As a new communication tool - one that operates across the spectrum from mass media to personal sharing - Twitter provides researchers with lots of fascinating material to assess what's known in media scholarship as Laswell's maxim: "who says what to whom in what channel with what effect." New research from Yahoo has taken a closer look at precisely that, finding that a very small fraction of Twitter users - just 20,000 "elite users" - generate about half of all tweets consumed.

The researchers - Cornell University's Shaomei Wu and Yahoo Research's Winter Mason, Jake Hofman, and Duncan Watts - have classified these "elite users" by culling information from Twitter lists, identifying those users who show up most frequently there. In addition, the research has placed these elite users into four categories: celebrities, bloggers, media outlets, and organizations.

The research finds that even though media outlets are by far the most active users on Twitter, only about 15% of tweets consumed by "ordinary users" are received directly from the media. In other words, users are paying attention to other sources of information or are receiving those tweets not directly from the media but as retweets.

Who Listens to Whom?

Some of the research's most interesting findings don't come from its discovery that those "elite users" are generating such a significant portion of tweets, but that those four categories - media outlets, blogs, organizations, and celebrities - tend to be siloed, often just consuming and retweeting the tweets of those in the same category.

The research finds "striking homophily with respect to attention: celebrities overwhelmingly pay attention to other celebrities, media actors pay attention to other media actors, and so on. The one slight exception to this rule is that organizations pay more attention to bloggers than to themselves." Bloggers, unlike those in other categories, are more likely to retweet information outside their own categories, reflecting the "characterization of bloggers as recyclers and filters of information."

Who Listens to What?

The researchers also looked at the content that was being tweeted, finding world news, U.S. news and sports news to be the most popular. It also examined the different lifespans of content, finding that media-originated URLs tended to be short-lived, while content originated by bloggers tended to be "overrepresented among long-lived URLs."

The longest-lived URLs, no surprise, were dominated by content such as videos and music, items that are shared and reshared on Twitter and appear to "persist indefinitely." That means there's no end in sight to this.

You can download the full research paper here.