Thursday, June 16, 2005

Why Is Yawning Contagious?

Today as I was riding home from campus on the bus, I was talking on the phone, and my interlocutor yawned. Almost immediately, I yawned as well. She made a joke about it, and I said that it wasn't my fault, because yawning is contagious -- when you see or hear someone yawn, you tend to yawn as well. I thought that was a well-known fact, but apparently she had never heard it, or noticed it before, so my first instinct was to prove that it was true by explaining to her why it happened. Then I realized that I had no idea why it happened. So I decided that when I got home, I would look it up. Let it never be said that I am not a geek.

So, I got home and started researching the topic, and quickly discovered that I was not alone. It seems that nobody's sure why yawning is contagious. There do appear to be some differences in individuals who are susceptible to contagious yawning and those who are not1. In particular, contagious yawners score lower on the Schizotypal Personality Questionnaire, which was designed to measure the symptoms of Schizotypal Personality Disorder. These symptoms involve less social and self-awareness, along with schizophrenia-like symptoms such as altered or unusual perceptions, particularly in social contexts, which can lead to paranoia. Lower scores on the test indicate lower levels of schizotypal symptoms. Contagious yawners also performed better when answering questions about stories designed to test for theory-of-mind ability. Finally, they also had much faster reaction times when asked to identify their own face presented on a computer screen. Steven Platek and his co-authors argue that these findings, that contagious yawners score lower on the Schizotypal Personality Questionnaire, and show better theory-of-mind and self-recognition performance, indicates that self-awareness and empathy underlie contagious yawning.

This would fit with what we do know, and can easily see about contagious yawning: it is automatic and unconscious. We don't try to yawn when we see or hear someone else do so; we just do. Self-recognition and theory-of-mind mechanisms are generally fast, automatic, and unconscious, and thus it is plausible, given the data described above, that they are involved in contagious yawning. But the data I described above is pretty thin, and is certainly open to alternative interpretations. To find out for sure, I looked to neuroscience. Unfortunately, when I got there, the picture got a bit muddier. In a very recent study (published in February), researchers had participants watch videos of yawning while they were scanned using functional magnetic resonance imaging (fMRI)2. They found that people who watched the yawning videos had increased activation in the right posterior superior temporal sulcus and in the anterior superior temporal sulcus in both hemispheres. These areas are associated with the processing of social information, and the increased activation in these areas thus fits with the theory that social awareness may underlie contagious yawning. However, they did not find activation in Broca's area, which is thought to house the human version of the mirror neuron system, and believed to be associated with theory of mind. Furthermore, they found that participants who watched the yawning videos showed decreased activation in the left periamygdalar region. This area of the brain is associated with the recognition of emotional facial expressions.

These last two findings are confusing, and perhaps inconsistent with Platek's theory. It appears that, while social information processing does underlie contagious yawning, action and emotion recognition, which are parts of our theory-of-mind abilities, are not associated with contagious yawning. However, to make things even more confusing, Platek and his colleagues have conducted their own imaging study3. When contrasted with laughing and neutral videos, yawning videos caused increased activation in the posterior cingulate and precuneus, areas associated with, among other things, autobiographical memory, emotion, and self-judgements. Thus, Platek's findings are consistent with his theory, but inconsistent with the only other imaging study of contagious yawning.

The take home message, then, is that it's not quite clear what causes contagious yawning. Sure, we can say with a high degree of certainty that social-information processing is involved, but that seems obvious. What's less obvious is what else is involved. Are empathy and self-awareness involved? The neuroimaging data is too inconsistent to say for sure.

However, if it turns out that empathy and self-awareness are involved in contagious yawning, then another finding becomes much more interesting. It was previously thought that, while yawning occurs in many animal species, only humans yawned contagiously. It turns out, chimps may yawn contagiously as well. James Anderson and his colleagues published a paper in late 2004 in which they presented six adult female chimpanzees with videos depicting facial expressions, including yawning. When the videos showed yawning, two of the six chimps yawned more frequently than when watching other expressions4. While this is obviously a preliminary finding, if it turns out that chimps do yawn contagiously, and that contagious yawning requires empathy and self-awareness, as Platek argues, then we would have strong evidence that chimps are self aware and have some level of theory-of-mind/empathy.

1Platek, S.M., Critton, S.R., Myers, T.E., & Gallup, G.G., Jr. (in press, 2003). Contagious yawning: The role of self-awareness and mental state attribution. Cognitive Brain Research, 17(2):223-7.
2Schurmann, M., Hesse, M..D, Stephan, K.E., Saarela, M., Zilles, K., Hari, R., & Fink, G.R. (2005). Yearning to yawn: the neural basis of contagious yawning. Neuroimage, 24(4), 1260-1264.
3 Platek, S.M., Mohamed, F.B., & Gallup, G.G. Jr. (In Press). Contagious yawning and the brain. Cognitive Brain Research.
4Anderson, J.R., Myowa-Yamakoshi, M., & Matsuzawa, T. (2004). Contagious yawning in chimpanzees. Proceedings of the Royal Society: Biological Sciences, 271, Biology Letters Supplement 6, S468 - S470.


Anonymous said...

Hmmm. Dogs yawn when they're in stressful situations, often to express that they're not interested in pursuing any potentially violent or stressful situation further. Take a look at I suspect this behavior goes back very far in our evolutionary history as a social palliative.

Anonymous said...

Yes, as to yawning, I always wanted to pass on my little story: I was in a car travelling somewhere on the open road and saw a person in a car coming towards me - yawning. I yawned too! Before that, I had thought that yawning might have been caused by something about air-quality, perhaps by low oxygen levels or something. Obviously not! Something about social interaction etc, as you say, seems to be closer to the truth.

Anonymous said...

If yawning is indeed contagious, one may ask what is the function of such a behaviour. Maybe it's a signal to warn groups about changing cycles in arousal: time to wake up everybody! or Danger, attention is decreasing!
Those interested in yawning may take a look at Olivier Walusinski fantastic website:
It's in French, but contains many documents in English.

Chris said...

oncle, I read some of the papers on that site, though not through that site. It appears, at least from that research, that the function of yawning, as well as its evolution, are still very open questions (one article lists 20 proposed functions from the literature).

Unknown said...

from Chris's post: "... if it turns out that chimps do yawn contagiously, and that contagious yawning requires empathy and self-awareness, as Platek argues, then we would have strong evidence that chimps are self aware and have some level of theory-of-mind/empathy."

How about the mirror test, doesn't that already count for evidence of theory of mind in chimpanzees (and bonobos and orangutans)? Also, deception in chimpanzees has been repeatedly observed. The deceptions can be so multi-layered that the chimps would pretty much have to have theory of mind to perform them.

Chris said...

Lizzie, there is a lot of evidence that chimps, bonobos, orangutans, and perhaps some gorillas, have some level of self-awareness, and perhaps rudimentary theory of mind. However, the debate still rages. If Platek's theory of contagious yawning pans out, and it turns out that chimps really do yawn contagiously (the study cited uses a sample of 6, with only 2 apparent contagious yawners), that would be one more piece of evidence.

Anonymous said...

How about energy levels? I mean did the subjects all have the same level of fatigue? If the other 4 had just waken, or have been up for a bit, and the other 2 were ready for sleep could this be a factor in how susceptible they were (or a human would be) to contagoius yawning?

Anonymous said...

Here's my theory...when a person's electochemical stimuli(chi) is lowered and they become fatigued...the magnetic grid of the earth (magnetosphere) activated a "relativity effect" on a person...electromagnetchemical stimulation of that person...resulting in a human yawn. The air, trees, everything on earth is regulated by these magnet keeps everything in balance.

Anonymous said...

Check out the research on mirror neurons -- there is evidence that when we see others do things, there is a pattern of firings in the brain similar to what would occur if we were to do the same action; perhaps this is what happens when we see others yawn, but it crosses the line into action.

professor mike said...

The answer is easy: the subject succombs to hearing the sound of a yawn, and in turn repeats this process, sort of like mating.

Anonymous said...

I found that social awareness has a lot to do with it. The more someone is aware of his/her surroundings, the more they are likely to yawn.

Unknown said...

hmmm.. just reading the post made me yawn (unvoluntarily, that is).

That would be in the absence of social interaction ;)

touchscreen point of sale software said...

You got a really useful blog I have been here reading for about an hour. I am a newbee and your success is very much an inspiration for me. Please come visit my site point of sale cash register when you got time.

time management plan said...

Wow! Thank you! I always wanted to write in my site something like that. Can I take part of your post to my blog? Please come visit my site time management techniques give me any valuable feedbacks.

Anonymous said...

Thank you for sharing such a nice article.
chaussures puma
puma speed cat
Nike Tn Chaussures
requin tn
nike shox
puma shoes
puma CAT
puma basket
puma speed
baskets puma
puma sport
puma femmes
puma shox r4 torch
nike air max requin
nike shox r3
shox rival r3
tn plus
chaussures shox
nike shox r4 torch
air max tn requin
nike tn femme
pas cher nike
tn chaussures
nike rift
nike shox nz
chaussures shox
nike shox rival
shox rival
chaussures requin
jeans online
cheap armani jeans
cheap G-star jeans

Natural Home Remedies said...

Hey congrats on the new posting come out
btw i love your blog although i have just stumbled upon it =)
Love the new pictures you got there! Please come visit my site Home remedies give me any valuable feedbacks.

Children Health said...

love your blog! Very cool! Please come visit my site Children's health when you got time.

Lethbridge Business Phone said...

Your summaries are always top-notch. Thanks for keeping us apprised. I’m reading every word here.

Lethbridge Business Directory, Lethbridge Agriculture, fishing & Forestry, Lethbridge Apparel & Accessories, business directory listings of Lethbridge Automotive, Lethbridge Business & Professional Services, Lethbridge Computers, Communications & Electronics, home garden furnishing, real estate business finderLethbridge Construction & Renovation, Lethbridge Education, Lethbridge Entertainment & Media, Lethbridge Family & Community, Lawyers Attorneys & Law Firms Directory Lethbridge Finance & Legal,dinning restaurants Entertainment serving Lethbridge Food & Beverages, Lethbridge Health & Medicine Doctors Hospitals, Lethbridge Home & Garden, Lethbridge Industrial supplies & services , Lethbridge Personal Care, Lethbridge Public utilities & environment, Lethbridge Real-Estate & Insurance, Lethbridge Shopping & Specialty Stores, shopping, retail, department stores company guide of Lethbridge Sports & Recreation, Lethbridge Transportation, Lethbridge Travel & Lodging

Unknown said...

New mexico insurance companies, insurance agents brokers and insurance guide. Comprehensive information about New mexico car insurance, home owner insurance, health insurance, life insurance and more.
New mexico
Home Health Care Insurance
, New mexico
Home Insurance
, New mexico
Hospitalization Insurance
, New mexico
, New mexico
Insurance Adjusters
, New mexico
Insurance Agents & Brokers
, New mexico
Insurance Annuities
, New mexico
Insurance Bonds
, New mexico
Insurance Claims & Services
, New mexico
Insurance Claims Processing Services
, New mexico
Insurance Consultants & Advisors
, New mexico
Insurance Employment Agencies
, New mexico
Insurance Examinations
, New mexico
Insurance Examiners