species other than humans (e.g., Anderson et al. 2004). Chimpanzees (Pan troglodytes), for example, yawn more when watching videos in which conspecifics are yawning than in control videos in which conspecifics are not yawning (Anderson et al. 2004; Campbell and de Waal 2011). Chimpanzees even show contagious yawning in response to 3D-animated chimpanzee yawns (Campbell et al. 2009). In gelada baboons (Theropithecus gelada) and bonobos (Pan paniscus), yawning is contagious and more frequent when subject and model have a stronger social bond, suggesting that contagious yawning might also be linked to empathy in nonhuman primates (Palagi et al. 2009; Demuru and Palagi 2012). Contagious yawning has also been documented in stump-tailed macaques (Macaca arctoides), although yawning responses elicited by unfamiliar video-recorded monkeys yawning were accompanied by self-scratching, suggesting that yawning was rather triggered by increased anxiety (Paukner and Anderson 2006).
 
Finally, dogs may also show contagious yawning when watching videos of humans or conspecifics yawning (Joly- Mascheroni et al. 2008), although these findings are controversial (Harr et al. 2009; O'Hara and Reeve 2010).
 
Although there are several actions other than yawning which subjects can copy from conspecifics, to our knowledge no study has so far compared primates' response when subjects are exposed to several different target actions. This comparison can be informative to understand whether different mechanisms trigger response facilitation of yawning as compared to other behaviors, i.e., whether contagious yawning might be linked to empathic skills while other behaviors are not. Apart from yawning, for example, individuals can copy other conspecifics' behaviors that are already present in the subject's repertoire, such as nose wiping (i.e., quickly touching the nose with the hand), scratching (i.e., rubbing the skin with the fingers), hand closing (i.e., making a fist with the fingers and then opening it again), and wrist shaking (i.e., quickly rotating the hand around the wrist). These behaviors are all typically present in the behavioral repertoire of great apes (see Nishida et al. 1999), but only contagious yawning has been linked to empathy (see above); nose wiping and scratching can be involuntary actions like yawning (e.g., Leavens et al. 2001), but they have never been linked to empathy; hand closing and wrist shaking are more under voluntary control than the other actions (Napier 1980) and have also never been linked to empathy. If different mechanisms trigger response facilitation to different target actions, subjects should respond differently in the different situations. In particular, subjects might show response facilitation whenever they are exposed to involuntary actions, or only when they are exposed to yawning.
 
In this study, we tested the four great ape species (Pan troglodytes, Pan paniscus, Pongo abelii, Gorilla gorilla) with two different setups aimed at assessing the propensity of individuals to spontaneously reproduce the following target actions: yawning, nose wiping, scratching, hand closing, and wrist shaking. Unlike previous studies (e.g., Anderson et al. 2004; Campbell et al. 2009), we did not have a condition involving the mouth in addition to yawning, but included several target actions involving other body parts. We did this because our main goal was not to assess whether individuals produced yawning upon seeing it, which had already been established by previous studies; instead, our main goal was to assess response facilitation more broadly (i.e., we did not only address how yawning varied under different conditions but also how other behaviors varied under different conditions).
 
As a model, we used a human experimenter repeatedly performing several actions online, and video-recorded conspecifics repeatedly performing several actions on a screen. We used both online and video-recorded models because subjects might attend differently to videos and live models, possibly showing stronger reactivity in the mirrorneuron system when observing live motor acts (Jarvelainen et al. 2001). All models were familiar to the subjects, as unfamiliar models might hinder response facilitation (e.g., Harr et al. 2009; Campbell and de Waal 2011). Our aim was to examine (1) which behaviors are subject to response facilitation, (2) whether response facilitation is triggered by both human models and video-recorded conspecifics, and (3) whether all species show evidence of response facilitation.
 
Discussion
 
Chimpanzees yawned significantly more when watching videos of conspecifics yawning and shortly after they had watched such videos, as compared to before they watched the videos. In contrast, their scratching behavior did not change across phases of the yawning video. For all the other behaviors of the human and video setups, no species produced more target actions when being exposed to the model. Finally, the individuals that were more ''reactive'' to yawning in the video setup were significantly less reactive to nose wiping in the same setup. No other correlations within and across setups were found.
 
As in previous studies, chimpanzees yawned more when and after watching videos of conspecifics yawning than under control conditions (Anderson et al. 2004; Campbell and de Waal 2010). Chimpanzees did not yawn more as a response to enhanced levels of anxiety, as their scratching behavior did not significantly vary across phases of the yawning videos (in contrast to stump-tailed macaques: Paukner and Anderson 2006). Interestingly, yawning was the only behavior that elicited response facilitation. However, response facilitation only occurred in the video setup, suggesting that contagious yawning in chimpanzees is more easily triggered by conspecifics yawning than by human experimenters yawning, despite conspecifics in our study being video-recorded and video-recorded conspecifics tending to elicit weaker reactivity in the mirror-neuron system than live conspecifics (Jarvelainen et al. 2001). This is in line with contagious yawning in animals having so far only been triggered by watching conspecifics or mirrorimages yawning (Anderson et al. 2004; Paukner and Anderson 2006; Palagi et al. 2009; Campbell and de Waal 2011; Demuru and Palagi 2012). If empathy underlies contagious yawning, contagious yawning should be triggered more frequently by familiar conspecifics living in the same social group rather than by human models, since the former have a stronger bond with the tested subjects (see Campbell and de Waal 2011). Dogs might be the only exception to this pattern, as they have shown contagious yawning when exposed to a human model (Joly-Mascheroni et al. 2008), but these findings are controversial (Harr et al. 2009; O'Hara and Reeve 2010).
 
Importantly, no action other than yawning elicited response facilitation. This result supports the hypothesis that contagious yawning might be triggered by mechanisms other than those eliciting response facilitation of other behaviors, even when these behaviors are involuntary. In addition, individuals that showed more response facilitation to yawning were those that showed less response facilitation to another involuntary target action such as nose wiping, confirming that reactivity to other involuntary actions might depend on different mechanisms than those triggering contagious yawning (Platek et al. 2003; Anderson et al. 2004; Campbell and de Waal 2011; Norscia and Palagi 2011). For example, it has been proposed that contagious yawning is a simple form of response facilitation that does not require empathic skills and thus also occurs in vertebrates that lack empathy (e.g., Yoon and Tennie 2010). However, the only study, to our knowledge, which tested yawning in species other than mammals showed that contagious yawning was never elicited in redfooted tortoises (Geochelone carbonaria) under different conditions, leading the authors to conclude that contagious yawning may involve more complex social processes than mere response facilitation (Wilkinson et al. 2011).
 
The three great ape species other than chimpanzees showed no effect upon watching either type of model performing target actions, including yawning. It might be speculated that chimpanzees better activate shared representations to re-enact observed behaviors, thus showing more reactivity to contagious yawning as compared to the other great apes. If empathy is really linked to contagious behavior, however, the fact that all great apes possess the cognitive skills usually considered to be prerequisites for the understanding of others' mental states, such as perspective taking and mirror self-recognition (e.g., Gallup et al. 2003; Braeuer et al. 2005), would suggest that all great apes should be responsive to contagious behavior. It is indeed conceivable that our small sample size, together with important interindividual differences in terms of reactivity to the target actions (e.g., Anderson et al. 2004), might be responsible for our results. Future studies with larger sample sizes are clearly needed to confirm our findings.
 
To conclude, our study provided evidence for differences in response facilitation depending on the target action and species. In particular, our study found response facilitation only when chimpanzees watched conspecifics yawn, but not when humans yawned, or when conspecifics performed other actions. These findings support the view that mechanisms triggering contagious yawning may be different from those involved in other behaviors, and that contagious yawning may involve more complex social processes than mere response facilitation, such as empathic skills.