When you see someone else yawn, why does that make you have the urge to also yawn?
607567
Urge to yawn on seeing someone else yawn is called reflex yawning. When you see someone else yawn, it sends a message across your brain that you also need more oxygen and as a response your open your mouth wide in an attempt to get in more air and your lungs expand (i.e you yawn).
412939
i think they are.. whenever i see anyone yawning i HAVE to yawn
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! :)
261027
Why is this the second most asked question on here?  If the guys would stop asking about the size of their "manhood", this would be number one!\n\nWhy we yawn when we see others yawning has baffled scientists for ages and a number of suggestions have been put forward to explain this phenomenon. What we do know is that yawning is an involuntary action- our brain does it without us thinking about it, even very young babies yawn showing that it's a built in action (Chimps do it too by the way). Just thinking about yawning can trigger the bit of the brain that causes a yawn. http://www.ratlab.co.uk/yawn.htm...\n\nMore theories can be found at the links below: \n\nhttp://www.world-science.net/exclusives/...\nhttp://www.yesmag.bc.ca/questions/yawn.h...
255818
The yawn reflex is often described as contagious: if one person yawns, this will cause another person to "sympathetically" yawn. The reasons for this are unclear; however, recent research suggests that yawning might be a herd instinct. Other theories suggest that the yawn serves to synchronize mood behavior among gregarious animals, similar to the howling of the wolf pack during a full moon. It signals tiredness to other members of the group in order to synchronize sleeping patterns and periods of activity. It can serve as a warning in displaying large, canine teeth, thus proclaiming, "don't attack while I am sleeping..." The contagion of yawning is interspecific (i.e., try yawning in front of your dog). Ironically, yawning in public is generally regarded as impolite in the West, but came into fashion in polite French society for a brief period in the late 18th century. Oddly, sometimes sympathetic yawning may be caused by simply looking at a picture of a person or animal yawning, or even seeing the word "yawn".
1177906
Yawning is your body's attempt to get more oxygen.  When you are tired, your breathing tends to get more shallow, and your body tries to compensate by making you yawn - bringing in more oxygen.\n\nHere's some more information on yawning, and why it's "contagious".
54372
Well, I don't know why yawns are contagious because scientists really don't know what cause yawn's in the first place. However, on a lesser level, I believe yawns are contagious because when you see someone yawn, you tend to think of how tired you are. Therefore, you yawn too. And plus it is pretty amusing when you have a yawn fest with someone and just cannot stop yawning back and forth.\nHope this helps!\n\nP.S. I yawned while writing this...twice actually ;)
345712
It is herd behavior, it signals when the herd needs to move on to something else. When one person yawns, it is passed along to 'pass the message.'
476267
I have no idea, but it happens every time I yawn LOL. I have seen people do it intentionally though.
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?  ^.^
526472
I learned somewhere that this is a survival thing--if you are yawning, there might be a lack of oxygen or you are about to need a lot of oxygen.  Your yawn alerts others so they supply themselves with oxygen as well.
977252
From Wikipedia:\n\n"A previous long-standing hypothesis is that yawning is caused by an excess of carbon dioxide and lack of oxygen in the blood. The brain stem detects this and triggers the yawn reflex. The mouth stretches wide and the lungs inhale deeply, bringing oxygen into the lungs and hence to the bloodstream. It is almost certain, however, that this hypothesis is not correct. One study has documented that this effect does not exist."\n\nGoes on to newer, updated theories.\n\nAlso:\n\n"The reasons for this are unclear; however, recent research suggests that yawning might be a herd instinct. Other theories suggest that the yawn serves to synchronize mood behavior among gregarious animals, similar to the howling of the wolf pack during a full moon."\n\nGoes on to give other reasons for contagion. <Yawn!> Enough!
397407
Though the other answers are right (that yawning occurs to signal tiredness when the brain demands extra oxygen due to slipping performance), I would like to add another related comment.\n\nI recently read in the newspaper that scientists are discovering that yawning is a signal of compassion.  Researchers conducted studies in which participants watched videos of people yawning and the researchers measured the time between the yawn of the person on the video and the ensuing yawn of the study participant.  They then somehow effectively linked this elapse to compassion; what they stated was that the quicker you yawn after you see someone else yawn, the the more compassionate you are.\n\nRegretfully, I don't know the web address of the article, which I found intriguing, but I think it is worth your time to investigate.
273757
Seeing someone yawn, hearing them yawn, or even hearing the word "yawn" triggers a reaction in our brain. Yawn contagion is largely unconscious. Wherever it might affect the brain, it bypasses the known brain circuitry for consciously analyzing and mimicking other people’s actions.\n\nThis circuitry is called the “mirror-neuron system,” because it contains a special type of brain cells, or neurons, that become active both when their owner does something, and when he or she senses someone else doing the same thing. \n\nSo basically, it's an unconscious thing that the brain does, in most cases.
196592
It is the brain requiring more oxygen. Which is why when someone else yawns you do to, it is your brain making sure that it has enough in case the other person takes it all. Not very likely to happen unless in a confined space, but the brain is always on survival mode.
662014
This came up in my sister's wildlife biology class--in the wild, animals that live in herds do something similar to a yawn when everything is peaceful and there is no danger lurking (like lions), and the yawn passes from one animal to the next as a signal.  Apparently the biological urge is in humans as well--maybe we are passing along that we are relaxed and not feeling threatened.
307772
Just a guess...  When you yawn, you take in more air than normal.  This means you get more oxygen than normal.  In a situation where it might be important to get more oxygen than your normal breathing urge will provide, an animal that yawns will have an advantage over one that doesn't yawn.  Since there is no disadvantage to yawning and occassionally there is an advantage, a mutation that causes an animal to yawn in response to another yawn would be passed on.