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. The “Truthy” project team at Indiana University used data-mining and network-analysis techniques to detect the activity.

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.