It is common to see someone yawning and unconsciously start to yawn as well, even if we are not tired ourselves. Why is yawning contagious? Scientists have given various explanations for the contagiousness of yawning, including the theory of empathy, primitive communication, and the psychology of conformity, but there is still no unified answer.
[Is the Primitive Reflex of the Brain Triggered?]
Recently, researchers from the University of Nottingham in the UK reported in the latest issue of the American journal "Contemporary Biology" that they recruited 36 adult volunteers and showed them videos of yawning. They asked some of the participants to resist yawning, while the control group was allowed to yawn freely.
During the experiment, the researchers continuously recorded the number of yawns of the volunteers and measured the excitability of the motor cortex of the brain using transcranial magnetic stimulation technology. The results showed that people's tendency to be infected by yawning varied, and the excitability of the motor cortex was closely related to the urgency of yawning. By artificially enhancing the excitability of the motor cortex, the urge to yawn could be enhanced.
According to the news release issued by the researchers, the yawning signal automatically triggers the primitive reflex of the motor cortex of the brain, and being infected by yawning is a kind of "imitation phenomenon", which means imitating the behavior or language of others, mechanically repeating specific actions or language involuntarily. This imitating characteristic is also a way for primitive humans to integrate into the collective. By imitating the same actions, they can express common attributes and avoid enemies. This imitating behavior is not limited to humans alone, dogs and chimpanzees also have the same tendency.
[Is it a Chain Reaction of Empathy?]
Yawning is not exclusive to humans. Animals such as cats, dogs, and birds also yawn, but the contagion of yawning only occurs between humans and advanced primates such as gorillas.
Neurobiologists have found that only vertebrate animals with developed cerebral cortex have the ability to recognize yawning and infect each other. This is the responsibility of "advanced consciousness and intelligence" of the brain, and it is a very complex social behavior because they can understand the thoughts of their companions, feel pain for the pain of their own kind, and feel joy for their own kind. Therefore, under the influence of "empathy", they will reflect their companions' yawning behavior on themselves, resulting in a "chain reaction" of repeating the same action.
In 2007, a study from the University of Connecticut observed the reactions of 24 children with autism and 25 normal children after watching videos of yawning. The results showed that the 25 normal children were more likely to yawn after watching the videos, while the children with autism had almost no changes before and after watching the videos. This to some extent proved the relationship between contagious yawning and the ability of empathy. It's like when you see someone fall, you will also say "ouch" to show empathy. Therefore, people who are not good at empathy and social communication are less likely to be affected by yawning, and these people are often not good at putting themselves in others' shoes.
[Unconscious Imitation of "Emotional Contagion"?]
However, some experts believe that contagious yawning is not empathy, but a kind of "emotional contagion". Chen Wei, an associate professor in the Department of Psychology at Shaoxing University, explained the characteristics of emotional contagion using the example of watching the movie "Jurassic Park": when the protagonist is chased by a giant dinosaur after being injured, the dinosaur repeatedly tries to bite the protagonist's leg. The whole scene is very tense and exciting, and the audience's reaction may be even more intense. When the dinosaur is about to bite the protagonist's leg, the audience will instinctively retract their own legs. This shows that the audience seems to feel that the threat is directed at their own legs, so they "begin to act" accordingly. This behavior of directly copying specific actions of others but ignoring the goal or intention of the behavior is also called unconscious imitation.
Chen Wei explained that emotional contagion is an intuitive response to the emotional state or needs of others, and does not include cognitive understanding of the situation and the psychological state of others. That is, when individuals perceive the state of objective things, a special natural response is generated. In contrast, empathy is a higher-level ability shared by humans and many other mammals. It allows us to stand in the shoes of others, understand and appreciate others' emotions, and generally includes two types: emotional empathy and cognitive empathy.
"As a direct intuitive response to the state of others, yawning allows people to experience the feelings of others, such as stress, anxiety, boredom, etc. Therefore, to be precise, the behavior of contagious yawning should be regarded as emotional contagion rather than empathy." Chen Wei emphasized.
