Contagious LaughterHave you ever wondered why it is so hard to suppress a laugh even if we know it is inappropriate? Or why the brain responds even when we smile at ourselves in the mirror or simulate laughing with enthusiasm?

We don’t really know why genuine laughter is contagious, but there are 3 main hypotheses:

Hypothesis 1: We can’t help it

  • Even though we laugh from all over our brain, the areas that control laughing lie deep in the sub-cortex, and in terms of evolutionary development these parts of the brain are ancient, and are responsible for primal behaviors such as breathing and controlling basic reflexes. This means laughter control mechanisms are located a long way away from brain regions that developed later and control higher functions such as language or even memory. Perhaps this explains why it is so hard to suppress a laugh even if we know it is inappropriate, or why the brain responds even when we smile at ourselves in the mirror or simulate laughing with enthusiasm. Once a laugh is kindled deep within our brains these ‘higher function’ brain regions have trouble intervening.




Hypothesis 2: We are tuned for laughter

  • Humans may be “tuned” for laughter much in the same way that songbirds are “tuned” for song, especially their own specific family song. While birdsong of one species may sound the same to you and me, there are subtle differences between various individual on that species. Certain nerve cells in the songbird’s brain “fire” in response to hearing his song. Perhaps humans have specialized nerve cells that respond to laughter. After all, laughter is a specialized vocalization, and we are “tuned” to respond to vocalizations with language.





Hypothesis 3: It’s because of mirror neurons

  • Another possible reason why laughter is contagious is because of mirror neurons. This is addressed in an article in Explore magazine entitled Strange Contagions: of Laughter, Jumps, Jerks, and Mirror Neurons (2010). The author, Larry Dossey, describes several cases of “laughter epidemics” and uncontrollable laughter called “laughing jags” (p. 119). The phenomenon that laughter is contagious is attributed to mirror neurons that fire in both the individual laughing and anyone witnessing the laughter.
  • Mirror neurons were discovered while studying the brains of macaque monkeys in the early 1990s. It was observed that the neurons on the frontal cortex of the monkey activated when he reached for a peanut. It was also observed that the same neurons fired when he merely witnessed the researcher reaching for a peanut. After such a discovery, the research was extended to humans and similar results were found. Dossey states that researchers now assume that mirror neurons fire during empathetic reflection of facial expressions and emotions, mimicry and the acquisition of language. The author goes on to discuss the idea that laugher is contagious because of said empathetic reflection, a psychological premise that has been scientifically validated as a result of the discovery of mirror neurons. This may explain why and how people with a warm, genuine, voluminous laugh can get everybody around them to laugh just by laughing themselves with sincere enthusiasm.
  • Humor, in contrast with laughter, requires higher brain functions (right frontal cortex, medial ventral prefrontal cortex, the right and left posterior temporal regions and possibly the cerebellum). This is why a sense of humor is a psychological trait that can respond to different types of humorous stimuli and therefore varies considerably between ages, genders, cultures, etc.




How long can YOU resist?

Here are 2 videos to see how long you can resist laughter contagion. Ready, set, go!

There are of course LOTS more videos like these on YouTube.com here.




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