Why is laughter contagious?

We posed this question to neuroscientist Dr Tristan Bekinschtein who works with the Medical Research Council Cognition Sciences Unit, Cambridge. Tristan - Laughter, you can think of it same as yawning. So, if you start to fake yawn, you would start to yawn for real, and you will be contagious either with a fake yawn or with a real yawn. Laughter probably works the same way. So, there are a couple of papers over the last 2 years, looking at fake laughter versus some sort of real laughter. I would say, mainly, it's about smiling and they do seem to recruit quite other similar network including the motor cortex and some other areas.

Hannah - So, the motor cortex is involved in controlling our muscles.

Tristan - Yes. So, the motor cortex, it's controlling the muscles of the face and the muscles of the larynx, and the muscles you would use for to laugh. But very strong laughter does involve whole body movements in general.

Hannah - Thank you, Dr. Tristan Bekinschtein from Cambridge. A study published in 1988 by Strack and colleagues indicates that simply gripping a pencil in your mouth to induce a fake smile can make you actually find things funnier. Participants with a pencil stuck between their mouth rated cartoon images as more entertaining that those with closed lips. You can try it on the move even if you don't have a pencil on you, simply by repeating "eeee".