基于社会功能假说探讨应激对传染性哈欠的影响

An exploratory empirical examination on the social hypothesis of contagious yawning

看到周围有人打哈欠,我们自己可能也会跟着打哈欠,这种由他人哈欠诱发的哈欠被称为传染性哈欠.传染性哈欠在生活中很常见,但原因和机制的分析还非常有限.哈欠的社会功能假说认为,哈欠可能具有交流功能,用以传递威胁或预警信息,使得哈欠的传染具有一定的适应意义.然而,该假说更多的基于动物观察推测而来,少有实证探讨,在人类群体中相关考察更是稀少.基于这一假说,研究对60名大学生采用社会压力任务激活应激状态,监测心电反应并通过正性负性情绪量表中文版与放松状态主观评定问卷对自己当前的情绪状态进行自我评定,采用眼中读心任务测量心理理论,同时采用匹兹堡睡眠质量指数和斯坦福嗜睡量表控制睡眠状况和警觉程度,考察心理应激与传染性哈欠的关系及其影响因素.结果发现,心理应激会显著增强传染性哈欠,却不会影响自发性哈欠.同时,被试的心率变异性越高,对应影响越不明显;心理理论越高,对应影响则越明显.上述结果为哈欠的社会功能假说提供了支撑,提示传染性哈欠在漫长的演化过程中可能承担着重要的交流功能,有着特定的适应意义.

Seeing other people yawning, we may also yawn accordingly. This phenomenon was known as contagious yawning, which could be widely observed in humans and was also documented in some social species like chimpanzees and bonobos.While contagious yawning has attracted the attention of many researchers, the function that contagious yawning might serve is still unclear. The social hypothesis of yawning proposed that, as a non-verbal form of communication, yawning synchronized the behavior of a group as well as communicating messages that group members could share. For example,when predators approach, baboons would yawn, which was hypothesized as sending a signal of danger. However, the hypothesis was seldom empirically examined. In the current study, we aimed to examine this hypothesis by exploring the influence of psychological stress on contagious yawning. Psychological stress is intimately related to the threatening environment, which implies that it might increase contagious yawning if yawning was evolved to communicate threatening messages. Accordingly, the heart rate variability(HRV) and theory of mind(To M) might regulate the above effect,considering that HRV is a physiological signal related to threat perception, and To M serves as a basis of social understanding.To examine the hypotheses, we recruited 60 college students and divided them evenly into two groups—The experimental group and the control group. For the experimental group, participants were asked to take part in the Trier Social Stress Test(TSST), which was used to arouse psychological stress. Then their contagious yawning was measured with two indicators: The impulse to yawn and the frequency of yawning(recorded by the camera) after seeing yawning videos clips. Moreover, we recorded participants’ HRV with Bio Pac MP150(Biopac Systems Inc, USA) and measured their To M with Reading the Mind in the Eyes Test. For the control group, measures and procedures were mostly the same as the TSST, but were far less demanding for participants. Besides, since sleep quality and sleepiness were related to yawning,they were included as confounding variables, and which were measured respectively with Pittsburgh Sleep Quality Index and with the Stanford Sleepiness Scale.The results showed that, compared with those from the control group, participants in the experimental group showed more intense yawning impulse and yawning frequency. Also, as predicted the HRV and To M did moderate the effects.Specifically, participants with high HRV showed less contagious yawning compared to those with low HRV;participants with high To M showed more contagious yawning compared to those with low To M. These findings provided empirical support for the social hypothesis of yawning. In evolution, contagious yawning might serve a survival function by alerting conspecifics to potential threats in the environment. Though this survival function of contagious yawning probably is no longer involved in everyday life of modern humans, contagious yawning itself has survived the flood of time along with other similar phenomena like behavioral mimicry and emotional contagion, probably all thanks to the mirror neuron system which remains significance with evolution by enabling human learning generally.