Obama's campaign announced last week that anyone who sends a text message of "VP" to a dedicated phone number will be among the first to learn the identity of the Democrat's running mate.

Researcher Allison Dale of the University of Michigan told The New York Times the move was clever.

"They're enticing people with a little bit of information," Dale says, "and once they have those numbers, they can use them again for mobilization."

Dale, a graduate student, was co-author of a study of 4,000 people released last September on the effects of text messaging, the Times said. The study found that people who received a text message reminder to vote one day before an election were 4.2 percent more likely to get to the polls.