Wow! This story gives me a tingling feeling all over!
I can tell you, anecdotally, that for our Twitter feed, @niemanlab, one of the best predictors of how much a tweet will get retweeted is the degree to which it expresses positive emotion. If we tweet with wonderment and excitement (“Wow, this new WordPress levitation plugin is amazing!”), it’ll get more clicks and more retweets than if we play it straight (“New WordPress plugin allows user levitation”).
For harder data, check out some work done by Anatoliy Gruzd and colleagues at Dalhousie University, presented at a conference last month. Their study looked at a sample of 46,000 tweets during the Vancouver Winter Olympics and judged them on whether they expressed a positive, negative, or neutral emotion. They found that positive tweets were retweeted an average of 6.6 times, versus 2.6 times for negative tweets and 2.2 times for neutral ones. That’s two and a half times as many acts of sharing for positive tweets. (Slide deck here.)