“Emoji reactions have been available for years on other services like Facebook, as well as on Twitter itself within direct messages. But what’s interesting about Twitter’s emoji choices for its latest test is that none of them are especially negative. There’s no “Angry face” like you’ll find on Facebook, or “Thumbs down” like in Twitter’s direct message emoji reactions.Twitter explains that it decided against choosing these negative emoji because people it surveyed said “they were concerned about receiving negative reactions to some of their thoughts.” A valid concern given how toxic many conversations on Twitter can be.”

Source : Twitter is testing emoji reactions for tweets – The Verge