The idea that yawns are contagious has been around since at least 300 BCE. But the past 2,300 years have not produced much good scientific evidence that this is the case, according to a study published in the journal Adaptive Human Behavior and Physiology.
The study concluded that the effect of witnessing another person yawn “is, at best, trivial.”
“I arrived to this topic by way of teaching myself how computer simulations could shed light on human behavior and psychology,” explained the study’s corresponding author, Rohan Kapitány of the University of Oxford. “I thought a small ‘toy problem’ would be to simulate how yawn contagion works. After building my first model, I went looking for a more formal and complete model from the literature and realized no such thing existed. I then began reading the literature on contagious yawning to make my model as useful as it could be.
“I found the written work to be dominated by strange and unreasonable methodological assumptions – some were an artefact of the history of the field, while the origin and purpose of others was less clear. This was when I became interested – here was a very ordinary phenomenon that was not clearly described, and could reasonably be dissected with various methodologies and statistics (which I was interested in cultivating).”
So how did Kapitany and his colleagues go about testing how contagious yawns are?
In a experiment, the researchers broke up 79 undergraduate students into smaller groups and had them sit around a table while they listened to Chopin’s Complete Nocturnes on headphones. Some of the participants wore a blind-fold, while the others did not. The sessions were carefully filmed so that the researchers could analyze the total number of yawns, the timing of yawns, and other factors.
They found that participants produced an average of two-thirds of a yawn per hour on average. They also found that yawns increased over-time, particularly when the participants could see other people. (When the participants could see each other, the average number of yawns per hour jumped up to about 3.5.)
But when the researchers analyzed the timing, they found that a yawn at any given moment did not reliably produce a yawn from another person within 3 minutes. So while people yawn more often in social settings, yawns themselves did not appear to be contagious to others.
“If there’s one thing we should take away from this study is that common sense should be questioned,” Kapitany told PsyPost. “The belief that yawns are contagious seems self-evident, but there are some very basic reasons for why we might be mistaken in this. If we fail to dissect that which we think we know, we might end up with conclusions that do not reflect reality. In this instance, the literature hasn’t questioned the basic features of contagious yawning, and ended up with a wide range of unstandardised methodologies and conclusions.”
“Our everyday experience of this phenomenon is not realistically tested in the lab,” he added. “Meanwhile, a large body of literature in judgement and decision making, cognitive heuristics, and basic statistics can explain the phenomenon away as being illusory. An understanding the true nature of the universe – even if illuminated by this somewhat ordinary phenomenon – always makes us richer.”
Kapitany acknowledged his study had some caveats. And there are areas for future research.
“All models are simplifications. And while I attempted to behaviorally replicate my model, it is far from perfect,” he told PsyPost. “If key authors in the field entertained my rather counter-intuitive position, they would be forced to confront these assumptions. For how long is a yawn contagious? Is it described by linear, or non-linear decay function? What is the cumulative effect of observing multiple yawns? If yawns are contagious, then these questions have answers. If yawns are not contagious, then these questions will be unanswerable – suggesting an alternative explanation from the one that presently exists.”
“Additionally, more cross-cultural research needs to be conducted. So what if people who are WEIRD appear to yawn contagiously (people who are White, Educated, living in Industrialized, Rich and Democratic countries)? If everyone of these people shared the cultural belief that yawns are contagious, we would likely see people yawning as an expectation response. But if contagious yawning is truly contagious and biologically adaptive, it should be universal. To the best of my knowledge, no attempt has been made to investigate this part of the question. And this is something I am attempting to address now (and in the future).”
So should we abandon the idea that yawns are contagious? One preliminary study cannot conclusively debunk the idea. But the research does show that people need to be more agnostic about the effect, rather than treating it as an established scientific fact.
“I may be wrong!” Kapitany admitted. “Maybe yawns are contagious! But if yawns are contagious, I would love to see more robust attempted to falsify the claim and specifically describe the phenomenon, rather than simply demonstrating it over and over it slightly different contexts with richer and richer explanations.”
“As I say in the final lines of my publication, I am more than willing to collaborate with more knowledgeable fellows of the field to improve the resolution of the model – and if I am wrong, perhaps such input would steer me in the right direction. Such advice might mean the model needs to be completely re-written (and I’m ok with that), but to re-write it, very basic questions (like the ones outlined above) need to be answered. So far, no-one has contacted me to improve this model, though.”
The study, “Are Yawns really Contagious? A Critique and Quantification of Yawn Contagion“, was also co-authored by Mark Nielsen.
