API is a set of routines, protocols, and tools for building software applications. They observed and analysed how the users appeared to respond to tweets that showed up in their stream.
Using an algorithm that ranked how positive or negative the content of a tweet was, researchers found that on average those who tweeted negatively had been exposed to about 4.34 per cent more negative tweets, 'Fusion' reported.
On the other hand, users who tweeted positively had seen about 4.5 per cent more positive content. According to Indiana Professor Emilio Ferrara, the correlation they discovered may be small, but it is significant.
Researchers monitored the brain activity of 114 people while they surfed the Web, finding that browsing a Twitter timeline generated 64 per cent more activity in the parts of the brain known to be active in emotion than other Web use.

They found about 20 per cent of Twitter users were particularly susceptible to the power of Twitter's emotional influence, with more than half of their tweets showing evidence of "contagion."
The study found that positive tweets were much more contagious than negative ones. "Whenever you share something online that content doesn't affect only you. In principle, it impacts everybody listening," said Ferrara.