If looking at the image above makes you yawn, you’ve just experience contagious yawning.
What is yawning? And why do we do so much of it? Neuroscientist and yawn expert Robert Provine says it’s “ancient and autonomic.” It stems from early evolution and is common to many creatures—even fish do it.
It’s autonomic in the sense that it roots in the brainstem, way down in the basement level of the brain, where certain responses are so built-in they don’t even qualify as reflexes.
Yawning has many triggers, including boredom, sleepiness, and temperature.
A 2014 study suggested that there’s a “thermal window” (at around 68°F) for human yawning; as ambient temperature approaches body temperature or goes down near freezing, we yawn less.
According to the paper, we may yawn to regulate the temperature of our brains. This isn’t the same as saying we yawn to take in extra oxygen, as evidence to date says we don’t.
It means that yawning might act to draw brain-soothing ambient air in through the nose and mouth.
Over the years, scientists have observed “contagious yawning” in chimpanzees, humans, baboons, bonobos, wolves, and, to a certain extent, dogs. Yawning feels good, so why not join in when someone else yawns?
Well, you’re not really “joining in,” because you aren’t copying the yawn on any conscious level. It happens because you just can’t help it. If you become self-conscious about a yawn, it stops.
While many past studies have documented the phenomenon, a more recent study, published in the journal Adaptive Human Behavior and Physiology, contends that yawns may not be contagious after all—or at least that we have not yet proven it.
Experimental psychologist Rohan Kapitány of the University of Oxford conducted a review of the scientific literature on contagious yawns and found very little conclusive evidence to back up our long-held assumption that yawns are contagious.
“The belief that yawns are contagious seems self-evident,” Kapitány said, “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 unstandardized methodologies and conclusions.”
Still, because Kapitány’s study was small and extremely limited, he and his fellow authors urge other scientists to challenge their findings with experiments of their own.
“I may be wrong!” Kapitány said. “Maybe yawns are contagious!” Kapitány says he’d like to see “more robust” attempts to falsify the claim that yawns are contagious rather than “simply demonstrating it over and over [in] slightly different contexts with richer and richer explanations.”
WHO DOESN’T CATCH YAWNS?
Some people with autism or schizophrenia don’t exhibit a yawn-contagion response. The same is true of children under the age of four years. This has led to a variety of theories about yawning’s relationship to empathy and the brain’s mirror-neuron system (MNS).
The idea here is that MNS deficits might lead to missing hidden empathetic cues that trigger contagious yawning. The MNS seems to be involved in the process to some extent.
fMRI scans on a range of people have shown that other parts of the brain also “light up” in response to images of yawning, perhaps more so than the areas normally associated with empathy.
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