The proportion of U.S. teen and young adult internet users who blog regularly has plummeted to about 14 per cent from 28 per cent in 2006, according to a survey by the Washington-based Pew Research Centre.

The study also found that just eight per cent of teens age 12 to 17 who use the internet report using Twitter, an indication that young people are not always the early adopters of new technology.

"The decline in blogging was really surprising for us until we stepped back and thought about some of the changes that were happening in social networking," said Amanda Lenhart, the author of the report and a senior research specialist at Pew.

The study found that in 2006, 28 per cent of internet users age 12 to 29 said they blogged regularly, but by autumn 2009, those numbers had dropped to 14 per cent of teens and 15 per cent of young adults.

During that same period, the percentage of internet users older than 30 who blog rose to 11 per cent from seven per cent.

The Pew study is the third to come out as part of the centre's Internet and American Life Project. A total of 800 teens and 2,253 adults were interviewed over the phone for the project.

Lenhart attributed the change in online behavior to several things but chiefly to the fact social networking sites are changing and that young people are migrating to Facebook from MySpace.

"While MySpace offers this very front-and-centre opportunity to blog — it's right there on the front of the profile — Facebook doesn't have that," said Lenhart. "Facebook prioritizes shorter updates, status updates, short posts."

Another reason for the decline of blogging is that younger people are being more cautious with their online personas, which might also explain why they don't tweet as often as older internet users, she said.

"Teens in the U.S. have been told that putting your personal information out there publicly is a very bad idea — that it's not safe, that people will come and harm you and your reputation," said Lenhart. "And I think because Twitter is so often used in a public way, teens, given all those cautions, don't see the utility of it."

Teens who do use Twitter tend to use it more as a way to get information about other people.

"They say they use it to follow celebrities or stay in touch with people they want to follow, but it's not so much a conversation for them," Lenhart said.

The survey has an overall accuracy of plus or minus 3.8 per cent 95 per cent of the time. For the adult findings, the accuracy is plus or minus two per cent, 95 per cent of the time.