Why Are Habits Like Yawning, Scratching, Crossing Legs Contagious?
There is such a thing called the yawning contagion — and while that, to me, sounds like a bunch of people waking up early in the morning and sitting around yawning in a park, it’s actually an interesting bodily phenomenon. We know yawning is contagious, and as someone who has yawned continuously while writing this article, I can attest to it. But why do humans and other animals mirror each other’s actions? Scientists have myriad explanations.
Yawning contagion is a form of echophenomena. It is defined as the “automatic imitation of another’s words (echolalia) or actions (echopraxia)”, and can can involve other habits, such as scratching, crossing one’s legs, even smiling or frowning, and can be the basis of neuropsychiatric syndromes such as Gilles de la Tourette syndrome (a nervous disorder characterized by tics).
The most common explanation of echophenomena is that emotionally intelligent animals are prone to mirroring an action seen in another animal out of empathy, which one 2010 study suggests children develop around the age of four. With the onset of the ability to empathize, young children start being susceptible to contagious yawning and other mirroring behaviors. On the contrary, a report showed that people who exhibit psychopathic traits, particularly those characterized by a lack of empathy, are less likely to be susceptible to contagious yawning.
The 2010 study also evaluated the mirroring behaviors of young people with autism, a condition associated with difficulty in communication, wherein people feel and exhibit empathy differently. It shows that the frequency of contagious yawning was less compared to those that didn’t have autism. Here, it’s not a lack of empathy that explains the absence of mirroring behavior, but differing perceptions of social cues and responses to them. Another explanation, for those with autism mirroring actions less is that people with autism tend not to make eye contact, which makes observing others’ behavior, and subsequently echoing it, difficult, a study shows.
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The evidence, however, is inconclusive. A review of studies shows the relevance of empathy in determining if a person would be affected by the yawning contagion is high in some, and absent in others, prompting researchers to investigate other sociable characteristics in humans that could contribute to understanding the phenomenon. The review also found that women are more likely to mirror others’ behavior than men, but failed to provide analysis. However, extrapolating the earlier argument, it is well known that women bear the burden of emotional labor in society, and while not evolutionarily evolved to empathize more, they are certainly expected to.
Aside from gender, the review found a correlation between experiencing contagion and age — one study included found 82% of participants under the age of 25 yawned after watching a video of someone yawning. The probability of catching a yawn decreased as the age of participants increased, which researchers said was reflective of how the older someone gets, the less attention they pay to those around them.
Some scientists say the mirroring phenomenon is an evolutionary trait that helps animals, and not just the emotionally intelligent ones, survive in the wild. In the face of a threat, if an animal exhibits a certain behavior, say face-scratching or yawning, it would be mirrored by the animals around it, thus continuing in a chain until surrounding animals know there is a threat. In this instance, the contagion serves to alert and is done through mirroring that acts as a way of communication, according to a study.
Contagious itching behavior in mice works in a similar way, exemplifying the evolutionary development of echophenomena. When study researcher Zhou-Feng Chen, director at Washington University’s Center for the Study of Itch, showed a mouse a video of other mice scratching, he observed the mouse started scratching within five seconds. When animals observe other animals exhibiting a behavior, they assume it’s useful, and start partaking themselves, Chen told PBSNewsHour. “’This behavior must be very useful. So, I better do it,’” he said, explaining the thought process.
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Yet another reason for echophenomena might reside in the brain. In monkeys, motor cells in the front of the brain with mirroring properties have been identified. They vary in their ability to perceive different actions, Wired reports on a study published in Cell: “Some motor cells only show mirror-like responses when a monkey sees a live performer in front of them; other cells are also responsive to movements seen on video. Some mirror neurons appear to be fussy – they only respond to a very specific type of action; others are less specific and respond to a far broader range of observed movements. There are even some mirror neurons that are activated by the sound of a particular movement.” This is because only sensory information from the perception of a particular action is not enough; the inner motor reaction also depends on “the angle of view, the reward value of the observed movement, and the overall goal of a movement, such as whether it is intended to grasp an object or place it in the mouth,” Wired reports. Mirror neurons are complex, and so far, their existence has only been documented in monkeys. It remains to be seen if these cells are present in humans, and if so, whether they act like they do in monkeys.
So, while scientists research this everyday phenomenon further, I choose to believe I hold 10 yawns per minute worth of empathy. *yawn*