why do people yawn? and why does it make other people yawn too ?
542822
yawning is usually a result of a slight lack of oxygen. therefore if one person yawns, the same conditions exist for others in the room.
55666
I saw something on this before..it said that if you yawn when other people yawn..your a sympathetic person.  In my observing this..I've noticed it's kind of true..particularly..there is a guy that I work with who NEVER yawns when he is around other people who are yawning.  He is not a very sympathetic person at all about anything..kind of rude..or short..I don't know..not very people friendly.  However my friend and I at work are very sympathetic..and we always yawn at the other's yawn! :)
33139
we yawn to equalise the pressure difference between our ears and the outside. when u yawn you equalise the pressure in your ears but there is a disbalance created in the atmosphere and hence others around you also start yawning....!!!!
335882
It is a "associative" reaction. You see someone yawn and it triggers the same reaction because in our experience yawning represents being tired. We therefore associate yawning by others or ourself with being tired.\n\nI get a similar associative reaction when my daughters and I say the Lord's Prayer every night at bedtime. Halfway thru the prayer they will both yawn like clockwork. They both associate the prayer with being sleepy. Puts them right to sleep every time!
435953
It's not that they are contagious.  Its just that people yawn because their brain isn't getting enough oxygen and when someone sees another person yawning they....yaaaaaaaawwwwnn.  And then another person sees THEM yawning and they think, "Hey, maybe MY brain needs more O2.  I think I'll just Yaaaaaaaawwwwn.  And then another person sees them yawning and they think, "Oh no, I don't have time to Yaaaaaaaaaawwwnnn."  And then another person sees them yawn and they sa...yaaaaaaaaaawwwwn.  I think this answer is making me sleepy.  Good night.
371295
Yawns are contagious because most of us when seeing another yawn, we will hold our breath unintentionally...those few seconds cause a lack of oxygen which is what makes people yawn! Try it out next time you see someone yawn...make a point to make sure you breathe regularly and you'll see that you won't yawn.
321997
Cause when you yawn, you are thought to release carbon dioxide, and when somebody else gets the carbon dioxide, then they have to release it.  Another theory is, a long time ago when humans first existed, it meant it was time to go to sleep, so everyone would know toy go to sleep.  Isn't that so cute?  ^.^
449198
Not contagious but we are affected by an others yawning. This is called "Alolomimea" funny name but its what its called. Scientists believe that the reason we react to other people yawning is because in our early history ("caveman times") we needed to regulate our sleeping patterns so we could all survive together. Kinda like one for all and all for one deal. So if one of our cavemen buddies was tired we would all need to rest so we could all effectively hunt as a unit. It served  us as a natural "hey dude im tired lets take a break so we can hunt better and not die" It's a true story!
260771
we yawn when we get bored and it is very embarrsing esp. in public places,with me once they start they go on and on. maybe you idnt check yourself form childhood and now its a habit. force yourself to stop opening the mouth you will gradually overcome it.
537048
Because according to psychology, they are sympathetic responses.  Its funny that in a test, people who didn't yawn after seeing others yawn were found to be anti-social.
394382
Yawns are contagious because people naturally emulate what they see others doing. For more, read a section in the Tipping Point by Malcom Gladwell.
15767
People sometimes yawn when they are bored.  This reminds others that they too are bored.  Have you ever seen someone on a roller coaster yawn?  Fortunately you have asked an interesting question, otherwise I would likely be forced to yawn <G>.
17567
Yawning is one of those bodily mysteries that scientists haven't completely figured out yet.  The best theory I could find was that you yawn because you're not getting enough oxygen to the brain (maybe there is a lack of oxygen in the space you're standing).  Whenever you're aware of someone yawning, it activates a reaction in your subconscious mind that acts as a threat response.  Basically, whenever you see someone yawn, it makes you body think there is a shortage of oxygen too, and you yawn in response.  No one knows if this is actually the case, but I think that it is a good theory.
1005855
(1)"Virtually any stimulus associated with yawns -- including viewing, reading about, and even thinking about, yawning -- evokes yawns. (Are you yawning yet?) Yawning spreads in a chain reaction through a group, a compelling example of human herd behavior and a reminder that we are not always in conscious control of our actions. The urge to replicate an observed yawn is clearly an automatic response triggered by our brains.\n\nStudies partially explain the reason for yawning. Although we yawn more when sleepy or bored, it is unclear whether yawning increases alertness. And scientific evidence refutes one of the most popular myths of yawning? that it happens in response to low oxygen or high carbon dioxide levels in the blood or brain. Test subjects do not yawn more when breathing air with enhanced levels of carbon dioxide nor do they yawn less when breathing pure oxygen. One fact explains a lot of apparently inconsistent data. People yawn most during behavioral transitions, such as just after waking and shortly before bedtime. Yawning may help facilitate those changes. Contagious yawning may synchronize a group's behavior so that, for instance, a whole family goes to sleep together."\n\n(2)  "Professor Andrews told Scientific American yawns may be contagious because we human animals are trying to communicate changing environmental conditions to others, possibly as a way to synchronize behavior. Obviously, this would be one of those caveman-type mechanisms that is no longer needed that our bodies remember and still do.\n\nWhen we yawn, we draw in more oxygen and remove a build-up of carbon dioxide. Larger groups produce more carbon dioxide. So one theory holds that we yawn when we're in large groups of people to purge the carbon dioxide--and in so doing, we set off a chain reaction. But Robert Provine, a psychologist at the University of Maryland, Baltimore County, tested the theory and says it's bunk. Giving people additional oxygen didn't decrease yawning and decreasing the amount of carbon dioxide in a subject's environment also didn't prevent yawning, notes the How Stuff Works Web site.\n\nWhatever the reason for yawns being contagious, How Stuff Works reports that 55 percent of people will yawn within five minutes of seeing someone else yawn. In addition, blind people will yawn after hearing others yawning. And we're sure that reading and writing about yawns is enough to induce one!"
220911
Why is yawning infectious? \n\nGemma Martin, London UK\nWhen you yawn, you equalise the pressure in your middle ear. This causes a small, localised pressure change around you, which affects others in the vicinity - and therefore they have to yawn to equalise the pressure in their own middle ears. \n\nJoe Lambert, Norwich, England\nIt's a left over mechanism from our days as troupe creatures. Infectious yawning meant that we slept togther as a group when the most tired required to sleep. \n\nPeter Brooke, By Kinmuck Scotland\nIn 1990,in Guardian Notes and Queries vol.1, an answer was that it was part of a mechanism to "synchronise wake/sleep cycles" among people in a social group, and that yawning is poorly understood. I don't know if progress has been made since then. \n\nivor solomons, norwich england\nThis applies only to group/troupe animals. It supplies a method for the most sleepy to forcefully communicate their need for rest and thus ensures that the group rests/sleeps together. \n\nPeter Brooke, By Kinmuck, UK\nYawning is essentially a reflexive method of increasing oxygen intake. Oxygen intake in this manner is primarily used as a means to stay alert. When we observe others yawn it triggers a warning to ourselves that we are in a situation where we need to be alert, hence the infectious desire to yawn yourself. \n\nAndy Preston, Otley, UK\nIf you accept the theory that yawning is related to breathing, as a means to either redistribute lung surfactant or to temporarily increase air intake, it may be that watching someone yawn triggers a subconcious concern about one's own ability to breathe, hence mimicking the yawn. Alternatively, it may be a throwback to primate warning signs, which involve displaying of teeth when threatened. The common response to this is a reciprocal baring of teeth. \n\nBrendan O'Sullivan, Birmingham, UK\nThere is no one answer to this question, other than unsatisfying ones like "because we evolved that way". Or more accurately, some species in our distant past evolved that way (if you yawn at a dog, it will often yawn back, and chimpanzees also exhibit contageous yawning). Yawning might help communicate to other members of a group that it's time for everyone to settle down for a snooze, but (like laughing and frowning), it's hard to explain why this particular behaviour should represent this meaning. \n\nAllan Dean, Wimbledon \nI've heard it's because when the alpha male in the group of apes (which turned into us)had checked everything out and knew it was safe to sleep he would yawn to other apes, as a message that all was safe, and they in turn would yawn the message through the group, so it's instinctive. \n\nDonna Thomas, Bristol, UK\nIt's because you're afraid that other people are stealing your air \n\nJimmy, Ceredigion, Wales\nSteven Platek, a professor of cognitive neuroscience at Drexel University in Phildelphia, has carried out research correlating the "echoing" of yawns with the empathetic response of the individual. In other words it is a kind of social response, and those deficient in the ability to make emotional bonds (schizotypal individuals) are less likely to yawn back. \n\nTony Dunlop, Zeal Monachorum, England
467214
Yawns are one of the brain's ways of getting oxygen and fighting fatigue. If someone yawns in response to your yawn it's because they are feeling the same fatigue you are.
204275
Yawning or "pandiculation," is still pretty much a mystery to psychologists. (I just asked a friend in the trade.) Aside from the obvious observations of how it's related to boredom and how it gets "contagious" after a certain period of development in people, there isn't that much information on it. Sorry. (Hey, this is info from an old friend, so you might want to check newer sources.)