Brian Knight, an economist at Brown University and Yosh Halberstam, an economist at the University of Toronto analysed nearly 500,000 communications during the 2012 US elections in a social network of 2.2 million politically-engaged Twitter users.
They found that both conservatives and liberals were disproportionately exposed to like-minded information, and like-minded tweets reached them much more quickly than those from people who disagreed with them.
"In political science, we know that who you speak to is very important in your voting decisions and political identity, and I think increased use of these platforms is going to make network behaviour even more relevant in politics," said Pablo Barbera, a doctoral candidate in politics at New York University studying social media usage and political polarisation.
The study, published by the National Bureau of Economic Research, found that 90 per cent of the candidate tweets that liberal voters saw came from Democrats, while 90 per cent of the tweets conservative voters saw came from Republicans, 'The New York Times' reported.
If people saw tweets at random, they would have seen about half from Democrats and half from Republicans, the researchers found. However, in some cases, social networks could expand the viewpoints people see, Barbera found.
For example, if a liberal in San Francisco who does not talk much with his conservative aunt in Florida sees the articles and updates she posts online. Over time, people who are inadvertently exposed to more diverse points of view could become more politically moderate, he said.