Laughing is contagious! That is why laugh tracks are used on many television shows – to get the viewer to laugh at the right moment. In 2006 a group of scientists exposed volunteers to different sounds to find out how their brain responded. Some sounds were positive such as laughter while others were negative such as screaming. Positive sounds had a higher response on the premotor cortex, an area of the brain that prepares face muscles to react to sounds. This could explain why laughter can be contagious. Laughing helps us interact socially and build strong bonds with each other.