Contagious yawning in virtual reality is affected by actual, but not simulated, social presence

www.nature.com/scientificreports OPEN Received: 23 March 2018 Accepted: 24 November 2018 Published: xx xx xxxx Contagious yawning in virtual reality is affected by actual, but not simulated, social presence Andrew C. Gallup1, Daniil Vasilyev2, Nicola Anderson2 & Alan Kingstone2 Contagious yawning occurs in humans and a few other highly social animals following the detection of yawns in others, yet the factors influencing the propagation of this response remain largely unknown. Stemming from earlier laboratory research, we conducted five experiments to investigate the effects of social presence on contagious yawning in virtual reality (VR). We show that, similar to a traditional laboratory setting, having a researcher present during testing significantly inhibited contagious yawning in VR, even though participants were viewing a virtual environment and unable to see the researcher. Unlike previous research, however, manipulating the social presence in VR (i.e., embedding recording devices and humanoid avatars within the simulation) did not affect contagious yawning. These experiments provide further evidence that social presence is a powerful deterrent of yawning in humans, which warrants further investigation. More generally, these findings also have important applications for the use of VR in psychological research. While participants were quite sensitive to social stimuli presented in VR, as evidenced by contagious yawning, our results suggest a major difference in the influence of social factors within real-world and virtual environments. That is, social cues in actual reality appear to dominate and supersede those in VR. Yawning is characterized by a powerful gaping of the jaw with deep inspiration, followed by a temporary period of peak muscle contraction and a passive closure of the jaw during expiration1. Physiologically, yawns enhance intracranial circulation2 and facilitate brain cooling3–5, which in turn could serve to promote cortical arousal6 and state change7 during behavioral transitions. Contagious yawning, which represents the reflexive triggering or release of this response as a result of sensing yawns in others, is a well-documented phenomenon in humans, as seeing, hearing and even thinking about yawning can induce yawn contagion7,8. Evidence for contagious yawning is also present in a small number of non-human animals, including some non-human primates, birds and domesticated dogs9. Spontaneous and contagious yawns represent intrinsically connected, yet distinct behaviors. Although indistinguishable in the motor action pattern described above, a number of important factors, in addition to their triggers (i.e., physiological vs. social), differentiate these two types of yawns. Spontaneous yawns, or similar mandibular-gaping patterns, appear to be a phylogenetically old and conserved across vertebrate classes10, while contagious yawning is a more recently derived feature present in only a few highly social species11,12. Consistent with this view, these two responses show distinct ontogenies, with spontaneous yawns emerging early on within intrauterine development in humans13, while contagious yawns do not appear until early childhood14. Furthermore, spontaneous yawns seem to be a universal act across members of a given species, whereas the expression of yawn contagion appears to show much more individual variability. For example, depending upon the methods and stimuli used, only ~30–60% of people show contagious yawning across laboratory and semi-naturalistic settings7,8,15–17, with similarly variable response rates observed for non-human primates18. The fundamental differences between these two yawn-types have led some researchers to propose that yawn contagion may reflect a form of higher-level social-cognitive processing (e.g., emotional contagion or state matching)19–21. Indeed, a large body of research has explored the proposed connection between yawning and empathy, with lines of supporting evidence coming from correlational studies15, in-group/out-group comparisons22, neuroimaging investigations23, and clinical studies24. Consistent with this view, one study even showed a negative association between contagious yawning and measures of psychopathy in a non-clinical population25. However, 1 Psychology Program, SUNY Polytechnic Institute, Utica, NY, 13502, USA. 2Department of Psychology, University of British Columbia, Vancouver, BC, V6T 1Z, Canada. Correspondence and requests for materials should be addressed to A.C.G. (email: ) Scientific Reports | (2019) 9:294 | DOI:10.1038/s41598-018-36570-2 1 www.nature.com/scientificreports/ a recent review of this literature concluded that the empathy/contagious yawning link is weak and inconsistent, with the majority of studies failing to observe the predicted effects derived from this empathy modeling hypothesis9. In fact, recent experiments have shown that the susceptibility to contagious yawning among humans is tied to the perceptual encoding of the act in others and is unrelated to psychological traits linked with empathy or emotional processing26. Others have argued that it is not necessary to implicate a link between contagious yawning and higher-order cognitive processes27,28. For example, given the physiological consequences of this motor action pattern (i.e., enhanced intracranial circulation and brain cooling), the spreading of this response through contagion could have evolved to coordinate group arousal or activity patterns and promote collective vigilance16,29. Further research in these areas is needed, but the fact that individual differences in contagious yawning may predict important aspects of psychological and perceptional functioning deserves further attention. Despite the involuntary and impromptu nature of yawns, and the potential benefits from this action, the expression of yawning is often stigmatized in social settings. In fact, yawns are interpreted as a sign of boredom and disrespect across different cultures30. This seemingly widespread, negative public perception surrounding yawning is presumably a result of the temporal associations between reduced states of alertness and sleep/wake cycles31,32, i.e., yawns are known to occur when individuals are bored or drowsy so this act might indicate one’s disinterest or reduced mental status. Some researchers have therefore speculated that yawning serves a primary communicative role, in which yawns signal internal states to others33,34. However, a central signaling perspective fails to take into account that spontaneous yawns are widespread among solitary species, and often occur when alone even among gregarious animals11,35. Moreover, yawns are triggered by a multitude of factors, and are associated with a markedly variable array of contexts, stimuli and internal states (i.e., not just when we are bored or sleepy)7,36, and as a result could not serve as reliable signals. Nonetheless, the presence of others, i.e., audience or mer (...truncated)