Is happiness contagious?

Smile, Kevin Bacon! The happiness of your social network depends upon it! See more emotion pictures.
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After actor Kevin Bacon commented in an interview that he had worked with everyone in Hollywood, or at least with someone who had worked with the people he hadn't, college students began playing the game "Six Degrees of Kevin Bacon." To win this game, you connect an actor back to Kevin Bacon using as few links as possible; links are found via the actor's and Kevin Bacon's mutual co-stars. Let's use Marilyn Monroe as an example: Marilyn Monroe was in 1961's "The Misfits" with Eli Wallach, who appeared in 2003's "Mystic River" with Kevin Bacon. Due to Mr. Bacon's extensive career, it's possible to do almost any actor within six links, though most examples require far fewer than that.

According to a study published in 2008, however, Kevin Bacon's real influence would be felt in his own neighborhood. If Kevin Bacon experienced a joyous event, such as winning an award for his acting, the happiness would radiate outward, infecting his co-workers, friends, neighbors and even the guy at his local coffee shop. What's more, the friends of those people would all become happier, as would the friends of those people. Just by the virtue of Kevin Bacon winning an award, people separated from him by three degrees have the potential to become happier as well.

That's because the 2008 study, conducted by Nicholas Christakis, a physician at Harvard Medical School, and James H. Fowler, an associate professor of political science at the University of California, San Diego, puts forth the idea that happiness is contagious in social networks. Christakis and Fowler are making quite a career out of finding phenomena infectious; they have previously posited that obesity and the likelihood of quitting smoking are also contagious.

How happy would you be if your paycheck had an extra $5,000 in it? According to Christakis and Fowler, that $5,000 wouldn't make you as happy as you'd be if your friend's friend's friend had a great day [source: Belluck]. Read on to find how to catch this joy.