Social media sites such as Facebook and Twitter are a big draw for narcissists, but the ego-boosting tools are used in different self-aggrandizing ways by different generations, a University of Michigan study suggests.

The study details how young adults of college age and their adult counterparts use social media in differing ways to bolster their egos and control perceptions of others.

Vain college-age students favour the mouthpiece of Twitter to amplify their opinions and views in cyberspace.

"Young people overvaluate the importance of their own opinions," said study researcher Elliot Panek. "Through Twitter, they're trying to broaden their social circles and broadcast their views about a wide range of topics and issues."

Adults who exhibit narcissism tend to prefer Facebook, which serves as a mirror.

"It's about curating your own image, how you are seen, and also checking on how others respond to this image," said Panek. "Middle-aged adults usually have already formed their social selves and they use social media to gain approval from those who are already in their social circles."

Researchers at the university examined whether the narcissistic behaviour was related to the amount of time each subject spent posting, reading posts and commenting.

The study was broken down into two parts and the subjects were categorized into two groups.

The first section tested 486 college students with an average age of 19 who answered questions about the extent of their social media usage. The students also took part in a personality assessment measuring exhibitionism, superiority, authority, and self-sufficiency.

"Among young adult college students, we found that those who scored higher in certain types of narcissism posted more often on Twitter," said Panek.

The second part of the study focused on 93 adults with an average age of 35 who completed a similar online survey.

"Among middle-aged adults from the general population, narcissists posted more frequent status updates on Facebook," said the report.

The university's study is among the first to compare usage of Facebook and Twitter sites to different age groups.

"It's important to analyze how often social media users actually post updates on sites, along with how much time they spend reading the posts and comments of others," said Panek.