Researchers have found evidence that political campaigns and special-interest groups are using scores of fake Twitter accounts to create the impression of broad grass-roots political expression. A team at Indiana University used data-mining and network-analysis techniques to detect the activity.

"We think this technique must be common," says Filippo Menczer, an associate professor at Indiana University and one of the principal investigators on the project. "Wherever there are lots of eyes looking at screens, spammers will be there; so why not with politics?"

The research effort is dubbed the Truthy project, a reference to comedian Stephen Colbert's coinage of the word "truthiness," or a belief held to be true regardless of facts or logic. The goal was to uncover organized propaganda or smear campaigns masquerading as a spontaneous outpouring of opinion on Twitter—a tactic known as fake grass roots, or "Astroturf."

The researchers relied largely on network-analysis techniques, in which connections between different members of a network are mapped out. Long used in mathematics and the sciences, network analysis is increasingly being used to study the Internet and social networks. The team received tips from Twitter users about suspicious messages and accounts, and then conducted network analysis to understand how these accounts were linked. They also tracked "memes"—keywords or Web links—that suddenly saw a big spike in usage. If the memes came from many otherwise unconnected accounts, they were likely to be legitimate. But if they came from relatively small, tightly connected networks of accounts, they were more likely to be Astroturf.

Menczer says the research group uncovered a number of accounts sending out duplicate messages and also retweeting messages from the same few accounts in a closely connected network. For instance, two since-closed accounts, called @PeaceKaren_25 and @HopeMarie_25, sent out 20,000 similar tweets, most of them linking to, or promoting, the House minority leader John Boehner's website, gopleader.gov.

In another case, 10 different accounts were used to send out thousands of posts, many of them duplicates slightly altered to avoid detection as spam. All of the tweets linked back to posts on a conservative website called Freedomist.com.