It is a scientific fact that during conversation, we mimic the actions and words of the person we are talking to. I had a childhood friend who would unconsciously finish everyone’s sentences with the same word they were saying. It was pretty annoying, but when I asked him why he was doing it, he was completely unaware he was talking at all. Laughter, according to Sophie Scott of University College London, is no different. I noticed this while sitting in class today. I was playing around on my computer while the professor played a video of an interview. The person being interviewed was very nondescript and boring, so my attention waned. I distinctly remember a part of the interview that caught my attention. The interviewer must have said something clever, because at that moment loud, boisterous laughter erupted from the video. I caught myself smiling and laughing along, even though I had no idea what everyone was laughing about. I caught myself and looked around the room to find that other students in the class were smirking and laughing, too. Why is it that we laugh or smile when others do, even if we don’t know why they are doing it in the first place?

A study by Scott had volunteers listen to a series of positive and negative sounds. They had their brain activity monitored via fMRI and measured the response to the sounds. It was found that the brain reacted more to the positive sounds, such as laughter, more than negative sounds (screaming, retching, etc.). The sounds triggered a response in the premotor cortical region of the brain, which is responsible for preparing the facial muscles to respond to sensory queues. The study states that because the response was much stronger for the positive sounds, this can explain why laughter is so contagious.

The study doesn’t exactly provide conclusive evidence, so I decided to dig a little deeper. Apparently, a laughter epidemic was actually recorded in 1962. In a small African village in Tanzania, Three girls began to laugh uncontrollably. Soon thereafter, 95 of 159 students were laughing and crying hysterically. The laughter continued for so long that the school eventually had to be closed, only to reopen later with 50 students still exhibiting the same behavior. The epidemic spread to nearby villages, and for two and a half years over 1,000 villagers were affected by an apparently bad case of “the giggles”. That must have been one hell of an episode of the Big Bang Theory!

It is now known that the two year long laughing fit was potentially caused by a stress-induced mass psychcogenic illness. Does this prove that laughter is contagious, or just that everyone in the village was going crazy? The answer is still convoluted, but the answer could possibly be revealed in an interesting point made by scientists for years (and my older brother). My brother and I were deciding what to watch on Netflix over thanksgiving break when he made an interesting point: movies are much funnier when you are watching them with other people than by yourself. This is true with all things, not just movies. According to researcher Robert Provine, laughter is up to 30 times more frequent in group settings rather than in private. Provine and his colleagues did an interesting study on what happens right before we laugh, in order to find the cause. They went to local malls and public places and recorded over 2,000 cases of natural laughter over a 10-year period from random passersby. Interestingly enough, they discovered that the majority of laughter does not actually follow jokes. It was recorded that most laughter followed statements such as, “How did you do on the test?” or “Do you have a rubber band?”

This helps conclude that laughs are involuntary, and act more as a social glue to bond people together in conversation. It is worth noting that laughter rarely interrupts speech, and usually occurs during pauses in speech or where a breath would normally occur.

The only biological mechanism we can identify for the contagious laughter hypothesis is the one stated in the study by Scott, however I challenge you to think about it in your own life. It is pretty difficult to force yourself to laugh, but if you walk into a room where your friends are telling a funny story, try to catch yourself cracking a smile. Studies say that is your premotor cortex at work. The question remains, is laughter socially induced, or is it a biological event?

http://www.livescience.com/9430-study-laughter-contagious.html

http://www.psychologytoday.com/articles/200011/the-science-laughter

http://www.nbcnews.com/id/3077386/#.Up4Kr2RDubY