Sunday, November 22, 2009

So, why is yawning contagious?

What intrigues me most about laughter is how it spreads. It’s almost impossible not to laugh when everybody else is. There have been laughing epidemics, in which no one could stop and some even died in a prolonged fit. There are laughing churches and laugh therapies based on the healing power of laughter. The must-have toy of 1996—Tickle Me Elmo—laughed hysterically after being squeezed three times in a row. All of this because we love to laugh and can’t resist joining laughing around us. This is why comedy shows on television have laugh tracks and why theater audiences are sometimes sprinkled with “laugh plants”: people paid to produce raucous laughing at any joke that comes along.

The infectiousness of laughter even works across species.


Shared laughter is just one example of our primate sensitivity to others. Instead of being Robinson Crusoes sitting on separate islands, we’re all interconnected, both bodily and emotionally. This may be an odd thing to say in the West, with its tradition of individual freedom and liberty, but Homo sapiens is remarkably easily swayed in one emotional direction or another by its fellows.

This is precisely where empathy and sympathy start—not in the higher regions of imagination, or the ability to consciously reconstruct how we would feel if we were in someone else’s situation. It began much more simply, with the synchronization of bodies: running when others run, laughing when others laugh, crying when others cry, or yawning when others yawn. Most of us have reached the incredibly advanced stage at which we yawn even at the mere mention of yawning—as you may be doing right now!—but this is only after lots of face-to-face experience.

Yawn contagion, too, works across species. Virtually all animals show the peculiar “paroxystic respiratory cycle characterized by a standard cascade of movements over a five- to ten-second period,” which is the way the yawn has been defined. I once attended a lecture on involuntary pandiculation (the medical term for stretching and yawning) with slides of horses, lions, and monkeys—and soon the entire audience was pandiculating. Since it so easily triggers a chain reaction, the yawn reflex opens a window onto mood transmission, an essential part of empathy. This makes it all the more intriguing that chimpanzees yawn when they see others do so.

Yawn contagion reflects the power of unconscious synchrony, which is as deeply ingrained in us as in many other animals. Synchrony may be expressed in the copying of small body movements, such as a yawn, but also occurs on a larger scale, involving travel or movement. It is not hard to see its survival value. You’re in a flock of birds and one bird suddenly takes off. You have no time to figure out what’s going on: You take off at the same instant. Other­wise, you may be lunch.

Or your entire group becomes sleepy and settles down, so you too become sleepy. Mood contagion serves to coordinate activities, which is crucial for any traveling species (as most primates are). If my companions are feeding, I’d better do the same, because once they move off, my chance to forage will be gone. The individual who doesn’t stay in tune with what everyone else is doing will lose out like the traveler who doesn’t go to the restroom when the bus has stopped.

(via Discoverblogs)

Also, does susceptibility to others' yawning mean you're a nicer person (empathy and all.. )?