London: The old adage that birds of a same feather flock together seems to be true even when tweeting.
A team of researchers who have studied millions of tweets on the microblogging site Twitter found that happier people tend to tweet together and it's also true for those who are less happy, the NewScientist reported.
It has long been known that social networks tend to have an "assortative" character, which means people are more likely to have friends who are similar in age, nationality, race or education and less likely to be linked to people who are different.
Psychologist Johan Bollen and his colleagues at the University of Indiana tried to know whether this is true even in online networks, like Twitter, and whether it's true for levels of happiness.
For their research, Bollen and his team tracked about 102,000 Twitter users over a six-month period, analysing the 140-character-or-less text from 129 million of their tweets with standard techniques from psychology.
Specifically, they measured the emotional content of the tweets as reflected in the presence of positive or negative words from a lexicon previously established by psychologists.
From this they could assess the "subjective well-being" of the users through their tweets. It was found that happier people -- those recording a high subjective well being -- tended to be tweeting and receiving tweets from people who were also happier.
The same was also found true for those who were less happy, Bollen said. "It turns out that Twitter users are preferentially linked to those with whom they share a similar level of general happiness," he said.
Bollen, however, said that they don't yet know why this is true. Happy or unhappy people may simply seek one another out, drawn by tweets expressing emotions similar to their own, Bollen said.
Or it could be that the emotions expressed even in short tweets have an infectious quality, lifting peoples' spirits or filling them with gloom, depending on what they read, he added.