Twitter may become less interactive and more an advertising broadcast medium like TV or radio

In one of the first studies to use social media as a laboratory for social science experiments, Stephen and coauthor Olivier Toubia, the Glaubinger Professor of Business at Columbia University, questioned what motivates people to post tweets. Are Twitter users motivated by broadcasting their thoughts and opinions or, rather, by their desire to increase their social status by accumulating followers?

The results, published in the May/June issue of the peer-reviewed journal Marketing Science, provide insights into that question and have generated a surprising prediction of what the social network may operate like in the future.

To investigate the question, Stephen and Toubia identified approximately 2,500 Twitter users who were being followed by a range of other Twitter users, numbering from 13 to more than 10,000. All were noncorporate, noncelebrity users, and they were not tweeting for commercial purposes. Half the users were put into a control group, and the authors recorded daily data on the participants' number of followers and their tweeting activity over a period of two months.

Stephen and Toubia then hired undergraduate research assistants to create 100 Twitter accounts. Following Twitter's terms of service, the assistants added realistic-looking names and locations for these accounts, and they had the accounts follow one other as well as popular users like Lady Gaga and Justin Bieber. The assistants even sent out simple tweets -- "It's a pretty day today" or "The sky is blue" -- to further support the illusion that the accounts were operated by real people.

Over the ensuing two months, the assistants used the new accounts to follow the users in the test group, gradually increasing each user's list of followers by 100. The authors monitored these accounts to see how the increase in audience size affected the users' tweeting activity.

Users who had few followers initially showed no change in their tweeting habits. Similarly, "high-end" users -- those with as many as 10,000 followers -- did not exhibit much change, likely because 100 additional followers was "a drop in the bucket," Stephen said.

Among "mid-range" users, however, the authors noted significant changes in tweeting activity. "Users with 13 to 26 followers did increase activity," said Stephen, speculating that these users were encouraged by the increase in followers to post more to a suddenly larger audience.

But users with slightly more followers -- from 62 to 245 -- showed the opposite instinct, posting less as their followers increased. These users had already achieved some level of status, Stephen said, and wanted to preserve it by avoiding posting anything that would offend their followers. "As they get more followers," he said, "they want to be careful about what they post." These results indicated to the researchers that many users were more interested in gaining followers than in using Twitter to broadcast their views.

The trend of users posting less as they accumulated more followers led the authors to one of the more striking findings in the paper.

There is a natural tendency, Stephen explained, for active users to gain followers over time. Add to that the authors' finding that users will post less as they gain followers, and it's natural to conclude, Stephen said, that Twitter users are going to post less.

But commercial users, celebrities, and institutions like schools and sports teams, Stephen said, will continue to post information to the people who want it. "So what it becomes is another advertising channel, a broadcast medium, as opposed to a socially interactive one," Stephen said.

Such a change is prevented, for now, by the influx of new users to the social media service. If Twitter should reach a point when no new users are signing up, the shift away from an interactive platform toward a one-way conduit for information would become more likely.

In such a scenario, Twitter would remain a viable channel for corporations, celebrities, and other high-end users to communicate with their fans, Stephen said. They might utilize their Twitter feeds the same way they use mailing lists to announce products and promotions to their followers.

"Longer term," Stephen said, "to get value, they'll need the people who start following them to react to these tweets and to retweet them." But as his and Toubia's model suggests, over time, regular users will be less likely to do so. Marketers using Twitter will be challenged to offer rewards and other incentives to engage users and counteract the tendency to tweet less, keeping the social network truly interactive.